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Gel batteries - to "equalize" or not???


gpigeon
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I have 24x Sonnenschein Energystore 2RPG1410 Gel cells which are charged via 2x Schneider 80 - 600 controllers and/or a Schneider XW+8548 Inverter.

The battery suppliers state that the cells should be equalized whereas Schneider say that Gel batteries should not be! I am the man in the middle!!

Any of our forum members with Gel cells?

As I have recently seen 2 high "mid point V dev%"  alarms recently on my Victron BMV702 I am a little concerned. The installation is only 4 yrs old and has been trouble free up till now. I log individual cell voltages regularly (se att) and no one cell is ever high or low. 

Another possibility is to use a battery balancer (say an HA02)on the highest and lowest average cells.

Any thoughts???

Thanks.

Bill.

battery log.xls

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Balancing and equalization are not strictly the same thing and not really done for the same reasons.

The short answer: All batteries types can be balanced, but not all equalized. Don't equalize gel batteries.

For the long answer: Spend a while reading up on things.

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"phil.g00", thanks for your reply.

15 hours ago, phil.g00 said:

Don't equalize gel batteries.

For the long answer: Spend a while reading up on things.

Reading up on things is doing my head in!!!! You + many others incl. Schneider say "Do not equalize gel batteries"!!!! See Att Sonnenschein data sheet which clearly states that they should be equalized! However, they will not recommend a charger to do it!

I now have one cell out of the 24 that drops to zero V (thus, I am getting a high "mid pt dev.%" alarm on my BMV702) when the battery V drops below around 48V. However, after charging that cell is fine.

I'm thinking that if equalizing can not be carried then perhaps balancing can be???

Please point me in the right direction if you think I should read up more....for the last week I have been doing a lot of reading!!!!

Thanks.

Bill.

energystore_gel_EPzV_instructions.pdf

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5 hours ago, phil.g00 said:

Then you'll see why it is applicable (even harmful) to gel batteries.

 

So, why does the battery manufacturer state (see prev. att) that equalizing is necessary???

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6 hours ago, gpigeon said:

So, why does the battery manufacturer state (see prev. att) that equalizing is necessary???

A colleague of mine sold a system with sealed lead acid batteries, with a 10 year (!) warranty, to a customer. The manufacturer recommended high voltages, as this one does. When the battery failed and a warranty claim was made, the manufacturer stated that the battery had been overcharged, so the warranty was void! There was much argument, and I can't recall what the resolution was.

Some gel batteries, usually those with AGM construction (absorbed glass matrix) do seem to be able to trap evolved gas more effectively, allowing the hydrogen and oxygen to be recombined after vigorous charging.

So I have no idea what to recommend. Hopefully, the manufacturer knows what they are doing (unlike the one I related above), and that they will honour their warranty if there are any problems. I would however stick strictly to the specifications, which isn't possible with cheap chargers. For example, I would definitely implement temperature compensation, which will reduce the charge voltages at high temperature (and increase them at low temperatures). I would stay away from chargers that regularly overshoot their target voltages. So Axpert types are double contra-indicated: no temperature compensation, and bad overshoots. Something like a Victron, possibly with an add-on for temperature measurements, would seem suitable.

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Equalization voltage are a higher voltage that cause the plates to bubble, and gas (water vapour) is lost, but it is easily replaced in a non-sealed battery.

The reason it done reverse acid stratification, it is a "shake up" of the electrolyte to remix it so there is an equal acid concentration throughout.

The bubbles on the liquid lead acid plates easily float to the top, if they remained on the plate they would make the plate effectively smaller by reducing electrolyte contact area, but they are un-hindered by the non-viscous acid. this action stirs up the thin electrolyte.

To a lesser degree if bubbles remain in suspension they would also make the battery less effective.

Yes. a byproduct of this process  is the battery bank is top-balanced, but batteries can be balanced numerous ways without doing this.

