# How are your GBS Batteries holding up



## evmetro (Apr 9, 2012)

My pack of 34 200ah gen3 gbs cells is holding up fine. I have my charge limit set for 3.4, and my discharge limit set for 2.8 with a 5 second timer delay. I suspect that more aggressive settings would be fine, especially the charge limit.


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## Ben Modified (Nov 3, 2013)

thanks for responding. so your charger shuts off at 3.4? Do you find that you quickly burn off a surface charge? if so, what do they quickly drop to? My bms (elite) allows the charge to reach 3.60 to 3.75, depending on the cell. A quick trip around the block will drop those reading to 3.32-3.36 After a few miles the number are all within .02 of each other at rest. I just switched from AGM's and it seems that the gbs batteries are much more vague. With the AGM's I always knew which battery was the strongest, weakest etc. With these it seems that every time I charge the characteristics change amongst the cells. any thoughts?


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## evmetro (Apr 9, 2012)

I set the cutoff voltage on a pc to whatever I want and then download all the profile settings into an Orion bms. I picked 3.4 volts just to be safe, but I am getting ready to try bumping it up a little. At 3.4, they rest at 3.33 as soon as the charger cuts off. I have all 34 cell voltages on screen in my dash, and they do run between 3.0 to 3.25 while I drive. They drop from 3.333 as soon as I start driving. These cells do sag below 2.8 occasionally, but that is why I have the 5 second delay on the discharge limit. I can do bad things with my accelerator, but I know that I only have a few seconds before my BMS settings take over.


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## Ben Modified (Nov 3, 2013)

Thanks so much. Thats very helpful information! Out of curiosity, what kind of range are you getting from the 200ah's?


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## evmetro (Apr 9, 2012)

They may read low and sag more than other brands, but they do give me 100 miles. I was not too excited to have 340 screws holding my bus bars on, but I like how they came in the banded four packs.


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## Ben Modified (Nov 3, 2013)

Impressive range! Thanks again


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## onegreenev (May 18, 2012)

Ben, 

100ah cells will sag more than 200ah cells under load. PM sent.


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## dougingraham (Jul 26, 2011)

Ben Modified said:


> This is my first post. I recently installed 100ah GBS Batteries in my 66 VW Bus. It seems that I have one bad cell. It sags badly on acceleration. A replacement is on order. I would appreciate feedback from people that have had these batteries in use for more than a year or so, to see how they hold up long term. Also, what charge and discharge limits you are using.
> 
> Thanks
> Ben
> http://www.diyelectriccar.com/garage/cars/454


Ben, PM sent.

With a bottom balance I have had no issues with these cells. I charge to 3.5 volts per cell limit and as I mentioned in the PM I have set the sag limit to 1.6 volts per cell due to operating at temps of as low as 16 degrees F. I have run the car to a standstill once without any issues. Something you never want to do with a top balanced pack. You will lose cells if you do. (I was half a block from home when I did this.)

It may be that your cell is fine. You might want to swap cells to verify that there is nothing wrong with the BMS monitoring that cell.

You mention that the cells are vague. They should be very similar until they get into the CV portion of the charge. Then yes they wander all over. This is why you cant accurately top balance during the CV portion of the charge. The diffusion delay makes this unreliable. The voltage ceases to mean much of anything once the it goes above about 3.45 volts.

Hope that helps.


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## Ben Modified (Nov 3, 2013)

Thanks for the information! Glad to hear that they are holding up.


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