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Amerwheel

Gotway Tesla - only get 82v charge

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Hi

Looking for some advice from any tech savvy people. Having some 'problems' with my retailer, who I've sent my wheel back to after having battery charge issues with my Tesla.

I measured the wheel at the 4 pin socket on the wheel with a multimeter and it reads a max of 81.8v even after full charge.
Also on all apps I've tested (android) it won't charge to any more than 94%. Although the retailer is now claiming that on his app it goes to 100%, even though I tested on 3 different apps and all never read beyond 94%!

He's saying that the only accurate way to check voltage is to dismantle and check voltage of individual battery packs and until that is done the fact that it reads 82v could just be a reading error and not anything wrong with the wheel.

So how accurate is a multimeter to the 4 pin port on the wheel? Could it be 2v incorrect?
BTW, my multimeter reads correct 84v on the stock Gotway charger and I've tested using 2 different ones. Both read correct voltage, ruling out charger problem.

Grateful for any ideas!

 

 

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29 minutes ago, Amerwheel said:

I measured the wheel at the 4 pin socket on the wheel with a multimeter and it reads a max of 81.8v even after full charge.

What's the precision of your dmm? 

https://forum.electricunicycle.org/topic/13629-multimeter-accuracy-needed-for-chargerbattery-measurements/?tab=comments#comment-233250

29 minutes ago, Amerwheel said:

Also on all apps I've tested (android) it won't charge to any more than 94%. Although the retailer is now claiming that on his app it goes to 100%, even though I tested on 3 different apps and all never read beyond 94%!

This same about 81.8V were reported from the apps?

Charge % are inaccurate - especially the 100% range is quite big (from about 4.16V to 4.2V single cell voltage)

Btw - how long did you charge?

29 minutes ago, Amerwheel said:

He's saying that the only accurate way to check voltage is to dismantle and check voltage of individual battery packs and until that is done the fact that it reads 82v could just be a reading error and not anything wrong with the wheel.

Maybe. As you can measure at the charge port the tesla seems to have no reverse polarity protection. They just have mosfets to cut off charging in case of single cell overvoltage. Can't say how they could influence measurement. Afair people used to measure GW battery pack voltage like this?

29 minutes ago, Amerwheel said:

So how accurate is a multimeter to the 4 pin port on the wheel? Could it be 2v incorrect?

Maybe a nice member with an GW wants to measure and report the result?

But one should wear googles and be very carefull to not short circuit the charge port with the probes!

29 minutes ago, Amerwheel said:


BTW, my multimeter reads correct 84v on the stock Gotway charger and I've tested using 2 different ones. Both read correct voltage, ruling out charger problem.

So the DMM seems to show about right values (despite maybe otherwise given precision)?

29 minutes ago, Amerwheel said:

Grateful for any ideas!

Pfff...

The retailer should have told you to measure at the battery output as this seems to be his "only right way" now.

Now just measurements from other GW owners disproving the retailers opinion should help.

OrHope you have evidence/testimonials. :( 

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Thanks for the reply,

Yes, multimeter reads 84v for both chargers, so I think is accurate.

I charged overnight with never got above 94%.

Wheel sometimes charges only to 90%, but I can get it up to 94% by riding it down a few %, then putting back on charge.

Apps tested: EUC world, Gotway app, Wheellog, all the same.

Dealer now has my wheel back, says nothing wrong, confirmed 82v with their multimeter at 4 pin port, but tells me that their app shows 100!!  WTF!

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11 minutes ago, Amerwheel said:

Wheel sometimes charges only to 90%, but I can get it up to 94% by riding it down a few %, then putting back on charge.

That's what i theoreticly think could help and so normally suggest as a first measure against cell imbalance.

You tried this also multiple times and got higher?

14 minutes ago, Amerwheel said:

Dealer now has my wheel back, says nothing wrong, confirmed 82v with their multimeter at 4 pin port,

And how much at the battery pack output?

