# Battery Talk/Battery Experts thread



## NEPMTBA (Apr 7, 2007)

I spoke with an e bike friend of mine who works in the field and he was talking of only charging you battery to 50 to 60 percent rather than a full charge. His tech was proven to him that a battery charged this way has a longer life than charging to full every time.

He compares this to Tesla's testing.

Now of course this compromises things on the other end if you need to go a long distance...
...so I'm not battery expert just talking batteries here.

Thanks for your time!


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## WoodlandHills (Nov 18, 2015)

Actually tests have indicated that there is little degradation if you charge up to 80%, not 60%. This is inline with my i3: the battery has a lot of headroom so it never gets fully charged, nor does it ever fully discharge.

Your battery management system (BMS) has a low voltage limiter (LVL) to take care of the discharge part, but you have to take care of the full charge part yourself. One thing to think about is how long the battery is resting at 100% charge: the longer it sits at 100%, the more chemical changes occur within the battery that degrade performance. If you charge to 100%, but immediately go for a ride, you will see almost no measurable change in battery life. On the other hand if you are in the habit of keeping your bike at full charge, ready to ride at a moments notice, battery life will suffer in proportion to how many hours it sits at 100%. 

A 90% charge is a good compromise, if your charger allows it, as is using a slower rate for smaller packs, 4a for 10/15ah packs as opposed to 6a for 20+ ah packs, for instance. I leave my packs either at 80% for longer storage, or at wherever they are run down to at the end of the day, then they get charged at the last minute before I leave to ride.

Finally, the worst thing you can do is to routinely plug in at the end of every ride and keep the bike on the charger 24/7. You need to occasionally balance charge overnight, but it should not be a weekly or even monthly procedure.


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## fos'l (May 27, 2009)

The other aspect that Tesla controls, which is ARGUABLY more important, is not to discharge past 20%. Keeping the battery in the 20/80 region is how they give an eight (or whatever) year warranty.


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