how is a battery charger used differently from a converter?

[rlphoto]

Using a PC power supply is a good idea. I have a new 250 amp PS because when I bought my PC case that was on sale, it had an upgrade to 350 amps. So, rather than swap the PS, they sent the case with the 250 amp PS and the 350 amp PS in a box for me to swap out. I just have to plug it in and see which wires output the 12V.

One question though. With the PC PS, won't the power being outputed by the PS go to the batter as well? Or should an isolator of some type be used to keep the power from going to the battery? Or, would the power going to the battery hurt it? I am no expert in this area of expertise.

I had planned to use a 12V charger to, so I'm glad I read these notes on why not to do that. I do have another idea to run past everyone. I may mount the 12V battery for the camper in the back of my Pickup with a connector to the camper. I'll wire that battery to the truck charging system through an isolator. That way, whenever we go riding around, the camper battery will get re-charged.

Please express your thoughts on these questions.

Dale

250-350 amp power supply? must be a heck of a computer. Maybe it is a new combination computer/arc welder.

Randy

[toypusher]

250-350 amp power supply? must be a heck of a computer. Maybe it is a new combination computer/arc welder.

Randy

Maybe that should be "Watt' not 'amp'???

[bdosborn]

Using a PC power supply is a good idea. I have a new 250 amp PS because when I bought my PC case that was on sale, it had an upgrade to 350 amps.
<snip>
Dale

You can't charge a battery with 12V. A deep cycle battery at full charge is at 12.9 volts. Its 50% discharged at 12V. You could run your appliances at 12V but not charge your battery. I'd check the output voltage of the computer power supply to make sure it will do want you want. Also, newer battery chargers have three charging modes that will maximize battery life. I like the charger that asianflava posted a link to. Batteries are expensive and amazingly fragile. One 100% discharge can ruin a deep cycle battery.
Bruce

[webbedouin]

rlphoto wrote:
"Now to figure out how to charge from the car alternator."

Alternator ouptut to a battery isolator, one leg of the isolator continues on to the existing car wiring and battery, the other goes to the trailer battery.

Be sure to check out how many amps your car alternator can put out, double that and get the appropriate sized cable and isolator. I use number 4 cable, that way if the car battery dies, all i need to do is jump accross the isolator battery connections and i can start the car off the second battery. Have done it by shorting the battery connections together with an uninsulated monkey wrench in a pinch, didn't even get a shock, but you can be sure i was NOT touching the car's negative ground.

Some newer cars won't be happy with the diode in the isolator in the line. Depends upon how the alternator senses the state of the car battery's charge. You can work around this by just isolating the trailer battery and tying the alternator output to the input of the isolator. In this case, The car battery can see the trailer battery (but not visa versa) so you might wanna disconnect the cable going to the trailer at the hitch while you're camped for a while because when the voltage in the trailer battery falls below that of the car battery, the car battery will charge the trailer battery and drain itself doing it. Start the car and then reconnect the cable to recharge in place or to go home. That's the only caveat.

[rlphoto]

Using a PC power supply is a good idea. I have a new 250 amp PS because when I bought my PC case that was on sale, it had an upgrade to 350 amps.
<snip>
Dale

You can't charge a battery with 12V. A deep cycle battery at full charge is at 12.9 volts. Its 50% discharged at 12V. You could run your appliances at 12V but not charge your battery. I'd check the output voltage of the computer power supply to make sure it will do want you want. Also, newer battery chargers have three charging modes that will maximize battery life. I like the charger that asianflava posted a link to. Batteries are expensive and amazingly fragile. One 100% discharge can ruin a deep cycle battery.
Bruce

So how do you keep a deep cycle battery from being completely discharged while in use?

[webbedouin]

Stop using it when the voltage gets low...

