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love2learn avatar image
love2learn asked

Over-amping batteries

I just purchased 2x Victron 100/50 MPPT. I noticed in the spec sheet that they can put out UP TO 60a. Combined, those 2 MPPT can put out 120amps to the batteries, which is 20amps over my bank's 100a max. At max sun/panel output, my theoretical combined max amperage from all panels is 79.7A. So even though my 2 MPPTs together can do 120amps peak, my batteries should theoretically never even come close to that right? Am I correct to assume that I am safe from over-amping the batteries because of my total solar panel theoretical maximum?


- MPPT 1 has 1080 watts worth of panels (which converted to 25.6v is 42.2a to batteries from MPPT1).

- MPPT 2 has 960 watts worth of panels (which converted to 25.6v is 37.5a to batteries from MPPT2)

- Batteries: 4x SOK 206ah 12v. 2 series, 2 parallel.

- Victron Multiplus 3000w 24v Inverter Charger.


Additionally, would I have any restrictions for generator/AC charging because of this, or does thee Inverter throttle this on its own? (the inverter can charge the batteries at 70amps)

battery charging
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5 Answers
Alexandra avatar image
Alexandra answered ·

@Love2Learn

You can set a system total charge current using dvcc on a gx when they are all networked through it.

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kevgermany avatar image
kevgermany answered ·

Your panels are the limiting factor here. You're going to be charging at over 28V, so you're well on the safe side of current ratings. The 60A is short circuit, not what it will deliver when charging.

If you want the generator running when the panels are putting out lots of power, Alexandra's DVCC recommendation is perfect, but check out the needed connections before you buy and miss something and need to go back for more.

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klim8skeptic avatar image
klim8skeptic answered ·

`100-50 is rated for 50 charge current.

100-50 manual.

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love2learn avatar image
love2learn answered ·

I was under the impression that 60A short circuit current meant that the MPPT output current can climb TO that point. As in, it can get up to, say, 59A output "before it trips".

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nickdb avatar image nickdb ♦♦ commented ·

The maximum output current is 50A at whatever voltage you're running at, it will throttle from that point, it won't pop. So the max output in theory is 25.6 x 50 = 1280W at 25C, this is beyond the ability of your panels.

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Alexandra avatar image Alexandra ♦ commented ·

@Love2Learn

The pv short circuit current refers to the pv side. So if parallel a bunch of strings that is the max it can short circuit without damage to itself.

A provision in case of mistake. See tech specs and the little reference to the 2 by the spec.

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love2learn avatar image love2learn Alexandra ♦ commented ·
Ahhh, somehow I missed the part of it being on the PV side. I was calculating the battery side, which caused me to scratch my head about the "50" number if it really was 60. Thank you!
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love2learn avatar image
love2learn answered ·

Thanks to all that jumped in to help! I'll probably just keep to using the generator when there is little-no sun out as I will not be getting any of the advanced GX solutions for my application (Color control, Cerbo, Venus, etc)

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