Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: eabadger on May 08, 2017, 09:00:12 AM



Title: second battery bank and stuff
Post by: eabadger on May 08, 2017, 09:00:12 AM
have read other posts about combining banks and am in the same position, i have a large 1000ah fla 24v forklift pack and a smaller one at 650ah both c5 rate, the second pack was kindoff a freebie as lots seem to be.
so what i have amassed is two victron 3000va multiplus's 1x lf 3000kw W7 inverter, 3x morningstar mppt 60 one tristar 45, soon 3 1600w ish arrays.
so in summer i think the tilting two arrays will keep main battery bank full so third through a diode spliter can charge smaller battery pack? this can be disabled in winter maybe.
i have two large swa feeding the house, currently one is generator connected only and feeds immersion in dhw tank very soon to be a ashp water heater and soon to be connected to the second new multi.
so thinking about, what if i use the ac2 on main victron to bring on the W7 inverter (ac2 only live when generator fed) then feed output of the W7 in to mains input on multi 2? which will paralel charge the main bank whilst the W7 charges the smaller bank, i can then combine the the two if needed when generator off?

also can i use the diversion mode of the tristar 45 to charge the second battery bank? so when first bank full it dumps to second? and brings on ashp?

just a few thoughts going round my head, i also have the morningstar control relay setup, if you lot can think of any other ideas.

steve


Title: Re: second battery bank and stuff
Post by: knighty on May 08, 2017, 03:35:22 PM
I'd just join them both together in parallel from the start

they'll both be at the same voltage/DOD

means you'll have to work a little harder to give them a full charge now and again... but it's not really different from doing that to each pack separately ?



in my eye's it's better to have two packs working gently than have one working hard and another doing nothing


Title: Re: second battery bank and stuff
Post by: eabadger on May 08, 2017, 06:26:07 PM
i thought this was a big no no? surely you would only get benefit of lowest power one? and kill higher power one by under charging?
sure i read that when first looking at this, i would sooner keep separate just in case and to give redundancy.

will dumping excess power with tristar in to second bank work?

steve


Title: Re: second battery bank and stuff
Post by: camillitech on May 08, 2017, 07:25:18 PM
i thought this was a big no no? surely you would only get benefit of lowest power one? and kill higher power one by under charging?




Absolutely Steve, you will simply feck your good bank. I have seen this many times and my advice is always to sell the fecked/dubious bank and concentrate on yer good one. A bit like the lunacy of carrying a spare outboard motor for when the good one fails. Having said that I'm in the same boat myself and am trying to incorparate a 10 year old set of forklift cells into my current set up, not because it makes any sense but simply cos I already have them. Once I finally figure out how to do it I'll let you know how I get on  ;D Ole Scruff has given me some good ideas and if you ever need one of these.

(http://i.imgur.com/upsrQQT.jpg)

I'm your man  ;D


Title: Re: second battery bank and stuff
Post by: eabadger on May 08, 2017, 07:43:15 PM
hi, in summer i think i will have too much pv, so third array can do the smaller iffy bank, the second victron generator input i can feed from the powerstar w7 inverter which is conected (will be) to the second bank, in winter genset on will charge two victrons one through the feed through on w7 the w7 will then also charge the second bank.
big one is, can i use the tristar diversion mode, to dump to the second battery instead of a big resistor?
going to give it a go unless someones comes up with reason why not?
i had not seen the ac2 output on the victrons till yesterday, so this will bring on the cheapy inverter, which although thirsty in standby has been mega reliable, even after old generator massively over volted it only killed a vdr!!

steve





Title: Re: second battery bank and stuff
Post by: camillitech on May 08, 2017, 07:53:22 PM

Big one is, can i use the tristar diversion mode, to dump to the second battery instead of a big resistor?






