Solar trickle charger?

pantherd90 · Post by **pantherd90** » 09 Jul 2006, 01:02

Was bored recently on eBay/Maplin Electronics and I noticed this:

http://www.maplin.co.uk/Module.aspx?Mod ... ar&doy=9m7

It claims to maintain your car battery with a solar panel that plugs straight into the 12v socket.

Figures for it are:
Output power: 1.5W @ 17.5V
Testing condition: AM=1.5,100mW/cm&square;
Cigarette lighter plug fuse rating: 0.5A
Cable length: 2.7m (9ft)
Dimensions: 352x125x14mm

My question is, would this really work? I mean would it slowly recharge the battery or at least stop it discharging, keeping it topped up? The output seems pretty low. Though I'm also slightly concerned as to whether it may blow any fuses/cause problems with the electrics.

The reason I'm asking this is because I've considered getting one for my aged Xantia. It keeps losing it's memory, or more specifically the car radio forgets the channel presets and code. This is a little irritating and on closer inspection I found that it was because the permanant 12v line only supplies 4-5 volts, at best. Whilst it had 4-5 volts (a short while after getting a new battery) the radio kept it's settings but through usage (or lack of) my car battery has started to supply less power again, causing the settings to be lost again. I was wondering if this panel might keep the battery in a good enough condition to keep the radio storing things properly.

Post by **Peter.N.** » 09 Jul 2006, 09:03

Two seperate points here really. Firstly, the 4.5 volts on your radio memory supply cant be due to your battery unless it is going completely flat meaning you cant start the car. A 'flat' battery will still usually read 12 volts. You have a high resistance connection in you 12v memory supply somewhere, easiest thing to do is run a new feed.

Secondly. The solar panel will keep a battery fully charged on an unused car providing it can see enough sunlight. All it needs to provide is enough current to compensate for any permanant draw, such as the clock, alarm etc. On a car that is used regularly this shouldn't be necessary because if the battery is in good condition it will be fully charged within a few minutes of starting the engine.

pantherd90 · Post by **pantherd90** » 09 Jul 2006, 09:22

Two seperate points here really. Firstly, the 4.5 volts on your radio memory supply cant be due to your battery unless it is going completely flat meaning you cant start the car. A 'flat' battery will still usually read 12 volts. You have a high resistance connection in you 12v memory supply somewhere, easiest thing to do is run a new feed.

I know that, my point is/was that due to the battery providing very slightly less output than when it was brand new the radio has slightly less than 4-5v on the 12v feed and thats enough to push it over the edge and into losing its memory again. Or so my theory went..

I could run a new feed but I don't really want the hassle and would be worried I'd get it wrong. How many non-switched 12v lines are there near the radio anyway?

DaveW · Post by **DaveW** » 09 Jul 2006, 10:13

As Peter said, it's very unlikely that a slight drop in battery performance is causing your problem.
Even a clapped out battery that will barely turn the engine over will give you around 12v and should be able to keep the radio memory alive. You should see 12v on the radio feed wire not 4-5v.
Check the feed connections for corrosion - work them in and out a couple of times and give them a squirt of switch cleaner or a smear of petroleum jelly.

If you still cannot see 12v then the easiest thing would be to do as Peter suggested and run a new feed (with an in-line fuse).

Dave.

Post by **Peter.N.** » 09 Jul 2006, 13:25

Is the cigarette lighter near enough?

pantherd90 · Post by **pantherd90** » 09 Jul 2006, 16:18

What in line fuse should be used.

AndersDK · Post by **AndersDK** » 09 Jul 2006, 16:31

A 1Amp fuse is more than adequate for the radio memory feed. This will fit a standard glass fuse and in-line fuseholder.
If you tap it from the cigarette lighter - this will be fused at some 10-20 Amps - which is capable of setting off a fire in small gauge wires.
Meaning you still need the in-line fuse.

