Solar panel charge

[Lizzy]

we have a 2004 Autoscruise, which came with a solar panel fitted. We are usually on EHU, but having to go off grid. The leisure battery doesn’t seem to be keeping topped up by the panel, and sometimes appears to be drained, with nothing connected. Is there something I’m supposed to switch on that I’m not? Does it make any difference what I have the battery charger settings on?
Any ideas? Thank you!

 

[John H.]

If by mistake you connect the panels first, the output voltage can rise and fool it into thinking there's a 24V battery connected. When you connect the 12V battery, it thinks it's a 24V battery that's completely flat, so it switches everything off.

The cheap controllers, that the dealer fitted to our motorhome, died (never to work again) if you connected the solar panel without connecting the battery first.

I learnt that the hard way.

 

[Lenny HB]

I have reconnected wires in the correct order. I have put the multimeter across the wires from the battery reading 2.4 across the panel 20.4. Controller still blank....

Did you mean 12.4 across the battery?
20.4 is right for the panel.

 

[autorouter]

20.4V for the panels sounds OK. Did you check they are the right polarity? I'm asking because the the wires both look black, so you or the previous installer might have made a mistake.

To check this, first practice on something with a known polarity, like a battery with clearly marked positive and negative terminals. If you reverse the connections, a minus sign appears in front of the voltage reading.

The battery reading is obviously not as high as you want. The next step is to use the multimeter to take a reading on the leisure battery terminals. That's usually easy, except that some leisure batteries are inaccessible, under the driving seat for example. If you get a good reading (12.0 to 14.8V) then look for a blown fuse or bad connection between the battery and the solar controller.

 

[Lizzy]

Did you mean 12.4 across the battery?
20.4 is right for the panel.

Nope 2.4

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[Lizzy]

The cheap controllers, that the dealer fitted to our motorhome, died (never to work again) if you connected the solar panel without connecting the battery first.

I learnt that the hard way.

Oh dear that could be it

 

[Lenny HB]

If the battery is down at 2.4v RIP.
Unless the regulator being is giving out some nasty electrical spikes which is upsetting the meter, worth seeing what the battery voltage is with the regulator disconnected.

 

[Lizzy]

If the battery is down at 2.4v RIP.
Unless the regulator being is giving out some nasty electrical spikes which is upsetting the meter, worth seeing what the battery voltage is with the regulator disconnected.

The battery is reading 12.0 so I’m assuming it must be the controller that is RIP? Would you agree?

 

[Lenny HB]

The battery is reading 12.0 so I’m assuming it must be the controller that is RIP? Would you agree?

Yep, I would disconnect both sides of it.
Do you just use your solar to keep the batteries topped up when the van is not in use or do you do off grid camping (no EHU)?
Just so we can recommend a regulator, if just to keep the battery topped up the Votronic SR range are reasonably priced but if using off grid I would go for one from the Votronic Duo MPP range

 

[autorouter]

Check that the battery voltage is reaching the controller. If not, it could simply be a blown fuse or a bad connection. To check this, disconnect the battery positive wire at the controller, and measure the voltage between the positive wire end and the negative terminal. If it's not the same as the leisure battery voltage (ie 12.0V) then the battery voltage is not reaching the controller.

If/when you reconnect, you'll have to do the 'battery first, then panel' reconnection procedure.

A separate point - is the 12.0V battery voltage while connected to EHU? It should be higher, between 13.4 and 14.8V if the EHU charger is working.

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[Lizzy]

Check that the battery voltage is reaching the controller. If not, it could simply be a blown fuse or a bad connection. To check this, disconnect the battery positive wire at the controller, and measure the voltage between the positive wire end and the negative terminal. If it's not the same as the leisure battery voltage (ie 12.0V) then the battery voltage is not reaching the controller.

If/when you reconnect, you'll have to do the 'battery first, then panel' reconnection procedure.

A separate point - is the 12.0V battery voltage while connected to EHU? It should be higher, between 13.4 and 14.8V if the EHU charger is working.

No I unplugged the EHU before measuring the battery. There is now no reading at all across the battery wires . Where would the fuses for these be????

