BMS temperature rise


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ynot

Member
Joined
May 28, 2021
Messages
75
Am installing a 36V 60 amp Daly BMS 10s on a freighter tadpole trike, the maximum load will be 30 amps at between 41 and 38 volts or 1200 watts max for very short bursts only at startup and on hills.
How much temperature rise to I need to allow for the BMS, it will be fixed to the floor of the trike in a plywood sandwich that forms the floor of the trike, I would like to glue it to the plywood beside one of the 5 Nissan Leaf modules that will be the battery in the trike floor. The trike is a fair weather only fun ride, but would like to at least partially close the edges of the plywood box. I could leave the edges open, or fit a couple of small muffin fans, they would not affect range at all. In fact the range is limited by my ability to sit on the damned saddle<grin>
Feedback would be appreciated. Thanks.
 

ajw22

Member
Joined
Nov 16, 2018
Messages
715
Impossible to say with the given data. These BMS all have chunky metal heatsinks that will soak up heat from short bursts, so that won't affect the temperature much. What's more important is the sustained power(current) usage/charging, and how the heatsinks and whole battery compartment is cooled. Ie. airflow, insulation, external heat (sun?).

Note that there are heatsinks on both sides of the BMS. So make sure both stay adequately cool.
Definitely avoid placing it flush with plywood, as that will act as a heat blanket for the heatsink. Have a gap on all sides of the BMS so that air can circulate over the whole BMS.
Sealing the plywood battery compartment is probably a bad idea, as that's going to trap heat.
Generally, the ideal configuration is to have aeration holes near the bottom to let in cool air, and near the top to let hot air out.
At least leave space to add forced heat extraction with a fan. If you really want to save energy, use temperature sensitive bimetallic switches. Not particularly accurate, but uses zero extra energy.
If dust/debris is not a concern, then using the riding airflow to help with cooling is a smart option.
 

ynot

Member
Joined
May 28, 2021
Messages
75
OK thanks AJ, gave myself a talking to, I guess if I need to ask a question like that the answer lurks in my brain.
Gonna leave it shtuck to the plywood, but will put a large heat sink/hold down on the other side.
I built a terminal block with an 80 amp fuse holder so that should keep things pretty cool.
And thanks for the fast feedback, - planning on closing up the battery today, once the honey do is done.
 
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