Ad the solar charger : they will provide some 0.1Amp charge current at best - which is more than the battery self discharging. The result is in fact a trickle charging of the battery.

bxbodger · Post by **bxbodger** » 09 Jul 2006, 16:53

These things are totally unneccesary on a modern car with an alternator putting out 60 amps or more- there's way more than enough juice to keep the battery charged.

Where they are useful is on an old car with a dynamo charging system-in traffic on a cold wet winter morning with the lights,wipers, and blower on an alternator has no problem keeping up but with a dynamo you're using elastic-trickery faster than the dynamo can put it in, so a solar panel can be of help if left plugged in all day.

And, yes, you should definately have 12v at the radio feed: the problem is not with your battery or charging system!!

pantherd90 · Post by **pantherd90** » 09 Jul 2006, 18:07

I'm aware that the problem is not my battery or charging system. What I'm saying is that is that I believe as the battery ages it output decreases. The radio manages to hold its memory with only 4-5v input when the battery is brand new (even though the battery is providing it with more) but it doesn't with less, once the battery has aged a little.

A 1Amp fuse is more than adequate for the radio memory feed. This will fit a standard glass fuse and in-line fuseholder.
If you tap it from the cigarette lighter - this will be fused at some 10-20 Amps - which is capable of setting off a fire in small gauge wires.
Meaning you still need the in-line fuse.

In other words, cut the 12v feed to the cigarette lighter, divide it into two feeds, one with a 1amp inline fuse to the radio and one without any fuse to the lighter.

Is the 1amp fuse at all likely to blow during starting the car or with a charge coming in through the lighter socket?

Thanks for all your help by the way. It is much appreciated.

DaveW · Post by **DaveW** » 09 Jul 2006, 18:48

There is no need to cut the feed to the cigarette lighter. You can tap a wire off it using a snap on connector - those little blue jobbies where you lay the through wire (to cig. lighter) in one channel and the tap off wire in another and then close it with pliers. This cuts through the insulation and connects the two wires together. At the current we are talking about this would be more than adequate. Anyone know what they are called ? **

The 1 A. fuse will not blow unless the radio develops a problem at some future time, but that's what it's there for.

Dave.

** OK, found them. Sensibly, they are called Snap Lock Connectors and look like this :

pantherd90 · Post by **pantherd90** » 09 Jul 2006, 19:31

Thanks for your help. Would a 3amp blade fuse be alright for the job? Alongside an inline blade fuse holder connected to the scotchloc at either end with 3amp wiring?

At 12v I'm guessing any bare wiring should be wrapped in insulation tape?

On an entirely different subject, does anyone know what the voltage reading should be for each of the wires to the Infrared receiver in the roof panel, I've tried different ones and a new keyfob and I still can't get the remote central locking to work.

jeremy · Post by **jeremy** » 09 Jul 2006, 21:14

What can cause all manner of problems is if you replace a radio with an on/off switch for one with an electronic shutdown, unless the radio power is wired so that it is switched by the key.

I'm not talking about the memory feed, but the power feed. I installed one on my BX which is not used much at the moment and it would flatten the battery in about a week or so. I have now taken it out and fitted it to the ZX which has a switched supply and the BX started first time after 5 weeks without it!

If any power feed for an accessory is below about 12 volts with a fully charged battery (12.5 volts) you've got a problem!

dnsey · Post by **dnsey** » 09 Jul 2006, 22:24

At 12v I'm guessing any bare wiring should be wrapped in insulation tape?

There shouldn't really be any need for bare wiring here - the Scotchlock connectors are insulated anyway. If you do end up with any bare conductors, heatshrink sleeving is a much better idea than insulating tape, which can easily lose its grip and unravel. Failing that, use self amalgamating tape.

mezuk04 · Post by **mezuk04** » 10 Jul 2006, 09:58

You can never have enough Scotch clips

Although I dont have the first clue when it comes to wiring 8)

jgra1 · Post by **jgra1** » 10 Jul 2006, 17:11

I have one of these panels from ebay

I thought of trickle charging car or bike or camper as most of them get only occasional use.. it only cost a couple of quid from Hong Kong..

but, i haven't used it yet for anything

sorry

John