How to Prolong eMTB Battery Lifespan

[MattyB]

That’s probably why the manual says charge to 100% and leave it overnight...expedience or KISS.

A cynic such as myself might suggest it is really not in the interests of the manufacturers for customers to understand how to treat their battery or integrate stuff into the chargers and BMS to help them manage the SOC effectively.

 

[wepn]

A cynic such as myself might suggest it is really not in the interests of the manufacturers for customers to understand how to treat their battery or integrate stuff into the chargers and BMS to help them manage the SOC effectively.

I can see why you’d possibly suggest that…the thought crossed my mind too. But I really did quickly dismiss that idea. With 2 year warranties, simple charge modes are likely to reduce warranty costs & increase sales with reputation & reliability obviously being major sales drivers.

There are very few manufacturers who have been in the business of building electric bikes for very long. I think the few survivors have avoided the massive electric bike corporate graveyard by focusing on reliability, service & reputation as much as they have on bike design & engineering.

Many of those that have focused on profit or have simply sought rapidly increasing cashflows to pay down large corporate loans have ridden off down that Olde Cemetery Road. Spesh know this & it shows in the quality of their dealer service network.

That’s why I think the concept of not introducing even more complexity may be the more likely rationale. If that’s so, logic says to me that simplicity can still be achieved with a straight forward & effective UI design. That would be something like 3 modes of SOC - charge level - and 3 modes of current - charge speed . Easy, intuitive operation wouldn’t be difficult to achieve.

 

[Zimmerframe]

I met an old boy out on the other trails the other day. He said he had a matra e-bike which was 12 years old. The battery wasn't any good now and would only do a couple of miles. He'd spoken to matra about getting a new battery. Unfortunately, they couldn't supply a replacement battery, only a replacement motor and battery, but that was €1200. So he was going to stick to short rides. I'm guessing if the bike was that old, it was probably hub motored, so he could buy a whole new hub motored bike for the same money.

 

[Binhill1]

So is it ok to leave overnight before recharging, I came in 2pm washed bike 4pm sometimes I charge to 70 sometimes I leave it till morning. As Maureen keeps saying this bike is taking over your life Colin heelllp

 

[MattyB]

So is it ok to leave overnight before recharging, I came in 2pm washed bike 4pm sometimes I charge to 70 sometimes I leave it till morning. As Maureen keeps saying this bike is taking over your life Colin heelllp

Of course you can leave overnight before recharging. The only time you need to charge relatively quickly afterwards is if you completely flattened the pack, but even then Li chemistry batteries have very low rates of self discharge and the BMS will leaving it at a safe storage level anyway (it isn't really fully flat). Probably the safest option if you do flatten it though is to pop it on the charger for an hour after you get back, just in case you did forget in the morning and then did not ride for some time.

 

[MrSimmo]

Late to the party on this. If its any help to anyone, I've got one of these where I store my emtb. Works a treat, I leave the charger plugged in all the time and when I get home from a ride, I plug in the bike then press the button on the unit to set for an hour or two which usually takes it to around 70-80% charge. If I want to go for 100% than I just press the button to set for 8 hours. Nothing more prescriptive, for me its a bike at the end of the day so spending too much effort/time doesn't reap the reward but for a tenner I couldn't complain.

www.amazon.co.uk/gp/product/B005C9S0I8

 

[salko]

For prolonging the battery life it's not good idea to start charging right after the ride, especially after steep climbing ... Give it at least a hour for battery to cool down before charge ...

 

[CygnusX]

back ground, i have been an RC Racer since 1993, i have gone through countless nicad, nimh, lipo and pb (lead acid) batteries, for the last 6 years, i have worked in a hobbyshop selling and helping customers with their batteries....lastly im a nerd and i like to dig into stuff i dont understand.

first there is no battery that likes to be left fully charged, batteries and or chemistry that say its ok, usually say a full charge is 80% of what the battery is actually capable of.

wife and i both bought pixel 3 phones. She charges hers over night with supplied charger which means its done in about 1 hr and then sits another 7 hrs being kept at 100% with the charger occasionally trickle charging it. she usually ends with draining it to 15-20% .my phone i charge in my car driving to and from work, the charger says 2A but reality is a powermeter said 1.5A, i keep my phone between 20-80% only bumping it up to 100% when i know im going to need the extra juice. after 1 year my battery had 96% capacity, and hers was 81% ....these batteries are not made for high peak discharge, but rather a steady discharge.

the lesson from years of RC, computers etc.:

*no lithium battery likes to be fully charged for longer periods of time. most are ok for a couple of days, especially since bikes uses a safer chemistry than RC cars, i have seen laptops, phones, tablets, RC batteries loose capacity rapidly from being left at 100% charge.

