Solar Battery Charger (Car)

[Bladerunner]

I have come up with an idea. If someone else has thought of it first then I apologise.

I am after a charger for a car battery and wondered if someone could recommend one. Nothing fancy, I have seen one on the top of a shed that someone was obviously using to charge some type of battery but I can't remember where I saw it, DOH! I am thinking that a car battery would not take much to keep charged but should still have enough power for the following.

What I want to do is set up a cigarette lighter socket that is linked to the car battery just like in your car. I have a usb adapter that fits the cigarette socket and lets you recharge virtually anything small. I am going to get a 10 piece adapter that would let me charge phones, NDS, Kindle, Ipod, smaller batteries, etc.

All my survival shows are on my ipod like Survivorman, Woodsmaster, Ray Mears, Dual Survival, etc. Plus the music would be nice if there was no electricity.

I am looking to get a Kindle for all my survival books, PDF's, Text files, Recipes, etc.

NDS and other handheld games would be great for young children to keep them occupied although personally I would have them up the chimney or cleaning out the looms.

I don't need anything with a massive power output, just enough for a car battery. I know there are many out there but can someone recommend a particular one that is a good price and will keep the battery charged. Or alternatively, suggest a Heath Robinson type thingy with instructions for a moron to understand.

Be lukcy (and charged)

[pietka]

I have 2 12v lead acid batteries in my room! I have 1 12v socket and from that I have a USB plug!

I use it to charge my phone, mp3 player and a couple of other things!

After a couple of weeks I take it up shedland and charge it for a day or so! On my solar set up!

I started off with a 13w solar briefcase from maplins about £50 comes with leads, 5A charge controller and crocodile clips! Does well for the lea acid batteries might need more umph! Other than that there's loads of complete kits minus batteries on E-bay!

[Ian]

I have a couple of the 13W solar briefcases from Maplins also. Unfortunately they are not waterproof. Indoors, against a window, over the winter, together they do not produce enough to keep my classic car's battery topped up, the output is unmeasurable. Summer in direct sunlight they are good.

My suggestions are:

1. Set up your car battery, cigarette lighter socket, USB converter and please don't forget an inline fuse in the circuit near the battery (or preferably two, one close to each terminal) and charge the battery from an ordinary charger. This lets you test if the system is what you want. A typical car battery will give days of your proposed use before it needs charging.

2. Buy and add on in parallel an outdoor solar panel, say 5-10Watts, Maplins have a number with various sizes and prices, make sure it is for use outside and has some sort of mounting system/bracket. This should keep the battery topped up and in good condition throughout the Winter and to a certain extent charge it from use in the Summer. Any further charging needed would come from your mains charger.

3. When you are comfortable with solar (it really is disappointing) buy a much larger panel 60-100W, and a 'leisure battery' which would allow you to take those uses you propose 'off grid'.

This strategy allows you to spread the costs, make sure the system is what you want, allows you to buy the panel when the price is right (say in the Autumn sales) and learn without the high upfront costs.

It is much cheaper and reliable in the UK to just use a car battery with a monthly tickle from a mains charger. This keeps it simple, maintained and portable. Adding solar is just for fun and experience which we all can't get enough of.

Sudden thought. Why not just use the car?

[Bladerunner]

Thanks for the advice. The reason I want a stand alone set up rather than just using the car is it is for after TSHTF.

I can currently charge my stuff from my computer, car or mains but after we permanently lose electricity things like Ipods just become expensive paperweights without the means to recharge them.

Plus I currently have all my suvival books and PDF's on my computer. I have way too much to physically print out so I was looking to get a Kindle and that would need recharging if we lost power permanently.

Thanks again for the help.
Be lucky (And powered)

[Ian]

Ah, so if you want to go 'off grid' you will need better kit.

Charging what you describe may take five to ten Watt hours of energy a day (typical iPhone usage is 7Wh a day for example)

A 'leisure' battery which withstands deep discharge better than a car battery which is really designed to give a high output for a few seconds a few times a day. The 'leisure' battery is designed to supply a low current for an extended period. The commonly sold type hold 110 Amp-hours of energy but you will only be able to get 60Ahs (circa 750Wh or about a couple of months use without charging) or so without damaging the battery. An ordinary car battery may last months to a couple of years if you are lucky.

Also to cope with our short, dim winter's days you will need the 60-100W solar panels to get a reliable ten or a dozen Watt-hours a day that you will probably need to charge things. Because of the oversize panels you will defiantly need a charge controller to prevent overcharging in the Summer.

I bet you would use the charger more in the Winter than the Summer as it would be mostly used for entertainment during the dark evenings.

Costs:
Battery £70-80
Panel £120-150
Controller £25-30

All is simply wired up and should give you eight to ten years of use before the battery dies.

[notrab99]

I have a similar setup. After looking around I decided to keep it simple and portable. But as my business is selling PC accessories I have lots of USB devices to play with and have now started to tailor the business towards LED torches, batteries etc so if SHTF I will be stuck with plenty of useful items. I just happen to have a 'leisure' battery from an old caravan in the shed (we only ever camp on sites with a mains hook-uk) so at first I hooked that up to a small solar panel. I realised that if you want to provide some mains-equivalent backup power then you need to spend a serious amount on solar panels and I don't want my house to stand out - you know when someone has installed a good solar system! So I have taken a step back and have just bought a much smaller lead-acid battery to match the solar panel I have. So now I can keep the leisure battery charged via the mains in case we have a few days without electricity and can easily chuck the small one in a rucksack if needed. But what I also realised is that it is quite possible that no power to the house could also mean no power to the mobile phone relay stations etc. so that urgency to keep your mobile powered up may not be the answer to communications. With that in mind I have bought some decent walkie-talkies (for local comms) and the latest addition is USB battery chargers (for AA and AAA). One last thought, make sure you keep your main battery in the shade behind the solar panel as they don't like to get too hot.

[nickdutch]

just dont forget the charge controller or your batteries go south.
PWM is ok, but may lose power
MPPT is the best