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o_teunico

Solar power for SORNed vehicles

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Hi all, 

My 88" is now on its third year of "baja temporal" status (Spain's equivalent to UK SORN).

One year after last firing up. Flat battery lead to permanent damage.

So, here is the question: has someone tried to connect one of those cheapo solar power systems intended for caravans to SORNed vehicles for maintaining the battery continiously topped?

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yus, quite common.

 

worth noting, if the diode fails then they backfeed at night and flatten instead of charge. guys on the rx8 owners club have had this happen to rac branded ones, among others.

 

personally id buy a cheap tiny panel (small prevents overcharging) and wire it up through a diode omitting a solar controller (no need to over complicate) 

 

i ran a setup like that for years keeping my trayback batterys charged whilst it was parked in my lorry.

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I put one on a works van, It gets very little use, its a 65 plate and only has 27k on it, mostly short runs to pick up a part etc. It has a tracker and the battery was always going flat. I put a ring panel on (a4 paper size, maybe 10w?) and it's only gone flat twice since, once someone left the lights on in the back and I'm not sure about the other time, probably the same. The panel is on the dash so we always leave it parked the right way, especially in winter when there isn't much light. It was the cheapest way to fix the problem but it's important to remember it's only overcoming the losses from the tracker, it would need to be much bigger to charge the battery. Ideally you could do with monitoring your drain but it's hard to do with such small values.

Do you disconnect the battery when not in use? Can you put a trickle charger on from time to time to top it up? On my caravan I just put it on a timer to power the caravan once a week on a Thursday night so that if we went away for a weekend it was fully charged ready to go. 

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I had a cheap small one, similar experience to qwakers - it flattened the battery! :blink:

By contrast our ambulance has 2x 200W panels and they produce a steady 4A each (~50W) on a sunny day (direct sunlight) which keeps up with the fridge nicely.

That said, we leave the ambulance parked for months at a time in a covered barn with the batteries & solar disconnected and it's never failed to start, much to TSD's annoyance :lol:

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Unfortunatelly there are no 220v mains where I have the 88. 

I have quick disconnects in the battery, and use them.

I have seen a caravan with a wind turbine, but its quite pricey compared to solar panels.

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I used a 'Ring' branded solar charger. I can't remember the charge rating, but it was absolutely no use at all, and resulted in the battery being flatter than without it.

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Our club trailer used to have a battery in for running a CB. We had a small solar panel (around 300mm2) on the roof at the time it was about £40 and it was the biggest you could use direct to the battery (No charger in line). The batterys were two red top racing batterys so about 60amph. That set up kept the batterys charged even with a days use of the CB once a month for 7 years.

Mike

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Isn’t the panel voltage going to vary with sunlight levels, hence the need for a controller?  If the voltage drops below that of the battery, unless you have diodes in the feed, you’ll backpower the panels and they’ll drain the battery.

I fancy the idea of a square patch of flexible panel embedded into a spare wheel cover on the bonnet spare for the main battery with a simple and cheap PWM controller.  No need for expensive top end large panels and controllers for the main battery if you don’t have big drains on it.

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At the time the research I did said under a certain wattage panel (I can't remember the wattage) you didn't need a charge controller. From memory the output was trickle charge at best. If we left the CB plugged in it would flatten the battery due to the CB's memory. It may of had a diode on the panel but it certainly worked. The trailer sat in a field only used for one or two days a month.

Mike

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8 hours ago, Snagger said:

Isn’t the panel voltage going to vary with sunlight levels, hence the need for a controller?  If the voltage drops below that of the battery, unless you have diodes in the feed, you’ll backpower the panels and they’ll drain the battery.

1. Yes but a small panel doesn't have the power to drag a car battery up to a bad voltage, a "30W" panel will manage 10W flat out in direct sunlight, so ~1A into the battery.

2. Yes a diode is a good idea, a lot of panels include one.

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I have one of the larger Ring ones that worked fine for a couple of years, now it has a broken wire or something.

Shame as I have no power where it is parked.

Marc

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