KS18XL Battery quickly drops immediately after full charge

[ONESHOT]

I've read a bunch of the battery related posts here and can't seem to find an answer to my issue with my used KS18XL.

I'll charge it to 99% go for a 30 minute ride roughly 10 miles and the battery will drop to 35%.  I'm cruising around 16-25mph.

I was told to leave it overnight to balance out the cells (use a quick charger) but from what I've read from other posts leaving it charged at 100% for more than 2 hours could just be draining the battery capacity.

My question is do I need to leave it overnight (100% for 7-8 hours) to balance or will the balancing be completed after 2 hours at 100%?

According to EucWorld when it's on the quick charger the specs are 100%, 84.4V, and 0.2A.

Appreciate any advice.

 

 

 

[meepmeepmayer]

15 hours ago, ONESHOT said:

I'll charge it to 99% go for a 30 minute ride roughly 10 miles and the battery will drop to 35%.

Something's definitely wrong there. One could suspect that only one of the two batteries is connected, but even then the range is too low imho. What's your weight on the pdeals?

Also I don't see how this could only be unbalanced battery cells.

15 hours ago, ONESHOT said:

but from what I've read from other posts leaving it charged at 100% for more than 2 hours could just be draining the battery capacity.

No, that's not true.

2 hours should be enough, but longer won't hurt either.

-

If you suspect unbalanced battery cells (or just want to rule them out), do an overnight charge (or just a few hours) at 100%. Make sure your charger doesn't stop at 0.2A or something.

But to me it seems like there's a bigger problem (?) because that low range needs to be explained.

[ONESHOT]

1 hour ago, meepmeepmayer said:

Something's definitely wrong there. One could suspect that only one of the two batteries is connected, but even then the range is too low imho. What's your weight on the pdeals?

Also I don't see how this could only be unbalanced battery cells.

No, that's not true.

2 hours should be enough, but longer won't hurt either.

-

If you suspect unbalanced battery cells (or just want to rule them out), do an overnight charge (or just a few hours) at 100%. Make sure your charger doesn't stop at 0.2A or something.

But to me it seems like there's a bigger problem (?) because that low range needs to be explained.

Thanks for the reply

Weight is 165lbs. I rode it today after leaving it at 100% for 2.5hrs last night.

Average speed was 15-18mph and it went from 100% to 35%-40% in 45 minutes of riding almost 14 miles.

Im going to keep it on the quick charge for 7hrs after 100% and do that ride again to test if it's the balancing.

Currently it's charging at 100%, 84.5V, 0.3A

[Denny Paul]

It does sound like a lot of battery is being chewed up... Are you taking your readings when the wheel is still in motion? The voltage (and battery percent) will read lower when the wheel is under load.

For reference, on my dad's ks18xl, riding fairly tamely much like yourself will result in about 30 miles of range before the wheel starts beeping annoyingly. He's on flat ground, 190 lbs.  Faster acceleration, hills, starting and stopping, wind, and cold weather all substantially affect range.

[Tawpie]

What's your tire pressure?

[meepmeepmayer]

Hm so your weight is not the problem.

Do you have a regular charger you can use instead of the quick charger? 0.3A seems a lot for "being finished".

Anyways, if the battery is full enough = if the voltage is high enough, the battery cell balancing should happen regardless of a charger being plugged in or not. The "keep it in for a few hours" thing is only to make sure that the voltage is high enough for the balancing to happen.

I don't believe your range problem has anything to do with battery balance anyways.

I would open the wheel to see if both battery packs are connected to the wheel. If one wasn't, that might explain your bad range. You can also disconnect one pack  (it can stay in, just unplug) and then the other to see how the wheel behaves with just that pack. This will give you info about each pack (whether it is ok).

CAUTION, make sure to never connect two packs together (again, or if one was unplugged initially) unless you are sure they have the same voltage (like 0.1V close). The easiest way to be sure that the voltages are the same (after they might have diverged when the packs weren't always connected together) is to just charge the wheel to full with only one pack connected, disconnect it, connect the other pack, charge to full again, and then re-connect the first one to get back to normal (= both packs connected to the wheel). Provided the packs are ok, if they are not you'll see that one pack doesn't charge to the full voltage, so check for that.

By the way, the fact that your wheel charges to >84V (full voltage) means all packs that are connected are ok (otherwise they wouldn't do that). So at least one of your packs (the connected one) or both of them (if they are both connected) are good.

