Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: clockmanFR on November 05, 2011, 11:03:34 PM



Title: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on November 05, 2011, 11:03:34 PM
This relates to "REAL FACTS 48v BATTERY SYSTEMS".
 http://www.navitron.org.uk/forum/index.php/topic,14872.0.html  (http://www.navitron.org.uk/forum/index.php/topic,14872.0.html)

I now have my PCB strip board and about to start assembly.

My very sincere thanks to Ericw for his wisdom and understanding, and more importantly his knowledge in the programming of the main Arduino Mega board.

The circuit will:-
        Read the 4 battery voltages for one of the 8 banks/strings.
        Display bank number & voltages.
        Then each bank.
        Display would be static for 10 secs.
This means that every batterry is read once per minute, could read faster but this allows the reed relays to operate only 500k times per year. (relay contacts have a maximum operating life).
Every 5th time around write all voltages to file on the removable SD card. This is every 5 minutes and 288 lines per day.
      File format will be CSV so the card can be read by a PC and displayed/plot in Excel.
      Choices for arranging files, 1 per day, per week, keep data for a year etc. Use 2Gb SD cards.
      If one battery is detected at low voltage, say 12.20v – then display info on 4th line – put marker in log file.
If low for 3 minutes the circuit will operate a separate relay that shuts the inverter down properly, it closes the circuit on the Inverter off button. This way the inverter fans etc shut down properly rather that just a dirty great Relay that disconnects the battery voltage to the Inverter.
       This inverter switch operation also log time and voltage to another file.
     A start up switch that has the batteries read faster than normal just before the Inverter is switched on.
      Remove SD card and read data on a PC anytime, possible swap over SD card so not to miss any readings.

This is designed for my particular 48v 4 12v batteries in strings at present up to 8 strings so we can watch 32 individual battery's, keep an eye on each and monitor there performance weakness and charging capabilities. My particular batteries are gel type so SG/ specific Gravity readings of the battery electrolyte/acid is not possible. So using this circuit we can deeply analyze changes and rectify the offending battery before it is badly damaged, IE, I put a 80watt PV panel float charge on it.

Pic 1, Is Ericw’s minimalist schematic drawing, After the first bank of 5 wires all the other banks only have 3 wires. Each of the 32 relays has a double contact so the Arduino will ask each relay in turn to switch on at the correct time for reading each battery voltage so a relay can read battery 2 positive on one switch then become a negative read on battery 3 and so on.
To protect this arrangement and the Arduino board we have transistor arrays with there own power supply.

Pic 2. My PCB layout drawing using standard strip board.
Pic 3. Just about all the necessary parts for assembly.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Justme on November 05, 2011, 11:41:35 PM
With the large delay in reading each voltage it could look like one battery is failing as it has a lower voltage but in reality there was a short on period high load at that time but not when the other voltages were taken.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on November 06, 2011, 11:48:34 AM
That's true, Justme,

But in reality the 3.7kw inverter is never fully loaded and in practice the voltage fall, as the batteries are loaded, is relatively slow, especially with the 700ah bank. And at normal working voltage of, start 53.10v down to 48.80v LVD, the time period between readings looks okay at present, but then we could allways alter this in the future. 


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on November 16, 2011, 10:20:57 AM
Progress so far.

Reasons for the Multi LVD.

If you recall one of my main concerns was that the UPS Inverter would let the 48v battery string get down to 40v before its LVD, (low voltage disconnect) operated and shut down the inverter. But at 40v it means that the individual battery is now down to 10v, and therefore, according to the wisdom'ites on this forum, the battery will start to receive irreparable damage. This damage is also confirmed as I lost a weak second hand battery very quickly due to the battery getting to low.

So let’s get a LVD switch to shut down at 49.2v, that’s 12.3v for each battery. Again the wisdom’ites on this forum have set 12.20v to 12.30v as a reasonable low voltage that will not cause problems to the battery.

But then I find that each individual battery has a habit of going lower than the average at 49.2v, ie, 12.4v, 12.5v, 12.3v and 12.0v,  and I noticed this discrepancy got expenditially worse as the voltage dropped. But to complicated matters further it was not always the same battery in that string that went low.

For several years now I use the old voltage meter to check how the batteries are behaving, and if I feel one needs rejuvenating, I clip a trickle charge of 100w PV power for a few days to assist that particular battery. I have 2 x 100w panels that are for spring/rainwater pumping but I can switch the power to where it is needed.

