Solar trickle charge with Fluorescent lighting

[Pionir]

Hi all,

I'm facing an odd conundrum. My car is parked in a communal underground car park with no windows and doesn't move very often. The last time it was 5 1/2 weeks and unsurprisingly the battery was dead (luckily a friendly neighbour gave be a jump start). Usually the batter lasts for 2-3 weeks.

I'd like to trickle charge it but there's no power supply in the car park although there are fluorescent strip lights.

I'm wondering if anyone else has successfully used a solar charger off strip lights or if the light will be the wrong frequency and if so which models?

Cheers, David

[miniman]

Pretty straightforward to hook a trickle charger into a fluorescent fitting

[Hip2Bsquare]

I tested this just yesterday.

I put a meter across mine and it gave an output of around 16v in sunlight and around 12v under flourescent lights (single tube, so not that bright).

HTH

[5lab]

if you don't need an alarm (sounds like the car is pretty safe) - why not just disconnect the battery when you leave the car?

[roverspeed]

in cold weather the battery will still probably discharge over that time scale without being disconnected.

How about one of the jump packs from halfords. Keep it in the house, hook it up to the battery on the occasions you are going to use the car. (pop it a few hours before hand methinks)

like below:

http://www.halfords.com/webapp/wcs/stores/servlet/...

[Pionir]

Thanks for the replies.

I was actually considering a booster/charger pack, but there's still the hassle of lugging it downstairs and fitting it into a corner in a small flat.

Disconnecting the battery is a bit too much effort too what with having to reset the radio code. The car park is also not totally secure - it's used for unloading by the local shop which has a door to their store room opening into it and they often leave the gates open

I think I'll give the solar charger a whirl as they're not that expensive and see what gives. I can always go down the booster route later.

Any thoughts on the capacity of charger I'll need? (it's an ST220 so quite a beefy battery)

[Fordo]

Hip2Bsquare said:

I tested this just yesterday.

I put a meter across mine and it gave an output of around 16v in sunlight and around 12v under flourescent lights (single tube, so not that bright).

HTH

i'm no electrician, but i believe its not just about volts. you might get 12v under florrys, but as soon as you put load on that - like trickle charging a battery, you'll find it wont do much.

florry lights hardly use much power in the first place, then they convert it to light and scatter that light in all directions. Not much energy will fall on the small surface area of the solar panel (which are pretty inefficient anyway)

(i do stand to be corrected though! i only have a 'university of life knowledge' of elecy)

I bought my old man a solar panel to keep his car batt topped up- quite a decent one two. He hung it behind a frosted window, and it just doesnt get enough light to do it's job.


I think battery pack would suit the OP's needs.

Or maybe have a word with the management company and tell them you have an electric car, and need a powerpoint installed in the car park....

[oldcynic]

Hip2Bsquare said:

I tested this just yesterday.

I put a meter across mine and it gave an output of around 16v in sunlight and around 12v under flourescent lights (single tube, so not that bright).

HTH

I suspect you need more like 14-16 volts to have any charging effect, and the recorded 12V will drop as soon as there is a load across it.
Use a charging pack which recharges off the car's lighter socket and keep it charging up whenever you use the car - then jump start the car whe you need to. Or fit a secondary battery system in the boot using some leisure battery kit (as found in caravans) and start the car from that when needed.

[Pigeon]

Something like that, yes. You will get bugger all charge off a solar panel under fluorescent lighting.

[entwisi]

one of teh classic car things was a simple "screw" type battery connector that disconnected the battery from the car circuits with a couple of twists. at worst teh radio code takes 30 secs to put in so that would b e one option.

add in a solar charger directly onto the battery to keep it topped up as much as possible and you should be good for 4-5 weeks easily.

One other option to consider was that years ago my dad fitted a split relay system that charged a car battery in teh boot ( for camping purposes). Surely something similar would give you an extra battery that could be used to jump start etc

[Huff]

Nail in the coffin on the PV panel idea, I'm afraid:

Solar panels are rated under a notional diffuse sky illuminance, usu. 60-100.000lux (lumens per sq m). Typical lighting levels in a garage will be of the order of 100-300lux. max. That's <1/200th the power output. Since PV 'behaves' most like a 'constant current' source, it'll only be able to push <<1/200 the panels rated current into a battery, if that, even though it may well read 12v + unloaded. Ain't going to work, sorry.

[DaveWM]

If you keep running the battery down to nothing (with radio, alarm etc) it won't last too long. Safest option is to disconnect the battery (it should be fine for a couple of months in storage). Get one of those "dis-car-nect" things to save messing about with spanners.

[Dr Doofenshmirtz]

Your idea of using a solar panel under artificial light will not work.
A float charge needs 2.25v per cell at around 50ma. Only an electric charger will provide this reliably.

[Hip2Bsquare]

oldcynic said:

Hip2Bsquare said:

I tested this just yesterday.

I put a meter across mine and it gave an output of around 16v in sunlight and around 12v under flourescent lights (single tube, so not that bright).

HTH

I suspect you need more like 14-16 volts to have any charging effect, and the recorded 12V will drop as soon as there is a load across it.
Use a charging pack which recharges off the car's lighter socket and keep it charging up whenever you use the car - then jump start the car whe you need to. Or fit a secondary battery system in the boot using some leisure battery kit (as found in caravans) and start the car from that when needed.

Yes, I didn't mention that putting a load across it (a completely flat battery) saw it dip to around 0.2v

Obviously not so much an issue if you are using it as a trickle charger outside but modern car electronics never sleep and consume more power than a solar charger is able to provide under artificial lighting.