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Is This Ok


john47
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I have recently (18th Feb) fitted a new 113ah battery and a 10w solar panel in the heki roof light with a controller near the battery. I have been taking readings over the last fortnight and wondered if the figures I have been getting are acceptable. I have an alarm and a Phantom tracker, the tracker is not activated so I don't know if that will be drawing any power.

 

All readings with multimeter

 

Battery fitted 18th at 13. 00, battery 12. 88v, panel 12. 95v

 

21st at 10:45 battery 12. 47, panel 12. 56

22nd at 17:00 battery 12. 51, panel 12. 53

25th at 11:30 battery 12. 53, panel 12. 61

2nd at 11:15 battery 12. 44, panel 12. 53

 

The weather here has been a mixture of clear skies and bright sunshine and overcast and or rain.

I was hoping for a gradual increase in the battery charge however I am pleased that the battery has apparently held a reasonable charge though I will be adding another 10w panel before next winter as since fitting the first one the weather hasn't been too bad.

2011 Lunar Clubman ES & 2007 Hyundai Tucson Ltd

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Looks like all is in working order to me. The battery is improving slightly and its is holding its own.

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My controller output to the battery normally shows 13. 5v when the battery is fully charged and the sun is out.

Land Rover is now back towing.

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If you've connected the panel directly to your battery then the two readings will be the same (no point measuring battery and panel). If they are not connected when you're taking these readings then there's something wrong with your panel because it should be a lot higher, 30V is not uncommon but maybe 19-25V should be expected (in the sun). If you have a PV controller then, as onwheelonmywagon says, it should be outputing around 13(ish) volts (or 1-2 volts higher than the battery)

 

A battery at around 12. 5V open circuit (i. e. nothing connected to it) would be about 75% charged. I'm guessing that you took your readings with the panel connected so yours might actually be lower, maybe 12. 3V and 60% charged.

 

Lead-acid batteries prefer to be kept fully charged but your panel seems only to be countering self-discharge. For improved battery health I would recommend getting a larger panel, maybe 40 watts and a small (5-10A) solar controller. This, I believe, would maintain your battery at 100%.

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I am using a controller which was supplied with the panel as a 'kit'. The panel is inside the van in the heki. I will try taking the panel outside and measuring the voltage produced, perhaps tomorrow as the forecast is sunny and clear skies. The panel was conne ted to the battery through the controller.

Edited by john47

2011 Lunar Clubman ES & 2007 Hyundai Tucson Ltd

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I have just come back from the van after taking some readings which now leave me with more questions. I first took readings with everything connected and they were similar to previous readings, 12. 53v for the panel and 12. 47v for the battery. These readings were taken on the controller connections. I then disconnected both the panel and the battery from the controller and took readings from the panel, 20. 3v and the battery, 12. 4v. Does this indicate a faulty controller? Should I do away with the controller and connect the panel direct to the battery? Is the voltage from the panel too high or is this normal, it was very sunny, just cotton wool clouds.

2011 Lunar Clubman ES & 2007 Hyundai Tucson Ltd

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I have just come back from the van after taking some readings which now leave me with more questions. I first took readings with everything connected and they were similar to previous readings, 12. 53v for the panel and 12. 47v for the battery. These readings were taken on the controller connections. I then disconnected both the panel and the battery from the controller and took readings from the panel, 20. 3v and the battery, 12. 4v. Does this indicate a faulty controller? Should I do away with the controller and connect the panel direct to the battery? Is the voltage from the panel too high or is this normal, it was very sunny, just cotton wool clouds.

2011 Lunar Clubman ES & 2007 Hyundai Tucson Ltd

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20. 3v straight from the panel open circuit voltage seems about correct to me. The output from the controller maybe slightly low. But on the other hand if the battery is at a constant voltage I wouldn't worry too much. After all it's only just March and it is a small panel

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Panel voltage is fine and as long as the battery terminal voltage increases when you connect the controller, your system is working fine. Ideally the controller output should be in the 13'ish volts range but this will depend on many conditions. Whilst you can connect a 10W panel directly to a battery (up to battery capacity divided by ten is the general guidance) my advice would be to avoid doing this. Your controller will do a better job.

 

My advice above stands.

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