Battery and live wire help

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R6bbie   1 mW

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Battery and live wire help

Post by R6bbie » Apr 24 2018 11:14am

My USB cable out of my battery (52v20ah) is cut and sparked. It's so close and can't get anything on the wire.
Any ideas what I can do? Thanks for your time and this is a great message board!
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Last edited by R6bbie on Apr 24 2018 7:09pm, edited 1 time in total.

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fechter   100 GW

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Re: Live wire help.

Post by fechter » Apr 24 2018 3:01pm

It's a little hard to see in the picture. You might be able to snip away part of the case to get a little more of it to work with.
If it was mine, I would just put a little blob of epoxy or silicone over the end so nothing can short out and use a separate USB converter.

If this is something that needs to be working again, you basically have to strip the end of the wire enough to solder new wires onto the end.
"One test is worth a thousand opinions"

R6bbie   1 mW

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Re: Live wire help.

Post by R6bbie » Apr 24 2018 7:07pm

fechter wrote:
Apr 24 2018 3:01pm
It's a little hard to see in the picture. You might be able to snip away part of the case to get a little more of it to work with.
If it was mine, I would just put a little blob of epoxy or silicone over the end so nothing can short out and use a separate USB converter.

If this is something that needs to be working again, you basically have to strip the end of the wire enough to solder new wires onto the end.
Thank you for your time, I think I will use Epoxy.

2nd part Q if anyone doesn't mind, I was out riding and I had about 17 miles and the battery died out and LCD would not turn on---story time----

I was using level 5 pedal assist (KTlcd3) the whole time doing 30mph and I noticed my battery level has dropped a bar at around 8 miles then at about 16 miles it went dropped another bar to half full battery per indicator. (it has 4 bars, lost power at 2 bars) then about a mile more into it max I saw the battery bar indicator flash empty and then the bike died, when I got home I plugged the battery in to charge and it and powered up the LCD to check volts and it had 48.1V and went to half full on the bars almost right away. My battery is 52V20AH and its from UnitPackPower on Ali it has 50bms, I am running 1500W rear wheel from Passion Bike from Ali.

Should my battery have died out like that? I was running it hard for sure, I'm pretty sure when I left my house the LCD said it had 52v and died at 48v.

Thanks again for any help

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Marin   1 kW

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Re: Battery and live wire help

Post by Marin » Apr 24 2018 11:36pm

Battery voltage can fluctuate depending on the load put on it, it's possible that with enough load on the battery it can hit the low voltage limit of the controller or bms due too voltage sag. This would cause a shut down but the battery can recover after the load is removed.

Also if you are trying to draw more current out of the battery than the bms will allow it will shut down until the load is removed. Often you need to restart the system to continue.

Carefully monitoring your battery voltage during use will reveal what is happening,

The battery bar indicators are not known to be very accurate, a digital meter is worthwhile if you really want to monitor usage,
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Benjamin Wassink   100 µW

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Re: Battery and live wire help

Post by Benjamin Wassink » Apr 25 2018 12:20am

Hi,

I would set P5 to zero and go for a testdrive. Now watch the battery indicator under full load.
If you get home first thing to do is messure the voltage on the pack after 10min setteling time. Not start charging right away!

Display manual:
https://www.google.nl/url?sa=t&source=w ... LM84EH8VY6

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amberwolf   100 GW

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Re: Battery and live wire help

Post by amberwolf » Apr 25 2018 12:22am

A wattmeter (like the Cycle Analyst, Watts UP, or other RC wattmeter) would be even better, because you can track how many Wh youve actually used, vs just the voltage or bars.

Recharge it thru the wattmeter after running it empty, and when it finishes the charge youll know about how many Wh it holds. Which you can confirm on the next ride if you run it dead again. ;)

YOu can also use the Ah function, and should get something close to the Ah rating of the battery, but the harder you use it the less close youll be to the rating.

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fechter   100 GW

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Re: Battery and live wire help

Post by fechter » Apr 25 2018 8:15am

It sounds like the BMS tripped prematurely. This may indicate the cells are not balanced in the pack. Restoring the balance is a pretty slow process with most typical BMS circuits and depends on how the charger works. Balancing will only happen when the pack voltage is at the maximum.

Typical balancing process is to charge the pack for a long time, like at least 24 hours. Some chargers will totally stop charging when they reach full, so no more balancing takes place. For chargers like this, charge to cutoff, then discharge the pack (run the motor) just long enough so the charger will start again and repeat the process many times.

If the pack is new, it may improve with a few cycles as the cells need a little 'break-in'.

If this still doesn't get you close to the expected capacity, then you need to open the pack enough to make voltage measurements of the individual cell groups.
"One test is worth a thousand opinions"

R6bbie   1 mW

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Re: Battery and live wire help

Post by R6bbie » Apr 25 2018 10:07am

fechter wrote:
Apr 25 2018 8:15am
It sounds like the BMS tripped prematurely. This may indicate the cells are not balanced in the pack. Restoring the balance is a pretty slow process with most typical BMS circuits and depends on how the charger works. Balancing will only happen when the pack voltage is at the maximum.

Typical balancing process is to charge the pack for a long time, like at least 24 hours. Some chargers will totally stop charging when they reach full, so no more balancing takes place. For chargers like this, charge to cutoff, then discharge the pack (run the motor) just long enough so the charger will start again and repeat the process many times.

If the pack is new, it may improve with a few cycles as the cells need a little 'break-in'.

If this still doesn't get you close to the expected capacity, then you need to open the pack enough to make voltage measurements of the individual cell groups.
Thank you very much, I will give this a try. You all are very helpful, I sure am enjoying this!

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Kris Lan   100 µW

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Re: Battery and live wire help

Post by Kris Lan » May 19 2018 2:31am

Problem solved ?

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