Car battery solar chargers - Again!

[John]

On a little used Land Rover the battery can/will discharge and if parked away from mains I was looking at a larger solar charger as my small one is not quite up to the job
Looking at these 2, both being the same size and price, and having protection against reverse charge and over chargecharging (it says )
would the 60w be more suitable than the 30w or do either deliver what they same
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or are these figures all snake oil....

[Wittsend]

Not snake oil - these things work.

Let's do the sums ... 30W divided by 12 Volts = 2.5 amps charging rate.

60W divided by 12 volts = 5.0 amps charging rate.

Both devices feature overcharging protection.
Given the UK's lack of sun, the 60W unit should put out a few more amps in dull weather.
Given the lack of price difference I'd go for the 60W unit.

Basically these are like the old fashioned battery trickle chargers of yesteryear.
Either unit should help keep your battery in tip top condition.

The price of solar panels (from China) are coming down all the time as better (more efficient) units are being made. Even on a dull day they should be putting out some amps.

Solar power is green and free (in daylight and the sun is out), independent of a mains supply making kit like this redundant !

[geoff]

Very CHEAP !!!!!

Tempting !

[simonbav]

I just had my offer of £11.50 accepted for the 60w version so do try to bargain if that floats your boat.

[Beowulf]

I just had my offer of £11.50 accepted for the 60w version so do try to bargain if that floats your boat.

Following your lead Simon, I made the same successful offer 
Thanks for posting this John 

[John]

I also made the offer but have yet to have a reply

[Worf]

Well, they just accepted £11.00 off me

How low can you go ?

[John]

I also made the offer but have yet to have a reply

Got my reply now and offer taken, just waiting for delivery now

[Beowulf]

It arrived this morning.
For £11.50 I wasn`t expecting something designed and built by Rolls Royce, but it does seem a bit flimsy. The panel is secured by 4 small suckers, each only 2 cm in diameter, can these really withstand a cold and very windy winter 
I`ll try securing it on the inside of the window looking out, where I assume it will still work, and at least it`ll be protected and I won`t have to worry about it being blown into next doors garden.

[Wittsend]

Yes, these are best fitted inside the vehicle !

In the past I've fitted solar trickle chargers to the sun visor ...



On the Rover P4 I have a solar charger sitting on the shelf behind the rear seats - though there's not much sun in the garage.

If you want exterior mounted panels then you need something more substantial...
e.g.


IIRC these are 2 x 50W panels outputting around 8 amps.

[Noddy]

We have two 50W panels on the cab roof of our Dormobile these are for chargeing the leisure battery. The effective output of panels is very rarely stated just the theoretical max output. Taking figures from the solar system on our house roof 80% of stated output is the best you'll get in high summer June and July So a 60W panel could give approx 50W actual. If a cloud passes over this will drop to 20W or less. This morning here in Lincs we had 10 10ths cloud although fairly bright. The 430W rated panels on the house were producing 36W each. A 60W pabel would therefore produce approx 5W ie 0.4 amp. In Dec and Jan on a dark dull day a 60W panel would struggle to produce 1W 0.08 amp. Solar powered trickle chargers have their uses but do have limitations as well.

Alec

[Worf]

Mine arrived today and seems to be working. The only drawback is having such a short lead from the panel to the usb socket, so cannot really be used outside, unless you can somehow waterproof the connector.

[Herald1360]

If you're worried about overcharging a lead acid battery by excess current from a higher powered solar panel it would be worth adding a voltage limiter across the panel's output set for the recommended maintenance voltage for the battery. Bear in mind that a passive voltage limiter could dissipate nearly 60W on a 60W panel to clamp the voltage on a fully charged battery under ideal sun conditions.

[simonbav]

If you're worried about overcharging a lead acid battery by excess current from a higher powered solar panel it would be worth adding a voltage limiter across the panel's output set for the recommended maintenance voltage for the battery. Bear in mind that a passive voltage limiter could dissipate nearly 60W on a 60W panel to clamp the voltage on a fully charged battery under ideal sun conditions.

Could you say a little more about practicalities please H? I can plug and play items and understand about the need to not overcharge a 12v lead acid battery but in the dark as far as what that hardware would look like. Are propriety bits available?

I put mine on a shelf under the translucent roof sheet, extending the necessary wires by a few feet. The battery voltage stepped up from 11.6 to 11.7 in a little over two hours under cloud. Its sitting on neoprene tape and held in place with cable ties.

[John]

my 60w panel came today but as it has no markings on the unit or packaging how do I know if I've been sent a 30w or 60w unit?
I plan to mount this inside against the glass so no concerns regarding points mentioned but still wonder about the input of the one sent and why are both 30w and 60w units are the same size and look the same