 

[Lizzy]

Yep, I would disconnect both sides of it.
Do you just use your solar to keep the batteries topped up when the van is not in use or do you do off grid camping (no EHU)?
Just so we can recommend a regulator, if just to keep the battery topped up the Votronic SR range are reasonably priced but if using off grid I would go for one from the Votronic Duo MPP range

I have only ever been away with EHU, but the lack of availability on sites from the massive popularity boost motorhoming has had, has forced me to give off grid a go. So, I need to know how to set up to be able to have lighting & the water pump working, if nothing else!

 

[Lenny HB]

I have only ever been away with EHU, but the lack of availability on sites from the massive popularity boost motorhoming has had, has forced me to give off grid a go. So, I need to know how to set up to be able to have lighting & the water pump working, if nothing else!

If you are not going to be using a TV and other loads of equipment your single battery and if your solar panel is around a 100watts you will properly survie in the summer months with one of the cheaper solar regulators like a Votronic SR140 (about £50).

If you think you are going to be using more power you will need to fit a second battery and solar panel, a suitable regulator would be a Votronic MPP250 (about £120) that will handle 250 watts of solar.
The Votroinc regulators can also keep the engine battery topped up.

 

[autorouter]

Where would the fuses for these be????

There should be another box somewhere, with all the power connections and a row of 12V fuses. It might be located in a cupboard or locker, out of sight.

How to check a fuse, using a multimeter: You check its 'resistance'. Resistance is measured in ohms, denoted on meters by the Greek letter omega, which looks like a headphone symbol. A good fuse will have a resistance of less than 1 ohm. A blown fuse will have a resistance of millions of ohms ie Megohms.

Turn the dial to the lowest resistance range. Touch the two probes together. You should get a reading of less than 1 ohm - 0.3 to 0.5 is typical. That's the resistance of the red and black test leads.

When the probes are separated, you are measuring the resistance of the air gap between them, which is several million ohms. The display will indicate an 'overload'- OV or OVL for example.

To test a fuse, touch the probes on the two blades of the fuse. It should give a reading of 1 ohm or less. If it carries on showing OVL, the fuse has blown.

I'd start with those fuses in the top left of your battery picture. It's likely to be a fuse very near the battery.

 

[Lizzy]

There should be another box somewhere, with all the power connections and a row of 12V fuses. It might be located in a cupboard or locker, out of sight.

How to check a fuse, using a multimeter: You check its 'resistance'. Resistance is measured in ohms, denoted on meters by the Greek letter omega, which looks like a headphone symbol. A good fuse will have a resistance of less than 1 ohm. A blown fuse will have a resistance of millions of ohms ie Megohms.

Turn the dial to the lowest resistance range. Touch the two probes together. You should get a reading of less than 1 ohm - 0.3 to 0.5 is typical. That's the resistance of the red and black test leads.

When the probes are separated, you are measuring the resistance of the air gap between them, which is several million ohms. The display will indicate an 'overload'- OV or OVL for example.

To test a fuse, touch the probes on the two blades of the fuse. It should give a reading of 1 ohm or less. If it carries on showing OVL, the fuse has blown.

I'd start with those fuses in the top left of your battery picture. It's likely to be a fuse very near the battery.

Thank you so much for all your help! I have learnt so much in the last 24h!

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[autorouter]

With your new meter, you can do lots of useful things.

For future reference, a battery not being charged should stay between 12.0V (fairly flat) to 12.8V (full). When being charged, it should be between 13.4V and 14.4V, maybe up to 14,8V if it is a gel or AGM battery. If it's 15V or more, something is wrong with the charger.

You can use this to see if your starter battery is charging from the alternator when the engine is running. While you are at it, you can see if the leisure battery is charging from the alternator when the engine is running.

You can check that the EHU charger is charging the battery when connected to EHU.

If and when you get the solar working, you can see if it is charging the leisure battery.

 

[Ivory55]

Thank you so much for all your help! I have learnt so much in the last 24h!

12volt electric in motorhomes makes splitting the atom look easy. Haha

 

[yamyam]

You guys don’t realise the amount of knowledge you have, and are so generous with your help. I’m waiting for the battery to fully charge then will return no doubt with more requests for help.

 

[Vipar]

If you haven’t bought a multi meter yet get one with a buzzer very handy when you are on your own. Only a couple of quid dearer

 

[Richard n Ann]

Just ordered one of these pocket ones.. Only 10mm thick, £7.36 on ebay.
Autoranging too