Love to know how you get on with this Steve, been thinking about it meself for yonks, personally methinks not but I'd luuurve to be proved wrong  :crossed


Title: Re: second battery bank and stuff
Post by: Scruff on May 09, 2017, 02:53:36 AM
also can i use the diversion mode of the tristar 45 to charge the second battery bank? so when first bank full it dumps to second?

There may not be enough delta voltage to have the results you except, you are trying to push current against an opposing voltage.

Dunno how tristars feel about having a voltage at the load terminals either

Ole Scruff has given me some good ideas

None that I particularly like on the matter it was just a primative split charge diode setup SOC triggered from a switch that was likely going to use more idle than it ever returned active.

Sorry to say it Paul but I think that switch is too Mad Max for the job. I reckon I could build you an SOC triggered latching contactor for less than the replacement power/control board I'm making at the moment for that behemoth.


and if you ever need one of these.
...
I'm your man  ;D

I may have a limited production run of zero consumption replacement off-gridder boards in the works for those.  whistle
If my chinesium DC - DC converters can't keep their smoke inside I'll just rectify an inverter feed.

will dumping excess power with tristar in to second bank work?

Ask MorningStar those guys are great. 30 employees world class operation!
support@morningstarcorp.com  


Title: Re: second battery bank and stuff
Post by: eabadger on May 09, 2017, 06:20:51 AM
hi,
i dont think voltage will be an issue as it will be minimum of the preset dump point, what will they think of load sensing a voltage? i dont think it will care, but if it does then a diode would solve that.
having slept on it and seen your thoughts scruff, i think i can see an issue, i will have no idea of spot resistance of the second battery, so current is the issue as limited to 45a!! so i can see this killing it, but we want to dump excess we can use the tristar to switch on a contactor which joins the batteries whilst the tristar is dumping?

those big contactors you have, i installed a new parking system in 2001 in a big new shopping center in the uk, our entries exits ticket machines etc added up to maybe 16a in one area, the buildings mains incoming "fuse" kept blowing so we were blamed, till i saw it, you had to pump up a hydraulic mechanism for several seconds to build up enough pressure  to fire the "knives" directly in to the cable!! the bang it made as the center powered back on. when i proved it wasnt us, they then said it must be the fairy lights tripping it. exhappy:

scruff you have a tristar mppt? what is your procedure for software changes out of interest? just had an issue with one of my new ones after setting a fixed ip address, in conversation with MS now, yes they are very helpful.

steve


Title: Re: second battery bank and stuff
Post by: Scruff on May 09, 2017, 08:35:02 AM
Hrmm yes, that's another theory I need to test. If a TriStar PWM can hold in a relay coil or if it needs a capacitor and a coil cascade....come to think of it all my contactors have 12v coils, cos that's how they come.

Firmware you mean?



Quote from: MorningStar
TriStar Firmware Updates


This is the latest (http://support.morningstarcorp.com/search/?search_product=96) firmware update for the TriStar charge controller.

To update the TriStar firmware, download this file and the MSLoad PC software utility.
This firmware update contains all fixes to date. Only the latest firmware update needs to be programmed into the TriStar.

>>> IMPORTANT NOTE: For firmware releases v13 and older, the TriStar internal bootloader must be updated. The boot updater file is included in the .zip file along with instructions. This update only needs to be performed once. Thereafter, firmware updates can be loaded normally. If updating a TriStar with firmware version v14 or newer, simply bootload the latest firmware (no need to run the bootload updater first). See the included PDF instructions for more information.



Dump the excess into an MPPT controller with the current limit set to 45A?


Title: Re: second battery bank and stuff
Post by: eabadger on May 09, 2017, 08:42:20 AM
i was just thinking the same about mppt as over current allowed and controlled!!
the mppt software has beta version for turbine control!

no, not firmware, any changes in msview, what do you do?? just interested in your way/procedure? as ms just said something to me that i cant find in manual.

steve


Title: Re: second battery bank and stuff
Post by: eabadger on May 09, 2017, 08:46:53 AM
our contactors on control gear at work are all 24v, i will see if i can salvage some.
am going to play today again with it, with new array we have trippled solar incoming and only doubled panels so far another 1600w to refit now shed roof slated, slating in france is great, as we use s/s hooks to put em on, no nails that they hang off, supported at bottom, ideal! quick and simple.


