- Sep 23, 2013
- 2,585
- 8,773
- Funster No
- 28,231
- MH
- Globecar Campscout
- Exp
- Since 2008 (started in a VW T4 campervan)
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.
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.
