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joshua-t avatar image
joshua-t asked

Max Charging Current for AGM batteries w/ Victron MPPT 100|50

I am currently running 5 100W solar panels in parallel through my Victron 100|50 MPPT controller, connect to 3 12v, 125Ah AGM batteries connected in parallel.

My batteries are rated for 30A max charging current.

I am about to upgrade the solar to produce more power to recharge faster (not quite generating enough to keep up with usage). I will add two 250W panels, connected in series, to a separate controller.

My question: I don't want to overcharge the batteries. They are rated for 30A max charge current, which is currently around what my Victron controller is sending them with the current setup. If I switch my 5 100W panels to a series connection (dropping the Amps, but increasing the voltage), would that change how much current the Victron is sending to my batteries so I have room to add another controller? Or is the Victron converting the power regardless of how I have the panels configured?

MPPT ControllersMPPT SmartSolarmppt chargingcharge current limit
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3 Answers
dkovacevic avatar image
dkovacevic answered ·

Hello Joshua,

If your batteries are wired in parallel, I believe that the 30A charge current would actually be 90A, because wired in parallel the current is split.

Daniel

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joshua-t avatar image joshua-t commented ·

Really? Is that for sure? Because that would make my day.

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jwfrary avatar image jwfrary joshua-t commented ·

@dkovacevic the 30amp will be for each battery so you have 90amps to play with before you have trouble.

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dkovacevic avatar image dkovacevic joshua-t commented ·

The 30A rating you shared- was that number on each battery, or is each battery rated 10A max charging current?

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jwfrary avatar image jwfrary dkovacevic commented ·

2c for a 125 ah battery would be 25 amp a little extra being an agm would be expected.

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rickp avatar image
rickp answered ·

You can set a max charge current in the settings. Using this, you can determine which wiring type gives you the best production, protection from shading, etc. Your post didn’t mention BlueSolar or SmartSolar, but both have this setting capability.

While it will read voltage on the bus it’s connected to, the Victron SCC will not read another brand’s SCC charge current, so you may need to limit the Victron to only the amount of current needed to reach 30A combined charging Your batteries need. I believe two Victrons can work together to do this, but don’t have that in my setup.

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Peter Buijs - NL avatar image
Peter Buijs - NL answered ·

Change log:


v1.50 – 13 May 2020

Released for all HW versions.


Bug-fix:

  • Change fast overvoltage protection threshold back to what it was before v1.47, on all non 250V models, due to possibility of mis-triggering on some systems (normally 12V, small battery and noisy load). The fast overvoltage protection threshold was changed, on v1.47, mainly for the units that have the new PV Short Protection strategy (250V models).


v1.49 – 16 April 2020

Released for all HW versions.


Bug-fix:

  • Fix issue that caused the charger to not go into synchronised charging over BLE when DVCC+Charge current limit is enabled on the GX Device that is connected to the charger.


Known issues:

  • In 12V battery systems that battery voltage tends to oscillate more (small batteries, thin cables, noisy loads, etc), there is a small chance that the fast overvoltage protection kick in when not supposed to. A smaller fast overvoltage threshold was introduced on v1.47, caused the protection to be more trigger happy. The intention of the smaller threshold was to reduce the possible overshoot when disconnecting the battery. This is a concern on the 250V chargers that have the improved PV Short Protection.



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