Battery charging

[spaciousskies]

Well I just discovered that I stored my battery fully charged (100%) all winter. I vaguely remember intending to read about best practice for this but then, you know, what a year. Now I am reading that you're supposed to store it at 40-50% charge. Can anyone quantify for me how much of a difference this makes? I understand it's about prolonging battery life, but by how much? I am not temperamentally inclined to fussing around with this type of thing so I'd at least like to know the price of my indolence.

 

[Mike TowpathTraveler]

There are numerous threads on this topic that can found on this forum.

And rest assured, you are going to get a good dozen plus opinions about what you should do and what you should expect. Opinions from the neophyte to folks who work very close to the battery industry.

So let me be the first to say that you are likely going to be fine, if you have a battery from the upper tier ebike drive manufacturers like Bosch, Yamaha, Brose or Shimano. I cannot speak about the lower tier battery packs.

On my 400wh Yamaha battery, placed into service on March, 2017, I always charged to 100% until the BMS shut the charging process off. In summer, 2019, I supplemented that 400wh battery with 2 500wh Yamaha batteries to increase my mileage range on long day trips. Those 2 were also always charged to 100% and BMS shut off.

12 months of the year riding, in all 4 seasons. I see little to no battery degradation in any 3 batteries; if there is any, it's miniscule. I ride exclusively on the HIGH power position on my Habike Full FatSix's Yamaha PW drive. One thing I always do is to let the battery rest at room temp after each ride, before charging to 100%. Never will I charge following a ride in near 100 degree temps or sub freezing or in between. There have been times in the winter when the batteries have sat for over a month due to bad weather outside halting any riding activities. And they sat, charged at 100%. Most times, I ride every day or every other day. The three batteries are rotated in no particular order.

Lots to consider there, I know. But it's worked for me. YMMV. And I'm sure there might be a couple of folks who will dispute what I've noted here, but this has worked for me. I don't get hung up on charging to 75, 65 or 87%.

Thinking the original battery had about 6000-7000 some odd miles on it before getting the two 500's. Right now, the odometer reads 12,400 plus miles. No issues at all with the battery's or the charger.

I think you'll be fine.

 

[AHicks]

Agreed, you're fine. Move on.
Read up on best practices, avoid storing full, avoid total discharging, and especially storing while fully discharged, and you'll be ahead of the game.

Know there is nothing written in stone here.

 

[harryS]

Well it is written in stone, as the guidelines are based on physical laws of chemistry, but these are still guidelines that many people don't follow. It matters most to owners that ride day in and day out, charging every day. If you left them in an unheated garage, probably little degradation. If you brought them inside, and they never got about 75F, same result.

I've got batteries from 2015 that were left charged at 100% thru the first few winters. In truth, they probably have less than 400 charges, but they work fine.

 

[AHicks]

Sorry Harry, if it makes you feel better I should have said there are no absolutes vs. nothing written in stone.

For instance, if we both had the same battery, purchased on the same day, and one of us were to charge our battery to 100% every time charging was necessary, where the other followed the 80%-20% rule religiously, there is nobody that can predict exactly how many extra charges the 80-20 battery will take with any degree of certainty. Granted, on paper, the 80-20 (or whatever percentages you'd like to use), SHOULD be able to be charged more times - but that extra quantity is a best guess at the absolute best. There is NOTHING WRITTEN IN STONE regarding that assurance/guarantee. THEN, there's the dozen or so other factors that also come into play regarding how long that battery is going to last....

So you do your best, and don't worry about the rest! -Al

 

[Dallant]

I’d say pop it in your ebike and ride it. Nothing you can really do about it now.