Main Contactor powered by DC-DC Converter ?

Electric cars, trucks, ATVs, NEVs - things bigger than a motorcycle.
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adriftatsea   100 W

100 W
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Location: The South, USA

Main Contactor powered by DC-DC Converter ?

Post by adriftatsea » Aug 31 2016 7:10pm

I'm building another 72V AC powered ATV/UTV thing using Nissan Leaf packs and would like to avoid using a 12V battery.

Some setups I've seen use a DC-DC Converter with a switchable 'enable' wire (Sevcon's DC-DC, some Delta-Q chargers, etc) that will turn on the DC-DC converter when pack voltage is applied. The DC-DC converter would then be able to fed 12v to the contactor and thus the controller/motor.

The downside's I've seen is that if the converter dies, you could be stranded without aux power to drive emergency flashers and such. In my application this isn't a problem. The other is to use a toggle switch rated for >72v - I'll be using a properly spec'd sealed Honeywell switch.

Is there any other reason this config is not more prevalent (Grounding, etc)?
[Santa Cruz Heckler] - Tangent 80:1 RC mid-drive, 12s 16ah, 44t, clutched derailleur, Fox 40/dhx5, Hope mono6ti. Pic:
[e-kart/buggy thing] - ME1003, Alltrax 7245, 400a, 20s60ah (leaf modules), CA3. Pic:
[Bad Boy Buggy XT] - Dual DC motors, Curtis 1268 @ 400A/ea, 14s120ah leaf modules, CA3

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