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Author Topic: Easterdown Equalisation Question  (Read 4023 times)
V
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« on: November 29, 2014, 09:19:36 PM »

Can anyone help me with advice on Equalisation charge parameters of Forklift Batteries using a Sunny Island?

I am struggling to work out the length of the Absorption time for the equalisation. SMA have been very helpful, but say that for the length of the absorb phase of the Equalisation, I should ask the battery manufacturer. My battery supplier feels confident about the set point voltage per cell, but says that the length of an equalisation for these Forklifts should be around an hour once the batteries are fully charged.

I'm not sure how SMA do their equalisation charge, eg, at what point does it start? I've noticed that the Boost and Full charges start when the battery SOC is 88% -90%.  I think that the SMA default, a 12 hour long absorb phase for the equalisation,  sounds like an awfully long time and my battery supplier thought so too.

I set the equalisation charge time to 2 hours for the last one, but the batteries did not end up at 100%, so that must be wrong. On a Full charge, @ SMA default of 6 hours, batteries SOC is 100% within 5 hours.  All advice and insights, as usual, gratefully received. 

PS.  I know I'm bad not to talk yet about what I now have in my off-grid system, but that will end up quite a long discussion and this equalisation is becoming a pressing matter as it is happening in 7 days, Mike is away for 2 weeks and I have  to babysit my nephew in London the day after the SI says the EQ is scheduled (not a last minute question at all!)

V.
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« Reply #1 on: November 30, 2014, 05:43:39 AM »

HI

Absorption charge is a different  subject than equalizing charge !

My batteries get an absorption charge nearly every day  during the summer   , simply because  sun is strong enough to fully charge most of the days upto ca 29.6 Volt  and reduce the charging Amps while volt is so high - absorption is part of the charging plan

Equalizing charge is a forced charge   at a higher voltage 31-32 Volt in my case   and i do this for 2-3 hours 

Billi
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« Reply #2 on: November 30, 2014, 07:21:39 AM »

Hi Vicky,

contact the battery manufacturer directly and they will provide you with a graph, from that you can program the parameters directly into the SI.

Good luck, Paul
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« Reply #3 on: November 30, 2014, 09:49:37 AM »

HI

Absorption charge is a different  subject than equalizing charge !

My batteries get an absorption charge nearly every day  during the summer   , simply because  sun is strong enough to fully charge most of the days upto ca 29.6 Volt  and reduce the charging Amps while volt is so high - absorption is part of the charging plan

Equalizing charge is a forced charge   at a higher voltage 31-32 Volt in my case   and i do this for 2-3 hours 

Billi

This is why I am worried about overcharging. The SI does a full charge every 14 days, see below.

The parameters that the SI ask for are:
Cell voltage setpoint for equalization charge in V = I've been recommended 2.45 which is the SMA default - I think this means 58.8 volts (for 24 cells)
Absorption time for equalization charge = ?? the default is 12 hours

I will contact the manufacturer tomorrow and see if I can get more information. I will also ask SMA once again if they can tell me a bit more about what goes into their version of an equalisation charge. All the manufacturers site says is:

"An equalising charge consists of a regular charge extended until the voltage and specific gravities of all the cells have remained constant over three successive hourly readings"

I think I would prefer to do a manual equalisation this time, especially as the full charge seems quite strong and last time the SOC was at 100% for the last hour of it.

For the Full charge:
Cell voltage setpoint for full charge in V = I'm using the default which is 2.45 (same as Equalization)
Absorption time for equalization charge = default is 6 hours and I'm using that

When the SI calls for a full charge (every 14 days) it does a bulk charge followed by an absorption charge until the batteries are at 88-90 percent. Then it starts counting down 6 hours. It seems to just carry on with the absorption phase until it gets to around 98% and then gradually reduces. Batteries always end up at 100% SOC. I've read this is good practice charging, so probably a good thing. But 12 hours seems pretty harsh. Most battery manufacturer's websites recommend 3-4 hours. Maybe I'm just being squeamish.

Hi Vicky,

contact the battery manufacturer directly and they will provide you with a graph, from that you can program the parameters directly into the SI.

Good luck, Paul

I'll contact the manufacturer on Monday (tomorrow).
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« Reply #4 on: November 30, 2014, 10:35:06 AM »

Hello V

I am not familiar with the Sunny Island  and why a full charge is not done  whenever you have enough solar  power
Perhaps the reason  is , that if the SI is in a gridconnected  or generator operated , to avoid  daily inefficient charging  to reach the 100% SOC

In an offgrid setup (where electricity is for free) , i would allow  more often  a full charge ,

You have a very nice  PzS  Battery bank ( had a look at your website)   , did you talk to your supplier   about  an electrolyte stiring(air) idea and hydrocaps   ? 

