Monitoring when charging is complete

[TheCaller]

I have seen quite a lot of posts that mention how solar panels have completed battery recharge by 8.30 - 9am in the morning. I wonder what readings people are taking to draw this conclusion?

Battery voltage will rise quite early on in the charging process & will remain high until charging is complete, possibly falling back in the later stages as the controller switches to float mode.

Charging current will start low as the sun rises, will increase as the sun gets stronger & will finally fall back as the batteries reach full charge. It will also fall back if the sunlight diminishes.

It seems to me that only falling charge current in continued sunlight indicates a full battery.

Not every solar controller reports current flow, so I wonder if some people are relying on voltage as an indicator of stage of charge.

In reality, it matters little. The system is clearly doing it's job, because otherwise people would be complaining of running out of power or short battery life.

The main danger is short battery life. The voltage readings may be disguising a battery that never reaches full charge. Voltage only becomes a meaningful measure of state of charge after the battery has been isolated from both loads & charging sources for some time - a situation that may rarely arise while the van is in use.

 

[Trikeman]

The things I go on is the output from the panels,

The Volts/amps when charging (little light at the top on remote).

And when the little green light flashes showing 'battery charged' - this generally happens by about 8.30-9.00 on mornings such as we have just had.


Hope it helps.

Regards,

Trikeman.

 

[TheCaller]

Sounds like yours is genuine then.

Not surprised, having followed your install thread with interest.

 

[pappajohn]

Apply any charging mode to a battery and the terminal voltage will show fully charged.....and is meaningless regarding charge state.

the true voltage is measured at the terminals when any charger is disconnected and the battery has stood for an hour or so with nothing draining it.

 

[Trikeman]

Apply any charging mode to a battery and the terminal voltage will show fully charged.....and is meaningless regarding charge state.

the true voltage is measured at the terminals when any charger is disconnected and the battery has stood for an hour or so with nothing draining it.

I'll not be getting my multi-meter out to check and disconnecting things when I'm enjoying myself away for sure - I trust my little flashing light, it works well and I've not been stuck yet.

Did do the 'normal' checks as you suggest when the system was new and ties up with the little flashing light so happy there.

Regards,

Trikeman.

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[John.]

Well I followed Trikemans advice as well & mine seems to work fine
too

 

[ES Cumbrian]

I fitted a NASA BM1 which gives me all the information I need.