Solar Panel Warning.

Don’t you believe it mate.
The 18 volts was measured at the battery. This was on a cloudy day too.
Volt drop is low on a full battery, and in bright sunshine, they would have reached over 20volts.

Hi Dennis
A little question .
Were did you actually measure the voltage?
Directly off the battery posts or the connectinion leads?
A poor connection between batttery & leads could give that result with some regs
But yes NEVER connect or disconnect a solar panel to a load especially electronic without a battery in circuit
Same as never disconnect a battery from engine while running
PETER

Hi Peter
I have 2 digital voltmeters connected permanently - each directly connected to a battery under the bonnet. There was no possibility of a loose connection as the voltmeters weren't disconnected and the controller was connected back in circuit before I noticed the high voltage. I have the knowledge, and I should have known better but " but hey - chit happens",
Regards Dennis

What size panel is that?

The open circuit voltage on 12V panels is normally well less than 20V and if it is a 100W or smaller panel, I fail to see how it can pump enough into the battery to raise the voltage to 18V (unless the battery is stuffed).
Having said that, a controller that is fussy about the connection sequence is not very well designed in my opinion.

Hi hl,
They are Sharp 130 watt panels which have an open circuit voltage of 22 volts.
They produce close to this voltage in bright sunshine under low load conditions such as fully charged batteries. Try measuring it some time. My batteries are in top condition. You need to do a little research on controllers to find out thier characteristics also.
Regards Dennis

Ok,
You win......

That is very high for 12V panels.

hl,
tis not a matter of winning or even loosing, but more of sharing relevant information :-)

The idea of a solar panel being called a "12v solar panel" is a bit of a misnomer, because they will deliver >17 Volts @ the panel.

It's just like the terminology '12v battery' that everyone uses and understands.
Because when they are 12v they are actually 1/2 flat, being 12.66v when charged (2.11v per cell - wetcell)

I can also remember when it was claimed you could not fully charge the aux battery from an alternator or even a solar panel will only deliver about 80% of the panel's rated wattage to the battery, both long since shown to be incorrect with efficient power systems.

Maîneÿ . . .

Hi All
I believe the real point Dennis was making was that his reg WAS NOT REGULATING
Under those conditions with a fully charged battery it is quite possible to overcharge the battery to that voltage with a higher voltage power source such as solar
In fact @ that point the solar panels would be operating @ their MAX OUTPUT
[volts by amps =watts]
A very rare occassion & not good for the battery

Peter

I agree...
I guess the main point is that poorly designed regulators allow this to happen.
I still think that most panels that are car mounted would not be able to push a battery of reasonable capacity much into overcharge, especially if there is a fridge and other loads on that battery. To get a good 12V battery up to 18V would take a while and well and truly cook it.
I used 2 80W panels on the ground and 90 Watts car roof mounted on our last holiday and still ran out after a week of running the fridge, charging a few laptops, talking on the radio........no chance of overcharging.

hl,
Maybe, your solar system is not operating at it's maximum rated performance ?
Maybe, you were camped in inclement weather conditions ?
Maybe, the regulator you use is not efficient ?

Yes, just too many "maybe's" and not enough answers.

Reasoning is 250 Watts (>14 amps) should give you enough amps to more than replace the current used by all the items you have listed.

I only use a 203 Watts solar system and run a fridge drawing 10 amps, which will be much more than you use, also with lights, computer and battery charging all done with an inverter, I've never seen the 200ah agm battery system showing below 12v (50%) in all the years it has been in use.

The way solar panels are rated is by their 'maximum' watts, most times these maximum watts are never seen by the regulator at all, and many lesser expensive panels are next to hopeless when used in low light conditions, this is what causes most of the real life, but avoidable lack of solar power problems.

Maîneÿ . . .

We had a few cloudy days.... that makes a lot of difference, other than that, the panels on the truck are obviously never at the optimum angle, but the 2 80W panels were moved around for maximum exposure.
Solar can be fickle....

hl,
you have me confused now, because you say "the panels on the truck are obviously never at the optimum angle, but the 2 x 80W panels were moved around for maximum exposure"
Do you mean "the panels (plural) on the truck are..." being more than one (1) panel?

"but the 2 x 80w panels were moved around for maximum exposure" obviously moving them is not working for you at all is it?
My system sits horizontal on the roof rack, indicating 'maybe' you have not invested wisely in solar components ?
Can I ask what you are using ??

Cloudy days don't make such a huge difference, as solar works by converting solar radiation not just direct sunshine, that's why you get much more current produced when under areas of Columbus clouds
Image Could Not Be FoundMaîneÿ . . .

Hi,
Well, there are 2 panels on the roof, a 30W and a 60W, the 2 extra ones are 80W Kyocera panels and they work very well when positioned correctly, the ones on the car get whatever, I make no particular effort to park for maximum exposure as they are mainly there to power the fridge and the car usually gets at least a short run every day, probably putting in as much from the alternator in 1/2 hour as the panels can do in a day. I have 2 100Ah batteries, one 80Ah and one 40 Ah (some in the truck, some in the trailer.
However, my usage is probably somewhat heavier than most people, with lots of gadgets and stuff (including an electric bike) that needs charging, hence the comments that we "ran out" after a week and all the batteries were pretty exhausted at the last day. I am an electronics person and do understand all the factors involved, believe me..... (I have built my own regulators, Ah meters based on PIC chips etc....

OK, as most portable panels have a reg mounted on the panel with a lead and plug on the end......how do you connect the battery 1st when the panel is hard wired to the regulator ??

gronk,
if it's connected this way as you say, I would think everyone with any solar knowledge will be telling you to disconnect it (regulator) and place it at the battery anyway

Maîneÿ . . .

Yep...thats what I have done, but the reg is still hard wired to the panel (albeit with 10M of wire )..

Are you saying I should add another plug ( would be 2 of course ) into the cct ????

No, just unscrew 'all' the cables and reinstall the system from scratch, only takes a few minutes and you know everything is done correctly and all is working as it is meant to be.
Even if it was just a 2 cable 'plug' you have to unplug and reinstall the other cables too.

Maîneÿ . . .

Sorry mate, I don't get it ??

I have a free standing panel with 10M of cable on it going to a reg which has an anderson plug on it that plugs into the side of the camper....and I only use the panel a few times a year...rest of the time its packed away at home..
How I use it at the present time is to put out the panel then connect the plug from the reg to the camper......but others are saying to connect the reg to the battery 1st , then connect the panel to the reg ????