My ReLions failed stranding the wife
 

And boy was she not happy.

2 batteries she left at 75% charged, she said they died when it hit 50%. The LEDs indicated Under Voltage protection. Towed her home SUV and put it into charge. Fuel gauge indicated two batteries 0% charge !!!

Been charging for a few hours and almost full… have a call and txt into tech support…..

I guess I should check individual voltage when not charging ??

Lou

Re: My ReLions failed stranding the wife
 

Tech support had me reset the BMS because they must have gotten out of sync… doing a full charge and will do some tests Tuesday.

Re: My ReLions failed stranding the wife
 

You have out of balance cells. Do have 48v batteries or multiple 12v batteries. If they’re 12v, then that’s your problem.

Cheers
Pat.

Re: My ReLions failed stranding the wife
 

Multiple batteries in series without a BMS managing all of them together is a very bad design that causes all sorts of balancing problems in the long run. It works with FLA batteries because the charger overcharges the batteries and keeps them top balanced. You can't do that with Lithium batteries. The BMS has to keep them in balance and it can't do that unless one BMS has control of all of the cells in the battery.

Re: My ReLions failed stranding the wife
 

Two 48v LiON in parallel with a BMS in each that talk via a CAM network.

I reset but not sure that is it..

Re: My ReLions failed stranding the wife
 

That's a different scenario and shouldn't result in out of balance cells. Individual voltages should be identical as they are in Parallel. It could in fact be a BMS issue or your SOC meter being out of calibration.

Most SOC meters will reset to 100% after a full charge and this is required to give the Coulomb based SOC meters (a must for LiFePO4) a starting point as they will drift over time. Have you completed a full charge recently? Also, when left for prolonged periods, SOC meters will loose count as they will not pick up inherit charge loss or power consumed by the BMS. A full charge will solve both of these problems.

Cheers
Pat.

Re: My ReLions failed stranding the wife
 

He says that each pack has separate BMS so they are not really in parallel. Only the total packs are in parallel not each individual cell.

Re: My ReLions failed stranding the wife
 

We full charge when we hit 70 or so percent on the fuel gauge… working with ReLion to see what’s going on.

I like to report here in case other run into it

Re: My ReLions failed stranding the wife
 

Which one of the other six was she....Grumpy ??

Re: My ReLions failed stranding the wife
 

Hi Volt_Ampare,

I understood but re-reading my post, I realise I could written it a little clearer.

What I meant to say is that the individual PACK voltages should be identical as that are in parallel, that is providing both BMS’s are enabled of course.


@Lou,
As to only charging to 70%, you may have a bad cell that is tripping one of the BMS’s. How is your SOC meter connected? Is it a voltage type, coulomb counting type or is it integrated with the pack? If it’s the latter, how does it handle the fact that there are 2 packs? It could be that it’s summing the capacity of both packs, and you have one pack charging fully and contributing 50% to the SOC but the other pack trips off early, only charging to 40% and thus only contributing 20% to the SOC. If that makes sense.

A similar thing could be happening during discharge, reducing the overall capacity.

Although not as bad as series connected packs, parallel connected packs can also be troublesome. This is why I always recommend a single pack with a single BMS. Parallel connecting at a cell level with a single BMS is the correct way to increase capacity.

Cheers
Pat.