So, noting the the limitations of a sealed battery vs an unsealed battery. Let us consider a full jar of water (the liquid Acid mimic) and a full jar of honey (the Gel mimic). As gently possible put a drop of food colouring on the surface of both jars and fit the lids. The food colouring mimics a high concentration of acid that must be mixed throughout the liquid.

Now shake both jars (the equalisation process) until the food colouring is mixed at an equal density throughout the water and the honey.

During this mixing process it will become clear to you how the viscosity of the electrolyte plays a role.

Edited by phil.g00
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I'm faced with the same dilemma with 12V monobloc Eastman tall tubular gel OPzV batteries manufactured by Eastman Auto & Power (India)

The rather impressive specifications (attached) state a cycle life of 1500 cycles @ 80% DOD, excellent PSOC recovery and an equalisation charge of 14.8V.

Should I really enable setting 33 on the Axpert MKS 3K-24 with the defaults? Not sure.

Eastman Tall Tubular Gel Specifications-2.jpg

Eastman Tall Tubular Gel Specifications-4.jpg

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On 2021/05/11 at 6:44 AM, phil.g00 said:

The short answer: All batteries types can be balanced, but not all equalized. Don't equalize gel batteries.

On 2021/05/11 at 10:26 PM, gpigeon said:

So, why does the battery manufacturer state (see prev. att) that equalizing is necessary???

I have conferred with the supplier of my AGM batteries and they said they too should/not necessary to be equalised?

On another angle, I believe my batteries have lost a significant amount of storage capacity despite the fact that my monitor records show that the average consumption over the last 22 months is 87 Ah/Day - with one incidence of a draw of 103 Ah (51.5 DOD) on one day. I have recorded 405 synchronisations and Nil total discharges. 

Can anyone advise how I should present an argument to the supplier that the batteries have not performed as expected?

My 4 x 200 Ah AGM batteries can only deal with my night time load of average 315 watts from dusk until midnight!

Thank you

 

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  • 2 weeks later...

Ok, so the inevitable has occurred.....I have had one cell fail totally. It charges up just fine during the day but drops to zero V overnight. 

After speaking to the battery supplier, I removed the faulty cell and changed all the charger settings to suit a "46V" battery. So far everything is going ok but naturally with 4% less capacity.

The warranty was only 5 yrs and I have had the system for 4 yrs so they are not too interested in a claim. In any case the battery has NEVER been equalized so they will most likely use that as an excuse as well. However, they have agreed to test the cell and try to "rejuvenate" it so I dropped it off with them last Friday. I was up your way "Coulomb" in Acacia Ridge at GNB/ Exide. Too many people in Brisbane for me...I was pleased to get back home to the bush!!!!

To make matters worse, that particular type/brand of battery is no longer made so I cannot simply replace the faulty one with a new one...apparently not a good idea anyway.

It will be interesting to see how this rejuvenation process does???

Ideas, suggestions, comments????

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14 hours ago, gpigeon said:

I was up your way "Coulomb" in Acacia Ridge at GNB/ Exide.

Heh. Probably about 3km from here.

Quote

Too many people in Brisbane for me...

I wish more would stay away. Traffic is getting insane at times.

Quote

It will be interesting to see how this rejuvenation process does???

Yes. If doing it from home, or with a miracle device from Ebay, I'd give it less than 1% chance of success. But with genuine battery experts, if that's what they are, I have no idea. Keep us posted.

Edited by Coulomb
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  • 1 month later...

Ok, latest update....

The dead 2RPG1410 cell is unrecoverable!!!!! No interest in a warranty claim because Exide say that the cell was never charged and equalised according to their specs. As stated earlier, the Schneider charger I have been sold is not capable of charging to their specs. in any case!!!! When are we going to get some experts in this solar industry? At the very least, one would expect that Schneider and Exide/Sonnenschein could talk to each other and develop compatible elements!!!!