Title: Re: second battery bank and stuff
Post by: Scruff on May 09, 2017, 05:00:27 PM
I use the RS232 interface. Once that's setup as com1 run MSview -> Devices -> Manual Connection -> TS MPPT -> Control Address 1 (default) -> Right click on device in LHS tab & Connect.

Tools -> TS MPPT Setup Wizard -> Ok -> Ok -> Create New -> Solar Charge ->

(http://i.imgur.com/j7EJp8r.jpg)

(http://i.imgur.com/HLBxdsk.jpg)

(http://i.imgur.com/xnZEs7m.jpg)

(http://i.imgur.com/EUHMtOM.jpg)

(http://i.imgur.com/c1xUVjM.jpg)

Everything else I leave as is, I'm not using the ethernets.

Program TS (making sure dip switches are set to custom and were set with the controller powered off) -> Com 1, Address 1





Title: Re: second battery bank and stuff
Post by: eabadger on May 09, 2017, 06:12:21 PM
ok, other than i use Ethernet the same.
but what do you do when you save settings? disconnect solar input?
i have had two in the past go bang, just had a brand new one go pop sh*tfan:
i changed ip address from dhcp to fixed and clicked save, it went bang when i clicked save.
ms very helpful but asked if i had done a reset, i said no, just saved network settings.
but i was curiouse and asked why, they said you have to disconnect solar on reset, so i read the manula, nothing, they have just emailed and said it is on page 33 of latest manual, my popped controller is 3 months from purchase and 1/2 an hour use, my manual makes no mention of pv disconnect, yours?
new one being dispatched foc.

steve


Title: Re: second battery bank and stuff
Post by: knighty on May 09, 2017, 06:16:29 PM
I know everyone says two banks in parallel will kill one... but why ?

unless one bank is knackered to start with and losing power while standing.... (so would discharge the other bank)  then what's the downside of paralleling them both ?

with OPs 1000ah and 650ah, you've got enough capacity that both bank voltages will be identical, you won't pull more from one bank than the other because you'll be pulling such a low C rate - a 5C rate is 8250 amps - almost 100kw




Title: Re: second battery bank and stuff
Post by: eabadger on May 09, 2017, 08:02:22 PM
everything i have read says it is a bad idea, we use the batteries hard at times, we live a normal life with xbox big tvs, dishwasher washing machine and soon ashp, with the two victrons at full chat we can pull 300a, the solar can charge up to 180a but i am taking advice on c5 charge rate from exide, but best charge rate on smaller bank will be less, maximum we will be able to get out is the smaller bank, also whether it would work i like idea of redundancy so prefer two at least of everything, even down to two swa's to house from solar shed, about 100m away.

with the iffy bank, it could well discharge good one surely?

steve


Title: Re: second battery bank and stuff
Post by: eabadger on May 09, 2017, 08:04:44 PM
work in progress, 3rd mppt along is the faulty one.
had fantastic day today, blue sky and windy, need to get second victron online as 1st one complains when running house and imersion, collecting the ashp for dhw next week when in in uk.

steve


Title: Re: second battery bank and stuff
Post by: Scruff on May 09, 2017, 08:36:27 PM
ok, other than i use Ethernet the same.
but what do you do when you save settings? disconnect solar input?


I isolate the pv input to begin with because they go bang if you disconnect the battery before the array. In order to reset the controller I need to periodically disconnect the battery input.

Manual?

but what do you do when you save settings? disconnect solar input?

Return to Custom Setpoint Summary Window and hit Program TriStar, reset tristar, reconnect PV.

Did they let you keep the broken one?