The New Circuit Concept.

I do not have vast wads of cash just to buy something similar of the shelf, so I am trying to keep the cost of this project down to about £100.

A knight in shining armour arrived, EricW, and suggested a new approach to this LVD problem.
Lets “get a Arduino Mega Board, like, http://www.ebay.co.uk/itm/Mega-1280-ATMEGA1280-54-I-O-Pin-USB-Cable-Arduino-Compatible-00916-/270826714991?pt=LH_DefaultDomain_3&hash=item3f0e87b76f
  Which is a mini computer that can be programmed to do tasks”. For us it is going to pulse a relay that closes its contacts, and sends the resultant voltage to be read, it does this quite quickly on every relay 32 off on my PCB board, (I only have 24 batteries, 6 strings of batteries at present but will add more soon), and these voltages are stored by the mini computer on to a removable 2Gb SD data card, like this ,, http://www.nuelectronics.com/estore/index.php?main_page=product_info&cPath=7&products_id=20&zenid=2bad6d8f5e9276b82f0cd6cb297c4a2b
  And this unit plugs directly on top of the mini computer Arduino Mega Board.
We are also adding a LCD display that will show what’s going on in real time, like this,,,http://www.ebay.co.uk/itm/20x4-LCD-display-module-HD44780-Green-LED-Backlight-UK-/250772597780?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3a63362c14 (http://www.ebay.co.uk/itm/20x4-LCD-display-module-HD44780-Green-LED-Backlight-UK-/250772597780?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3a63362c14)
   And which particular battery shut down the LVD, and show the voltages of the rest. It was also shows readings at start up of the Inverter, and also show readings just after LVD as the batteries recover.

Now the 2Gb SD data card can be put into your PC in the comfort of your home and all the readings can be looked at, and then you can see which particular battery needs some loving attention, as well as all the other possibilities, of caring for the power supply, but the most important is that you can use the batteries to there FULL POTENTIAL, knowing that the mini computer will monitor and take action, LVD.

The Circuit.
We have used ULN2003 16 pin transistor arrays to trigger the relays, small reed types, I can not specify these at present until Maplin Electronics get some more in, if they do, then I can use the pin layout on a proper fabricated PCB. (Anyone interested).

I have used strip board for the trial, and this can be easily modified where appropriate.
Once you have the main + and – 48v small cables coming in then each bank only requires 3 cables, so on my 6 bank that’s just 1off  5 core ribbon cable for the first String/Bank and then 5off 3 core ribbon cable for the other 5 Strings of batteries. I have spade males fastened at each battery link, and I will keep these cables all at the same length.

Pic 1, The latest modified PCB strip board actual layout. I also have a mirror copy of this so when I turn the PCB over I can see on the mirror drawing the track side.
Pic 2, The PCB.
Pic 3, The track side.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Justme on November 16, 2011, 11:56:59 AM
LVD's are a problem. If set to save the battery from damage then when under full load they will cut off to soon, if set for full load voltage then at low loads they will allow damage. What is really needed is a method that measures the load & alters the LVD to match.



Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on November 16, 2011, 07:07:06 PM
Justme, I noticed that when my inverter is loaded at 3.5kw, then watch those batteries voltage go down. But at say 2kw they steady out at 51.0v and have a slow voltage drop/decline that is reasonably proportional, and predictable, but which individual battery triggers the LVD at say 12.20v or 48.8v.?

As i have allready mentioned the data storage will log all the voltages on a time log as well, so we included a switch that is pressed when the Inverter is switched on for logging the voltage. So if i give some known datum loadings, then by using this system it will give you a graph etc, that tells you proportionality of voltage drop at what loadings, and therefore give you a management system that will optimise your batteries use for different loadings.
 This particular information is important, as it then can be offset against what power is also coming in, in this instance my wind turbines, and therefore with extrapolation you can get an accurate calculation for what goes into the batteries by what is being taken out.

Well, that's the Plan?

However, i see your point, and one could modify the program that for particular timed voltage drop then a different LVD voltage could be activated. In theory i suppose, but i am not the programmer, and we have to get this lot working first!.
 

