recharging 12volt batteries?????

Looking for some tips or advice on camping or where to camp? Post you questions or comments here. General Camping information.

recharging 12volt batteries?????

Postby skip » Thu Apr 12, 2007 5:26 pm

hey i was thinkin of geting an old car batterie and running some 12 volt lights off it how do you recharge them?
skip
Captain Camping
 
Posts: 56
Joined: Wed Apr 04, 2007 5:49 pm

Postby Komodo » Thu Apr 12, 2007 5:32 pm

battery charger?

Or do you mean while camping?
Image
A place I'd rather be...
Mitchel Road, Bomjinna. Central West Victoria (Jan '08)
User avatar
Komodo
Grandpa Talks Alot eh?
 
Posts: 846
Joined: Wed Oct 18, 2006 1:35 pm
Location: Frankston South [VIC]

Postby skip » Thu Apr 12, 2007 6:06 pm

how long would a batterie last with 2-3 12 volt lights running off them ( i know what your guna say how longs a piece of string ) but how long does the average last. can you charge them while your camping or do you have towait till you go home?
skip
Captain Camping
 
Posts: 56
Joined: Wed Apr 04, 2007 5:49 pm

Postby Komodo » Thu Apr 12, 2007 6:09 pm

LOL your right how long is a piece of string (and i dont want to hear twice as long as it is from one end to the middle)

Depends on what sort of wattage the lights are, how long you are going to have them on for, are you going to have them all on at once. And of course how big your battery is.
Image
A place I'd rather be...
Mitchel Road, Bomjinna. Central West Victoria (Jan '08)
User avatar
Komodo
Grandpa Talks Alot eh?
 
Posts: 846
Joined: Wed Oct 18, 2006 1:35 pm
Location: Frankston South [VIC]

Postby Fonty » Thu Apr 12, 2007 7:07 pm

This is very basic coz I'm no techie, but I did live in a solar powered house for a while and that kinda rubs off.

Your car battery has a certain amount of 'amp hours'. A typical battery might have one hundred amp hours of electricity stored in it. Smaller batteries will have less, and larger more of course and there are different types of batteries such as deep cycle ones which you're gonna have to ask someone else about. :grin:

So lets say an average battery has 100 amp hours. For a 12 volt battery 12 watts is one amp. So a 25 watt globe, (which isn't all that bright) is nearly 2 amps. So running a 25 watt globe for half an hour will drop your battery's juice by one amp hour, leaving you with 99. You can work out the math from there. For example if you were running 3 50 watt globes for say 5 hours each night that would drain your battery real quick. (4 amp hours+ each for 5 hours = 20 amp hours times 3 globes = 60 amp hours in one night)

There is a complication though. Unless technology has changed a lot in the last 15 years, a car battery starts dying pretty quickly if you let it drop my lower than 80% full capacity. You can only let this happen a few times before the battery loses it's charge permanently and becomes useless. And also if you let the charge go down too much the voltage is effected also. So it is important to only use so much and recharge it regularly.

If you are setting up your camp for weeks at a time you could look into getting a small cheap solar panel. Or a generator or get it wired to your car. And/or a much bigger battery. :) I think the smallest set up we lived with was two 6 volt batteries in series with 250 amp hours and two solar panels to charge it. It was plenty for just lighting the small house we had. The larger house we lived in had a series of 6 2 volt batteries but I can't remember how many amp hours in them. Again though we only used it for light and the two solar panels were plenty to keep us charged up also.

Hope this isn't too confusing. :)

Andrew.
Image Truth is often painful, but ignorance is never bliss.
User avatar
Fonty
Camping Veteran
 
Posts: 158
Joined: Thu Feb 22, 2007 11:23 am
Location: Ferntree Gully, Melbourne

Postby Komodo » Thu Apr 12, 2007 7:24 pm

Fonty is on the money.

I = P/V

I = Current or Amps

P = Power or Watts

V = Volts or Voltage

Car batteries rest at 13.8

Because P = V * I that means the lower the voltage the higher the current draw.

Also batteries are a funny thing. Drawing power from a battery lowers the voltage but if you stop the current drawer and let the battery rest then the voltage will slowly rise back to 13.8 but the RC (reserve capacity) will be dimished to the AH rating of the battery is therefore lower.

Ok so thats enough of the Tech talk.

Let us know how long you expect to use your lights or at least the watts of the lights you intend on using
Image
A place I'd rather be...
Mitchel Road, Bomjinna. Central West Victoria (Jan '08)
User avatar
Komodo
Grandpa Talks Alot eh?
 
Posts: 846
Joined: Wed Oct 18, 2006 1:35 pm
Location: Frankston South [VIC]

Postby clackerz » Fri Apr 13, 2007 11:16 am

This is a very interesting topic.
I was thinking of doing the same thing:
run some lights (mainly the cooking/sitting area) off batteries and charge them during the day off my generator.
So obviously I need to first have an idea of how many lights I am going to run and what wattage globes I will be using.
I don't want to be really running my generator at night (I have camped near people who have and the drone of the generator through the night kinda takes the atmosphere away!)
There's water at the bottom of the ocean!
User avatar
clackerz
Captain Camping
 
Posts: 71
Joined: Tue Apr 10, 2007 3:32 pm
Location: Melbourne SE 'burbs

Postby Komodo@home » Sat Apr 14, 2007 9:01 pm

Generators suck balls.

Go with LED lighting if you can. heaps more energy efficient
Komodo@home
Captain Camping
 
Posts: 93
Joined: Wed Mar 21, 2007 8:50 pm

Postby clackerz » Mon Apr 16, 2007 11:11 am

Komodo@home wrote:Generators suck balls.

Go with LED lighting if you can. heaps more energy efficient


Fair enough, but wouldn't having a gen be a good back-up to recharge the batteries at some point?
There's water at the bottom of the ocean!
User avatar
clackerz
Captain Camping
 
Posts: 71
Joined: Tue Apr 10, 2007 3:32 pm
Location: Melbourne SE 'burbs

Postby Komodo@home » Mon Apr 16, 2007 12:10 pm

yeah but most generators 12V output is about 6-8 amps a set of jumper leads on to your main battery and your vehicles alternator can put out 60-120amps
Komodo@home
Captain Camping
 
Posts: 93
Joined: Wed Mar 21, 2007 8:50 pm

Postby clackerz » Mon Apr 16, 2007 2:15 pm

Komodo@home wrote:yeah but most generators 12V output is about 6-8 amps a set of jumper leads on to your main battery and your vehicles alternator can put out 60-120amps


Oh I see my gen (from the specs - http://www.gmcompany.com.au/index.cfm?m ... ts&pid=398) max is 8A.
I didn't realise the car was so much higher.
There's water at the bottom of the ocean!
User avatar
clackerz
Captain Camping
 
Posts: 71
Joined: Tue Apr 10, 2007 3:32 pm
Location: Melbourne SE 'burbs


Return to Camping Tips and Locations

Who is online

Users browsing this forum: No registered users and 6 guests