Solar problem

Algarvedave

Free Member

Messages
8
I recently bought a 200w portable solar panel and a Vitron mttp 75/15 charge controller to charge my leisure battery. For two weeks all was good, it was producing around 150/160w when in full sun on a trip to Morocco. Now I’m back home but can’t get more than around 20w, admittedly on a less than full sunny day. However when I switch on my compressor fridge the charge controller shows that I’m getting around 50w. Is this increase normal or do I have a problem somewhere?
 
merl said:
Indeed. You can't keep pumping in power to the battery forever, when it's full the charge controller will stop sending it power and the current will fall/ stop. Turning on your compressor fridge allows the solar controller to start delivering current in order to keep up with the drain caused by the fridge.
Click to expand...
Thanks. I’m new to solar so thought the watts shown was the watts produced by the panel not the power needed for the battery. That makes a lot of sense and really answers my question.
 
I would say Admin has hit the nail on the head. To see a full harvest potential you need a less than full battery, and possibly pretty low if a lead one.
You could try turning on everything - Fridge, TV, all the lights, whatever you have - and see what it goes upto.
 
After your great answers I have another question.
I have a voltage sensitive relay attached to my leisure battery. It obviously clicks on when I start my vehicle engine and charges both batteries - until today. The VSR is now clicking on and off constantly and it doesn’t seem to be charging the leisure battery which is showing 10.40v and doesn’t change when the VSR clicks on or off. The starter battery is fine and fully charged.
So does it look like the VSR is screwed or the leisure battery? OR is it because the leisure battery needs charging up properly to get them balanced?
Any more checks I can do?
 
Algarvedave said:
After your great answers I have another question.
I have a voltage sensitive relay attached to my leisure battery. It obviously clicks on when I start my vehicle engine and charges both batteries - until today. The VSR is now clicking on and off constantly and it doesn’t seem to be charging the leisure battery which is showing 10.40v and doesn’t change when the VSR clicks on or off. The starter battery is fine and fully charged.
So does it look like the VSR is screwed or the leisure battery? OR is it because the leisure battery needs charging up properly to get them balanced?
Any more checks I can do?
Click to expand...
Nothing to do with balance.
If the relay is clicking on but it's not delivering current to the leisure battery then there is a break in continuity between the VSR contacts and the leisure battery. This could be.
VSR faulty.
Fuse between VSR and L battery blown.
Bad connection in the wiring between the VSR and L battery.
Check the fuse, it SHOULD be closed to the leisure battery.
If the fuse is ok then you need to get a multimeter out and start checking continuity between VSR and L battery and for an output voltage at the VSR when the engine is running.
 
Thanks. I have checked the output of the VSR with the engine running- it’s 10.9 when the VSR clicks in.
I guess that shows the fault is the VSR?
Although there is a fuse between the engine battery and the VSR there isn’t a fuse between the VSR and the leisure battery. Do I need to fit one, what size should it be?
 
Last edited:
Algarvedave said:
Thanks. I have checked the output of the VSR with the engine running- it’s 10.9 when the VSR clicks in.
I guess that shows the fault is the VSR?
Although there is a fuse between the engine battery and the VSR there isn’t a fuse between the VSR and the leisure battery. Do I need to fit one, what size should it be?
Click to expand...
There should be fuse protection at every power source. In the case of a VSR it is just a relay so doesn't need a fuse close to it but you should definately have a fuse close to the leisure battery on the cable between the two.
What size depends on how it is cabled. The fuse should be lower than the ampacity (current carrying capability) of the cable.

To check what is happening with the VSR, check the voltage on both terminals with the engine off and then engine on. It depends on the VSR but the voltage difference should be fairly small. I would have usually said check the ground connection on the VSR as that is a common reason for them not working but if you are hearing it click in when the engine voltage rises then the ground will be ok.
 
When you say check the voltage on both terminals I assume you mean on the VSR , the incoming terminal and the outgoing terminal?
 