[Woody]

Coservative power usage. It is the same priciple if you had only 20 gallons of water in the tank, use it wisely. My deep cycle battery has lasted 5-6 days with kids. they have to learn to turn off the lights when not using them. Of course it doesn't work at home either. Digital meters for your battery will tell you where you stand on the power and consumption for a visual reference. It helps

[An Ol Timer]

Nearly everything in these last few posts were erroneous. I suggest that you take some time to search these subjects out from past posts as they are there. Also take some time to look at the PS power supply and look at the output voltages and their amperages. If you want to know about charging your deep cell from your vehicle and also how to isolate it from the vehicle battery I suggest some reading about VW campers as they've been doing it successfully for years. I had an 85 Westfalia for 15 years and it had a vehicle battery under the passenger's seat and a deep cell under the driver's seat as well as all the needed devices for charging and isolation. I won't post or answer back on this subject as we have too many done-it-alls that just want to argue.

[WoodSmith]

Or you can install a cool battery monitor like Michael did
http://www.tnttt.com/viewtopic.php?t=3935&postdays=0&postorder=asc&start=12 He even provided a link in that thread for the plans.

[BobR]

I used a Guest 2606 3-stage smart charger. Fully automatic 6-Amp, 12-volt charger/maintainer, comes complete with 6' AC cord and 4' DC outputs with alligator clips. Fully potted, waterproof, vibration-resistant. This unit will power the load up to 6 amps when plugged into a 110vac source. If the 12vdc load exceeds 6 amps, the power will be drawn from the 120AH deep cycle battery. Never had a problem since 2001.

http://www.marinco2.com/showProduct.asp?p=2606

[rlphoto]

Coservative power usage. It is the same priciple if you had only 20 gallons of water in the tank, use it wisely. My deep cycle battery has lasted 5-6 days with kids. they have to learn to turn off the lights when not using them. Of course it doesn't work at home either. Digital meters for your battery will tell you where you stand on the power and consumption for a visual reference. It helps

So I need a meter hooked up at all times so I can see it. Just a simple 12v dash type meter would work I guess? That amp meter is really nice.

I just realized that I have a sunpro digital multimeter that will give me amps and volts. So I have a starting point.

[rlphoto]

rlphoto wrote:
"Now to figure out how to charge from the car alternator."

Alternator ouptut to a battery isolator, one leg of the isolator continues on to the existing car wiring and battery, the other goes to the trailer battery.

Be sure to check out how many amps your car alternator can put out, double that and get the appropriate sized cable and isolator. I use number 4 cable, that way if the car battery dies, all i need to do is jump accross the isolator battery connections and i can start the car off the second battery. Have done it by shorting the battery connections together with an uninsulated monkey wrench in a pinch, didn't even get a shock, but you can be sure i was NOT touching the car's negative ground.

Some newer cars won't be happy with the diode in the isolator in the line. Depends upon how the alternator senses the state of the car battery's charge. You can work around this by just isolating the trailer battery and tying the alternator output to the input of the isolator. In this case, The car battery can see the trailer battery (but not visa versa) so you might wanna disconnect the cable going to the trailer at the hitch while you're camped for a while because when the voltage in the trailer battery falls below that of the car battery, the car battery will charge the trailer battery and drain itself doing it. Start the car and then reconnect the cable to recharge in place or to go home. That's the only caveat.

Cool!

I spent hours researching this stuff but sometimes it helps to have the right person explain it. Boy am I dumb on 12v volt stuff. Never had a reason before to get into it this deep.

Randy

[cracker39]

Sorry, guys, the PC Power supply is 250 watts, not amps. Just got my terminology wrong. Using a simple conversion process, that appears to be about 20 amps output at 12V. I think that should be sufficient for me. The vent fan I plan to use draws 2.2 amps. Lights should use from 1-3 amps each depending on number of bulbs and wattage, and I'd never have more than 3 bulbs in use at any one time. I'm not sure about a 12v portable tv (9")...yes, I need the TV. My wife can't miss her soaps, even while camping). Us old-timers do a lot of just sitting around, just enjoying being out in the woods swatting mosquitoes.

Dale

[cracker39]

Randy, that's what's so great about these forums. The guys and gals with knowledge and experience can keep us novices out of trouble. And I am a novice in some areas. I've learned SO MUCH since joining a week or so ago, and at my age (66) I thought I knew it all .

I am working on my 3rd version of my trailer plans based on things I've learned in the last couple of days. Each time I do, I find I can simplify something that I made too complicated, or correct a structural mistake. And I'm positive that this won't be the last version I'll create.

Dale