Internal resistance

[swarls]

So yesterday my cnhl battery I bought on the black Friday sale finally arrived. On arrival I checked their internal resistance pretty much immediately and it looked pretty good, 1-3 milli ohms per cell. So I charged them and everything looked fine (cells perfectly balanced) and went for a small bash. When I got home I checked the battery again and realized one of the cells wasn't discharged as much as the others (like 0.1 volt more then the rest). So I checked the internal resistance once again and to my surprise, one of the cells (not the one with more volts) has a internal resistance reading of 33. Did some more measuring and it was all over the place, every other measurement one of the cells had a high internal resistance. Put the pack back in storage charge in the hopes that it would help, but it's still the same. Tried both channels of the charger (skyrc ultimate D260), with balance board or directly into the charger and the readings always were all over the place. Never had this issue before, tried another pack and the readings for that pack are not consistent either (yet not as bad as with the cnhl one..).

So what do you guys think about this? Faulty pack or faulty charger?

Already contacted cnhl about the issue, but I don't expect an answer till Monday, so I thought I'd ask you guys for help..

Thanks!

 

[Diem Turner]

Sounds more like it's the charger to me. If it were just the one pack that was doing it, I'd say it's the battery. But since you're observing the same behavior on different batteries, I feel comfortable saying that it's the charger. I assume you don't have a second charger, otherwise I'm sure you would have tested it. Do you have a friend with a charger just to verify that the batteries are alright?

 

[swarls]

Sounds more like it's the charger to me. If it were just the one pack that was doing it, I'd say it's the battery. But since you're observing the same behavior on different batteries, I feel comfortable saying that it's the charger. I assume you don't have a second charger, otherwise I'm sure you would have tested it. Do you have a friend with a charger just to verify that the batteries are alright?

Yeah, I'm also leaning more towards the charger. But since the reading on the cnhl pack go ridiculously high and the other pack does not, I thought I'd ask you guys for your opinion.

The only other person I know that's into rc is my brother, but he lives quite far away. Might ask him to bring along his charger when we meet at my mom's for Christmas. But would love to know whether I have a ticking time bomb at my place or not a bit sooner than that..

 

[Diem Turner]

Yeah, I'm also leaning more towards the charger. But since the reading on the cnhl pack go ridiculously high and the other pack does not, I thought I'd ask you guys for your opinion.

The only other person I know that's into rc is my brother, but he lives quite far away. Might ask him to bring along his charger when we meet at my mom's for Christmas. But would love to know whether I have a ticking time bomb at my place or not a bit sooner then that..

Understandable. Leave it at storage voltage for a day and see if there's any noticeable drift in terms of voltage. If the voltage holds steady you should be fine.

 

[Hector_Fisher]

I agree with @Diem Turner, need another charger to check out now. Internal resistance doesn't just randomly vary up and down. It fluctuates slightly with voltage but otherwise usually should be constant, and very slightly increasing over time and use.

Definitely need a second-opinion from another charger on this one.