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Eric M. avatar image
Eric M. asked

Multiplus Compact curiousity

I have a Multiplus Compact 12v 2000va 80a, in a van with 600ah lifepo4 batts and a thorough dc system. I’ve been scanning the provided docs, and I can’t seem to find a way to increase the charger output limit. I have all setting maxed out - ie 80amps, and my batteries can handle tons more…


Basically, wondering why I’m only getting ~500w charging my 12v batteries, with only ~300w drawn by DC. When I cut off big DC loads, the drawn AC current doesn’t then go to charging my batts, it just drops the amount of the load. How can I maximize charging speed?


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MultiPlus Quattro Inverter Charger
0c7928e2-e192-4b40-b1d2-9fd0c3ebb1d4.jpeg (385.1 KiB)
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dagamma avatar image dagamma commented ·
Do you have DVCC enabled?
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Eric M. avatar image Eric M. dagamma commented ·
I do, but it’s set to the battery manufacture parameters which are well above what the Multi gives off.
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klim8skeptic avatar image klim8skeptic ♦ Eric M. commented ·
Try upping the ac input current limit.
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Eric M. avatar image Eric M. klim8skeptic ♦ commented ·
I had tried that to no avail.. 15a is the rating for the different outlets I've been using, but even so, at that with 120v it should have access to 3000w
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2 Answers
nickdb avatar image
nickdb answered ·

One obvious point: at 100F (37.7C) the system, internally, is well above 25C so will be derating.


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Eric M. avatar image Eric M. commented ·
Is that a feature built in, without settings.. That it lowers output during high temperature? I’ve noticed without fail batts get to about 100°F in ~20 minutes during charging, and that would coincide with the timing that the full charge load drops significantly (on first plug-in I’m getting ~1.3kw). Temperature drops once it hits absorption/float, but at that point it’s not giving full juice to validate.
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nickdb avatar image nickdb ♦♦ Eric M. commented ·

What batteries are these?

What are your charger settings on the multi?

Do you have a shunt, or is there a BMS or you using the multi to calculate SOC?

Sorry, lots of questions. Systems will automatically adjust their performance based on temperature, this also applies to a batteries management system.

You may also have temp compensation on in the inverter charger settings which would affect charging.


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Eric M. avatar image Eric M. nickdb ♦♦ commented ·
The charger settings have Lithium on, set to 80a, and 14.9a input limit. No temp compensation was recommended for Lithium so I don't have that on.

I have a shunt, its accurate to within 2-3%, and yes the batteries have an internal BMS. Looking on the website, looks like the BMS has overheat protection, so I'm starting to imagine thats whats slowing the charge.

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nickdb avatar image nickdb ♦♦ Eric M. commented ·
If you can connect to the bms that may provide more insight.
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JohnC avatar image
JohnC answered ·

Hi @Eric M.

It seems your Multi can handle near to it's DC limit into the DC Loads, but not into the battery. The battery is where I'd be looking, managed?, derated?, whatever?.

There may be a 'safety margin' applied to the full 80A, so you mightn't see that hard on the redline. I doubt your issue is the Multi though.

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Eric M. avatar image Eric M. commented ·
Fair point, must be the internal BMS maintaining temperature at 100F. It quickly rose to 100.4F and stayed there. I'm new to Lithium so I hadn't considered the BMS might play a factor. Thanks!
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