 


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: ericw on November 16, 2011, 07:49:09 PM
In principle the load current could be monitored by a Hall effect based current transformer and the cutoff voltage adjusted.
As the whole circuit is tied to the battery being measured it has to be done in an isolated manner.
There are still a few unused I/O pins on the Mega board.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on November 19, 2011, 07:55:00 PM
I do wonder sometimes if any one out there is interested in this?

Would any one be interested in a simplified kit form, and ready to go software. ? That's when we get it going and tested okay. 


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on December 31, 2011, 10:39:21 AM
Progress so far.

Reasons for the Multi LVD.

If you recall one of my main concerns was that the UPS Inverter would let the 48v battery string get down to 40v before its LVD, (low voltage disconnect) operated and shut down the inverter. But at 40v it means that the individual battery is now down to 10v, and therefore, according to the wisdom'ites on this forum, the battery will start to receive irreparable damage. This damage is also confirmed as I lost a weak second hand battery very quickly due to the battery getting to low.

So let’s get a LVD switch to shut down at 49.2v, that’s 12.3v for each battery. Again the wisdom’ites on this forum have set 12.20v to 12.30v as a reasonable low voltage that will not cause problems to the battery.

But then I find that each individual battery has a habit of going lower than the average at 49.2v, ie, 12.4v, 12.5v, 12.3v and 12.0v,  and I noticed this discrepancy got expenditially worse as the voltage dropped. But to complicated matters further it was not always the same battery in that string that went low.

For several years now I use the old voltage meter to check how the batteries are behaving, and if I feel one needs rejuvenating, I clip a trickle charge of 100w PV power for a few days to assist that particular battery. I have 2 x 100w panels that are for spring/rainwater pumping but I can switch the power to where it is needed.


I'm quite taken aback by the statement "the battery will start to receive irreparable damage... if it goes down to 10Vdc".
It's simply not the case.
As some of you know I have run my own UPS business for the last 10 years.
And over that time I have tested 1000's of batteries.  Both in UPSs and tested batts individually.
Running a battery that is in good condition, down to 10Vdc does no irreparable damage.
If that was the case then every UPS would only be able to handle 1 power cut before the batts needed replacing.
Also battery manufacturers quote the capacity of a battery down to around 10Vdc.  They wouldn't quote a voltage to run down to, if it was going to damage the battery.

When a batt is run down under load, the batt will suffer some 'wear & tear'.
I.E. the are only so many times a battery can be cycled (discharged & charged).
The depth of the discharge effects the number of cycles.  Maybe this is what was meant by the 'wisdom-ites'?
From a Yuasa NP24-12 datasheet ....
LIFE EXPECTANCY:
STANDBY USE 3 to 5 years
CYCLE USE (approx.)
100% depth of discharge 250 cycles
50% depth of discharge 550 cycles
30% depth of discharge 1200 cycles

It is true the battery will have a shorter life if 100% discharged compared to say a 30% discharge.
But then you need a much bigger battery bank if only going to 30% discharge.
And don't forget batts suffer wear & tear all the time they are being trickle charged.
If you want to increase the life time of your batts then stop charging when they are fully charged.

12.3Vdc as a low voltage cut off point is very high indeed.
I often test batts from UPSs individually.
E.G. a 12v 7Ah batt with a 100 watt load.
Once it is under load, the starting voltage is about 12.3Vdc so would have no run time if I used a cut off of 12.3Vdc.
I personally run down to 10.5Vdc.

I guess my post will generate some questions.  Please ask on here and I will try and answer.

Regards
Andy the UPS, Inverter & Battery Man
PS: I have loads of UPSs & Inverters for sale.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Justme on December 31, 2011, 03:01:30 PM
There is a huge difference between UPS & off grid battery use.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on December 31, 2011, 03:42:28 PM
There is a huge difference between UPS & off grid battery use.

Err, there isn't that much difference (relating to the batts) assuming you're using SLA AGM batts.
What "huge differences" do you think there are?

Off grid batt use is more cyclic, but I've already covered the depth of cyclic discharge.
Regards
Andy the UPS, Inverter & Battery Man


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 01, 2012, 02:31:27 PM
Hi Andy,
Its true i am afraid, there is a difference between Inverter UPS battery systems than Off Grid battery banks.

As i originally said somewhere in my posts, when i allowed the UPS LVD to function and auto shutdown at about 42v for a couple of months, i very quickly lost 2 of my 12v 110ah battery's, with 2 others damaged, (would not hold voltage). To me caring for the expensive batteries is a must as i need them to last as long as possible and at the same time give their best.

