Why does my MPPT 150/60 not seem to want to maintain the float level?

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camagg asked May 5, '23

Why does my MPPT 150/60 not seem to want to maintain the float level?

Newly installed Victron MPPT 150/60...not bluetooth. Used to charge two LIFEPHOS batteries of 300 amps each in parallel. Used in parallel with a Midnite Classic 150. There are 2.25 kilowatts of panels on the Midnite and four 545 watt panels on the Victron.

The Victron cycles perfectly until it reaches float and here it seems to go to sleep on the job. All current that flow from the batteries is negative and there in no input from the Victron to maintain the float voltage. The preset float voltage, according to the manual, is 27 volts. I have seen the batteries drop to 26 volts and still there is no charging shown by the Victron.

A defective Victron MPPT or is there something I'm missing...as always.

Thanks!

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Answer 1 · 2023-05-06T19:15:44Z

Mike Dorsett answered · May 06, 2023 at 07:15 PM

I've had a similar problem with an MPPT 75/10 on a 12V system. However this does not have a parallel charger. The problem also seems to have resolved itself after some time left on.

Have you tried setting the float voltage of the MPPT to a value higher than that of the Classic? LiFePO4 batteries should have a float voltage closer to 27.6V

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camagg commented · May 07, 2023 at 01:19 PM

Thanks for the input, Mike.

The MPPT that I have is the basic without bluetooth or precise adjustments. It is preset with values for certain circumstances and I have it set for the only option that is listed for LIFEPHOS batteries. This option sets the absorption voltage at 28.4 v. and the float at 27.

Yes, I have tried setting my Midnite Classic at a lower voltage than the Victron but the only result is the batteries drop to below the float set in the Midnite and then that system goes to charge but the system for the Victron stays off.

Nothing I can't work around but a bit aggravating to an obsessive compulsive guy.

Thanks!

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