Solar Panel performance

[silverseal]

I recently "found" an old battery which was next to a marina skip. It was marked Macro and was a 65 amp hour car battery.

I also have 15 watt solar panel and so mated the two to see what effect a 15 watt panel would have on the battery, in the depths of winter.

Day 1 Jan 14 Voltage 11.09 volts Conditions past sun, part cloud
Day 2 Jan 15 Voltage 11.87 volts Conditions sun, cloudy pm
Day 3 Jan 16 Voltage 12.09 volts Conditions bright then overcast
Day 4 Jan 17 Voltage 12.68 volts Generally cloudy
Day 5 Jan 18 Voltage 12.68 volts Sun, overcast pm

Readings were taken the following morning ...the panel having been disconnected overnight, so allow the battery to stabilise.

I am quite impressed!

 

[VicMallows]

Impressed with the battery (I've picked up quite a few good ones at Marinas) or the Solar Panel?

Vic

 

[William_H]

I am glad you are impressed however there is more to the story. A battery will increase in voltage with a little charge. If it is a good battery this may even get you an engine start however you would find that the actual charge capacity is quite low. You need to monitor current from the solar panel into the battery. This will give you an idea of actual; performance of the panel in winter. The open circuit voltage will be quite high so the current into the battery will be quite uniform regardless of charge. The goodness of the battery can only be determined by seeing if it will start your engine (car or boat) and then running lights etc to determine if the capacity is going to suit your needs. I hope ity is usefull regards will

 

[Superflid]

[ QUOTE ]
I recently "found" an old battery which was next to a marina skip.

[/ QUOTE ]

Not just me, then!

My boat is an ongoing project with no engine at the moment. Rescued battery is hooked up to 5W solar panel and bilge pump. Over the 3 weeks of use so far the battery voltage has gradually risen to almost exactly the same as yours.

 

[steve_cronin]

Good to hear that you disconnected the panel at night. Had you not then unless there is a diode in circuit, the battery will discharge through the panel when there is insufficient light to maintain a positive PD.

Steve Cronin

 

[boatmike]

In other words Volts....shmolts. How many amps?

 

[VicMallows]

Will,
Post was somewhat tounge-in-cheek, though I have indeed 'rescued' quite a few batteries. Wondered why you were up at that hour 'till I realised where you were!

Vic

 

[silverseal]

Currently it is running half a dozen 20 watt dichroic spots and a radio for about 4-5 hours a day, without problems - point taken however will it start the engine?

 

[Superflid]

[ QUOTE ]
Good to hear that you disconnected the panel at night. Had you not then unless there is a diode in circuit, the battery will discharge through the panel when there is insufficient light to maintain a positive PD.

Steve Cronin

[/ QUOTE ]

Forgot to add, diode is included!

Not expecting battery to be up to starting duties, just glad of a freebie now and again.