How can I discharge a 36v battery pack

Batteries, Chargers, and Battery Management Systems.
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bbolin   1 mW

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How can I discharge a 36v battery pack

Post by bbolin » Sep 07 2017 8:32pm

Want to test the amp hour of the battery. Have 5 of them. Would also like to test charging them.

Know I could use 3 12v light bulbs in series but is there a better way? Resistor packs?

10s2p 18650

Thanks

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amberwolf   100 GW

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Re: How can I discharge a 36v battery pack

Post by amberwolf » Sep 08 2017 2:59am

If you have a wattmeter on your bike you can just ride until the pack's BMS cuts out, and note down the results. ;)

If there's no BMS you'd want to watch the individual voltages of teh cell groups, so you can stop the discharge at the LVC point you prefer.


You can buy resistors and whatnot to make a discharger of the right current to simulate the bike's load, but if you want to see what performance the packs actually have in use, use them with the actual load. ;)

kdog   10 kW

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Re: How can I discharge a 36v battery pack

Post by kdog » Sep 08 2017 6:07am

Take the element out of an old 2000w heater and dump the power into that. it'll probly run near 6-700w (assuming you're on 110v) if that's too high choose a lower wattage one. Put it in a bucket of water if it needs cooling or blow it with a seperate fan. Old school kettle would probly work too. Plenty of cheap options.

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Ykick   100 GW

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Re: How can I discharge a 36v battery pack

Post by Ykick » Sep 08 2017 10:35am

kdog wrote:Take the element out of an old 2000w heater and dump the power into that. it'll probly run near 6-700w (assuming you're on 110v) if that's too high choose a lower wattage one. Put it in a bucket of water if it needs cooling or blow it with a seperate fan. Old school kettle would probly work too. Plenty of cheap options.
Also parallel several heater elements (space heaters, toaster ovens, range elements, clothes irons) together in order to bring the total DC resistance down to something around 10 Ohm or less.
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999zip999   100 GW

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Re: How can I discharge a 36v battery pack

Post by 999zip999 » Sep 13 2017 2:57pm

Run it thru a cheap volt ah watt meter check DrAngle thread https://endless-sphere.com/forums/viewt ... s#p1317986 for a cheap one.

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neptronix   100 GW

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Re: How can I discharge a 36v battery pack

Post by neptronix » Sep 13 2017 9:04pm

I use 3 12v 50W halogen bulbs connected in series to do this.
Efficiency is everything :bolt:

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bbolin   1 mW

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Re: How can I discharge a 36v battery pack

Post by bbolin » Sep 13 2017 9:18pm

Did purchase a 36v to 12v converter and a 400W (Bestek) inverter and drained using a box fan. Have also ordered a 5 pack of 100W halogen 12v bulbs and ceramic bases.

I'm going to try the light bulb method ( 3 in series ) also. I'm sure it will be a lot faster. What would happen if I use 4 12v bulbs in series on a 36v battery?

Very new at much of this stuff

bbolin   1 mW

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Re: How can I discharge a 36v battery pack

Post by bbolin » Sep 14 2017 6:33am

Another idea I found is to use DC water heating elements. Seems some solar people dump loads when their battery banks are full. They come in assorted sizes 12/24/36

999zip999   100 GW

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Re: How can I discharge a 36v battery pack

Post by 999zip999 » Sep 14 2017 10:40am

How are you going to monitor the amp draw the Watt hours taken out and voltage lvc ?
Last edited by 999zip999 on Sep 14 2017 11:13am, edited 1 time in total.

bbolin   1 mW

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Re: How can I discharge a 36v battery pack

Post by bbolin » Sep 14 2017 11:00am

Yes I purchased a power analyzer

https://www.amazon.com/Power-Analyzer-J ... LCD+Screen

This site does not make posting URLs very easy. Maybe I'm doing it wrong but usually highlight the text I want to make a link and insert it.

999zip999   100 GW

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Re: How can I discharge a 36v battery pack

Post by 999zip999 » Sep 14 2017 11:16am

It didn't say voltage range ? I wish the sites had basic info. Now a piece of paper.

bbolin   1 mW

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Re: How can I discharge a 36v battery pack

Post by bbolin » Sep 14 2017 11:32am

Not sure what your saying here??

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