14 minutes ago, Amerwheel said:

but tells me that their app shows 100!!  WTF!

Which app? And which voltage does it report?

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Hi, thanks,

Yes tried multiple times, by riding out, charge, then ride out a bit and charge again. This helped but not above 94%.

Dealer has only measured at the charge port. They got same reading as me... 82v.

The weird thing is that all apps measured 81.8v (approx) but they are saying they get full 100%!

They used the official Gotway app to measure. First they used the old one from 2016 or so, then I asked them to download the latest Gotway app!
they reckon they both read 100% even though both our charge port readings are 82v.

I used EUC World, Gotway and Wheellog and all seem to correlate with my multimeter reading of 82v or approx 92/94%

 

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Posted (edited)
33 minutes ago, Amerwheel said:

Hi, thanks,

Yes tried multiple times, by riding out, charge, then ride out a bit and charge again. This helped but not above 94%.

Dealer has only measured at the charge port. They got same reading as me... 82v.

The weird thing is that all apps measured 81.8v (approx) but they are saying they get full 100%!

That's BS! 81.8V are 4.09V per cell - no app (should) show(s) 100% for this!

GW wheels (like about all others) show 100% starting from ~4.16V per cell! So beginning from 83.2V!

They made a screenshot showing voltage and %?!

But at least app, your multimeter and charger seem to show/deliver accurate voltages!

Quote

They used the official Gotway app to measure. First they used the old one from 2016 or so, 

Don't know to much about GW voltage reporting - just in the "old" times each wheel reported up to 67.2V. Also the 84V wheels - so one had to tell the app (?or it new by the bluetooth id?) to use a factor to "get the voltage up?

So maybe if new GW wheels now report real voltage values up to 84 V and the old app recalculates up from 67.2V it would show 100% all the time....

Edit: That was wrong - charge % is afaik a reported value too and not calculated by the app... 

33 minutes ago, Amerwheel said:

then I asked them to download the latest Gotway app!
they reckon they both read 100% even though both our charge port readings are 82v.

Hm. Then that's not the reason...

Quote

I used EUC World, Gotway and Wheellog and all seem to correlate with my multimeter reading of 82v or approx 92/94%

That's the correct % for the voltage.

3.3V per cell is 0%

~4.16V per cell is 100%

82V is 4.1V per cell

And (4.1V-3.3V)/(4.16V-3.3V)=93%

So from all this it seems your retailer tries to bs you...:(

Edited by Chriull

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I'm starting to wonder the same thing! I offered to go and collect the wheel as they are quite nearby, so I can see their actual readings, but they said I can't come over, they need to ship it to me!
Hmmmmm... 

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Posted (edited)
23 minutes ago, Amerwheel said:

I'm starting to wonder the same thing! I offered to go and collect the wheel as they are quite nearby, so I can see their actual readings, but they said I can't come over, they need to ship it to me!
Hmmmmm... 

Seems that's the times a legal expenses insurance comes in handy...

Edited by Chriull

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9 hours ago, Amerwheel said:

Hi, thanks,

Yes tried multiple times, by riding out, charge, then ride out a bit and charge again. This helped but not above 94%.

Dealer has only measured at the charge port. They got same reading as me... 82v.

The weird thing is that all apps measured 81.8v (approx) but they are saying they get full 100%!

They used the official Gotway app to measure. First they used the old one from 2016 or so, then I asked them to download the latest Gotway app!
they reckon they both read 100% even though both our charge port readings are 82v.

I used EUC World, Gotway and Wheellog and all seem to correlate with my multimeter reading of 82v or approx 92/94%

 

That is BS. 82V on the Tesla indicates that something is wrong about the battery, worn cells possibly. I assume that your wheel is rather new so this is not acceptable by your dealer and they should repair or replace the battery. I just charged my new Tesla V2 1480wh fully and let it balance for several hours (measuring the watts from the outlet deducting that from the watts when the charger is not plugged in to the wheel, to determine when the balancing is complete). Both my chargers outputs 84.5V and EUC World reports 84.0V on my Tesla.