1 good battery + 1 bad battery = 2 bad batteries. The good one discharges into the bad one that just loses charge. So effective lower capacity and holding voltage, higher self discharge, decreased efficiency and increased cycling. Like most things battery related it's a slow death.  




Title: Re: second battery bank and stuff
Post by: camillitech on May 09, 2017, 11:24:08 PM
I know everyone says two banks in parallel will kill one... but why ?

unless one bank is knackered to start with and losing power while standing.... (so would discharge the other bank)  then what's the downside of paralleling them both ?

with OPs 1000ah and 650ah, you've got enough capacity that both bank voltages will be identical, you won't pull more from one bank than the other because you'll be pulling such a low C rate - a 5C rate is 8250 amps - almost 100kw




Because one bank usually is knackered (or at least worn out), or else why would you have two? Two banks make no sense in anything other than a 'critical system'. It's like replacing a cell or battery in a good bank, unless the cell/battery is the same as all the others in terms of capacity/spec it will feck them or they will feck it. I have much experience of this having lived 'off grid' since 1985 and looked after many battery banks at work since 2001. If you have two battery banks of the same age and spec then all will be peachy but that is seldom the case. All the posts I see on here and elsewhere are about about dudes like myself who acquire a used bank of unknown provenance or replace their own with a new/better one and then like to get some extra mileage out of their old one.

No matter how clever your charger is it either needs to carefully monitor voltage/current or have some clever algoritham for monitoring SOC. None of these methods will work with batteries of different spec/charecteristics, which is inevitable if the bank is your old one, came with that ole forklift off eBlag or 'the back of a lorry'. Sure you may well be lucky or Irish  ralph:, or be able to make one out of milk cartons but in 90% of instances it will end in tears. Trust me, I speak from experience, I can quite catagorically say that I have ruined more batteries than most people  ;D



Title: Re: second battery bank and stuff
Post by: jonesy on May 09, 2017, 11:28:46 PM
Does this sound right.
The older battery will have a higher impedance.  Charging current will preferentially go to the newer battery due to its lower impedance,  meaning the old  battery will only get a decent current once the newer one is nearly fully charged. You may not even hit float .
The new battery could end up charging the old one if float isn't hit, thus reducing overall efficiency.

You could come up  with a scheme to use all power to charge main, then swap to older battery. Then discharge old battery first, swapping to new one as required.  This would use up the old one getting it to the scrap yard before it let's you down on age.


Title: Re: second battery bank and stuff
Post by: camillitech on May 09, 2017, 11:37:23 PM
Does this sound right.
The older battery will have a higher impedance.  Charging current will preferentially go to the newer battery due to its lower impedance,  meaning the old  battery will only get a decent current once the newer one is nearly fully charged. You may not even hit float .
The new battery could end up charging the old one if float isn't hit, thus reducing overall efficiency.

You could come up  with a scheme to use all power to charge main, then swap to older battery. Then discharge old battery first, swapping to new one as required.  This would use up the old one getting it to the scrap yard before it let's you down on age.

Yes it does sound right Jonesy but the voltage on the new bank is dragged down by the older bank, result, new bank gets cooked, charger overworked and the old bank is just as bad as it ever was.

You could come up  with a scheme to use all power to charge main, then swap to older battery. Then discharge old battery first, swapping to new one as required.  This would use up the old one getting it to the scrap yard before it let's you down on age.

Exactly what I'm aiming for and also what I think Steve had in mind.

Paul


Title: Re: second battery bank and stuff
Post by: Scruff on May 09, 2017, 11:42:53 PM
Sure you may well be lucky or Irish  ralph:,
 ;)


I see no problem with it if: both batteries are isolated have their own chargers and the feckered battery can only feed the good but not vice versa. In which case series diodes are acceptable because something is better than nothing and it's just a contingency.

So voltage/soc controlled contactors and diodes or charge controllers i reckon there's potential.

The simple answer is no, don't make a bi-directional loop unless you want to accelerate the ageing of a good battery for very little gain.


