Jam battery deterioration ??

[OldBean]

My Year 2017 (purchased April 2018) battery will only charge to 4 bars no matter how long I leave it on charge .....2700 miles mostly ridden in Eco mode. used to charge every ride but now allow battery to get down to 1-2 bars .
Somewhere on here it advised to expect 5% drop per year so say its a 3 year bike it would be 15% down but looks more like 20% now could there be a fault ? ?

 

[sdcoffeeroaster]

Well like us the li ion batteries age, lol. 1 bar could mean 85-90% if there is any hysteresis in charging VS discharging but not sure. It's something I've been concerned enough about to make my own DIY TEC pack to lessen the degradation of the battery and avoid full or large charging cycles. With the 2 lb 250 wH extra pack my first 15-23 miles can be on the external pack and then I only use 1 or 2 bars on the main pack. I've had about a dozen rides with the new pack and so far I'm really happy with it. I'm hoping the main pack will last longer this way since I'm not sure how hard it will be to get a battery replacement in the states without Focus out now. My hoverboard batteries in my DIY pack are available all over so no problem there. I just don't see another bike as good or any better than my 2018 Focus Jam2 C so I want it to last.

 

[steve_sordy]

The number of bars may be down, but is the miles of range declared after charging, or even the range you expect on trails you ride regularly?

 

[RCDallas]

Unfortunately it sounds to me like there's a issue with either the cells being way out of balance or more likely, IMHO, there are some dead cells within a parallel group or two preventing them from reaching full charge due to increased resistance in the effected branch/s. When a battery looses capacity it should still charge to the full 42v (4.2vdc per series group), which is what the BMS uses to determine the state of charge. Reaching only 4 of 5 bars would indicates a lower battery voltage at cutoff, which can easily be seen at the battery pos and neg terminals. Anything less then 42v is a sign of a battery going bad, not necessarily due to capacity loss...

There is another possibility which would be a better outcome...the charger might be bad i.e. not able to provide the voltage necessary to reach full charge. That would be the first thing I would try to eliminate as the problem. Do you have a TEC pack to check the charger with or another charger available, a fellow rider with a focus to try?

 

[OldBean]

yes my TEC pach charges fine.