Unanswered Battery Maintenance

[pollywaffle]

Ok, so the nerds at endless sphere always talk about never charging your battery to 100% because it shortens its life. Conventional wisdom from NASA studies say you should only charge your battery to 70-80% and try to never run it below 20% and certainly not to zero percent. It also says to keep your battery around 50% for storage and even overnight.

On the other hand, EMBN on youtube tell us to charge your battery up to 100% after every ride but to let it cool down after a ride before you do this. They also say manufacturers say to charge up to 70% for storage.

Personally, if I know I am just going to smash out a few laps on my next ride I will store my battery at 50-60% and charge it up to around 80% before the ride. I only really fully charge my battery if I am commuting 20kms to my next ride.

However, Shimano reckon their batteries are good for 1000 cycles so if you fully charged it four times a week it would still last four years (tho I think it only puts out 300wh at that point). That's more or less the life of a well (ab)used bike I suppose.

I am wondering what others do and their experiences, especially those who have ridden ebikes for a few years.

 

[All Mountain Coaching]

I just use it. Charge it fully because I need the range, ride as much as I can. Leave it as is or leave it on charge. Life is too short to worry about it.

 

[flash]

The figures you quote (NASA) are for a LiPO cell that has no attached BMS.

You can't overcharge or over flatten your battery if you have a *normal*, ie: store bought, ebike. The inbuilt BMS sorts that out (Many home built systems do NOT have batteries with a BMS but if you own a Brose, Yamaha, Shimano etc, you do). When your motor turns off the battery has around 3.4 volts per cell left. You'd need to get to around 3V per cell to kill the battery. 4.2V per cell is fully charged. The figures you quote (NASA) are for a LiPO cell that has no attached BMS. Your bike battery is LiFe4PO and has a robust BMS built in to prevent the issues you mention. And that enormous brick is a smart charger. You'll be fine just charging your battery when it suits unless you're not riding for more than a couple of weeks. The smart cahrger and BMS will keep your battery in good health.

Charging to 100% is fine as the BMS will prevent overcharge. LiFe4PO batteries are much more stable and safer than LiPO batteries. You can safely leave them fully charged for several days. Storage of 70% is correct but not absolute. Between 55 and 80% should be fine. Some sophisticated BMS units (not on bikes yet as far as I know) will automatically drain a full unused battery to storage state after a set period of time. Usually this is about a week to 10 days for the ones I know of.

Usually I put my bike on charge the night before a ride. But sometimes I have a fully charged battery for a week. It's not a huge issue. I'm travelling for three weeks from tomorrow so I took between 1 and two bars off each of my Shimano batteries on the last ride.

Gordon

p.s. Only some of the information EMBN presents about batteries is accurate. They've made some glaring errors in the battery advise they present.

 

[eBikeLife]

I think you should not worry about this issue. My battery (and most others) got minimum 1000 charge cycles on them, and anything more than that is a bonus.
The fact is that if you charge your battery only 80% and dont use it when it hits only 20%, then you will never really enjoy many of the benefits of the bike, that is long rides in mountains, woods or whatever you prefer.. Because you will always be stuck with a battery that you only use 60% off.
Live the dream, go for wild rides, and forget about the battery.

 

[pollywaffle]

Gordon
.

Thanks Gordon! That’s exactly the sort of info i was hoping for.

I crashed badly on an aftermarket bbshd and installed a Bluetooth bms to replace the damaged one in the battery pack just to discover that one cluster of cells would only charge to 3.4v while the rest were at 4.2v. Tried charging the low cells individually but they wouldn’t hold 4.2v for very long so retired that pack. Bought a new pack and later a commencal.

Edit: EMBN and the whole GBN etc is really just paid advertising at the end of the day. Don’t get me wrong they present some great stuff but they are advertising for their numerous sponsors too.

 

[Pdoz]

For perspective, these batteries cost about as much as a decent mobile phone. Do we get fussy about charging our phones?

 

[pollywaffle]

For perspective, these batteries cost about as much as a decent mobile phone. Do we get fussy about charging our phones?

I am the first to complain when my mobile phone battery starts to degrade.

After 1000 cycles my shimano battery will only be 300 watt hours instead of 500. That’s a massive loss in range.

 

[sam.spoons]

I think you might find that your battery is better than that after 1000 charge cycles, Shimano warrantee that your battery will still have not less than 60% capacity after 1000 cycles so yours may well have considerably more at that point (this has proved the case with EV batteries which have been around for considerably longer than mainstream eBike batteries).

 

[RiderOnTheStorm]

If you're interested in battery maintenance and best practices to extend your battery lifespan, take a look at this other thread which covers this topic quite extensively:

Do's and Don'ts for e-bike battery care. What do you do to keep your battery performing at its best?

What is your experience and recommendations for taking care of your lithium-ion batteries and maximize their lifespan and performance? What do you do to keep your ebike battery in top shape? Over the years, I wrote down a few best practices and made the list below. I'm interested in your...

www.emtbforums.com

 

[Getitright]

I just use it. Charge it fully because I need the range, ride as much as I can. Leave it as is or leave it on charge. Life is too short to worry about it.

From what I have read elsewhere:

• Do not store the battery fully charged or in a low state of charge. Around 60% is ideal.
• OK to part charge.
• Fully charging occasionally helps maintain cell balance.
• Deep discharge (below 20%) can shorten battery life.
• If you let the charge level drop below 20%, you risk the battery protection system shutting down. For example, if you increase power going up a hill and the voltage sag under load pulls the battery voltage below the allowed minimum, everything will shut down until you reduce the load and the battery voltage recovers.

I tend to fully charge the night before a ride but, i there is plenty left, I'll do a second or even a third ride before charging.

I wouldn't get to obsessed with this. If you follow these rules most of the time, your battery should have a good long life. It's more important to enjoy riding than to try and eek out the last few charging cycles before replacing the battery.

 

[E Bob]

So full charged best, but low to 60% ideal, just not as low as 20%..... iv fully charged all my batteries some times left on all night, go out next day and completely flatten... Still no issues with any batteries.
Fully Charge them up and fully flatten them, lifes too short...

 

[sam.spoons]

AFAICS here is a lot of confused information about Li-Ion battery care on the web, I'm no expert but a couple of things I've picked up are that storage is safer at 60-70%, higher and there is an increased risk of fire (which is still tiny compared to a petrol powered vehicle) but the BMS will prevent (or at least limit) any damage caused by over-discharge. As E Bob says, life's too short to worry if your battery is going to have 79% capacity left after 500 cycles or 81%, just charge it and ride it and if you know you are going to be storing it for a while leave it at around 65%.