I am building a project that will draw around 300 amps at 12vdc, for about 40-60 minutes then it will rest for a few minutes. For this projects application it will be very impractical to build a dedicated circuit. How can I power this on a standard(American) wall outlet?

I was thinking of using multiple optima yellow top deep cycle batteries hooked up in parallel and having a heavy duty battery charger that will constantly be charging the batteries at around 100-200 amps that way during the rest period the batteries will completely recoup and during the use the constant charging will allow the batteries to last for at least an hour. Will this work?

If I have to build a dedicated circuit, do I have to step up the voltage to 240Vac? If it is necessary to use a dedicated circuit, can you guys please recommend a 120V (or 240V) to 12v high current converter.

  • \$\begingroup\$ You're using the term 'circuit' fairly loosely here, and in several places it's ambiguous whether you're talking about a house-wiring circuit, or an electronics circuit used to convert AC to DC. \$\endgroup\$
    – W5VO
    Jun 1, 2014 at 19:43
  • \$\begingroup\$ By dedicated circuit I meant a and AC circuit that has its own breaker and is only meant for my project \$\endgroup\$
    – Joel
    Jun 1, 2014 at 19:58
  • 2
    \$\begingroup\$ Do the math! 12V * 300A = 3600W, while 120V * 15A = 1800W. You would only be able to operate at a 50% duty cycle under ideal conditions, and a lot less than that once you take the various power conversion and storage efficiencies into account. \$\endgroup\$
    – Dave Tweed
    Jun 1, 2014 at 19:59
  • \$\begingroup\$ I understand that it I need 3600W, however it is not very practical for this application to use the 240V so I was trying to see if there was a way that I could use the 120v outlet \$\endgroup\$
    – Joel
    Jun 1, 2014 at 20:11
  • \$\begingroup\$ I wouldn't want your electric bill. \$\endgroup\$
    – tcrosley
    Jun 2, 2014 at 9:54

2 Answers 2


100A at 12V is about as much as you can get from a 15A outlet. That means you'd have to allow a lot of recovery time (hours, not minutes).

If the 240VAC outlet/hard-wired is an option, you could consider simply connecting a couple Meanwell RSP2400-12 166A supplies (or similar) in parallel. No mussing with batteries, then, and you'll get (just) the 300A you require.

  • \$\begingroup\$ How would you recommend hooking them up? Should I have multiple 240VAC outlets and hook the outputs up in parallel \$\endgroup\$
    – Joel
    Jun 1, 2014 at 20:06
  • \$\begingroup\$ I would recommend reading the manuals very carefully wrt paralleling. It is explicitly allowed, with 0.9 of double the current, but a mistake could be costly. You just need to parallel the inputs and connect them to the 240V source. There are several types of plugs available in the 35A to 55A range, probably an electric stove or dryer type would be most common in a US home. \$\endgroup\$ Jun 1, 2014 at 20:17
  • 1
    \$\begingroup\$ I found the data sheet for the RSP2400-12 and it has a whole section on hooking up in parallel. I really appreciate all of your help!! \$\endgroup\$
    – Joel
    Jun 1, 2014 at 20:31

120 volts isn't going to work.

If you have a 240 volt, 20 amp circuit, you can get 4800 watts (maybe). On average you are consuming \$ 12v * 300a = 3600W \$ then multiplied by duty cycle of (60 - "a few minutes")/60 minutes.

As for recommending a 240 input to 12 volt DC converter, I will leave it to others who shop around for such high power battery chargers.

  • \$\begingroup\$ Try arc welder. \$\endgroup\$ Jun 1, 2014 at 21:38

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