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Charging Strategy - Levels and Frequency


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As a Tesla owner for some years now (no, not the GotWay type, but the 85kWh 4 wheel type) I agree with what most of you are writing, but have one extra comment: 

If you have to charge to 100%, the high amp charging is a no-no the last part! Use low amp charging the last part to 100%. 

I usually do slow-charging all the way of my Tesla, but on longer trips when supercharging, I only see the 100kW+ if the battery is almost empty, then dropping fast and then just a few kW the last part until the battery is full. This is fully automatic and is for a reason: to prevent damage of the cells. 

Personally I try to keep the battery between 20% and 80-90% when in daily use, but sometimes top it up to 95-100% just before a longer trip. This is very normal for big battery EVs and I think a good thing to follow for EUCs as well if you want to keep the battery alive for some more charging cycles vs the 0-100% charging. I don't know how many, but some say two to three times as many charging cycles. Have even heard higher numbers.

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This is not true. Li-Ion has no problems with memory. A full charge every 12 to 15 full cycles is recommended but only to allow the BMS to balance the cells in a serial configuration. It has nothing t

Yes, that’s correct, 2 years and one day after first using your wheel the batteries self destruct ?. OK, only joking. Someone has probably decided that, since the stated life of most 18650 cells

Yes, i do log ALL my charges….. In a way @Marty Backe is doing it, having a Kind of log for every Wheel: The only difference is: I am having only wheels with a lot of WATThour...KS18s

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1 hour ago, Jorgen said:

If you have to charge to 100%, the high amp charging is a no-no the last part! Use low amp charging the last part to 100%. 

Any LiPo charger will do that automatically.

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I think a good analogy is candy and cavities. Sure, candy causes cavities, but if you brush your teeth right after (ride your wheel right after charging to 100%), then you're not actually developing tooth decay (battery decay).

So Bob Eisenman charging his Monster to 100% is very different from Marty Backe charging his Monster to 100%, because Eisenman is going to be back on that wheel in a matter of hours or a couple days, whereas Backe's Monster is going to be sitting around for a week or two getting cavities, because he's using his other wheels. 

So a Charge Doctor would have a much bigger positive effect on Marty's wheels than Bob's Monster. Think of it as a Charge Dentist, I suppose.

 

 

 

 

 

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1 hour ago, Scouts Honor said:

I think a good analogy is candy and cavities. Sure, candy causes cavities, but if you brush your teeth right after (ride your wheel right after charging to 100%), then you're not actually developing tooth decay (battery decay).

So Bob Eisenman charging his Monster to 100% is very different from Marty Backe charging his Monster to 100%, because Eisenman is going to be back on that wheel in a matter of hours or a couple days, whereas Backe's Monster is going to be sitting around for a week or two getting cavities, because he's using his other wheels. 

So a Charge Doctor would have a much bigger positive effect on Marty's wheels than Bob's Monster. Think of it as a Charge Dentist, I suppose.

Great analogy, although I'm not convinced yet that I'm getting any cavities :D

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13 hours ago, Jorgen said:

then dropping fast and then just a few kW the last part until the battery is full. This is fully automatic and is for a reason: to prevent damage of the cells. 

Thats not (only) to Prevent damaging of the cells. On the last 5-10% of the charging the BMS starts to balance the individual cells and top them all up to get them to the same Level.

So no matter if you use a 10Amp charger or a 1 Amp charger, at the end of charging the amperage will sink down to balance.

That means no matter what charger type you are using….the last 5-10% Always take the same time to charge.

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i may be wrong so please correct me if needed - doesn't the instruction booklet for the KS18s state batteries last two years?  does KS provide any guidance on how/when/frequency/best practice to maximize their supplied battery configurations?  or how their qa team came to the two year estimate?  

also - with all the variables that factor into distance/performance per charge cycle, how will i know if my batteries need replacing or are degraded?  is this when they 'exhaust with fire'??

i charge when i think i need to but generally when it gets down around 20% or if i know i will need as full a charge as possible on next ride.  my ewheels supplied charger stays at 80% max and i often forget to unplug and let the trickle charge to get it up to 90% or so.  i have never seen the KS or Darkness app display 100% charge for my 18s.

in the six months of ownership and 1100 miles i can state without issue my KS18s is a workhorse that continues to make me think nothing but awesomeness as i leave my subaru in the driveway.

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24 minutes ago, Holt said:

I charge when i think i need to but generally when it gets down around 20% or if i know i will need as full a charge as possible on next ride.  my ewheels supplied charger stays at 80% max and i often forget to unplug and let the trickle charge to get it up to 90% or so.  i have never seen the KS or Darkness app display 100% charge for my 18s.

That's not really good - by this the bms never balances the cells and your about to see performance degradation till the batteries are not usable at all anymore.

Your chargers is misadjusted to not provide full max voltage? You should look to solve this problem!

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1 hour ago, Keith said:

...

Just nitpicking really, but this isn’t entirely true. If the batteries get seriously out of balance then some will start to reach 4.2V even on a 90% charge. Their voltage will get held at that voltage so this will limit just how out of balance the battery can get.

Yes - out of balance cells could also be balanced with lower voltage. But "later" and not as "even". So by this higher remaining difference:

Quote

However you are perfectly correct not occasionally charging to 100%+ so the cells are fully balanced and also discharging down to 20% pretty much guarantees that  eventually one or two cells will get out of balance and go below 0% charge and hence be permanently damaged.

+1

I'd expand this thought that by this "remaining higher difference" one has performance loss and higher "battery stress"

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