Algarvedave said:
Thanks. I have checked the output of the VSR with the engine running- it’s 10.9 when the VSR clicks in.
I guess that shows the fault is the VSR?
Although there is a fuse between the engine battery and the VSR there isn’t a fuse between the VSR and the leisure battery. Do I need to fit one, what size should it be?
Click to expand...
Measuring at the VSR terminals with a good ground/ negative connection you should get the same14+ volts at both terminals when the engine is running and the relay 'clicks' in. If you've got 14+ volts on the input and 10.9v on the output like you say then the VSR is knackered but you MUST make sure you have good connections while you're taking measurements otherwise you'll end up misdiagnosing and getting in a pickle.
What worries me is that you say no the leisure terminal is only reading 10.9V. IF there's no fuse between the LB and the VSR then the LB terminal at the VSR will be the same as the LB voltage and 10.9 volts is essentially a dead battery.
If your LB actually measured more than 10.9V but you're only reading 10.9 at the VSR then the cable/ connections aren't continuous and there's a break somewhere.
Yes that lead should be fused at BOTH batteries, what size cable is it?
 
merl said:
Measuring at the VSR terminals with a good ground/ negative connection you should get the same14+ volts at both terminals when the engine is running and the relay 'clicks' in. If you've got 14+ volts on the input and 10.9v on the output like you say then the VSR is knackered but you MUST make sure you have good connections while you're taking measurements otherwise you'll end up misdiagnosing and getting in a pickle.
What worries me is that you say no the leisure terminal is only reading 10.9V. IF there's no fuse between the LB and the VSR then the LB terminal at the VSR will be the same as the LB voltage and 10.9 volts is essentially a dead battery.
If your LB actually measured more than 10.9V but you're only reading 10.9 at the VSR then the cable/ connections aren't continuous and there's a break somewhere.
Yes that lead should be fused at BOTH batteries, what size cable is it?
Click to expand...
Ok, thanks. When I checked the output from the VSR I had disconnected the lead from the VSR to the LB and the engine was off and the reading was zero. Now with the lead reconnected and with the engine running the reading at the output terminal was 10.7v when the VSR clicked in and obviously zero when it clicked off. The reading at the entry terminal to the VSR was over 14v with the engine running and the VSR clicked on but only 10.49 when the VSR clicked off. It was 12.84v with the engine off.
With engine off the LB is showing 10.4 and the VSR LB terminal is showing the same 10.4.
The cable from the engine battery to the VSR is 16mm2 and has a 100a fuse.
The cable from the VSR to the LB is the same but no fuse.
It would appear that more checking is necessary.
 
Last edited:
I have now connected a solar panel to my LB and it’s receiving 130w. My LB is showing 13.59v and with my engine running my VRS is on and staying on.
From that I assume that there isn’t an issue with the VRS but maybe with the LB.
Once charged I will check if it’s holding its charge. If not I guess it’s goosed.
Does all this sound logical or am I missing something?
 
Algarvedave said:
I have now connected a solar panel to my LB and it’s receiving 130w. My LB is showing 13.59v and with my engine running my VRS is on and staying on.
From that I assume that there isn’t an issue with the VRS but maybe with the LB.
Once charged I will check if it’s holding its charge. If not I guess it’s goosed.
Does all this sound logical or am I missing something?
Click to expand...
TBF it sounds like the VSR is knackered? .
Using the same meter for all measurements measure the Leisure battery voltage at the battery.
Now measure the voltage between ground and the VSR output terminal ( the one going to the leisure battery)
The two readings should be the same.
Alternatively (with the engine NOT running) you can do a continuity check ( ohms reading) between the leisure battery positive and the output terminal of the VSR, basically you're checking that the two are 'connected'.
If the above is ok and the input to the VSR is over 14V with the engine running but the output isn't a similar voltage (with the engine still running) AND you hear the VSR click in then the VSR is almost certainly knackered and needs replacing.
If you DO want to go further the next thing to check is that the thin negative VSR lead is actually connected to ground/chassis/negative. Best way to do this is to use a cable piercing test probe into the ground lead near the VSR ( https://amzn.eu/d/1zSHjQR) but you can carefully push a pin through the centre of the cable and conduct another continuity test to a known chassis ground or battery negative, again you're checking that there is a connection.
TBF if you can hear the relay clicking in then the earth is almost certainly OK.
I'd fit a 70A ish fuse in there as close to the battery as practically possible, the exact value isn't particularly critical.
 
Last edited:
To me it sounds like the contacts in the VSR are faulty unless I have missed something. VSR replacement? Maybe it was faulty from new and has now failed.
Maybe it has been working hard on engine start up because the battery is getting tired?
 
You must log in or register to reply here.

Users who viewed this discussion (Total:72)

Back
Top