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No battery solar motor system? Answered

Hi all!

I am competing in this solar boat race and one of their rules was that for a sprint race and a slalom race, the batteries have to be disconnected. We have 4 panels, each rated at 64W(18V), a victron MPPT 75v/15amp charger (bluetooth activated), 240W DC motor (up to 48V), 3000W PWM motor controller.

My question is, how should I configure this electrical system with solar power only? Batteries have to be disconnected and not operable.

Things that I've tried:

I put 4 panels in series (72V) and connected them to the MPPT charger. Then the load I connected them to the PWM motor controller. This was not ideal since the motor barely got any power(very slow), and the panels would over volt up to 76V which was past the 75V as advertised and system goes into overvoltage protection.

I also thought of connecting the leads of the solar panels in 36V config (2 parallel, 2 series) directly onto the PWM motor controller but decided that it was safer to ask y'all for some help first. I am open to buy a new MPPT controller that goes over 75V and return the old one, only if that is the best thing to do.

controller link: https://www.amazon.com/Victron-Smart...ords=mppt&...

Solar panels (MSX64) link: https://www.solarelectricsupply.com/...arex-MSX64...

Thanks in advance! :)


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2 years ago

A) Is it your intention to speed control the motor during the race ?

B) Are you allowed to use a capacitor ?

How large of a capacitor ?


Answer 2 years ago

A) Speed control would be ideal, but during the sprint race I'm pretty sure that I only need to go all out.

B) I'm pretty sure that we can use capacitors since the rules don't say that we can't. I think the bigger the capacitor the better? I'm not sure how much current these 4F supercapacitors can handle. But ideally we only need it for a few minutes. Would I wire these capacitors to the load or the battery terminals on the solar charge controller to charge them up? And, what configuration should I use for a 24V system?(5Series, 2 parallel?)


Our motor runs on about 18-20A max @24V (not 240W).