Solar power battery chargers. Do they work?

Soul_Glo · 09-13-2015, 05:29 AM

Parking at the airport for 2-3 weeks. Was thinking about the Halford 6w charger. Worth a shot? Better one available? Or save my pennies?

Thanks

MrPogle · 09-13-2015, 06:19 AM

Your battery won't go flat in 3 weeks unless it is already knackered. In which case put the money towards a new battery.

Soul_Glo · 09-13-2015, 06:36 AM

A lot of after market gear on the car. Full viper security package: tilt sensor, glass break sensor, back up battery siren, proximity sensor and electro-luminescent logo. Out of all those items the logo has the highest draw of 0.25 amps per day. After a week of no charge the battery can go from 100 percent down to 85-90 percent and a resting voltage of 11.9-12V. So imagine 3 weeks without a charge. My goal is to keep the battery topped as much as possible and try to negate any losses. The battery is in great condition and was replaced last year. I am hoping it goes into deep sleep and that this helps.

MrPogle · 09-13-2015, 08:54 AM

There is no such thing as 0.25 amps per day. Amps are a measure of current not energy. If your battery discharges at 15% over a week you will still lose less than 50% over 3 weeks so, personally, I'd save the money.

BTW a resting voltage of 12v suggests your battery is not in good condition, assuming that you genuinely mean "resting" I.e. not connected to anything.

Soul_Glo · 09-13-2015, 10:54 AM

My bad MrPogle that was milli amps so it would be 0.00025 in amps. The resting voltage is after a week of no driving. With every day use it rests at a healthy 12.4v. Those are the readings while it is still hooked up in the car so not a true measure of rest I guess. Going to trial a cheaper variant from maplin and see if it works.

Aragorn30d · 09-13-2015, 12:04 PM

An Open circuit voltage of 11.9v on a 12v car battery would be "completely flat" and it wouldnt even crank the engine.

But reading the voltage from the in car electronics is different as theres load on the battery and various voltage drops and losses in the connections and cables, so though the car might be displaying 11.9v, this isnt the true resting voltage of the battery.

If your worried about it going flat, you could simply disconnect the battery negative lead.

MrPogle · 09-13-2015, 01:25 PM

Quote:

Originally Posted by Aragorn30d

If your worried about it going flat, you could simply disconnect the battery negative lead.

Yeah but then his security system wouldn't work. For what the solar charger costs, you could buy a cheap battery and put it in the boot as an emergency starting solution just in case. Or hook it up to the car instead of your regular one just to power the car whilst you are away. I can see the wife and kids standing round with the suit cases whilst you arse about with spanners in the long term car park.

AirAndre335i · 09-13-2015, 02:49 PM

OOOO very interesting! I may have to try this too!

Do you just connect it to the terminals under the bonnet? Or directly to the battery?

MrPogle · 09-13-2015, 03:38 PM

I'd hook it up in the boot INSTEAD of your usual battery as the presence of a flat battery causes issues when cranking. I wouldn't have both batteries connected at the same time for any length of time unless they were identical. Careful use of jumper cables should ensure the car is never without power so you don't lose settings etc. This is just my uneducated opinion and I profess no qualification (unless it's O-level woodwork.)

Soul_Glo · 09-14-2015, 12:28 AM

Very well. I know where I can get hold of a battery. Same make, model, ah, cca etc. Interestingly, I read an article on this as it was my initial thought i.e. two batteries in parallel.. Maplin didn't have the 6w solar version in stock. I can stick an isolator switch on it but my only concern is the vent... I will have to chase the vent tubing some how so it vents properly... or modify the existing venting tube... if I can sort that out tonight then I'm good and if not then I will have to try to track down a charger from somewhere...

Soul_Glo · 09-14-2015, 12:41 AM

Quote:

Originally Posted by AirAndre335i

OOOO very interesting! I may have to try this too!

Do you just connect it to the terminals under the bonnet? Or directly to the battery?

Either is fine.

MrPogle · 09-14-2015, 02:23 AM

Does the vent matter? If it's sitting there for 3 weeks providing a trickle of current and not being charged, it isn't going to be doing any venting, is it?

335ier · 09-16-2015, 11:13 AM

To answer the question yes they do work. I had a remote garage with a few 12v halogen lights hooked up to it. The garage wasn't used a lot in the dark but I'd say the lights were on maybe 40 minutes- ish a week. After a year I though I'd give the battery a charge, charger said the battery was already fully charged.

If you do go with the solar thing remember the cigar socket goes to sleep so might not work that way, you would have to attach it to the charging points under the bonnet not straight on the battery as I was told the computer goes out of sync with the level of charge in the battery?? don't know if this is true.

