Using DC Generator as input to MPPT Charge Controller

Thread Starter

AdelCraft

Joined Jul 9, 2020
2
Hi,

I need to charge a battery from a DC generator (DC motor used as generator). The voltage can get up to 40V and the current up to 4A. At first, I planned to use a buck converter to maintain the voltage at 5V an then power the charge controller with that 5V, but I found on internet that MPPT charge controllers can already do this (regulate the voltage). Can I directly connect the DC generator to an MPPT charge controller without any risk of damaging the battery?

Thanks.
 

Irving

Joined Jan 30, 2016
815
Not quite. An MPPT controller varies its load to find the maximum power point, usually for Solar PV panels where the voltage v current is a non-linear relationship depending on radiance level, but increasing amps always decreases volts and vice-versa. Solar MPPT controllers charge 12 or 24v battery banks of several kW.

That's not the case with a generator, increasing speed increases volts, but also increases available amps. Connecting generator to a Solar MPPT will likely do it some damage (though there's some views otherwise out on the web, the majority suggest not).

If your generator can deliver 160W, charging a sub-5v (i'm guessing) Li-ion cell is a bit wasteful... you should be aiming bigger! but if thats all you want to do then the buck converter is as good a a way as any.

There are specific wind MPPT charge controllers, but again they expect bigger batteries, typically 12 or 24v.
 
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