question

kiersten-cornwell avatar image
kiersten-cornwell asked

Why is my solar charge controller still in bulk charge when monitor shows batteries as 100% charge?

BMV 700 shows batteries at 100% charge, but solar charge controller still shows it's in a state of bulk charge. I have checked both manuals, checked settings for both are in line with what's in the manuals... any ideas please?

Battery Voltage shows as 13.15V

BMV Settings:

  • Battery Capacity 100Ah
  • Charged Voltage 13.2V
  • Tail Current 4%
  • Charged time 3minutes

Solar Charge Controller Settings:

  • Absorbtion voltage 14.4V
  • Float voltage 13.8V

Should I be increasing the charged voltage to 14.2?

Why is the BMV showing 100% charged when the charged voltage has not been achieved?

Thanks

battery charging
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1 Answer
JohnC avatar image
JohnC answered ·

Hi @Kiersten Cornwell

It's probably syncing too early. Your Tail Current is too high and Charged V too low. Conceivably it could even be syncing early in the day if you have solar winding up.

Try setting Charged V to just below Float level, but not so close that Temp Comp on your charge Float setting might reach. Let's say 13.5V.

I use 0.6% Tail, but I'm not suggesting you go that low. Maybe 1-2% until you get a feel for what's happening. What you need to do is watch your batts when you know they're close to fully charged, then take note of the Amps they'll accept and whether charge is tapering. You need to decide then where to set that Tail (1A = 1% for you). Yes I know the 4% is default, but that's likely way too high for you.

Further down the line there's a little more to getting accuracy than just this, but it's a start point..

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