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Author: Subject: Solar battery charger advice
number-1

posted on 20/5/24 at 04:28 PM Reply With Quote
Solar battery charger advice

Does anyone use a solar charger for keeping a battery charged in either a kit car or motor home? Ive seen the below but wanted to know if its suitable to keep the battery charged or not? If not, what specs should i be looking for?

This

Thanks

N1

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HowardB

posted on 21/5/24 at 06:08 AM Reply With Quote
Looks very interesting if it does all it says - clearly aimed at batteries in leisure use, as in it mentions controlling the load. Even if it trickles a few hundred mA in that will help combat a flat battery over time.

I used a much smaller one - 300mA max on my Land Rover, that worked ok, and still today powers a bank of LED lights in the garage

50 seems like a deal?





Howard

Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)

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cliftyhanger

posted on 21/5/24 at 06:42 AM Reply With Quote
I have 2 lockup garages with cars stored in them. So wanted solar chargers for both.
Just last week I bought 2x controllers (look to be the same as used in that kit) for under 7 each https://www.ebay.co.uk/itm/354764150871

And 2x 10w panels for a similar price https://www.ebay.co.uk/itm/285765761066

The 10W panel is overkill for trickle charging a car battery, but they will not be positioned in anything like an ideal position. For a motorhome, a bigger charger may well be a good idea especially if it gets sporadic use or has a battery drain from equipment.

And as per my standard operating proceedure, I have been away or busy since they arrived.

I intend to add a 12v led lamp in each garage too. But that will need only work when the car is connected. Unless I buy a couple of cheap rechargeable work floodlights (10 each thesedays)

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sebastiaan

posted on 21/5/24 at 10:36 AM Reply With Quote
watch out, because those solar charge controllers (and all other ones....) have a current drain of ~10-15mA from the battery when the sun doesn't shine (i.e. at night). Which means the panel needs to be able to overcompensate for that during the day also in the darkest december days. Otherwise you'll end up draining the battery.

Worst-case math; 20 hours discharge at 10mA = 0.12W during 20 hours. Needs at least 0.6W from the panel during the remaining "light" 4 hours per day. Which may get close during december and a PWM solar charger. And that is only to compensate the losses from the charger, not the car itself.

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jacko

posted on 21/5/24 at 11:06 AM Reply With Quote
The last post is this the same with house solar set up or is it completely different on houses
Thanks
G





555

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cliftyhanger

posted on 22/5/24 at 08:35 AM Reply With Quote
quote:
Originally posted by sebastiaan
watch out, because those solar charge controllers (and all other ones....) have a current drain of ~10-15mA from the battery when the sun doesn't shine (i.e. at night). Which means the panel needs to be able to overcompensate for that during the day also in the darkest december days. Otherwise you'll end up draining the battery.

Worst-case math; 20 hours discharge at 10mA = 0.12W during 20 hours. Needs at least 0.6W from the panel during the remaining "light" 4 hours per day. Which may get close during december and a PWM solar charger. And that is only to compensate the losses from the charger, not the car itself.


Thank yopu for the warning, I hadn't considered that aspect
And I hope the 10w (0.8a) charger will be enough to keep the battery and controller satisfied! Glad I didn't get the smaller 5w panel.
I reckon that controller will use 0.2ah/week from the battery at .015w draw. That needs only an hour at full output from the 10w panel (exteremely unlikely to happen!) but even at 10% efficiency that is only 10hrs light.
Or are my calcs wrong?

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