Thread: solar battery maintenance

You'll get around 1.2 amps maximum out of a directly connected 20W panel so it is unlikely to damage anything short term. I wouldn't leave it connected long term though without a regulator. Small regs start from around $20.

20A 12V-24V LCD Display PWM Solar Panel Regulator Charge Controller & Timer PWM | eBay

Originally Posted by bee utey

20A 12V-24V LCD Display PWM Solar Panel Regulator Charge Controller & Timer PWM | eBay

Many thanks for that. Its not the cost, its that didn't happen to have a controller to hand and wanted to make sure it was safe within reason

Thanks for the link too. If they post outside of Aus I'll be ordering one

Pretty sure Jaycar say to fit a regulator for 20 watts and above. Trickle feed solar panels often don't have a regulator. I have used a 15 watt panel as a trickle feed without problems, because the Defender seems to have a slow drain, maybe because of the trailer brake display. Regulators are dirt cheap - $20. I've got a 10A one in the Defender plus a spare one I haven't used yet. My regulator is then connected to a 10A circuit breaker just for added protection.

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for charging you'll be fine.

for maintenance.. maybe but I wouldn't unless you've got a parasitic drain constantly on the battery

Jaycar and altronics have a small black box regulator which would be ideal the same sort of one is available from ebay and the like for a lower cost.

Hi Magnet, as Dave posted, "unless you have parasitic drain" and you do.

The isolator will be using a constant small amperage and while all the new versions have the TIME-OUT feature, this only operates if the battery voltage drops below 12.7v and stays below that level for seventy two hours.

With your setup, using the solar to charge and maintain the batteries, every "SUNNY" day, the solar will raise the voltage over 13.2v, the TIME-OUT reset voltage level, and so your isolator will be on all the time.

This is not a problem and will allow you to use the 20w solar panel with out a regulator.

BUT, after a few days of sunny weather, in the afternoon, while the solar is getting good sun coverage, measure the voltage and make sure it is not above 14.5v.

I have 2 x 15w panels keeping the boat batteries charged...

Seems to be working fine. Haven't observed any ill effects in 18 months. (Sadly the boat hasn't gone out on the water due to other factors).

Motors are started and run regularly and battery condition always appears good.

Thank you Drivesafe that was just what I was looking for.

For completeness the system fitted is your D3-BS = SC80-LR + ABG-25

Just so that I'm clear, when you say

Originally Posted by drivesafe

measure the voltage and make sure it is not above 14.5v.

Am I to take this measurement at the battery with the panel connected?

In real world use is there a likelihood that this combination will exceed 14.5v or will the parasitic drain keep it at this level?

If it stays at 14.5v or less can I keep it connected long term for on going battery maintenance?

I bought the wattsup meter that you mentioned some time back. I plan to connect that between the panel and the battery to get a continuously updated read out.

Sorry if I'm missing the point but I'm new to solar and the wattsup meter

You should take the measurement with the panel in full sun with all of the batteries fully charged and all of the vehicles loads off. (parked for 3 days undisturbed or however long it takes your particular vehicle to go into hibernation mode)

from memory the total parasitic draw from a D3 in hibernation mode is in the order of a 200mA and the traxide is 80 or so.

your 20W panel will push an average of 20ah into the batteries if you set it up correctly which is something like twice what the parasitic load is.

Given long enough (or if you go park in the tropics) that will eventually cook your batteries if left unregulated.

Personally (and this is one of those things drive save and I have differing opinions on) I think 14.5 is too high for a floating voltage and should be considered to be the peak disconnect voltage.

I would also check the current flow while its hooked up.

The numbers I would be looking for would be around 13v with good current flowing from the panel (so on a 20w panel up to 1.7A) with the amps reducing to 0 by about 14.2V