# How do I use cheap MPPT charge controllers for DC-DC conversion?

Asked by muhammajelly (547) January 29th, 2013

I have 24V transformer wired into mains. I wish to power 12V applications in the 60A range and will have a LOT of voltage drop in the line (0–8V) but the voltage drop won’t always be constant. How can I use an MPPT charge controller to accomplish this? I couldn’t find a cheap DC-DC converter able to and voltage regulators able to just converted excess voltage into massive amounts of heat.

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I understand someone could answer this question later—but having waited ½ hours without an answer I am going to make some product orders now. I am still interested in the answer but real need has passed.

Welcome to Fluther, @muhammajelly. I claim an interest in “electronics” but I never heard of MPPT controllers until now. Googling, I see they’re mainly used for solar power conversion by adjusting the amps-volts tradeoff to gain a few percent in efficiency, according to this curve.

The output of a 24v transformer wired to mains will be alternating current, so somewhere there’s a rectifier & power supply if you’re using a dc-to-dc converter. 60 amps strikes me as a lot of current. Are you starting a car, lol?

…converted excess voltage into massive amounts of heat.
“You can’t win, you can’t even break even.”

gasman (11261)

Here is info on MPPT:
http://www.windsun.com/ChargeControls/MPPT.htm

You have 24VAC right now? Gonna need to change it to 24VDC first…

RocketGuy (8286)

60A rectifier/caps are a non-issue.

Hooking 60A MPPT charge controller to 24V transformer and 8D starting battery worked. 8D is hooked to load. I was afraid it wouldn’t function but in fact it did *so far.

12 VDC at 60 amps requires 720 watts be drawn through the primary (in a loss free system and not accounting for the voltage differences when AC is converted to DC). Therefore the primary of the transformer requires 120 VAC at 6 amps. Can your transformer handle more than 30 amps through its 24 VAC secondary?

Bill1939 (8118)

@Bill1939 It has so far.

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