Battery problem

[Jost]

A little background: I've been working with lipo batteries for some time but in the r/c modeling hobby. The 18650 batteries seem very similar from what I've been reading so I believe I have a problem with my new battery pack.

I have a store bought e bike that uses a 48v dolphin pack with a little over 11ah. Reading about these systems and comments by others with this bike indicates that the controller can handle a 52v pack. I purchased such a pack and was delivered yesterday. My plan is to have the 48v pack as a back up but also as a pack for my recumbent build (looking at the ezee geared, ca3 etc from Luna). The new pack is 52v 13.5ah ga dolphin pack.

No damage to the box it came in. The battery looks fine from the outside. Before starting the charge, I checked the voltage of the pack and it was slightly over 31v. I realize these batts are not the same as my r/c packs but I don't believe, from my reading, that this pack should be that low. I plugged in my Luna charger and monitored the charge. After 3hrs, it had come up to a little over 41v (this measured by stopping the charge, unplugging the connector and checking with the dvm).

However, I was out of time so did not plug the charger back in. This morning, I was going to continue the charging but it measured just over 29v......did not continue the charge. It appears I have a rather expensive paperweight. Before contacting the vendor, I just wanted to check in with the group and confirm I'm not missing something that I could do to bring this batt up to proper voltage. Also, if that can be done, can I expect this batt to have a normal life span (my bike, this was planned for, is a cruiser type commuter and the system is not pushed hard (I've had the bike for several months and do not nor want to hot rod ride this rig)).

Appreciate any insight you can provide.

Thanks,

Jim

 

[dogman dan]

Self discharge sounds like a defect to me.

 

[Jost]

Thanks for the reply.

I've contacted the vendor, fingers crossed......

Jim

 

[Jost]

The vendor responded quickly by email and is indicating to go ahead and charge it longer to see if it will come up. I'm concerned that even if I can bring it up, with the symptoms it's exhibiting, will I be able to expect normal performance and life span?

I'm new to this version of lipo batts (if any of my r/c hobby batts were having these problems, they wouldn't go into a model but would be taken out of service): For these bike packs, I only charge to 100% every 7th or 8th charge (it's my understanding that the bms won't be able to balance unless charged to 100%). The normal charge is to 4.05v per cell. I only use 80% or less capacity (usually 60-70%). With this regimen, I believe I'm treating these batts correctly for maximum longevity, please correct me on any details I might be doing wrong.

Thanks for your help,

Jim

 

[OptimusPrime]

I wouldn't trust that thing in my house! Charge and store it in your barbque grill! Regardless of what happens those cells have been seriously stressed. I'd insist on a replacement.

 

[Jost]

Tried charging it again yesterday. Same symptoms, got it up to around 45v. Had to run an errand (unplugged charger) and when I returned, it had dropped to 37v in less than an hour. When charging, it was outside and near nothing flammable......

emailed this info to the vendor and am waiting for a reply. If it can't hold a charge with no load, not going to work trying to run a bike.......