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« Reply #5 on: November 30, 2014, 10:58:33 AM »

From the Rolls battery manual for their batteries.

Equalization - Preventative
Individual cells will vary slightly in specific gravity after a charging cycle. Equalization
or a “controlled overcharge” is required to bring each battery plate to a fully charged
condition. This will reduce stratification and sulfating, two circumstances that shorten
battery life. Equalization of the battery bank is recommended every 30 to 180 days,
depending on the usage of the individual system. To equalize the cells, charge the
batteries until the voltage elevates to the “Equalization” voltage shown in Table 2. Charge
parameters and maintain for 2 to 3 hours per bank. A constant SG for 30 minutes is a
good indication of cell equalization. It is recommended to water the battery cells half way
through the equalization. This will assure the water is mixed with the electrolyte.

METHOD
Corrective equalization can take a very long time depending on the degree
of sulfation.
1. If you have a recombination cap, remove during equalization.
2. Set the charging controls to the recommended equalization settings according
to voltage.
3. Charge at a low DC current (5 A per 100 AH of battery capacity). If grid power is not
available, use solar panels or a good DC source when possible. At high voltages,
charging with generator can be difficult and hard on the inverter.
4. Once every hour, measure and record the specific gravity and temperature of a test
cell. If the temperature rises above 46ºC and approaches 52ºC, remove the batteries
from charge.
5. If severely sulfated, it may take many hours for the specific gravity to rise.
6. Once the specific gravity begins to rise, the bank voltage will most likely drop, or
the charging current will increase. The charging current may need to be lowered if
temperature approaches 46ºC. If the charge controller was bypassed, it should now
be used or put back in line.
7. Continue measuring the specific gravity until 1.265 is reached.
8. Charge the batteries for another 2 to 3 hours. Add water to maintain the electrolyte
above the plates.
9. Allow bank to cool and check and record the specific gravity of each cell.
The gravities should be 1.265 ± 0.005 or lower. Check the cell electrolyte levels and
add water if necessary.
It is recommended that a specific gravity reading of one pilot cell is measured
and recorded on a regular basis when it is thought that the bank is fully charged.
The measurement should be compared to previous readings. If the measurement is lower
than the previous reading, a longer absorption time and/or higher voltage setting should be
used. The longer the absorption time and the higher the bulk voltage, the more water will be
consumed but less equalization will be required.
Note: The specific gravity should rise as the cells use water. Look for trends in the specific
gravity over a period of time and make small adjustments as necessary.
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« Reply #6 on: November 30, 2014, 11:47:42 AM »

Hi Billi,
Thanks for the vote of confidence in my batteries, I think Paul Byrne is an absolute superstar of FLA's for off grid (hope I'm allowed to say that here - he only sells forklift batteries, nothing else). That's why I want to take good care of them.

Since the Solar went in (in September) the generator has only been on once for a bulk charge followed by a full charge. Today a Boost charge is going by sunlight alone. Currently 1 hour gone, 1 to go and SOC says 92%. Voltage just changed from 58.8 to 58.4, so I assume the SI is starting to move the charge lower. As it's only 11am I will have at least 3 hours of bright and sunny float charge after the Boost finishes.

But I've talked lots to SMA about parameters because my system wasn't set up correctly. They reckon an electrolyte pump is the best idea and I'm going to look into that. As it is, since the solar went in there have been a lot of days where the batteries were gassing and I've put about 17 litres of de-ionized water back into them - always check them after a boost or full charge. At first Paul was keen on the hydro caps, but later said it can be too easy to over water using those. Trojan say on their website that observation is the best way to water batteries and I quite like fussing over them.

So I'm hoping, for the moment, that the electrolyte has been mixed well.

From the Rolls battery manual for their batteries.

Equalization - Preventative

And THANK YOU so much, Tinbum. That sounds like a good recipe for manual equalisation. What I'm now thinking is to ring SMA and ensure that I can achieve this with a succession of manual equalisation charges set to either 1.5  or 3 hours, with a watering session in between. I'll also find out what Eternity (manufacturer of my FLA's) think.


All further advice, opinions and insights as always, gratefully received.



 
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« Reply #7 on: November 30, 2014, 12:08:01 PM »

The best advice I could give is that your can't love them too much!!