Listening to the wise old sages on this forum who are actually using batteries Off Grid day in day out, made me understand real operating usages with batteries. And it was seemed that 12.2v to 12.3v LVD was a good way to care for operational batteries without causing them excessive deterioration.

Again, i will report back on how this 12.2v LVD works with my particular system, but with my observations to date, the last 18 months my 20 12v 110ah batteries have behaved. But the new circuit should give me more accurate data.

Also recharge times are not consistant like a UPS when it reverts back to mains supply, some times my batts get a quick charge if its sunny and its blowing a good wind, sometimes becalmed it can take days just trickle charging from overcast solar PV.  Again, the new circuit data will give me info on the most efficient charging rates. 

Sustainability matters to me so the care and quality of my equipment and its longevity is very very important.

 Unfortunately as i get older and wiser, i realise that a lot of data sheets issued by manufacturers is not allways telling realistic tales.. ::)
 


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 01, 2012, 02:41:52 PM
Now that Crimbo is over and the new building is usable, (orders by her indoors to get it finished by 21.00hrs New years eve),  i can at last get back to this circuit and start messing with the programming bit.     :cross


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: biff on January 01, 2012, 03:22:56 PM
lo clockman,
           i hope you have had a good christmas, your new circuit is truly impressive and a credit to your know-how. as you know we all have our little problems and work to improve our lot.its funny,but i worried for ages that our turbine would overspeed because out controller was in danger of frying and losing the grip on things but there i was with a few boxs of the said controller and all i had to do was just connect another controller to the bank bring my resistors up to 4kw which would have been more than enough to weather any force 8 unattended,
     we live and we learn,our weather has been truly horrible,wet ,slushy,windy and dark so nothing has been done to our turbine,instead we came through christmas using our generator for so many hours each day and the new pv works very well but of course needs a bit of sun.
                                                                                                                                         biff


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 02, 2012, 06:43:01 PM
what oh biff,

Good news that you had a good Christmas, sad to here you have no Sun, been lovely today but squally showers, i get 5 minutes warning as i can see the rain coming.

Its true, your spot on as usual, things that you worry about can be rectified with a little thought. but i was so sorry to here how your babe 'bit the dust'. My No1 is squeaking each time it turns into the wind, (needs Grease) No2 needs balancing, No 3 is down and is under reconstruction (properly).

Regards PV and trackers, how's your swing system coming on?
Mine, the Mrs spent 2k on bits for the gite to get it operational for New Years eve night, 4 staying, but it bust me getting it operational, the skirting boards and mouldings still had wet Caulking on the primered timber surfaces, as the folk settled in.
Today, just fitting the stairs bottom door and mouldings and caulked up.
 
Mrs has let me off for the rest of this week as i have the new faster and lighter Pedal car to build, success on that front as i have got another Engineer, Pascal he's French, to start manufacturing bits and has joined the team. We are putting 2 cars on the Normandy circuit, 6 races this season, but hopefully others will take over the load? (they all want to get on the French TV)  ::)

My PV Trackers are going ahead but i might have to scrape around the barrel ab-it to find 3k as the Mrs spent 2k.  :( spentrpe   

Happy New Year biff, and to Mrs biff,  and the hounds etc.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on January 02, 2012, 07:24:54 PM
Hi Andy,
Its true i am afraid, there is a difference between Inverter UPS battery systems than Off Grid battery banks.

As i originally said somewhere in my posts, when i allowed the UPS LVD to function and auto shutdown at about 42v for a couple of months, i very quickly lost 2 of my 12v 110ah battery's, with 2 others damaged, (would not hold voltage). To me caring for the expensive batteries is a must as i need them to last as long as possible and at the same time give their best.

Listening to the wise old sages on this forum who are actually using batteries Off Grid day in day out, made me understand real operating usages with batteries. And it was seemed that 12.2v to 12.3v LVD was a good way to care for operational batteries without causing them excessive deterioration.

Again, i will report back on how this 12.2v LVD works with my particular system, but with my observations to date, the last 18 months my 20 12v 110ah batteries have behaved. But the new circuit should give me more accurate data.

