Rev Electric problems , dead cells and no shelf life ????

I bought a 5s and 4s pack about a year ago or so and ended up shelving them. About a half year ago or so I noticed the 5s pack puffed . I reached out to Steve @ OSE and he told me to send it back to him . Anyway I got busy with life and never did send it . Now I finally have time for boats and trying to get back to the hobby . I know there was a issue with my 5s pack but now the issue is with the 4s. 4s pack reads zero volts!! ... I thought Lipo’s could be stored for several years with minimal deterioration like my Zippy’s that have been battlefield tested and why they may not be as powerful as the Graphin type they don’t crater when not in use as I have noticed putting them into service from a year of sitting on the shelf and then back to the shelf , they seem like the perfect battery for somebody who is off and on with the hobby. Now the Graphin 4s pack seems totally dead and not puffed while the 5s Graphin pack is talking a different language that my volt tester, I mean when I reached out to OSE with the dead cell issue on the 5s he said send it back , but I didn’t just because I got caught up with life . I don’t really care about a refund or an exchange, I just need to know the skinny on the shelf life. For all I know these are really good pack and I ruined them by not using them . All my 8000mah 30c zippy packs are fine. Thank you for the comments Attachment 162867Attachment 162868Attachment 162869

Your suppose to keep your packs at storage voltage which is 3.8 to 3.9 Your packs are at 3.3 which is 100 % discharged so that's why they puffed. Lipos use to hold there voltage better when they where 20c or less. Todays lipos are more robust when it comes to discharge but need to be checked for cell voltage about every 6 months or less because they self discharge at a slow rate. At 3.75 a lipo is 80% discharged. You never want to go below that. If you do when you run your boat, charge it back up as soon as possible. Lipos degrade when left at full discharge or fully charged. Ideally you want to charge no later than the day before you go run. After your run, you need to check your cell voltage and see if it needs to be charged back up or not. Most chargers today have a storage function that will either charge or discharge your pack until storage voltage is accomplished. Hope this helps.

Mark

Yes that helps Mark , thank you ! Not the first time I have been at fault for ruining my own stuff lol

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Originally Posted by MarkF

At 3.75 a lipo is 80% discharged. You never want to go below that.

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Hi Mark , I just picked up 4 2600mah 65c 4s packs. I charged all 4 packs on my parallel board and then discharged all of them down to 3.75 volts with the Icharger 306b and 5400mah is all that came out of them , does this sound right ? The cells where all perfectly balanced at the end of charging and discharging. 1350mah capacity per pack doesn’t seem right to me although my 30c 8000mah 4s Zippy pack showed 3600mah capacity using the same charge and discharge method, I can’t tell you how many times I have put over 5000mah of charge into this pack. Am I missing something? All packs were about 55F Thanks Mark

I think it's because your parallel charging and discharging. If you want to figure out how many mah are in the pack, then you need to charge and discharge separately. You want to discharge at .5 an amp down to 3.7 if looking for mah. Keep in mind that your mah go down as the pack gets used and ages. And don't expect to see 2600 mah when you check. If you get 2500 + with a new pack that is normal. It is not good to leave your pack at 3.7 for long periods. Charge it back up to storage after you run your test.

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Originally Posted by MarkF

I think it's because your parallel charging and discharging. If you want to figure out how many mah are in the pack, then you need to charge and discharge separately. You want to discharge at .5 an amp down to 3.7 if looking for mah. Keep in mind that your mah go down as the pack gets used and ages. And don't expect to see 2600 mah when you check. If you get 2500 + with a new pack that is normal. It is not good to leave your pack at 3.7 for long periods. Charge it back up to storage after you run your test.

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Thanks again Mark !

It is also worth noting that you do not want to keep them in the garage (although that often is the most convenient place to store them).
LiPo batteries do not like the cold.
Some packs still run perfectly fine with some small amount of puff, however I always keep my packs in a LiPo fire safe bag to be safe.

-Liberty