solar panels

Hi just wondering if I used alligator clips to attach solar panel to battery can I run a cable straight of battery to run fridge while sun charging battery
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Reply By: Rangiephil - Tuesday, Dec 22, 2015 at 16:57

Tuesday, Dec 22, 2015 at 16:57
As long as the solar panel has a regulator of some sort, you can run a fridge off the battery the panel is attached to.
I do it all the time.
But to be clear , the fridge must be attached to the battery and not directly to the solar panel.
Regards Philip A
AnswerID: 594067

Follow Up By: Bigfish - Tuesday, Dec 22, 2015 at 20:31

Tuesday, Dec 22, 2015 at 20:31
Yes, must have that regulator
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Reply By: Iza B - Tuesday, Dec 22, 2015 at 20:43

Tuesday, Dec 22, 2015 at 20:43
What sort/brand fridge? If running an Engel, no need to be concerned about using a regulator. My experience is that the battery will sink the panel voltage anyway. Been doing it that way for years.

Have you put a meter across the battery while unregulated panel output is applied to the battery?

Iza
AnswerID: 594072

Follow Up By: Gronk - Tuesday, Dec 22, 2015 at 21:07

Tuesday, Dec 22, 2015 at 21:07
Are you saying if you feed 17+ volts into a 12V battery, the battery will "sink" that extra voltage ??

I'm sure we could all save lots of money on regulators if that's the case !!
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Follow Up By: Member - Phil G (SA) - Tuesday, Dec 22, 2015 at 22:14

Tuesday, Dec 22, 2015 at 22:14
The voltage will only crank up when the battery is fully charged.
Its a case of knowing your system. I also sometimes run a solar panel without a regulator when I know the battery charge is down and I want to get every electron of solar energy, and I know there is no way that battery will reach full capacity with just solar charging.
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Follow Up By: Stephen F2 - Wednesday, Dec 23, 2015 at 00:20

Wednesday, Dec 23, 2015 at 00:20
Engel 39l older model about 2007 thanks
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Follow Up By: Gronk - Wednesday, Dec 23, 2015 at 14:20

Wednesday, Dec 23, 2015 at 14:20
The voltage will only crank up when the battery is fully charged.


The voltage will go above 14V before the battery gets fully charged. There is no advantage to have the voltage above approx 14.4V, in fact it might do a bit of harm. And it won't charge faster by not having a reg in line....especially a MPPT reg. If it was the case, there would be regs that let full panel voltage thru until it was 3/4 charged and then throttle it back to normal volts.....but there aren't any made like that....for a reason.
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Follow Up By: Iza B - Wednesday, Dec 23, 2015 at 15:44

Wednesday, Dec 23, 2015 at 15:44
From experience, older model Engels will happily run on unregulated aircraft power anywhere up to 32 Volts, RMS measured on a moving coil volt meter, as long as there was a battery in the circuit.Battery power down to 10.9.

You can get a bit of confidence by putting the panels, without regulator, and the battery in the sun and check terminal voltage every half hour or so. Open circuit panel voltage of around 22 Volts will drop pretty dramatically when connected to the battery, especially if the battery is down a bit. Once there is a circuit established, voltage gets dropped on all the resistances, including internal battery resistance.

Old school battery maintenance for FLA required "boiling" the batteries for about half an hour every week. Hydrogenation happens when the battery is fully charged and leads to dry batteries. GEL and AGM are a lot more sensitive so keep an eye on the terminal voltage if you do the experiment suggested. When I was poor, I ran a 40 litre Engel off a 90 AH Deep Cycle charged by two 36 Watt (nominal) recycled panels without a regulator, for months at a time. I would change the angle of the panels every hour to get every bit of charge I could.

If you are at all worried about applying high voltages to your battery, check out the voltage profile put out by something like a D250S at the end of the charge protocol.

Iza
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Follow Up By: Gronk - Wednesday, Dec 23, 2015 at 17:04

Wednesday, Dec 23, 2015 at 17:04
Don't know why you want someone to experiment with old school ideas. Use a regulator and be done with it.

A fridge constantly running off a small battery that tries to get topped up with 70W of solar is not a way most people will try to go camping. Boiling batteries is not something you do with deep cycle batteries you use for camping.

And what "high" voltages does a 250S put out ??

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FollowupID: 862439

Reply By: Member - mechpete - Wednesday, Dec 23, 2015 at 09:35

Wednesday, Dec 23, 2015 at 09:35
just do it ,you won,t have any trouble
mechpete
AnswerID: 594081

Reply By: The Bantam - Wednesday, Dec 23, 2015 at 11:35

Wednesday, Dec 23, 2015 at 11:35
should be no problem ...... but best to avoid aligator clips ...... better to install a plug and socket.

cheers
AnswerID: 594085

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