Title: Re: second battery bank and stuff
Post by: eabadger on May 10, 2017, 07:38:22 AM
i want to use all my pv whenever possible with some redundancy without any chance of killing my main bank, yes the second one i was sort of given, it is ok and whilst i have been moving stuff it has ran our house two days withiut any charge, so maybe ok, but at least proved good as a backup.
we live in the countryside and i go away to work a fair bit, if something breaks whilst i am away i have to talk wife through fixing it, it puts a strain on me going to work, so wanted redundancy.
so plan is now, left multi main house supply, middle multi ashp, but both these can be swapped with a manual changeover switch, to feed main house supply, the righthand side inverter works like multi sort of in as far as it works in ups mode, so left multi is genset connected, its ac2 becomes live, this powers w7 inverter and fires a relay to start it up, the output then feeds through to middle multi, both multi's are charging the good bank, the w7 charges other.
to get the power back out of the old bank i manuly switch on the w7 inverter, which will power the multi as if grid connected, as for solar charging, my soon to be installed 3rd array can be diode split at the controller with possibilty to turn off second feed to smaller bank in the winter.

update on the MPPT, new one on the way, the broken one "please recycle however you see fit".
from what i now understand, do not commit any changes to the software with the solar connected, do not use the reset control feature on msview when solar connected. page 33 on the new manual is not as clear cut as i thought, just says dont disconnect batteries when solar connected, anyway, now we know what not to do, if i were them i would remove reset control from msview or at least put a second knock on the commit button.
if i can fix it, i think the fets gone, i will experiment with wind turbine mode.
morningstar support are very very good, i think they should make this issue more clear, but cant knock the backup.



Title: Re: second battery bank and stuff
Post by: Scruff on May 10, 2017, 08:46:44 AM
my soon to be installed 3rd array can be diode split at the controller with possibilty to turn off second feed to smaller bank in the winter.

Unless you get wan of them ideal lossless diode jobs like Sterling does I'd stay the eff away from series diodes in charge circuits they're woeful. It'll drop your regulation voltage by 0.7V best case scenario. If you fit it upstream the controller then it's fine or at the very least have the sense wires bybass the diode.

I've run parallel controllers off the same array to isolated batteries before. Works great, self-regulating too.

update on the MPPT, new one on the way, the broken one "please recycle however you see fit".

I'll give you 15+P&P fer it. :crossed  ;D

Open it up and send us some nudey photos  (of the TriStar not yourself) might be salvageable.


from what i now understand, do not commit any changes to the software with the solar connected, do not use the reset control feature on msview when solar connected. page 33 on the new manual is not as clear cut as i thought, just says dont disconnect batteries when solar connected, anyway, now we know what not to do, if i were them i would remove reset control from msview or at least put a second knock on the commit button.

What and stop giving people free replacements? Quiet you!

if i can fix it, i think the fets gone,

Would be my suspicion too.
Overcurrent, smoke.

morningstar support are very very good, i think they should make this issue more clear, but cant knock the backup.


The only tech support I've contacted who haven't first replied with "have you read the manual?"  :fight

Mine comes with mechanical protection. I can't fit the RS232 in at the same time as PV inputs.  ralph:

(http://i1348.photobucket.com/albums/p725/Sir_Liamalot/Grid%20Hopping/DSC_1852_zpsaf3z19sq.jpg)


Title: Re: second battery bank and stuff
Post by: Tinbum on May 10, 2017, 09:58:22 AM
I've had one go and repaired it. see https://www.navitron.org.uk/forum/index.php/topic,16171.30.html


Title: Re: second battery bank and stuff
Post by: Fionn on May 10, 2017, 10:56:43 AM
A DC changeover contactor betweeen each bank and the inverters / chargers might make most sense but it could be hard on the electronics.
As has been said I think checking in the old bank for it's recycling value is the best course of action though.


