Charging with shorepower vs. Victron MPPT controlled solar

[SFH]

Hi,

I have a small charging problem.

When I charge using shorepower my Victron BMV-702 batteri monitor shows 100% when charging is completed and charger goes into floating. All good..

If I charge using my solar panels through my Victron MPPT 150/80 I never get to more than 98% before the MPPT controller floats.

I guess it is a settings problem but not sure what to change.

Any good ideas?

[john61ct]

No charge source nor most shunt-base AH counting BMs can be trusted to know when 100% Full is reached on its own.

That is **your job to tell them**, and keep everything calibrated so their performance matches your judgement.

Let's say you have a 600AH bank, and the manufacturer definition of 100% Full is .005C trailing amps. That's half an amp per 100AH capacity, or 3A for 600AH.

And not counting loads, which is why current accepted needs to be measured at the bank.

Keep adjusting charge source "Hold Absorb Time" parameter until you see it doesn't drop to Float until trailing amps at the Absorb V setpoint has fallen below 3A.

This should be calibrated so it happens most of the time, under your various usual load conditions.

Every time possible when you observe that happen correctly, you reset the BM, i.e. notify it the bank is now 100% Full.

The more frequently you do this the more accurate it will be.

Adjusting Charge Efficiency factor and Peukert number may also help.

But these gizmos are never exact, best you can do is "good enough".

To learn more, go to Maine Sail's http://marinehowto.com and search for the three articles containing "Battery Monitor" in the title.