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Comment: Hardly Exciting (Score 2) 84

by DoctorTuba (#40653573) Attached to: A Build-It-Yourself Electric Vehicle
This is no more a DIY EV than Lego Mindstorms is autonomous robotics. It's a one size fits all kit and the fit at 15 miles and 21 mph is pretty lousy. It might be a fun toy if priced at under $500, but where's the educational value? I'd guess it uses rudimentary components (simple DC motor, rheostat, lead-acid batteries). You could get the same education building an electric RC car, plane, or boat.

Comment: Re:Power problem answered: (Score 3, Insightful) 212

by DoctorTuba (#40494119) Attached to: Ask Slashdot: How To Add New Tech To Old Van?
Surging can be handled, but even a high output (180 amp or greater) engine alternator won't be able to deal with the load. That's why auto manufacturers are looking at moving to 24 or 28 volt systems in the near future. I won't get into the inverter issue but I'll make a suggestion on the 12 volt supply side for your toys.

1. Power your kit from a small bank of sealed automotive batteries (gel or AGM) which can be mounted in any orientation and safer than traditional wet batteries. If you plan on pulling power from them for extended periods without recharging (eg gaming all night) consider deep cycle batteries. Build secure mounts for them in the back of your van so they don't move around and have some protection in case of an accident..

2. Charge these batteries with a high output alternator driven from the driveshaft (do a web search on "driveshaft driven alternator"). This will only charge your batteries while the van is moving, but I do assume you're planning on driving it some of the time.

3. If you don't know how to hook up the batteries in parallel, or attach them to the alternator, or how to correctly size, crimp, and route the wiring find someone who does and do it right. Screwing up here could make things a little more intense than you'd like.

Doing it this way has a number of advantages. The two big ones are:
1. The system is completely isolated from vehicle electrics so, for example, completely draining the rear batteries won't keep you from starting the van.

2. Having the batteries and alternator both at the rear of the van makes the wiring easier.

Logic doesn't apply to the real world. -- Marvin Minsky