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billys1337 avatar image
billys1337 asked

MPPT and multiplus charging together

Hey all,
Looking for some advice for using a "BlueSolar Charger MPPT 150/60" and a "MultiPlus Compact 12/1600/70" together in regard to charging.
I have the multiplus, a smart shunt, gx cerbo and the bluesolar MPPT all visible in VRM.
Both chargers work, however the issue is that they see slightly different voltages and so don't sync the charge stages properly. I kind of corrected this by decreasing the absoption and float settings of the MPPT and this helped, they both went into absorption a few minutes apart, great!

However, after about 2 hours the MPPT then went into float, but the multiplus stayed in absorption. Then the MPPT throttled back its charging watts until it was 0 and basically just stopped doing anything while the multiplus was still putting in its full amps in absorption stage. I'm guessing the MPPT saw the high voltage on the system from the muliplus charging and decided it was too high so stopping charging.

So, my question is, what can I do about this? I need the MPPT to keep charging as long as there is sun and the battery needs it, if the muliplus was the one scaling back i would be fine with that but how can I control which one floats first? what causes the chargers to decide they are done absorption and start floating?

Does the "tail current" setting have anything to do with that in the MPPT settings victron connect app? I don't see this setting for the multiplus in the VE config windows app.

Cheers for any help

MPPT ControllersMultiPlus Quattro Inverter Chargerbattery charging
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2 Answers
seb71 avatar image
seb71 answered ·

Make sure that the SmartShunt is set as "Battery Monitor" in Cerbo.

Read about DVCC and enable it.


Is this a home/house system or boat/RV?

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billys1337 avatar image billys1337 commented ·
Thanks for your reply, the smart shunt is set as battery monitor.

I will enable DVCC again, I had it enabled but was told by my victron dealer that DVCC is not needed for my system as i use lead acid batteries and not lithium (the guy told me DVCC is for a system with a BMS).

This is for my house, but the setup is probably more comparable to a boat/rv. It runs 2 fridges and a few other minor things at night and charges during the day from solar (the muliplus is getting its AC input from a grid tied PV system)

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seb71 avatar image seb71 billys1337 commented ·

the muliplus is getting its AC input from a grid tied PV system

Ah, that's why you also charge the battery with Multiplus (not just the MPPT).


Set all chargers (MPPT, Multiplus) with the same charging settings.


Also, if the battery can't take all the available PV power and there are no loads (or not large enough), the MPPT will reduce production.

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billys1337 avatar image billys1337 seb71 commented ·

Maybe it will be different with DVCC enabled?.. but as it was today this did not stand to be the case, the MPPT (in float) reduced its production down to 0 while the multiplus (in absorption) was still charging at full amps, if i disabled the multiplus then the mppt would ramp up right away to full production again.

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billys1337 avatar image billys1337 commented ·
Hey again, so today after doing what you suggested (enabling DVCC) the system was all reading the same voltages in VRM so this was a good sign, both went to absorption at the same time but the problem remains, the solar charge control went into float after about 2.5 hours but the mutliplus still absorption. The combined charge current during the absorption for both chargers had ramped down to about 30 amps (about 50% of max), but as soon as the mppt went to float then the voltage was too high and so if effectively turned off and the mutliplus was doing 30 amps in absorption.

At that point i turned off the mutliplus and the MPPT took over again.

:(

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Alexandra avatar image
Alexandra answered ·

@billys1337

All devices should be set the same Absorption and Float voltages and battery type.

The MP should not be charging at full amps in absorption, that should be low amp charge state. Something is off there.

What firmware do you have, are you using ESS or is this a mobile install?


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billys1337 avatar image billys1337 commented ·

MP is v506
MPPT is v1.61
Cerbo is v3.01
Smartshunt is v4.14
All latest firmware i believe.
NO ESS

The multiplus was working fine before I added the MPPT, it would enter absorption and slowly ramp itself down all as expected, and I believe this would still happen with the MPPT added, its just that the MPPT enters float first. I reduced the charge current on the multiplus after I added the MPPT.
I should clarify when i say the multiplus is charging at full.. it is charging at the charge current I specified in in VE configure > charger settings, which I set to 40 amps.
I also use an assistant that is "charge current control" so I can use a separate control system via the inputs on the MP to stop the muliplus from charging if the grid tied system is not making enough but all this does is ether limit it to 0 amps and disable the charger or 40 amps, it does not do anything in between, and this does not usually stop it from ramping itself down during the absorption phase when it gets there, this has been working fine for many months.

Only with the addition of the MPPT do I now have these added complications.

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