Title: Re: second battery bank and stuff
Post by: Justme on May 10, 2017, 11:19:03 AM
IF both banks are in good condition & the same type then you should combine the banks. Even if they are different capacities. When wired correctly they would share the load & charge proportional to their size.

IF one bank it stuffed or a different type then you should not combine them.

The only exception is IF you need to keep mission critical functions at all times.

IE life support or military defense to name two.


Title: Re: second battery bank and stuff
Post by: eabadger on May 10, 2017, 07:40:31 PM
Hello,
if as i have you have dissimilar bank sizes, you will always be limited to smallest capacity one, which will be less than when new and unknown, plus self discharge and greater loss's are a given, not going that route myself, has anyone else who is off grid?

anyway, got it working and worked well, connected the w7 to the second multi, which is connected to the immersion heater, the w7 is off the dodgy (for want of a better word) bank, when w7 powered up the victron sent power through and also charged the main battery bank, i assume very lossy but good way of separating and gives me redundancy.
i hear what is said about redundancy, military/hospital etc, but tell that to my family if i am away for 10 days and they have no power, who do you call in to fix our things?
new mppt is on the way, i will take pics as i open up the popped one, if i get chance before Sunday i will get new parts from rs next week.
when the new mppt arrives i should have got the third array up to charge the dodgy bank and set up the rd1 to control it all.
we did 18kw today in pv which is a first plus we heated all dhw to 64* 250l of it, chuffed.

steve


Title: Re: second battery bank and stuff
Post by: eabadger on May 10, 2017, 07:53:25 PM
timbum, thanks for heads up, will explore further, the new manual gives a power down and up method, but doesnt mention not clicking reset control on msview until after you click pv disconnect, tech support said you must.
i wonder if on boot it can handle it?
last two i had fail, one possible after reset, one maybe static after storm, i had to send back to dealers who sent out a new one.
anyway whatever new one on way, if i fix old (thanks for offer scruff) i will try as turbine controller mode.

steve


Title: Re: second battery bank and stuff
Post by: Scruff on May 10, 2017, 08:37:54 PM
has anyone else who is off grid?


I'm sure Justme probably has.

I did for a while, in the summer the PV could feed the losses in the Autumn I retired the dud and not much changed...'cept I'm sure the remaining battery had suffered for the cause. Ah back in the days of 100% discharge and asymmetric loading. That lead owed me nothing.


Title: Re: second battery bank and stuff
Post by: Justme on May 11, 2017, 07:17:58 PM
Having a small bat linked to a bigger one will not limit you to the size of the smaller one.

If the cables are sized & wired correctly each bat will supply & receive a charge proportional to its size.

The biggest factor is, are both bats the same type & in good condition.

If they are it will work fine.

If one is duff, why the hell are you wasting energy trying to charge it?





Title: Re: second battery bank and stuff
Post by: Scruff on May 11, 2017, 10:43:54 PM
Common practice for vehicle dwellers. I link 235Ah (semi-traction) with 90Ah (starting) for light engine electrical loads and it works. Boats often will link service battery, bow thruster and engine starter for charging.

Works fine once you know what you are up to and the limitations .


Title: Re: second battery bank and stuff
Post by: eabadger on May 12, 2017, 07:53:27 AM
hi Justme, have you or are you doing this then? or have you done it? can you describe how you have done and for how long?
if the two batts are in parallel you will only ever get power of the smallest, or you will kill the smallest if i go to 80% dod on the bigger, the smaller will be 0, also on charging it will be the same, my bigger bank needs a 5 hour absorption time the small was 3.
by doing what i am now doing we are utilizing something not scraping it or damaging my good bank, yesterday i was able to boost my victron to heat my dhw using method i described above, so renewable result as far as i can see, which after all is what all of us are after?
these batteries at no cost may give me one extra or two extra days without running the genset, remember all the stuff i have used was lying around looking for a new life.

scruff, victron do a battery combiner just for this, it is meant to be "smart" with emergency override.

steve