I use battery power for my large scale locomotives. 4 pack Lipo cells charging using a Tenergy balanced charger/discharger. Occasionally I will get the “connection break” error message. So contact cleaner on the connections will help. But what does it mean if the charger has already started in the charge cycle and has been charging for several minutes and then the “connection break” message occurs? Contact cleaner and restarting the charge cycle and in about 2 minutes the error message occurs again. Does this indicate the battery pack is getting faulty and should be replaced?

I have an older LiIon pack that does th same thing. I think that means it’s toast - but if I put it on the dumb charger it will cycle back and forth between charging and full =for several hours, then eventually be usable, but the capacity is reduced. My guess is that the protection circuit is breaking the connection for some reason.

Thanks Jon. My thought was the pack needs replacing but not sure. I also thought it might be the charger? But then it doesn’t happen on all battery packs

thanks again for the response

Chuck Agonis said:

Thanks Jon. My thought was the pack needs replacing but not sure. I also thought it might be the charger? But then it doesn’t happen on all battery packs

I’ve seen similar events, especially on the packs I make myself. The protection circuits seem to fail and do all kinds of weird things.

But sometimes it’s the charger. My pal gave me 2 packs that wouldn’t charge on his fancy charger, but they charge fine on mine! I suggest trying a different charger, and a different protection board.

It might be interesting to leave a voltmeter on the charger output, and see if the voltage varies when it says connection broken.

Are you using the balancing connections?

Greg

I suspect the multiple comments shared above have more to do with suspect cells than PCB’s and or chargers. In my experience with Lithium-Ion batteries. a single cell acting-up is the typical problem herein. The PCB reacts to over-under voltage thresholds at the least. Battery protection ICs typically use MOSFETs to switch cells in and out of circuit. Fancy and or smart chargers look at individual cells (if connected for balance charging) and or the battery/cells combined voltage, internal resistance and more. Accordingly cells that are suspect skew a monitored threshold and the charger recognizes a connection error, (said “connection error” is the result of the PCB opening the circuit). The charger may also shut down due to realizing voltage/current/time thresholds.

In short if your able to rejuvenate a battery with a dumb charger, that a smart charger has issue with, suggests at least one bad cell is in play. Rejuvenating a problematic battery will inevitably result in a capacity reduction.

I’ve shared in previous posts over the years that single cell Lithium-Ion failures are not unusual and typically overlooked or ignored in batteries. Multi-cell batteries wired in parallel and especially high capacity batteries with sets of cells in series-parallel configuration to gain higher mAh ratings often have a suspect cell unbeknownst to the user. Load testing batteries will divulge this anomaly (accomplished by recording the static voltage and subsequently applying a two Amp load and noting the voltage therein). Generally the voltage will drop some, if the voltage drops sharply and or the volt meter goes blank and recovers after the load is removed, you have a problem. Smart chargers with cell balancing features, together with batteries with cell balance pigtails will monitor/expose a suspect cell while under charge.

Michael

Yep, I agree, that was the path I was headed down, I suspect a cell.

Greg

Mike and Greg,

thanks much for the input and insight. You have given what to focus in on

thanks again——much appreciated

chuck

We could be wrong, but I’d exhaust that possibility first.

Greg

removed

removed too

Michael Glavin said:

I suspect the multiple comments shared above have more to do with suspect cells than PCB’s and or chargers. In my experience with Lithium-Ion batteries. a single cell acting-up is the typical problem herein. The PCB reacts to over-under voltage thresholds at the least. Battery protection ICs typically use MOSFETs to switch cells in and out of circuit. Fancy and or smart chargers look at individual cells (if connected for balance charging) and or the battery/cells combined voltage, internal resistance and more. Accordingly cells that are suspect skew a monitored threshold and the charger recognizes a connection error, (said “connection error” is the result of the PCB opening the circuit). The charger may also shut down due to realizing voltage/current/time thresholds.

In short if your able to rejuvenate a battery with a dumb charger, that a smart charger has issue with, suggests at least one bad cell is in play. Rejuvenating a problematic battery will inevitably result in a capacity reduction.

I’ve shared in previous posts over the years that single cell Lithium-Ion failures are not unusual and typically overlooked or ignored in batteries. Multi-cell batteries wired in parallel and especially high capacity batteries with sets of cells in series-parallel configuration to gain higher mAh ratings often have a suspect cell unbeknownst to the user. Load testing batteries will divulge this anomaly (accomplished by recording the static voltage and subsequently applying a two Amp load and noting the voltage therein). Generally the voltage will drop some, if the voltage drops sharply and or the volt meter goes blank and recovers after the load is removed, you have a problem. Smart chargers with cell balancing features, together with batteries with cell balance pigtails will monitor/expose a suspect cell while under charge.

Michael

Michael, thanks for taking the time with a very informative post. I now have a better understanding of why the battery in my USAT GP9 only lasts only 30-40 minutes after a full charge. Just ordered a new Airwire 14.8V 6800 mAh Lilon battery and we’ll see what happens now. I knew it couldn’t have been the original incandescent bulbs draining it that fast! Nice name by the way…