Batt Life. Best Target Voltage before top off for long trip?

Got this eBike with 22Ah 36V battery.
My charger is 3.5 Amps.
I do around 60 km (40 miles) from 41.7V (almost full) to 35.0V (never tried going lower than that yet).

It takes almost 9 hours to charge back to 41.7V which is a pain and can ruin any spontaneous plan to just hop on the ebike and go since I might not have time to wait that long. Here's my charge graph.



I work long hours.
So I charge my ebike in the week-end up to 4.0 VOLTS. It sits like that sometimes for a week or two if I'm really too busy to have the pleasure of going for a ride.
Then, two hours before my trip, I charge all the way up to 41.7V...

Sometimes, I dont have time and cant go bike that day.... So the battery stays there at 4.0 Volts.
Will that hurt the battery at 4.0 V for a week or two, and if I do that strategy for the next 2 years ?

What about you guys ? What level of voltage do you charge to for mid-short term storage. ? You know, that voltage you leave it at before topping off the charge to go on a long bike trip ?
In your opinion what is the best compromise voltage for mid to short term storage ??? (for a whole 6 months storage during winter, I'd just store around 35-36V).

4.0 V too high ?

This is a 10S10P Chineuse NMC Li-Ion battery 22Ah or 26Ah, not sure.... 36V (specs here : https://endless-sphere.com/forums/viewtopic.php?f=4&t=89258#p1310142).

Thanks for the input guys.
Matador

3.92v is the "official" voltage that no voltage related aging takes place. Thats what the US army uses for their items. Its about 60-65% of 4.20v capacity. But chemistries have changed multiple times since that research was done. There is still thermal based degradation below that voltage.

Unless you're so dirt poor that another 3 months extra life
In a 4-5 year life battery makes a difference to you, 4.0v storage in the fridge is fine. (Not intended as an insult if you really are dreading paying for a new battery in a few years time. Apologies if you were offended)

LOL, no offence taken. :lol:
No, I'm not that poor. I'm just a battery enthusiast and want to maximize efficiency and usage to the best.
Truth is, with 22Ah 36V batt, I could just charge up to 3.7V and not run out of just for most of my commutes.
But at 42V fully charged, it feels a bit quicker and has more pep...

3.92 V it'll be then... Today I had it charged to 4.02V for the coming week.

Matador

This is one noticable downside of 18650 cell types.
The difference in performance from 3.8-3.9 v, and 4.2 v cell voltage is much more prominent than other , higher C rate packs.

Your bms should take 5 or 6amp charging rate. Your seller should know. 3.90 should be fine for storage. But would check after 2 months so the bms or you don't have self discharge. I would charge if in storage and cell at 3.5v

Thanks for all the great replies!
Just broke my elbow yesterday when I lost balance and falled from the bike.
Thank god I had my helmet on, but I think I might have a small radial head fracture. If I'm not better tomorrow, I'll go see a doc.... right now my elbow is making my life miserable.

Matador

The pack is 22Ah so why not buy 8A charger.....i charge my 25Ah pack in 3 hours 3.6v to 4.11v with a 8A charger

fal of the bike i hope you get well soon man

Joachim said:

The pack is 22Ah so why not buy 8A charger.....i charge my 25Ah pack in 3 hours 3.6v to 4.11v with a 8A charger

fal of the bike i hope you get well soon man

Click to expand...

You're right Joachim. I think I should save up for a cycle satiatior (a have a 52V BBSHD back in Canada and a 36V Arrow eBike in NYC that I will bring back across the border... Might as well get this awesome charger)

Thank you for the kind words Joachim. My elbow is still swelling. If it's gonna get worst by tomorrow, I'm going for x-rays and medical consult.

Matador