*Batteries dont like it hot, luke warm is about it, any hotter and they start to deteriorate

*Batteries dont like freezing temps. ice crystals can mess up the insulator, once in use the battery will heat up enough that using it in freezing temps is ok, but at diminished capacity (temperature affects internal resistance of the battery so voltage sag when cold is more pronounced than when its warm)

*Batteries dont like to be discharged too far, taking it down to 3V repeatedly will shorten life

*lipos today dont mind fast charging, in RC we often charge a 5Ah battery at 15-20Amps (4C charge rate) and batteries seem to deal with this just fine, when in cylinders and packed together the charge has to be slower as not to build heat among the 40 cells inside the battery, so i get why they only charge at 4-5Amps...slow charging also give the balancing circuitry a better chance of balancing the cells and get a fuller charge
*the high discharge batteries i got for flashlights etc INR chem say 0.5c to 1C charge rate, that means a 5000mah battery should be charged between 2.5 and 5A, my 20Ah battery should theoretical be able to handle 10-20A charge

the recommendation from just about all makes of lithium batteries is .:
*keep battery between 20-80% charge (Tesla does this) and it will last MUCH longer than a battery thats used 0-100%
*keep at room temp (Tesla's have battery coolers that work even when car is off)
*never leave fully charged for long periods of time (some variations do better than others)
*never leave a discharged battery for long periods of time, it will self discharge into an unrecoverable state
*for long term storage charge to 70% but still use it every 3-6 months
*slow charge gives BMS more time to balance the pack out
*allow battery to cool before charging

 

[Tooks]

I agree with a lot of what has just been posted, some of it accurate and sensible advice, but I would add the following.

Everything wears out, batteries included, it’s the cycling of batteries that ultimately kills them.

The BMS is also there to take care of some of the stuff, so you don’t have to. It should not be possible to over discharge an e-Bike battery, nor overcharge it. There is evidence that charging repeatedly at high C rates does degrade battery packs more quickly, but whether that’s noticeable or not over the average life of an e-bike I doubt, and anyway the supplied chargers are usually well below 1c.

My background is not dissimilar with regard to RC stuff and I’m on my third electric car. The Tesla example isn’t typical of most EVs by the way, they do allow the traction battery to be 100% charged and used, whereas most EV BMSs keep a top and bottom buffer automatically to try and extend the life of the battery. 8 years or 100k miles is the typical warranty period for an electric car battery pack, I think it’s fair to say that most bicycle manufacturers don’t warranty their batteries for any longer than they have to!

I think we need to be careful not to overplay the requirements of looking after an e-bike battery. For most regular riders, charging just before they go out for a ride, chucking it in the shed on return at 20-30% charge and then repeating as necessary should be perfectly fine.

Whilst e-Bikes are great, we shouldn’t be making excuses for poorly designed and implemented battery and charging systems.

 

[CygnusX]

I think we need to be careful not to overplay the requirements of looking after an e-bike battery. For most regular riders, charging just before they go out for a ride, chucking it in the shed on return at 20-30% charge and then repeating as necessary should be perfectly fine.

Whilst e-Bikes are great, we shouldn’t be making excuses for poorly designed and implemented battery and charging systems.

i agree....my personal use i try and stop charge at 80-90% (hard to know with 20% increments ...5 led's) my bike came with 20Ah battery, to get that capacity i think they use 21650 cells (40 cells in groups of 4 to get 10S) and they top out at 5Ah capacity, which leads me to believe that bulls runs their packs from 0-100% with no buffer other than it might turn off the last led at early to try get the user to stop before it hits voltage cutoff

im certain their BMS has low and high voltage cutoff.

i take the battery out of the frame currently, as the garage gets crazy hot over the summer here in california, and i had a couple of rc batteries go bad even though i followed my own rules, so its down to a bad batch or heat, and given the batteries where from two separate orders i suspect the heat killed them