Also recharge times are not consistant like a UPS when it reverts back to mains supply, some times my batts get a quick charge if its sunny and its blowing a good wind, sometimes becalmed it can take days just trickle charging from overcast solar PV.  Again, the new circuit data will give me info on the most efficient charging rates.

Sustainability matters to me so the care and quality of my equipment and its longevity is very very important.

Unfortunately as i get older and wiser, i realise that a lot of data sheets issued by manufacturers is not allways telling realistic tales.. ::)

Hi Leslie,
I'm afraid I have been very much misunderstood in my previous post.
I think part of the reason is the incorrect use of terminology.
And perhaps you missed my caveat about batts in good condition?  (by good condition I mean the batt is new or virtually new, the quality of the manufacture of the batt, etc)

I'm an electronics engineer.  Bachelor of engineering B.Eng. 2:1
In electronics when we say 'irreparable damage' we mean something has had a 'sudden and total failure'.  E.G. a transistor blowing up.
What you described with 2 of your batts failing within a couple of months is what I would call wear & tear.
The rate of wear & tear can vary considerably.
A brand new quality battery should be able to withstand 100% discharge (e.g. down to 10.5Vdc) a couple of hundred times.
But a used battery can be very different.  I've had used batts that deteriorated quite a lot from a few 100% discharges/charges (cycles).  But equally I've had used batts that have been fine with 100% cycles.
And there are other factors to take in to account.
E.G. the size of the load.  I suspect the manufacturer's use a small load when testing the number of 100% cycles. Probably the 20 hour rate.
Also the charge rate, the ambient temperature, etc are all factors when cycling the batts.

In my previous post I quoted number of cycles vs depth of discharge.
Effectively I was saying for cyclic use, a lesser depth of discharge gives disproportionately more cycles.
From the example in my previous post.... 100% depth of discharge 250 cycles and 30% depth of discharge 1200 cycles.
If it was proportionate then at 30% depth discharge, you should get 100/30 x 250=833 cycles.  But you actually get 1200 cycles.
But it is disproportionate, so I was agreeing with you that it is better to do lesser depth of discharge in cyclic applications.  Hence my saying I've been misunderstood.  :)

Also your sample size is very small.
You can have poor batches of batteries.  Even brand new ones direct from the manufacturers.
I bought a batch of brand new batts of a well known make and they were terrible.  Less than half their supposed run time.  I had bought this make before many times and they were fine.  Just got a bad batch on that occasion.

To Summarise....
As we've said a lesser discharge is better.  But a cut off of 12.2Vdc is very high.  You must have a very small load relative to your battery bank?
Stop charging the batts when fully charged.  Constant trickle charging will cause wear & tear to the batts.
Keep an eye on ambient temperature.  You should lower your charge voltage as temp goes up.
Measure the voltage drop across your battery cables at full load.  I.E. measure it to make sure your cables are thick enough.
The best batts to use (IMHO) are the ones that have terminals accessible for each cell.  E.G. Yuasa do a 6V one with 6 terminals.  Over time it is nearly always the middle cell that fails.  But it can be bypassed as all terminals are accessible.
Most 12v battery failures are a single cell failure.  The other 5 cells are normally fine but can't be accessed.

Regards
Andy the UPS, Inverter & Battery Man


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: pb on January 03, 2012, 02:43:18 PM
Did you consider using something like a chain of LTC6803s instead of your big stack of reed relays?  That would avoid the need to bring the actual battery voltages onto the CPU and, in turn, would make it rather easier to measure the load current since you could now just use a shunt in the battery negative lead rather than a Hall sensor or CT.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: ericw on January 03, 2012, 05:41:03 PM
Certainly an interesting chip which I wasn't aware existed and it would have made the design much easier.
Looking at the 48v battery application note it does seem to need quite a lot of (cheap) components but with 8 banks of batteries the cost would be starting to rise.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 03, 2012, 06:49:32 PM
Looks like each LTC6803s is about £15 each. Measures up to 12 individual cells at max 5v each.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 04, 2012, 09:42:45 PM
Well i managed to get through the Arduino tutorial and do some basic programming and get it to talk.

Now that Christmas is moved on, i can now get this circuit working?

Tested the circuit board and all the bits and all seem to function now, but had to add a jumper wire on the 0v feed as i had missed it, and only found one dry solder joint, (actually i had missed the joint when soldering up).