Edited August 21, 2021 by meepmeepmayer

[meepmeepmayer]

5 hours ago, Tawpie said:

What's your tire pressure?

Really good point!

The tire pressure can be crazy low but look totally ok when you're not standing on the wheel. So check yours, it's on the tire and should be something like 2.5 -3 bar (36-43 psi).

You might just be running with an effectively flat tire. That would explain everything, no battery worries needed.

[Seba]

On 8/20/2021 at 7:15 AM, ONESHOT said:

I'll charge it to 99% go for a 30 minute ride roughly 10 miles and the battery will drop to 35%.  I'm cruising around 16-25mph.

First and most important - what is the voltage reading when you get 35 % of battery level? Second - what is the battery circuit resistance value? You can find it on the second screen in EUC World app. 

Also it would be very helpful to record a tour using EUC World, so we can examine the graphs. Recording EUC World tour is an easy, but great way to investigate suspected battery problems. So charge your wheel to full, then go for a ride recording it with EUC World (fourth page). Finally share the tour URL here.

On 8/20/2021 at 7:15 AM, ONESHOT said:

My question is do I need to leave it overnight (100% for 7-8 hours) to balance or will the balancing be completed after 2 hours at 100%?

Battery won't balance after one charge, regardless how long it will stay connected to the charger. Balancers built into King Song BMSes are very weak and they will only do their work if you always and repeatedly charge your battery to full.

[ONESHOT]

On 8/21/2021 at 1:31 AM, Tawpie said:

What's your tire pressure?

Tire pressure is at 40psi

[ONESHOT]

On 8/27/2021 at 9:45 AM, Seba said:

First and most important - what is the voltage reading when you get 35 % of battery level? Second - what is the battery circuit resistance value? You can find it on the second screen in EUC World app. 

Also it would be very helpful to record a tour using EUC World, so we can examine the graphs. Recording EUC World tour is an easy, but great way to investigate suspected battery problems. So charge your wheel to full, then go for a ride recording it with EUC World (fourth page). Finally share the tour URL here.

Battery won't balance after one charge, regardless how long it will stay connected to the charger. Balancers built into King Song BMSes are very weak and they will only do their work if you always and repeatedly charge your battery to full.

Last time I was at 33% voltage was 73.4V.

Probably rode for an hour with hills average speed roughly 15-20mph.

 

Good advice I'll EUC record the park loops I've been doing and will post results here soon.

 

Thanks again

 

[Hyperion]

What's the total distance on the wheel?  

 

Maybe I'm just used to old school lithium batteries but I would worry about the cell balance. Especially on uses cells without knowing how the last guy treated them.

If it were me, I would leave it on the charger any time I'm not using for a few days and see if it gets better. 

 

 

[mrelwood]

23 hours ago, ONESHOT said:

Last time I was at 33% voltage was 73.4V.

That doesn’t add up. If you are checking the percentage on the EUCw app, make sure you’re not using the custom battery percentage curve. A more linear one is better for analyzing wheel and battery performance. 73.4V with a linear scale should show up as ~56%. That might be in line with one of the batteries being permanently offline.

[M640x]

On 8/19/2021 at 10:15 PM, ONESHOT said:

I've read a bunch of the battery related posts here and can't seem to find an answer to my issue with my used KS18XL.

I'll charge it to 99% go for a 30 minute ride roughly 10 miles and the battery will drop to 35%.  I'm cruising around 16-25mph.

I was told to leave it overnight to balance out the cells (use a quick charger) but from what I've read from other posts leaving it charged at 100% for more than 2 hours could just be draining the battery capacity.

My question is do I need to leave it overnight (100% for 7-8 hours) to balance or will the balancing be completed after 2 hours at 100%?

According to EucWorld when it's on the quick charger the specs are 100%, 84.4V, and 0.2A.

Appreciate any advice.

 

 

 

I had something similar going on when I first got my 18XL.  It's been some months now and I don't remember the numbers but I do remember that the wheel always seemed to have a lower battery % than I thought it should have considering the really casual riding I was doing, flat ground, tire pressure etc.

I use the EUC World app.  There is a setting which will show different battery levels depending on the option that is chosen.  In settings under "General" there is a setting called "Battery level, select battery level algorithm".  There are 3 choices, Standard, Optimized and Custom.  I had mine set to "optimized".  When I set it to "standard" my battery % increased to a level that seemed to be more correct considering the riding circumstances.  Since then all my rides appear to be "normal" as far as battery % is concerned.