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Hi, To charge my traction batterys I use a sterling 60 amp charger @14.8 or 15.1volts. when the batterys are being charged from solar or wind, they are getting around 13 volts. Does this mean due to the lower voltage the batterys wont ever rewch fully charged (float mode) by solar or wind alone.

Asked by: anthony spanswick  | 1.59pm, Monday 2 March

WW says:

The lower voltage output of your solar/wind charger will probably mean that the batteries do not receive top-up charge, and are probably cycling somewhat below 100%. The higher voltage in a mains-powered charger help overcome internal resistance to charge, as the batteries become nearly full.
Depending on the type of wind/solar controller, you may be able to alter the voltage output (such as choosing different battery type). Many have internal dip switches to change the charging profile. Basic charge controllers do not- most PWM (pulse width modulation) controllers do, while almost all MPPT (maximum power point tracking- the most expensive) controllers allow for customisation of the charging profile.
It might also be worth checking that the cables, both from the wind/solar panels to the controller, and especially those from the controller to the battery bank are sufficiently thick, to avoid voltage drop. If the wires from the controller to the battery bank are less than 4mm2, then voltage drop may be significant; larger diameter wires will give better performance in many cases (within reason, wires cannot be too thick, but certainly can be too thin).
Let us know what controller you have (as well as the size of your solar array/wind generator) and we may be able to offer more detailed advice.

Mark Langley  | 2.43PM, Monday 2 March

I would also consider measuring the voltage at the controller output and at the battery connections (with a multimeter) which would show up any voltage drop.

Mark Langley  | 3.28PM, Monday 2 March

The time to measure for any volt drop is on a bright sunny day, with maximum current flow.

Rupert Smedley  | 5.52PM, Monday 2 March

Readers say:

Thankyou for quick reply. The controller is a viewstar 20 pwm for the solar. I didnt know you could adjust the settings, so I have looked at a pdf instruction manel and increased some of the settings to the upper limit as my batterys are open acid. At the moment 0.6 of an amp is going in @13.0 volts. The panels I have are 2x 100 watts and I have used the same cable that came with the panels from new to run down to the batterys. Hopefully the volts will increase tomorrow with increased amps if the sun returns!
Many thanks anthony

anthony spanswick  | 4.31PM, Monday 2 March

The volts coming into the controller terminals matches the reading from the batterys. No voltage loss between batterys and controller.

anthony spanswick  | 4.42PM, Monday 2 March

Hi, Today amps around 8.3@13.6 volts. Battery side only 13.1 so I will need to look at the controller to battery leads. Do you know if I can increase 13.6 to 15.1! The volts increase as the amps increase and I think the max amps with 200 watts is 11 amps, so its nere to the top end

anthony spanswick  | 10.22AM, Tuesday 3 March

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