Herself has just bought me a solar panel, described as being 4w. Out to play with it at once of course! I checked the battery with my meter, and it showed 12.38v, with the panel connected. When I disconnected from the battery and put the meter across the clips on the solar panel, it showed 18.2v, in bright sunshine. Is this possible, or am I doing something wrong?
solar panels
- Thread starter emmerson
- Start date
Hi Emmerson,
That is exactly what I would expect, and it is perfectly normal.
For a solar panel or any other charger to work, it has to be able to produce a higher voltage than the battery it is trying to charge.
Although the panel produces 18V at its terminals, it can't produce much current, so as soon as any type of load (like a battery to be charged) is connected the terminal voltage will fall. You tell us the panel is rated only 4Watts, so at best it will only produce 1/3 amp, at 12V so its not going to make a massive or sudden difference to your battery
To check if the panel is working, disconnect everything from you battery and measure the voltage at its terminals, Now connect the solar panel, If it is working you should see a small increase in the terminal voltage of the battery.
A 4 Watt panel will only provide a small trickle charge to a caravan battery, It would be enough to keep a battery topped up as long as virtually nothing else is using the battery.
That is exactly what I would expect, and it is perfectly normal.
For a solar panel or any other charger to work, it has to be able to produce a higher voltage than the battery it is trying to charge.
Although the panel produces 18V at its terminals, it can't produce much current, so as soon as any type of load (like a battery to be charged) is connected the terminal voltage will fall. You tell us the panel is rated only 4Watts, so at best it will only produce 1/3 amp, at 12V so its not going to make a massive or sudden difference to your battery
To check if the panel is working, disconnect everything from you battery and measure the voltage at its terminals, Now connect the solar panel, If it is working you should see a small increase in the terminal voltage of the battery.
A 4 Watt panel will only provide a small trickle charge to a caravan battery, It would be enough to keep a battery topped up as long as virtually nothing else is using the battery.
Thanks prof. All I want it for is to keep the battery up when the van is not in use, and occasional use on the car. We now only use the Range Rover for towing, so it spends a lot of time idle, and the alarm drops the battery too low to start it after about ten days, so I'm hoping this panel will help.
Hi Emmerson,
Interesting to read that you think the alarm flattens your LR's battery in 10 days! That is similar to the experience that I had with my Audi. (only noticed it when I went on holiday for 10 days without the car). However, given that it has a 120amp/hr battery that meant that it was suffering a current drain in excess of 500mil/amp. That was far too much even for an alarm. I decided to investigate and put an ammeter in the battery circuit and got a reading of 750mil/amp with all consumers off. To isolate the cause I removed one fuse at a time with no effect until I came to the permanent live to terminal 9 of my 13 pin. Here it dropped by 560mil/amp. I have not yet isolated the actual cause which is between the fuse and the pin (too cold to mess about outside) but have simply left the fuse out. Just thought that maybe you could have a similar problem and my experience may help.
Interesting to read that you think the alarm flattens your LR's battery in 10 days! That is similar to the experience that I had with my Audi. (only noticed it when I went on holiday for 10 days without the car). However, given that it has a 120amp/hr battery that meant that it was suffering a current drain in excess of 500mil/amp. That was far too much even for an alarm. I decided to investigate and put an ammeter in the battery circuit and got a reading of 750mil/amp with all consumers off. To isolate the cause I removed one fuse at a time with no effect until I came to the permanent live to terminal 9 of my 13 pin. Here it dropped by 560mil/amp. I have not yet isolated the actual cause which is between the fuse and the pin (too cold to mess about outside) but have simply left the fuse out. Just thought that maybe you could have a similar problem and my experience may help.
Spray WD40 into the 13pin socket and see if this stops the current drain which may be caused by moisture.
The voltage will vary according to the load. If you put a metre across a battery with nothing connected you will probably get 13.8 volts. Connect it up and it read 12.8. The 1 volt is lost by overcoming internal resistance inside the battery. This loss is directly proportional to the current so the more load the higher the loss in the battery.
On batteries going flat, I have been loosing power in storage. Have spoken to the manufacturer of the caravan loom. He tells me that there are permanent lives to Thetford fridge, Sony Radio and alarm. All flatten. The alarm apparently always takes current when a new leisure battery is connected.
On batteries going flat, I have been loosing power in storage. Have spoken to the manufacturer of the caravan loom. He tells me that there are permanent lives to Thetford fridge, Sony Radio and alarm. All flatten. The alarm apparently always takes current when a new leisure battery is connected.
I found that one of these cheap meters that replaces individual fuses was valuable in finding where I was losing power. In my case the big drain was a naffly wired up radio. It will also indicate the current you are getting from a solar cell; mine is left doing that most of the time.Waffler said:
http://www.maplin.co.uk/Module.aspx?ModuleNo=217879
Anyway this is a nice little bit of kit to have in your tool box. It is the sort of item your family can buy you for christmas without breaking their piggy bank and in my case more welcome than a couple of pairs of socks!
The N48CY version is the one that suites the "normal" size fuses.
Looks useful JTQ.
Two queries.
1/ is it fused?
2/ will it read micro amps?
Thanks in advance.
Agree best way to test for battery drain is to monitor current.
Two queries.
1/ is it fused?
2/ will it read micro amps?
Thanks in advance.
Agree best way to test for battery drain is to monitor current.
Ray;
It is fused; you simply remove the subject circuit's fuse plugging the removed fuse into the side of this units "plug" before that goes in place in the fuse holder. Then the subject circuit functions just as before whether or not you flick the on meter switch for a readout or not.
That way in addition to a diagnostic tool it can be left inplace as a "push to read" meter. I use it like that to periodically check my solar cells instantaneous yield. It has its own internal 12 volt battery [supplied] to power the readout so switching off is desirable to save drain on that, but as I said being "off" still leaves the monitored circuit functioning and of course correctly fused.
No it does not go down to micro or milli amps but only to two places of decimals, hundredths of an amp. Full scale is quoted as 20 amps.
John
It is fused; you simply remove the subject circuit's fuse plugging the removed fuse into the side of this units "plug" before that goes in place in the fuse holder. Then the subject circuit functions just as before whether or not you flick the on meter switch for a readout or not.
That way in addition to a diagnostic tool it can be left inplace as a "push to read" meter. I use it like that to periodically check my solar cells instantaneous yield. It has its own internal 12 volt battery [supplied] to power the readout so switching off is desirable to save drain on that, but as I said being "off" still leaves the monitored circuit functioning and of course correctly fused.
No it does not go down to micro or milli amps but only to two places of decimals, hundredths of an amp. Full scale is quoted as 20 amps.
John
I thought I'd done an update on this thread, but the gremlins must have eaten it! Anyway, my Range Rover hasn't been used for ten days, with the 4w solar panel connected, and it started instantly! So that's a result for me.
I thought I'd done an update on this thread, but the gremlins must have eaten it! Anyway, my Range Rover hasn't been used for ten days, with the 4w solar panel connected, and it started instantly! So that's a result for me.
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just spent 5 weeks in OZZ , both cars had been standing in temps down to minus 9 F , for 5 weeks no solar panels or any external assistance both cars started first turn of the key
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just spent 5 weeks in OZZ , both cars had been standing in temps down to minus 9 F , for 5 weeks no solar panels or any external assistance both cars started first turn of the key
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