So now await bench testing and installing the software and formating the SD card.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 04, 2012, 10:21:15 PM
Hi andy, cheers for the enlightenment.

Yes i would like brand new 2v individual batteries, plus forklift to move them, but sadly my pockets are not very deep at present, perhaps one day?.

On my 2 gel batts (actually felt pads between the plates) that failed, when i took the top off, it was the first cell and the last cell that had failed and both had buckled plates that had shorted out on the opposing top plate grid connection, as a i said in a previous post there seems to be only about 5 to 8mm clearance during normal working conditions.

Regards cyclic conditions even at 1200 cycles that's only 3 and a bit years and accordingly the batteries are stuffed, so hence me setting a high LVD voltage at this time, however it is very possible to re set the LVD lower depending on the load.

In general my observations,  800amph batts, with turbines and PV off after a full charage the batteries settle at 52.6v after 5 days.
Switch the 3.7kw inverter on and a 1.3kw load, with battery's at float mode 54v, voltage drops in 5 minutes to 52v approx and gently falls to 51v over the next hour. The voltage then holds at 51v for many hours and then starts to drop, at 48.2v i shut the inverter down. However during this time the turbines and PV are still kicking power in, so the rate of power draw from the 1.3kw load is at present unknown. Hence the circuit and the data storage system.

Once the charge rate has dropped to float mode i normally switch on the inverter and use the power. So its unlikely the batteries will get overcharged, and i am more concerned that they are not getting enough charge!  :o

Regards cables i use 16mm/2 as standard but would like to use 25mm/2 but then it becomes a fight with a snake with rigermortice, (they tell me).


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on January 06, 2012, 04:56:10 PM
Hi andy, cheers for the enlightenment.

Yes i would like brand new 2v individual batteries, plus forklift to move them, but sadly my pockets are not very deep at present, perhaps one day?.

On my 2 gel batts (actually felt pads between the plates) that failed, when i took the top off, it was the first cell and the last cell that had failed and both had buckled plates that had shorted out on the opposing top plate grid connection, as a i said in a previous post there seems to be only about 5 to 8mm clearance during normal working conditions.

Regards cyclic conditions even at 1200 cycles that's only 3 and a bit years and accordingly the batteries are stuffed, so hence me setting a high LVD voltage at this time, however it is very possible to re set the LVD lower depending on the load.

In general my observations,  800amph batts, with turbines and PV off after a full charage the batteries settle at 52.6v after 5 days.
Switch the 3.7kw inverter on and a 1.3kw load, with battery's at float mode 54v, voltage drops in 5 minutes to 52v approx and gently falls to 51v over the next hour. The voltage then holds at 51v for many hours and then starts to drop, at 48.2v i shut the inverter down. However during this time the turbines and PV are still kicking power in, so the rate of power draw from the 1.3kw load is at present unknown. Hence the circuit and the data storage system.

Once the charge rate has dropped to float mode i normally switch on the inverter and use the power. So its unlikely the batteries will get overcharged, and i am more concerned that they are not getting enough charge!  :o

Regards cables i use 16mm/2 as standard but would like to use 25mm/2 but then it becomes a fight with a snake with rigermortice, (they tell me).

Hi Leslie,
A few months ago I was offered a load of 2 to 3 year old 6V 160Ah Yuasa Endurance batts.  I didn't take them due to the weight and price being asked.  And they are difficult to sell on ebay.
But if I know you and others on here would want them then maybe next time I could get them.  Are you interested?

A fully charged SLA AGM battery should settle at 13 to 13.1Vdc.  So 4 in series would be 52.4Vdc  So looks like you've got some good batts there.
So basically a very large battery bank and a very low load.  ;)

Better if you could stop charging the batts when fully charged.  Some UPSs do that, some don't.

AWG wire gauge here....
http://en.wikipedia.org/wiki/American_wire_gauge
16mm2 is about 5AWG which has a resistance of 1mOhm per metre. 
So your UPS (I mean inverter) at full load would draw 3700 watts from a 48Vdc battery bank.  Which is 77amps.  Round up to 80 amps to allow for inefficiencies.
So at full load you would drop 80mVolts per metre of cable.  May not sound a lot but over a few meters of positive cable and likewise negative cable it can start to add up.
So you had 3 metres of positive cable including what is inside the UPS and the same on the negative side.  So 6 metres in all.  Then almost half a volt dropped at 80 amps.  Or to put it another way 40 watts worth!
But then you probably never run at full load.  :)

I used 2x 8AWG which comes to the same resistance.
Expensive heavy duty cable, isn't it?

