battery university chart showing discharge vs cycles

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Clubserg   1 mW

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battery university chart showing discharge vs cycles

Post by Clubserg » Jul 20 2018 4:24pm

I found a chart that showed you can get over 3500 cycles if you only discharge your battery less than 10 percent. and it went down accordingly 20 percent les?charges ending at full discharge only 800 cycles. so. I have a second question. why does all the suggested info say to only stay between 30 and 80 percent of battery full charge. and to not charge it up all the way every time. so. I have a 52 volt battery. new and I've charged it 5 times after short discharge to balance out load. and it charges to 59. the lowest I've let it het is 52. today. and. it does not seem to have the torwue or top speed as it did 5 volt ago. I would. rather. charge it up every time to take ad stage of that power. after all the manufacturer made it to charge all the way not to 80 pet any right. let me know if I missed something. or if I wrong about it having more power on fill charge.

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wturber   100 kW

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Re: battery university chart showing discharge vs cycles

Post by wturber » Jul 20 2018 8:27pm

Clubserg wrote:
Jul 20 2018 4:24pm
I found a chart that showed you can get over 3500 cycles if you only discharge your battery less than 10 percent. and it went down accordingly 20 percent les?charges ending at full discharge only 800 cycles.
Well, the 10% discharge makes little sense for the vast majority of e-bike applications.
Clubserg wrote:
Jul 20 2018 4:24pm
so. I have a second question. why does all the suggested info say to only stay between 30 and 80 percent of battery full charge. and to not charge it up all the way every time. so. I have a 52 volt battery. new and I've charged it 5 times after short discharge to balance out load. and it charges to 59. the lowest I've let it het is 52. today. and. it does not seem to have the torwue or top speed as it did 5 volt ago. I would. rather. charge it up every time to take ad stage of that power. after all the manufacturer made it to charge all the way not to 80 pet any right. let me know if I missed something. or if I wrong about it having more power on fill charge.
By that same logic, you could say that the manufacturer "made it" to have 100% of its amp-hour capacity. So why not drain it all the way? The answer, of course, is that the manufacturers can't wave a magic wand and change what chemistries do. Their engineers can tweak away and make certain trade-offs, but they are none-the-less constrained by the chemistry.

Regarding full charges, my understanding is that the biggest problem with that is not the full charge per se., rather it is leaving the battery at full charge. So what I and some others do is to charge to 80% or so as a standard, and then we top off the battery before a ride to do two things:

1) Help packs that don't have a balancing BMS stay balanced.

2) Get full capacity from the pack with minimal stress on the battery.

If you know your ride is going to be well withing the range of a partial charge, then there's no strong reason to top the battery off so long as you do that every now and then.

I'd also suggest that while these methods will prolong your battery life, from a utility standpoint, sometimes it just makes sense to use your batteries to the fullest capacity. It is what you do most frequently/routinely that probably affects battery life most.
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