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9 hours ago, Amerwheel said:

They used the official Gotway app to measure. First they used the old one from 2016 or so, then I asked them to download the latest Gotway app!

Actually, the old GW app only had a precision of 10%!

 If they are fighting back with the percentages, the voltage itself is enough to prove that the wheel has an issue. The individual battery cell group voltages are so badly unbalanced that the BMS cuts off the charge prematurely.

 If the wheel is under warranty, do not take anything else for a solution but to replace the faulty pack or the whole wheel! That wheel is already borderline dangerous to ride, and it gets worse fast.

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thanks for your thoughts guys, pretty strange (as I've never got a charge more than 94% in past 5 months!), but this morning retailer has now sent over an EUC World screengrab showing the following:

Min voltage 82.1v at 97%

Max voltage 83.3v at 100%

Tested on EUC World. They claim they used my charger to get this... All I can do is get it back here and test myself I guess...

Thanks again

 

 

 

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I would try to determine if the BMS is interrupting the charge.

It's not so hard:

  1. (Open the shell to provide access to the mainboard battery connector.)
  2. Using a DMM, measure the charger output voltage (when not connected to the EUC).
  3. Charge the EUC until the charger light remains green for 30mins+.
  4. Disconnect the EUC mainboard from the pack. (This provides a convenient place to measure pack voltage while the charger is still connected.)
  5. Using the same DMM, measure the pack output voltage at the mainboard connector (while the charger is still connected).

If your BMS interrupts the charge, I expect you'll observe >500mV lower voltage in step 5, than step 2. This indicates a problem and warrants further action.

If the step 5 voltage is within 100mV of the step 2 charger output, I think your pack is happy.

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4 hours ago, Amerwheel said:

thanks for your thoughts guys, pretty strange (as I've never got a charge more than 94% in past 5 months!), but this morning retailer has now sent over an EUC World screengrab showing the following:

Min voltage 82.1v at 97%

Max voltage 83.3v at 100%

Tested on EUC World. They claim they used my charger to get this... All I can do is get it back here and test myself I guess...

Maybe you have good luck and the replaced a battery pack, but just don't tell it?

33 minutes ago, RagingGrandpa said:

Disconnect the EUC mainboard from the pack. (This provides a convenient place to measure pack voltage while the charger is still connected.)

One should be able to measure battery pack voltage at the legs of both big capacitors, too?! 

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18 hours ago, RagingGrandpa said:

 

I would try to determine if the BMS is interrupting the charge.

It's not so hard:

There are even easier ways that doesn’t even require opening up the wheel:

1) Use a charge doctor, charge buddy, or what have we. Check the charging current after the charger led has turned green. 0.00A -> BMS has cut off the charge.

 If Doctor or his colleagues are not available:

2a) A little before the maximum charge has been reached, power on the wheel but continue charging. Connect to the wheel with EUC World and start logging. After the charger led has been green for at least 15 min, inspect the logs. If the voltage starts to drop nearing the end, BMS has cut off the charge.

2b) Monitor the vehicle voltage manually from any connected app as the charge voltage approaches the maximum. If the voltage starts to drop after the charger turns green, BMS has cut off the charge.

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1 hour ago, mrelwood said:

If the voltage starts to drop nearing the end, BMS has cut off the charge.

Afair many people here reported that their wheel holds the battery viltage very well over time, but looking at the charge graphs at https://lygte-info.dk/review/batteries2012/Sanyo NCR18650GA 3500mAh (Red) UK.html there is some (small) drop at the end of charging. Should be less with our smaller charge currents?

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56 minutes ago, Chriull said:

there is some (small) drop at the end of charging

^ only after the charger has been disconnected.

Our AC chargers are 'dumb' and never turn off their output (even after the saturation indicator lamp turns green).

So, assuming it's a typical 'dumb, endless' charger, I agree with @mrelwood that you should never observe a decrease in voltage while the charger is connected. (If you do, it indicates the charging was interrupted, likely by the BMS.)

