Battle of the bulge

[chilly2]

Hello,

I have 4 Weize 12v 100ah batteries purchased from Amazon between late June and September of 2023.

Initially the first two were in parallel running a 12v inverter. I decided to go to 48v so purchased two more. They have been running in series for about two weeks.

The last couple of days I noticed an E01 battery over discharged error each morning despite the inverter cut off being 50v, and today I disconnected all the batteries to test their voltages. The first battery, purchased in June, was at 10.58v. The second at 12.57v, and the newer ones at 13.1v.

Looking the first battery over I noticed at either end there was ever such a slight curvature, which I confirmed by resting a flat edge on it, which I could rock slightly. While I haven't tried to open the battery, this sounds like one or more of the cells might be bulging inside. None of the other battery cases have this curvature.

My gut feeling is the battery can't be trusted now, but thought I'd ask here in case there is some way to TLC it back to health.

I have contacted the seller and am not hopeful of resolution given the source, but stranger things have happened.

Thanks.

 

[rodrick]

It sounds like your batteries have gotten out of balance recharge each individually to full

as far as the slight bulge does it sound different from the other ones when you tap on it, can you push on the ends and see if you get any deflection compared to the others

you can fully charge that one and do a capacity test to get some more info on the battery health

 

[chilly2]

It sounds like your batteries have gotten out of balance recharge each individually to full

as far as the slight bulge does it sound different from the other ones when you tap on it, can you push on the ends and see if you get any deflection compared to the others

you can fully charge that one and do a capacity test to get some more info on the battery health

Thank you for the reply, Rodrick

I have it charging by itself at present and will update with findings.

It doesn't feel much different than the others to tap on. Harder at the base, hollow towards the top.

 

[rodrick]

Thank you for the reply, Rodrick

I have it charging by itself at present and will update with findings.

It doesn't feel much different than the others to tap on. Harder at the base, hollow towards the top.

Hopefully it’s just a balance issue, you may want to get a balancer on the pack to keep from having any more issues

 

[chilly2]

Hopefully it’s just a balance issue, you may want to get a balancer on the pack to keep from having any more issues

I had a look on Amazon and saw a few. What are your thoughts on these...

https://www.amazon.com/dp/B09ZTB9NL8 - expensive but really nice read out. No reviews.
https://www.amazon.com/dp/B07L8WKKC3 - cheaper with mixed reviews.

I don't mind spending on the pricier one as long as it works but would prefer to save.

ps. all this has me thinking I should have just saved up for an EG4 LL type battery.

 

[OTRwSolar]

With 4 separate batteries (and 4 BMS's) in series, there's lots of potential for imbalances (and other assorted problems) to occur.

*IF* the warranty claims fall-thru, I wonder if you'd be better served (long-term), opening up the battery cases, removing/disconnecting the (4) 4s BMS'S, wiring all 16 cells in series, then installing a 16s BMS??? Just brainstorming here.

This way you'd be able to monitor the individual cells, plus install an active balancer (16s Heltec 5a Active Balancer - $60-$65). Right now you're operating blind, with no quick, efficient way to resolve imbalances.

 

[chilly2]

With 4 separate batteries (and 4 BMS's) in series, there's lots of potential for imbalances (and other assorted problems) to occur.

*IF* the warranty claims fall-thru, I wonder if you'd be better served (long-term), opening up the battery cases, removing/disconnecting the (4) 4s BMS'S, wiring all 16 cells in series, then installing a 16s BMS??? Just brainstorming here.

This way you'd be able to monitor the individual cells, plus install an active balancer (16s Heltec 5a Active Balancer - $60-$65). Right now you're operating blind, with no quick, efficient way to resolve imbalances.

It's certainly something I can consider. I'll have a look at that BMS.

I wonder, does this happen regardless of the battery form? By that I mean if you have 4 rackmount batteries that can talk canbus / rs485 to each other do they still have the same problem, or is it only open loop / isolated batteries that have the problem?

I will admit I thought when the battery instructions said 'just connect them in series / parallel up to 4 deep' that they would manage themselves. Wishful thinking eh?

 

[MisterSandals]

I will admit when the battery instructions said 'just connect them in series / parallel up to 4 deep' that they would manage themselves. Wishful thinking eh?

It requires the 4 batteries to be nearly identical in capacity and resistance. How well matched were your 2 pairs of batteries?

 

[chilly2]

It requires the 4 batteries to be nearly identical in capacity and resistance. How well matched were your 2 pairs of batteries?

They were the same model ordered from the same supplier over the space of 4 months. Ideally they should have been purchased together but I couldn't afford it at the time.

https://www.amazon.com/gp/product/B09F2LLMY3

 

[chilly2]

The 10.57V battery let me charge it back up. It actually made it to 104AH and is resting at 13.64v. Working through the others.

 

[rodrick]

I had a look on Amazon and saw a few. What are your thoughts on these...

https://www.amazon.com/dp/B09ZTB9NL8 - expensive but really nice read out. No reviews.
https://www.amazon.com/dp/B07L8WKKC3 - cheaper with mixed reviews.

I don't mind spending on the pricier one as long as it works but would prefer to save.

ps. all this has me thinking I should have just saved up for an EG4 LL type battery.

The second one has a couple of different labels it’s sold under, the biggest complaint is is the noise they make both seem to work ok and will help solve your problems, if you want to have a display your cost is going to be higher but may be easier than using a dmm to check each battery

the option of building a 16s battery out of these is a good option if the balance unit doesn’t work matching battery voltage to system voltage is always the best way to go it eliminates most of the problems you have with series’s batteries you will have 1 bms watching over the battery and balancing the cells as one unit and you will have Bluetooth monitoring of the battery, just a thought you might consider

 

[sandyponce]

I had a look on Amazon and saw a few. What are your thoughts on these...

https://www.amazon.com/dp/B09ZTB9NL8 - expensive but really nice read out. No reviews.
https://www.amazon.com/dp/B07L8WKKC3 - cheaper with mixed reviews.

I don't mind spending on the pricier one as long as it works but would prefer to save.

ps. all this has me thinking I should have just saved up for an EG4 LL type battery.

Did you ever get that battery balancer? I am having similar issues as you with four chins 12.8v 200ah and was looking at a similar digital display balancer but cannot find any reviews on it. I also considered opening the batteries and making one 48v but I am afraid my skills are limited to do so.

 

[chilly2]

Did you ever get that battery balancer? I am having similar issues as you with four chins 12.8v 200ah and was looking at a similar digital display balancer but cannot find any reviews on it. I also considered opening the batteries and making one 48v but I am afraid my skills are limited to do so.

I didn't yet, as after balancing them with full charge, etc they seem to have recovered. There is a YouTube video on the cheaper one. The guy doing it said it worked for him.

 

[sandyponce]

I didn't yet, as after balancing them with full charge, etc they seem to have recovered. There is a YouTube video on the cheaper one. The guy doing it said it worked for him.

I did balance mine the first time I connected them. But after a few months they were off again. I did it again about a week ago and so far they are holding within a .10 volt diference. I hope they keep that way longer this time.
Thanks for answering!