storage of e-bikes/batteries

[Alex728]

Having joined the ranks of those with more than one e-bike, I've decided to keep the Powacycle Salisbury for the moment and use it as a backup or for journeys into town / shopping as the extra power is welcome when carrying stuff back, plus I feel slightly more comfortable locking the Salisbury up in town than I do the Wisper

They are both insured anyway, but I think the Wisper definitely has more "bling" appeal to the less desirable folks..

Whats the best way to preserve the battery on the Salisbury as I am doing less miles on it? (its still in good condition doing 26 miles on a charge). I read on some electronics site that Li-Ion batteries should be stored at 40% charge, but I have got it fully charged at the moment and probably won't ride it again until the end of next week when I have to go into town - will this be OK?

 

[flecc]

Just carry on as you are Alex, as long as the battery is charged at least once every three months it will be ok with intermittent use.

That 40% is often misunderstood and wrongly recommended. It mainly applies to long term cold storage when a battery is out of use for extended periods of months. Then they should be stored at between 20% and 40% charge at as near to zero as practical, but not frozen, a refrigerator is ok. Here's the effect of temperature on lithium battery life, showing the capacity left after each period at each temperature and charge level when stored. As you'll see, the 40% makes less difference than temperature:

The one practical thing you may be able to do with intermittent use is to leave the recharge until before you want to use the bike again, rather than charging it after use and so storing it short term at full charge. If you were able to do that always, it might preserve about 10% of start capacity in any one year.
.

 

[monster]

if you are going to leave it for more than a month you might want to unplug the bms. a number of people have reported dead battery packs (not mfr specific) after leaving them untoched over the winter period. the BMS drains the cells much faster than the cell's self discharge rate.

 

[Mike63]

Hi....do I assume the BMS is the connection between the bike and the battery ?

On my Wisper it would be so easy to disconnect when leaving overnight, Is this advisable ?

.....Mike

 

[Alex728]

The BMS is actually the circuit inside the battery that regulates the current from the charger. It is important as it stops the battery overheating and catching fire when being charged - which was the main reason why lithium-ion batteries took so long to reach the market, having been first evaluated in the 1970s!

It isn't practical or advisable for owners of ready-built bikes to do this, but I think Monster has built his own machine and battery pack.

 

[flecc]

And regardless of the BMS discharge, they ideally should be recharged at least every three months to keep the cells healthy. Leaving them over a whole winter is always risky, despite theory saying they should be ok.
.

 

[Wisper Bikes]

Wintering your battery

Ideally Lithium batteries should be stored with 40/50 charge in them. We recommend simply making a note in your diary and charging the battery for 90 minutes every 8 weeks. Simple but it does help with the longevity of the cells.

All the best David

 

[monster]

ok its probably silly and impractical to sugest people open up their battery and start messing around inside.

what i would suggest though is buying a 7 day timer socket and leave it on the charger on that. every seven days the battery will topped up. plug a "watts up" meter or multimeter into it and monitor the voltage for the first week. make sure the battery is not getting drained through the charger. then you can just set a 7 day top up program and forget about it after that.

 

[Tiberius]

what i would suggest though is buying a 7 day timer socket and leave it on the charger on that. every seven days the battery will topped up. plug a "watts up" meter or multimeter into it and monitor the voltage for the first week. make sure the battery is not getting drained through the charger. then you can just set a 7 day top up program and forget about it after that.

That is actually not a bad idea.

For 12 V lead acid batteries you can get special (intelligent) chargers designed to be left permanently connected. Its the sort of thing that's done with camper vans over winter. As far as I know, neither the standard lithium charger nor the battery BMS is set up for permanent float connection. They will need the power cycling, so I like Monster's idea.

BTW, Matthew, welcome to the forum.

Nick

 

[bode]

I had actually just bought a 7-day timer for this very reason, as we are going away for nearly 3 months during the winter.
What I was a bit unsure about, though, was how long a charge to give the battery each week? It is a 36v 10ah Li-on.

 

[monster]

one hour should do. your charger won't over-charge the cells. probably only needs ten minutes though.