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5KW BLDC Motor Controller wiring

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Tommycat:

--- Quote from: Bikemad on October 11, 2018, 11:13:51 AM ---
A pre-charge resistor can be used to limit the current for a second or two before connecting the controller directly to the battery (i.e PreCharge the controller through the resistor using a momentary push switch before energising the contactor).

Alan

--- End quote ---


A product such as XT90S connector might be something you would want to concider at your battery voltage. As it contains a pre charge resistor circuit that you only have to plug it in slowly to work... as opposed to extra components and wiring.  :)


See an example here...

https://lunacycle.com/batteries/connectors/black-xt90-spark-resistant-connector-male-female-set/

Bikemad:
A 90 Amp connector might struggle to cope with the high current load from the 5kW motor running at full power, which, according to the dynamometer data, can be in excess of 175 Amps!  ;)

Alan
 

Tommycat:
Yikes... yes I was just looking at the 52 voltage of the batteries, not the amperage. Good catch Alan!   :)

Jusp:
Thanks for all the info. This really gets me up to speed.

On the pre charging circuit, this should be a low amp circuit in parallel to the contactor. A sufficiently high resistor will guarantee that.

 I already planned to power my contactor from the 12V house battery. It should not be too hard to get some electronics that first switches on the precharger, and then the contactor with a delay of a few secs. A $1 microprocessor with two relays may do the job. This is a boat, so a startup time of up to half a minute should not hurt. But I do like something automatic that people cannot forget or ignore.
Do you have any idea on the capacity of the controller capacitors?

Jusp:
Checked digikey.com, a relay rated 10 amps at 250V max, at 12V coil voltage costs $1.30.
At Alan's suggested 30 Ohms the precharge current is about 1.5 amps, which the relay should be able to easily handle. Charging a 1F capacitor (probably somewhat larger than the one in the controller, but hey, I saw a fair spark) should take some 30 secs.

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