I was thinking of doing a deal on 3kva inverters/UPSs.  Buy 2 get 3rd one free.  Would anyone be interested?
£230 each with cables and conversion done ready to use.

Regards
Andy the UPS, Inverter & Battery Man


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: biff on January 06, 2012, 06:30:58 PM
hi andy,
        i would certainly be intrested in the yousa 6volt 150ahs but would need a pallet of 20 at least, i would normally get about 36 x 100ah yousa on a pallet(40kgs each) but these might be a lot heavier,
                                                        biff


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 06, 2012, 06:33:09 PM
Hi Andy, thanks for your information. Especially that i have 40 watts in losses, but then its rare that i run at full load, however the last 2 days the inverter was running at 3kw because the turbines were kicking out serious amounts of power.

Regards Batteries, i had been getting, (chap retired) my Gel jobs 4 off 110ah (a string) for £160 - £180 range. My New deep cycle industrial jobs for a string best price has been £360.

So would defiantly take 8 off your 6v 160ah batteries, if the price was right, no rush, have friends that will store and i can allways pick them up or send the Mrs, me or her travel up the Uk from Dover to Newark, Notts about once a month. Ebadger, (he's off Grid) is just down the road so together we may be able to arrange something. 

I get my 16mm/2 and other armoured cables from e.bay some one somewhere allways has offcuts and the price is about scrap value, one just has to wait. And considering i have 2 PV trackers to install and another wind turbine to put up, good cable is allways handy.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on January 07, 2012, 01:03:32 PM
Hi Andy, thanks for your information. Especially that i have 40 watts in losses, but then its rare that i run at full load, however the last 2 days the inverter was running at 3kw because the turbines were kicking out serious amounts of power.

Regards Batteries, i had been getting, (chap retired) my Gel jobs 4 off 110ah (a string) for £160 - £180 range. My New deep cycle industrial jobs for a string best price has been £360.

So would defiantly take 8 off your 6v 160ah batteries, if the price was right, no rush, have friends that will store and i can allways pick them up or send the Mrs, me or her travel up the Uk from Dover to Newark, Notts about once a month. Ebadger, (he's off Grid) is just down the road so together we may be able to arrange something.

I get my 16mm/2 and other armoured cables from e.bay some one somewhere allways has offcuts and the price is about scrap value, one just has to wait. And considering i have 2 PV trackers to install and another wind turbine to put up, good cable is allways handy.

My figures were example figures.
At full load-ish, measure the voltage drop across either the positive lead or neg lead.  Need a good multi-meter like a Fluke.  See what it measures.
Plus if you have a fuse in series with the batts, measure across that too.  You might be surprised how much you drop across the fuse!

What make / model are your new deep cycle batts?
£90 per New batt sounds too cheap.  What's the date code?
You can call any lead acid battery deep cycle.  Inc leisure batts!  :(
And I doubt they are really industrial grade.
In electronics you have 3 grades - commercial, industrial and military.
For example, take PSUs.  The PSU in a PC is commercial and would cost about £20.  An industrial PSU would be more like £200.  I don't what a military spec PSU would be, but probably 10 times as much again.

Google, shopping Yuasa EN160-6 batts comes up with £220 to £340 depending on which model of EN160-6.
But I have missed the boat on the last lot.  But if I get offered them again and they are not too old I can offer them on here.
For Yuasa EN160-6 that are no more than 2 to 3 years use, I would be looking for about £50 each.
I would have to pay a lot for them as scrap lead prices are sky high.  Plus I've got to drive a long way to get them.

Regards
Andy


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 07, 2012, 06:06:07 PM
Andy, count me in, 8 definitely for £50 each.

No fuses, (can't risk the turbines not being connected), except the isolator and DC MCB 100amp for the inverter and the DC MCBs in each Turbine controll box.

Regards my 12v new jobs, no idea nothing written on them, but weight wise each is about 30Kg. My gels ones are 32kg. I go on weight.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on January 07, 2012, 09:34:19 PM
Andy, count me in, 8 definitely for £50 each.

No fuses, (can't risk the turbines not being connected), except the isolator and DC MCB 100amp for the inverter and the DC MCBs in each Turbine controll box.