09-13-2015, 05:29 AM	#1
Soul_Glo Major General 13347 Rep 7,484 Posts Drives: G20 Join Date: May 2013 Location: Manhattan, NYC iTrader: (1)	Solar power battery chargers. Do they work? Parking at the airport for 2-3 weeks. Was thinking about the Halford 6w charger. Worth a shot? Better one available? Or save my pennies? Thanks
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09-13-2015, 06:19 AM	#2
MrPogle Captain 69 Rep 605 Posts Drives: F10 550i M-Sport LCI Join Date: Dec 2012 Location: Cheshire iTrader: (0)	Your battery won't go flat in 3 weeks unless it is already knackered. In which case put the money towards a new battery.
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09-13-2015, 06:36 AM	#3
Soul_Glo Major General 13347 Rep 7,484 Posts Drives: G20 Join Date: May 2013 Location: Manhattan, NYC iTrader: (1)	A lot of after market gear on the car. Full viper security package: tilt sensor, glass break sensor, back up battery siren, proximity sensor and electro-luminescent logo. Out of all those items the logo has the highest draw of 0.25 amps per day. After a week of no charge the battery can go from 100 percent down to 85-90 percent and a resting voltage of 11.9-12V. So imagine 3 weeks without a charge. My goal is to keep the battery topped as much as possible and try to negate any losses. The battery is in great condition and was replaced last year. I am hoping it goes into deep sleep and that this helps.
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09-13-2015, 08:54 AM	#4
MrPogle Captain 69 Rep 605 Posts Drives: F10 550i M-Sport LCI Join Date: Dec 2012 Location: Cheshire iTrader: (0)	There is no such thing as 0.25 amps per day. Amps are a measure of current not energy. If your battery discharges at 15% over a week you will still lose less than 50% over 3 weeks so, personally, I'd save the money. BTW a resting voltage of 12v suggests your battery is not in good condition, assuming that you genuinely mean "resting" I.e. not connected to anything. Last edited by MrPogle; 09-13-2015 at 09:10 AM..
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09-13-2015, 10:54 AM	#5
Soul_Glo Major General 13347 Rep 7,484 Posts Drives: G20 Join Date: May 2013 Location: Manhattan, NYC iTrader: (1)	My bad MrPogle that was milli amps so it would be 0.00025 in amps. The resting voltage is after a week of no driving. With every day use it rests at a healthy 12.4v. Those are the readings while it is still hooked up in the car so not a true measure of rest I guess. Going to trial a cheaper variant from maplin and see if it works.
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09-13-2015, 12:04 PM	#6
Aragorn30d Lieutenant Colonel 175 Rep 1,596 Posts Drives: E90 330d Join Date: Mar 2015 Location: Fife iTrader: (0)	An Open circuit voltage of 11.9v on a 12v car battery would be "completely flat" and it wouldnt even crank the engine. But reading the voltage from the in car electronics is different as theres load on the battery and various voltage drops and losses in the connections and cables, so though the car might be displaying 11.9v, this isnt the true resting voltage of the battery. If your worried about it going flat, you could simply disconnect the battery negative lead.
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09-13-2015, 02:49 PM	#8
AirAndre335i Second Lieutenant 39 Rep 234 Posts Drives: E92 335i Pre Lci Join Date: Apr 2015 Location: Central London iTrader: (0)	OOOO very interesting! I may have to try this too! Do you just connect it to the terminals under the bonnet? Or directly to the battery?
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09-13-2015, 03:38 PM	#9
MrPogle Captain 69 Rep 605 Posts Drives: F10 550i M-Sport LCI Join Date: Dec 2012 Location: Cheshire iTrader: (0)	I'd hook it up in the boot INSTEAD of your usual battery as the presence of a flat battery causes issues when cranking. I wouldn't have both batteries connected at the same time for any length of time unless they were identical. Careful use of jumper cables should ensure the car is never without power so you don't lose settings etc. This is just my uneducated opinion and I profess no qualification (unless it's O-level woodwork.)
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09-14-2015, 12:28 AM	#10
Soul_Glo Major General 13347 Rep 7,484 Posts Drives: G20 Join Date: May 2013 Location: Manhattan, NYC iTrader: (1)	Very well. I know where I can get hold of a battery. Same make, model, ah, cca etc. Interestingly, I read an article on this as it was my initial thought i.e. two batteries in parallel.. Maplin didn't have the 6w solar version in stock. I can stick an isolator switch on it but my only concern is the vent... I will have to chase the vent tubing some how so it vents properly... or modify the existing venting tube... if I can sort that out tonight then I'm good and if not then I will have to try to track down a charger from somewhere... Last edited by Soul_Glo; 09-14-2015 at 12:40 AM..
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09-14-2015, 02:23 AM	#12
MrPogle Captain 69 Rep 605 Posts Drives: F10 550i M-Sport LCI Join Date: Dec 2012 Location: Cheshire iTrader: (0)	Does the vent matter? If it's sitting there for 3 weeks providing a trickle of current and not being charged, it isn't going to be doing any venting, is it?
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09-16-2015, 11:13 AM	#13
335ier Lieutenant 37 Rep 408 Posts Drives: F31 335d Join Date: Nov 2008 Location: england iTrader: (1)	To answer the question yes they do work. I had a remote garage with a few 12v halogen lights hooked up to it. The garage wasn't used a lot in the dark but I'd say the lights were on maybe 40 minutes- ish a week. After a year I though I'd give the battery a charge, charger said the battery was already fully charged. If you do go with the solar thing remember the cigar socket goes to sleep so might not work that way, you would have to attach it to the charging points under the bonnet not straight on the battery as I was told the computer goes out of sync with the level of charge in the battery?? don't know if this is true.
	Appreciate 0 Quote