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Trying to reconcile old hf controller with hand held multimeter

Mysal12

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Nov 25, 2021
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Been running solar for a long time. First set up was a 45w hf kit with the old controller (see pic).
Currently running two 175 w 24v panels to four 125 ah 12v sealed lead acid batteries through a 30A charge controller.

I have been using the hf controller, connected to only the Batts, as a distribution box since it has 3v, 6v, 9v and 12v taps as well as the led display. I felt a couple tenths loss was acceptable.

I usually rely on the hf charge controller led for battery voltage. Occasionally I would check battery voltage at the hf connection to the battery bank. Those readings are usually within a couple of tenths.

Last week the hf display read 12.8 initially and after a week of using two 13w CFL for 7 hours and charging phones the voltage reading on the hf led steadily decreased to 12.2 under mostly cloudy skies. At one point I got a low voltage shutoff because I left the flash light lit while charging the phone. They recovered to 12.4 overnight with no lights etc. This all seemed like a large drop considering the bank and panel size.

I went looking for issues and tidied up some of the connections at the batteries, 30A charge controller and switched battery order wiring on 1 battery for better balance.

The result under sunny skies was that on the hand held meter the Batts showed 12.88 v after a couple hours but the hf led showed 12.4. Only a little odd. After sun down, I found it strange that the battery voltage on the hand held rose to 14.4. It was back to 12.9 before sun up then rose to 13.4 under sunny skies. Seemed normal except the hf led read 12.2 through the whole process.

This was the case through another 24 hours. Battery voltage at the battery takeoff point for the controller was significantly higher than the led display. Sometimes as much as 2 volts.

Question is am I misunderstanding the led function or is this indicating a problem? Thoughts? Suggestions?

Thank you for the help.
 

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