Regards my 12v new jobs, no idea nothing written on them, but weight wise each is about 30Kg. My gels ones are 32kg. I go on weight.

It does of course depend whether I get offered any more.  And what age they are.

Do you not have a fuse between a couple of the batts?
What happens if your batt string gets shorted out?    thousands of amps!  cable melting!  fire!  batts knackered!  :)

Looking at Yuasa AGM data sheets....
EN160-6   6v 160Ah weighs 35Kgs.  Think of it as a 12v 80Ah.
And NPL100-12   12v 100Ah weighs 39Kgs

Stick your batts on your bathroom scales.  See what they weigh. 

PS: No one interested in my buy 2 get 3rd one free offer on inverters(UPSs)?

Regards
Andy the UPS, Inverter & Battery Man


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Justme on January 07, 2012, 10:18:47 PM

Stick your batts on your bathroom scales.  See what they weigh. 



If I do that I might bust the scales. The book weight on the single battery I am using is 1200kg & the back up (the one I was using but keep on stand by fully charged till I get more charging power & join them together) comes in at 570kg.


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on January 08, 2012, 10:09:24 AM
If I do that I might bust the scales. The book weight on the single battery I am using is 1200kg & the back up (the one I was using but keep on stand by fully charged till I get more charging power & join them together) comes in at 570kg.

Have you got a link to your battery?
Is it actually a number of 2Vdc cells linked together?

Andy


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: jonesy on January 08, 2012, 12:40:35 PM
With LVD give yourself an over-ride option. My 12 year old 24V/400Ah Yuasu NPL AGM pack was down to 24.8V after 10 days/200Ah use in cloudy/rain.  I looked at the sheets which showed I could go down to 21V.  It's not ideal, but it's better than a slap from the missus when she misses  a TV program :-)  Whether it would cause permanent damage, the manufacturer thinks not.  I tend to agree.  When I got these batteries at 9 YO, they were at about 6V instead of say 11-12, after a year+ of storage (and a standby life since new) If you aggressively cut the inverter off at say 50V, it could also be dangerous (keep a torch with you at all times?)

To monitor each battery, you could use a simple potential divider array into the ADC?  If you havent got enough inputs, use a couple CMOS  switches like the  the 4066. For the current, measure across the fuse using the ADC and 0.1% resistors to drop the voltage down and subtract in software.  If you've got 12 bits and a 2.5V reference that'll give 0.6uV resolution (and not too much switching noise)   I use a hall effect device robbed from an old inverter.  Does the inverter have a serial interface you could get the info from?


Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: clockmanFR on January 09, 2012, 07:12:28 PM
andy, regards your comments,
What happens if your batt string gets shorted out?    thousands of amps!  cable melting!  fire!  batts knackered

Here is a pic of Hugh Piggotts "A Wind Turbine Recipe Book", the page of the power management system he recommends.
Its the same as mine, if its good enough for Hugh its brilliant for me.



Title: Re: Multi Battery Monitor, LVD, Display & Data Storage.
Post by: Andy the Inverter Man on January 14, 2012, 10:55:22 AM
andy, regards your comments,
What happens if your batt string gets shorted out?    thousands of amps!  cable melting!  fire!  batts knackered

Here is a pic of Hugh Piggotts "A Wind Turbine Recipe Book", the page of the power management system he recommends.
Its the same as mine, if its good enough for Hugh its brilliant for me.

Just having a quick look at the above jpg of the batteries, etc.
I would definitely put a fuse between each pair of batts for the following 2 reasons.
1) Imagine you have 2 batts in series and the batts are side by side, so the +ve and -ve terminals are just a few inches apart.  Now what happens if something like a spanner is dropped across them.  None of the fuses in the original diagram are going to blow.  The cable will get hot and might melt depending on Ah of batts and AWG of cable.  May well damage your batts.
2) If the +ve and -ve cables some how get shorted together.  Perhaps the cables get trapped and the insulation cut.  Again no fuse protecting the batts in the original diagram.

Also I've never seen a fuse used in conjunction with a digital volt meter!
And the ammeter should have an internal fuse making the external one redundant.
I'd keep the inverter and load controller fuses.  Though they both should have internal fuses, so unlikely to need external fuses.

Regards
Andy the UPS, Inverter & Battery Man