Charging to 80% without a Satiator

Thomas Jaszewski

Well-Known Member
Scientist of a lithium factory
Thanks for the response. I'd like to know more but without anything more than unattributed quotes, there's little to review or confirm.

Which scientist and which factory? It would help us all to learn how we've been sold down the wrong path.
Thomas talks about charging his battery to full for years and still getting 5 + years on his pack so I think that tells us something too
It's still just an anecdote, with no proven conclusion. One guy, one battery shouldn't be the standard for how we charge.

Micah Toll a young engineer, as well as Justin Elmore a highly successful eBike engineer both agree that 80% makes sense. Paul Lynch owner of one of the most respected battery builders in China also suggests that undercharging extends cell life.

 
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Feliz

Well-Known Member
I usually charge my batteries to 90-100% if I'm going for a ride relatively soon but I store batteries in the 20-80% range. I also rarely run a battery down below 50%.

Justin from Grin Technologies is my idol, not only is he a great eBike engineer but more important to me is that he is a real eBike enthusiast and has been for years. They make some awesome products and touring their facility and meeting their staff is equivalent to visiting eBike heaven.
 

MarkF

Active Member
I agree with Justin too. Some of the confusion with the testing that has been done is the test are not real world. The test that was done to come up with the 80% rule was done as follow. They charge a cell to 100% and discharge to 100%. They take another cell and charge to 80% and discharge too 100%. They do this in a lab at a non stop pace. This is not how we use our packs. If you look at what else they say, they say these 18650 cells only last 2 to 3 years. Sure when you charge and discharge to 100%, then yea they only last 2 to 3 years. We know that is not correct. The way real people use there batteries is not this way.
Thomas you said yourself, that you have a battery you charged to 100% and it lasted 5 years. Why would this be if all the experts say these cells only last 2 to 3 years. Well they only last 2 to 3 years if you cycle your cells like they do. But we don't.
Also Thomas you come from a DIY world where people make there own packs and don't always do a good job. Yes they had problems but I wouldn't say it was the batteries fault why they screwed up there packs.Especially when you buy cheap cells to begin with or fakes. Bike manufacturers do a better job now at building their packs and are more reliable for this.
My factory has been making ebike packs for the Chinese market for over 10 years. They made lead acid, then switched to NIMH. They are still a big supplier of ebike packs but decided not to make 18650 as there are enough that do that. I don't claim to be an expert, I just pass on what I hear from what I consider to be a reliable source. YMMV
 

Thomas Jaszewski

Well-Known Member
I’ll exit with the following comments. First I have few battery building customers. Next, it would be completely irresponsible for me to suggest any customer exceed the charging rate of the builders specifications. My builders insist that higher rates are hard on batteries. And set suggested limits. Typically 5A. Lastly cherry picking my anecdotes won’t likely stand as solid evidence. Grin does cater to DIY and in no way suggest a Satiator user charge at rates higher than makers stated limit. We should be careful, especially in this forum, not builders mostly finished eBike buyers, to ever suggest anyone can or should charge at rates beyond their system specifications. Sure, some makers are selling systems designed to charge at higher rates. But to suggest it’s the proper procedure because Grin has a 8A limit is promulgating poor advice. Good discussion! Thanks!
 

DDBB

Well-Known Member
Most if not all Lithium cells can easily accept a 3C charge rate with no adverse effects on the cells or pack longevity. Some of the charge connectors may not be up to the task of pushing much more than 2 -4 amps though. I would not want to melt a connector trying to charge at a high rate just to save some time
 

cellistpilot

New Member
With the 52 volt 19.2 amp battery in my RCS e-bike I would like to know if there is any downside to charging it at a higher rate, like 7.5A fast charge, verses a lower rate, like 2A slow charge. Will you get any less total charging cycles of battery life, everything else being equal, charging at the fast charge rate?
 

MarkF

Active Member
Some of you think charging at 1c is irresponsible when the cells are rated for it. High rates Thomas would be charging more than 1c. Since most chargers are charging at 1/5 the 1c rate, saying charging at 1/2c is not hard on the cells or is it considered overcharging. I don't think you understand the math behind whats going on here. Obviously a BMS that is set lower is the BMS limit and not the cells. Of course you can't charge more than the BMS will let you. 2 amps on a 10ah battery is .2c That's 5 times lower than the cells are rated for. All this doom and gloom is ridiculous. There's simple physics involved here and you can either choose to ignore it or you can embrace it. But never fear it.
A 1000 wh battery is capable of being charged at 1c or 20 amps. So 2 amps is quit low.
cellistpilot
7.5 amps is less than 1/2c so you are way under the 1c charge rate which means it will make no difference compared to 2 amps. I don't know how many battery packs have a limit built into the BMS but whatever it is, it seems to be way under 1c. But that doesn't mean it's the correct charge rate of the cells.