# Bypass DC Converter on 2000 Ford Think Neighbor



## major (Apr 4, 2008)

aerobat52 said:


> I have a 2000 Ford Think Neighbor and none of the 12v items work (no headlights, brake lights, horn, or wipers). I am new to the EV world so please correct me if my assumptions are wrong.
> 
> My assumptions:
> 
> ...


Hi aero,

It is a bad idea to tap one of the 12V batteries in a series string for accessories. That will drain that particular battery more than the others. So when the pack is charged, that one will not come up to full SoC (State of Charge). It might be OK for a time or two, but soon that one battery would die from overdischarge. 

I'd suggest installing a separate 12V battery with a separate charger (12V) and keep it isolated from the main pack and even from the DC/DC. It would require charging each time you charge the main pack. But may be a less expensive/complex choice than replacing the DC/DC.

The by-pass method you describe may present other problems which are not apparent like ground loops. I recommend you not try it.

Regards,

major


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## madderscience (Jun 28, 2008)

Another reason not to tap the traction pack is that the traction (high voltage) pack on an EV is generally isolated from the chassis. The 12V system is not. If you tap a battery, you have now grounded a point in the middle of the traction battery to the chassis. This might or might not immediately cause any problems, but it reduces safety. On a 72V vehicle that might not be too terribly dangerous but on higher voltage cars that could be a major issue.

72V to 12V converters are not that expensive as 72V is in golf cart territory. I see a whole bunch on ebay ranging from $40 to somewhere around $100. I suggest replacing the sevcon unit.


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## sailfish11 (Sep 15, 2007)

I know it's been a couple weeks, so you may have already resolved this. But have you hooked a multi-meter up to the DC-DC output to check if it's putting out 12-14V? You could just have a loose wire somewhere.


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