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friaras avatar image
friaras asked

Does higher voltage carry more Amperage? I'm getting higher Amps with lower voltages.

Victron 150/35 with BT dongle, LiOn Batts at 36 volts, 7X100 watts panels, 12 gauge 25ft cable to the charge controller, when I switch the charge controller to 48 volts, the voltage goes up but the Amperage goes down. If I switch back to 36 volts, the voltage goes down and Amps go up. I understand that is negative resistance, the backup system setup remain the same no other changes, except that when the batteries have been charged at 36 volts to full, I switch to the GTI and divert the charge controller output to the house to use excess power. the GTI can accept 20-60 volts input it can generate up 3.5Kwh on a good day which is half of my daily power consumption year around except during Summer months where my consumption goes way high because of the AC unit.

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klim8skeptic avatar image klim8skeptic ♦ commented ·

7 panels in series is very close (probably over) the pv input of 150v.

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friaras avatar image friaras klim8skeptic ♦ commented ·

It hovers around 130 Volts max I have seen is 136 Volts, at 48 Volts, is indoors and external fans, so it stays very cool to the touch even on very sunny days. At 36 volts it drops dramatically hovers around 100 volts, at 14 Amps, daily GTI output is around 3.5Kwh, very happy with the 150/35 CC from Victron.

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klim8skeptic avatar image klim8skeptic ♦ friaras commented ·

Given I don't know how cold it gets where you live, or any specs of your panels, I can only speculate that the Voc of your array is likely to be over 150v in cold weather. The controller will be damaged, or let smoke out if exposed to voltages greater than 150v.

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Matthias Lange - DE avatar image Matthias Lange - DE ♦ commented ·

For the same power you need less current if the voltage is higher.

P=U*I

e.g. you can have 1000W with 1V and 1000A or with 1000V and 1A.

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2 Answers
ejrossouw avatar image
ejrossouw answered ·

@friaras@gmail.com To answer the question. Yes higher voltage results = lower current. It why my preference is for 48v systems where feasible as it means lower current and as a consequence thinner (cheaper cables) as well as less heat.

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friaras avatar image friaras commented ·

You would think that at higher volts higher amps, but in my case is the opposite. I was getting good power today, the panels got p to 567 watts, not bad for this time of year. I switched from 36 volts (12.7) amps to 48 volts and Amps dropped to around 7-9 Amps, which is more beneficial for generating more watts? Sorry I'm kind of new at this.

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ejrossouw avatar image ejrossouw friaras commented ·

@friaras@gmail.com No problem. As in M. Lange's reply, you still get the same power. The benefits however with lower current is that it typically results in less energy lost through heat etc. Worth having a read. https://www.victronenergy.com/blog/category/technical-articles/

Good to remember that equation from school days Watt=VoltsxAmps ;)

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friaras avatar image
friaras answered ·

Thanks for the info, I appreciate it.

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