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54 minutes ago, Chriull said:

Afair many people here reported that their wheel holds the battery viltage very well over time, but looking at the charge graphs at https://lygte-info.dk/review/batteries2012/Sanyo NCR18650GA 3500mAh (Red) UK.html there is some (small) drop at the end of charging. Should be less with our smaller charge currents?

If the BMS cuts off the charge prematurely, the pack voltage will start dropping immediately, since the full capacity hasn't been reached. The drop is not big, but it is recognizable. If the charger turns green and the BMS continues normally with the tail of the balance charging, the voltage doesn't drop at all.

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so wheel is back in my hands... checked voltage on arrival and just over 83v, plus 100% on EUC World. This is about 1.5v over what I've ever managed to achieve (94%)!
How they got it to this I don't understand - unless a different charger was involved in the process or batts have been switched out, which I reckon is unlikely.

Will run it down some and recharge and see.

Thanks

 

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1 hour ago, Amerwheel said:

so wheel is back in my hands... checked voltage on arrival and just over 83v, plus 100% on EUC World. This is about 1.5v over what I've ever managed to achieve (94%)!
How they got it to this I don't understand - unless a different charger was involved in the process or batts have been switched out, which I reckon is unlikely.

Will run it down some and recharge and see.

Thanks

 

To be on the save side you can try to charge both packs individually. There is still 1V missing compared to your charger output voltage!

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Ok thanks, will look into that, it was on 83.3 at max so I'm missing a 0.7 of juice.

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On 7/31/2020 at 10:38 PM, Amerwheel said:

Ok thanks, will look into that, it was on 83.3 at max so I'm missing a 0.7 of juice.

Now we are getting close enough to put it on measuring device tolerances, (possible) charge port protection diodes, cheap chargers, GW traits etc. I don't think my 84V MSX has ever reported above 83.3V an hour after unplugging the charger. If you get it up to 83.3V with your charger, I'd say that the issue has been resolved. Possibly by the distributor charging the packs individually.

In any case, I would make sure to balance charge the wheel often. Leave it on the charger at least for a few hours after the charger LED turns green.

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18 hours ago, mrelwood said:

charge port protection diodes

 

18 hours ago, mrelwood said:

83.3V an hour after unplugging the charger

 

18 hours ago, mrelwood said:

Leave it on the charger at least for a few hours after the charger LED turns green.

Facts! :)

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My brand new KS S18 is having this same issue...

What should I do?

84.1V on charger no connection.

Battery 82V after a few minutes of the green light coming on.

Watched the charge, battery BMS cuts off at just above 83V and immediately drops to 82.5 then a few minutes later this drops to 82V where the

KS Apps saying 95%. Eucworld 93%

KS app considered 82.9V 100% and allowed the battery to charge a little more for like 5minues (slightly above 83V) before green light and voltage drops. 

I'm assuming this will only get worse over time, and my range will be less...

Save me internet. Leaving the charger on green does nothing, BMS won't allow more charge. Dropping the voltage/% a tiny bit and reconnecting the charger doesn't do much, just sits at 82V and goes green instead of going above.

 

Any suggestions?

 

Thanks

 

Dan

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44 minutes ago, Daniel Hollinghurst said:

<S18> battery BMS cuts off <while charging> at just above 83V

I'm assuming this will only get worse over time, and my range will be less...

We don't have an in-depth analysis of KS BMS to refer to... but if it were Gotway for example, yes, it would mean your pack is imbalanced.

You could prove if you're balanced or not, by opening the enclosures and probing each cell group in each pack. Quite laborious.

You could also try to prove which of the packs is good and bad, by disconnecting all but 1 from the mainboard and repeating the charging attempt. If it charges without cutoff, that pack is good, move on to the next...

ACtC-3fr6CuVXokAehWa2IXUFQZTFqB12SxufsrB

Edited by RagingGrandpa

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