Batteries really need to be watched and even then it can go wrong. I though I had mine set up really well but somehow one of the cells seemed to drop behind the others despite me doing equalisations- don't ask me how as I simply don't know but equalisations will now be longer and more often. That cell ended up getting extra special treatment of an individual charge to bring it back up to the others.
« Last Edit: November 30, 2014, 12:17:18 PM by Tinbum » Logged

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« Reply #8 on: November 30, 2014, 12:33:12 PM »

I have a set of eternity batteries, as does my neigbour, when bulking or during absorb (2 hours 29.2v) the noise of the reaction going on is enough to tell me that I don't need an aerator, they bubble and hiss like a good un, from top to bottom.
The cell voltage set points I got from Paul did not seem to make sense, I just used standard traction cell set points, works fine, they may use a bit of water but I am in no doubt about state of charge.
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« Reply #9 on: November 30, 2014, 01:48:39 PM »

Batteries really need to be watched and even then it can go wrong. I though I had mine set up really well but somehow one of the cells seemed to drop behind the others despite me doing equalisations- don't ask me how as I simply don't know but equalisations will now be longer and more often. That cell ended up getting extra special treatment of an individual charge to bring it back up to the others.

Did the bad cell bring down the entire bank? How did you spot the problem? Was it with SG measurements?
I haven't done a full SG measurement yet, when new installer showed me how to use it, it was clear that the nozzle thing isn't really long enough to reach the electrolyte. It's on my list to replace the tube with a longer one.

I have a set of eternity batteries, as does my neigbour, when bulking or during absorb (2 hours 29.2v) the noise of the reaction going on is enough to tell me that I don't need an aerator, they bubble and hiss like a good un, from top to bottom.
The cell voltage set points I got from Paul did not seem to make sense, I just used standard traction cell set points, works fine, they may use a bit of water but I am in no doubt about state of charge.

Can you tell me what the standard traction cell set points are?

What I did was send Paul the SI defaults and he thought they were OK. And he thought the duration of the charges (full and equalise) could be a bit excessive.

Do you check the SG regularly?
« Last Edit: November 30, 2014, 01:59:54 PM by V » Logged

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« Reply #10 on: November 30, 2014, 02:07:55 PM »


Did the bad cell bring down the entire bank? How did you spot the problem? Was it with SG measurements?
I haven't done a full SG measurement yet, when new installer showed me how to use it, it was clear that the nozzle thing isn't really long enough to reach the electrolyte. It's on my list to replace the tube with a longer one.


No, The 48v bank was made up of 3 parallel banks of  8no 6v batteries in series and I noticed it when taking voltages across each 6v battery. I then confirmed it with SG readings and one cell was noticeably less than the others.

Durite do a good hydrometer, not cheap but good.  Durite 0-472-00

These are also excellent;
http://uk.rs-online.com/web/p/water-fillers/4236657/?origin=PSF_409432
« Last Edit: November 30, 2014, 02:11:08 PM by Tinbum » Logged

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« Reply #11 on: November 30, 2014, 02:34:25 PM »

I don't take SG readings, thoughI intend to with the new ones, I kept an eye on cell voltages to start with to make sure they were all very similar, if there is a dodgy cell it should flag up pretty quickly, thankfully they are all the same as we had them delivered to portugal and replacing duff cells would have been a pain.
I believe 29.2v, 2 hour absorb and 27.6v float are pretty standard for traction cells, the concensus is to crank up the absorb a few tenths of a volt for aged cells.
You have to remember these batteries are designed to be charged fast so they can earn some money, not sit on charge in warehouse for half a day.
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« Reply #12 on: November 30, 2014, 03:11:32 PM »