So, Exide have provided me, at 20% discount, one 10EPzV800 replacement cell. I picked it up yesterday and hope to have it up and running tomorrow.

My question to you guys is....what do you think of mating up different types/ratings of cells ? ie 23x 1410Ah cells and 1x 800Ah cell.

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14 hours ago, gpigeon said:

what do you think of mating up different types/ratings of cells ? ie 23x 1410Ah cells and 1x 800Ah cell.

That limits your battery to effectively 800 Ah, wasting 43% of your other cells (I assume all 24 will be in series). Worse, you will need special protection for the 800 Ah cell, because any voltage based solution isn't going to notice the smaller cell going below 1.75 V and becoming damaged. A few deep discharges and it will be ruined. A battery monitor programmed for 800 Ah would be safe.

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8 hours ago, Coulomb said:

That limits your battery to effectively 800 Ah, wasting 43%

Coulomb....I understand and agree with your reasoning, but it not as bad as you state. For some crazy reason, perhaps just to confuse us mere mortals, the 2RPG1410 cell is 1410Ah @ c/100 rating whereas the 10EPzV800 is 800Ah @ C/5 rating! The 2RPG1410 is actually only 1000Ah @ C/5 rating.

So, I am losing only 20% of my capacity. Yes, still not good I know.

Considering that the highest discharge I have seen in 4 yrs of operation is 196Ah (that was just the other day after 2 consecutive days of very heavy cloud) the 800Ah cell would have only been discharged to say 200/800 = 75% DOD. Normally the batteries are fully charged by10am even on a cloudy day. (10kW panels)

Anyway, I will stick with what I have for the moment and keep an eye on things.

Cheers.

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My little brain is battling to understand,

 

i have 2 battery banks with 4 x 200ah, 

Highest would read 14.2 volts the lowest would read 12.84 volts and the rest of the two 

after the balancing HA02, I get 13.8v per battery across all 8

 

if it’s bad to equalize the Gel batteries, should one leave the mismatched voltage battery banks?

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17 hours ago, Vince MacMahon said:

if it’s bad to equalize the Gel batteries, should one leave the mismatched voltage battery banks?

There are two somewhat incompatible uses of the term "equalise" here.

With flooded lead acid batteries, it is common to equalise the cells by a periodic overcharging (the equalisation charge), which brings up the low cells but over-charges the full cells. The full cells boil away water to hydrogen and oxygen gas (no naked flames please!), but it's no big deal, you just add more water at your next regular watering session. Gel cells have only a small quantity of water that can't be replaced, so you can't afford to do this, generally, unless the cells are designed to retain the gases under pressure, so that the water can recombine after the overcharge is over. Naturally, you have to adhere strictly to the manufacturer's limits if doing this, since exceeding these limits will cause the cell to vent and the water can't be recovered.

The other sense of the word is some sort of balancing circuit that takes excess charge from a full cell or module of cells, and pushes it (perhaps with slight losses) into cells that need extra charge. This is most unlikely to result in overcharging of a cell if done properly, so this form of equalisation is safe.

To answer your question, no, don't leave the modules unmatched; allow the balancer to do its job, as this isn't the potentially bad form of equalisation.

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Thanks,  the core reason I purchased the HA02 was to ensure equal charge across the batteries, I was annoyed to find 4 different voltages per battery in each of the battery banks. now, they are all equal, if you monitor for a longer period, goes up and down with 00.01. keeping in mind that the inverter flat charge is already set per the battery spec. the issue is not overcharging but the individual batteries were been charged at different rates (despite the inverter float charge values). 

What I pick up a lot here is we also talk across purposes when referring to lead acid batteries, I think in future would be best to state which specific chemistry the lead acid battery is (e.g. AGM, Gel or flooded). I would also never want to own flooded batteries because of the additional maintenance (top ups, etc.). 

Life expectancy is also generally different (AGM vs Gel Batteries - Which battery type is better? (canbat.com))

 

 

 

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