I wish I was up to speed on all kinds of battery specs and info,
                                                        I have 60 forklift sells in series 36floride x 600ah and 24 powersafe,la x 800ah. They get along fine but one gang is a heavier drinker than the other and there have been times when they have been boiled dry,which is a true criminal offense,I can excuse myself on the grounds of being unable to the house for a good 6 months ,due to some health problems.I just filled them up with a delightful glugging of rain water..to the top.and watched them bubbling away happily and the water rising and overflowing Shocked Roll Eyes. Now I know that this is a terrible confession for a moderator to make and I have no excuse apart from being dim. But they recovered and I did the same again but this time fed them nice distilled gear.The flourides could drink the Powersafe under the table. But an equalising charge? Now that is something that could go badly wrang,,very wrang,I have two controllers handling 2kw of juice each and when |I want to give the cells a lift, I remove one dump load and watch the voltage climb to 146/7. An hour of that kind of slog is plenty and I am mindfull of my floride cells being under greater pressure,so I revert back to the 2nd immersion dump.
  This works very well for us, In theory it should not but the reality on the ground is that it does and it works well, We have a decent 48 hours reserve of normal house operations before we even begin to get worried should both the sun and the wind decide not to play ball.Most days the bank stays up in the dump load or just below and a few hours after dark it drops down to 123/4 if there is no wind and stays there the whole evening.We would be using a steady 350watt at least. circulation pump,freezer,telly,chargers and lights.
  We regard the Batteries as a kind of buffer and try and keep them within a very tight voltage spectrum,,No big discharge and not too much of the big boosting and hopefully they will stay young and fresh fingers crossed!.We do the hoovering when the sun shines bright or the wind is blowing in from the sea,Trying to use it as it comes in,a form of direct drive.
  I am not trying to encourage people to organise their bank like me because I know that it is the wrong way to do it,however it was only meant to be used for a while,just to see if it would work and that was well over 6 years ago. All my studies and info searches have told me that it would be very difficult to get 60 perfect cells to behave properly in a perfect installation. So It is hard to know. I do understand that our installation is far from perfect but it seems to work very well.No cells have been replaced,just the same old 60 cells.
   I bought 2 hydrometers a few weeks ago but I was afraid to use them in case they gave me some bad news hysteria,meanwhile my 60 little darlings hiss and bubble with enjoyment, each time they get a good dose of sunlight and wind,Who could ask for more.
                                                               Biff
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« Reply #13 on: November 30, 2014, 05:57:33 PM »

...and I noticed it when taking voltages across each 6v battery. I then confirmed it with SG readings and one cell was noticeably less than the others.


Phew! Voltages were taken and recorded when the batteries arrived. All pretty close.

Thanks DaveSnafu, my Eternity's arrived the same condition as yours it seems.


...But an equalising charge? Now that is something that could go badly wrang,,very wrang,I have two controllers handling 2kw of juice each and when |I want to give the cells a lift, I remove one dump load and watch the voltage climb to 146/7. An hour of that kind of slog is plenty.

I am increasingly thinking that this is what I should do, especially since I was told that if I had an electrolyte pump there would be no need for equalising charges. So it's all about the bubbles? Presumably I could get the multimeter out for a simple double check?

We regard the Batteries as a kind of buffer and try and keep them within a very tight voltage spectrum,,No big discharge and not too much of the big boosting and hopefully they will stay young and fresh fingers crossed!.We do the hoovering when the sun shines bright or the wind is blowing in from the sea,Trying to use it as it comes in,a form of direct drive.

When we moved into the cabin in May it was batteries, SI and generator only. Because of incorrect settings our batteries  never got above 86% while still cycling down to 50% SOC. SMA showed us where this was wrongly set and helped us do the first proper full charge which didn't happen until June. Since then I've been a bit obsessed with keeping the batteries between 80 and 100% SOC. When we got the solar set up in September we struggled to get below 95%SOC, but then I was told that I should be cycling the batteries. At that point it was suggested I should switch off the solar for a few days  Undecided . Then it began to rain and mist, but we still struggled to cycle the batteries below 88% SOC. Only now, end of November, have we gone below 65% and then with two days of sunlight - back in the 90's!

Sadly, I tend to feel like I am getting 'full marks'  and have passed the 'off grid test' when I see >94% on the SOC but I wonder if this is just selfish and I'm not 'working' my forklifts and will be punished for my hubris. My original thinking was to cycle the batteries between 100 and 80%, only going to 50% at a push. But then I was told that the first 10 cycles should cycle between 50 and 100%SOC.

In any case, the Equalise charge only happens when the batteries are nearly full. I am inclined to reduce the equalise to something more like the full charge, and certainly not 12 hours. I'm also tempted to reduce the full charge time from 6 hours down as well. Quick calculation of your 'lift' voltage is 2.45 volts per cell, which is what Paul Byrne and SMA suggested for the Full and Equalise charges. Definitely sticking with that. Thanks so much!

Very interested to know if any other SI people use the 12 hour default or not?

Thanks,

V.
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« Reply #14 on: November 30, 2014, 06:23:25 PM »

Phew! Voltages were taken and recorded when the batteries arrived. All pretty close.

My voltages were all ok when I first got the batteries, it was after about a years use that I noticed it. I guess for some reason that cell never recharged quite as well as all the rest after each discharge and my equalisation wasn't long enough or often enough.
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