Non diving - CAR CHARGER info

[8dust]

Ok, not diving related at all, at least not at this point, but I need some advice from the pool of smartguys out there...

Short version is, I’m building this video thing for my son’s soccer games and the giant contraption incorporates an LCD screen that is designed to be mounted in a car headrest. There is a bunch of other stuff involved, but the main issue is powering the screen, for which I’ve purchased a 12v 2.6a/h lead-acid battery which as the screen is reported to use 6watts, should draw .5a @ 12v... at least that’s what I figure after a bunch of googeling. But here’s the rub... I would like to be able to charge it on-the-road, preferably from my truck (if the other pieces seem to all work, and the thing proves useful, version 2.0 may incorporate a solar panel for some sort of constant charging while operating deal) but what I can’t seem to figure out is:

... What’s the output of my truck (2009 GMC full-size) accessory port/cigarette lighter....?

Seems like it would be 12v..., yes? but I don’t understand enough about the whole electrical thing to get is... would the battery just draw the amps it need to charge? Does the port put out a fixed flow of amps? What I’d like to do is just chop the end off one of the dozen old cellphone car chargers, put some blade connectors on the wire ends, and plug it in to the dashboard... but I’m none too interested in any exploding battery acid in my still beautiful and plush country-Cadillac leather interior.

Any help on this final aspect of the project would be greatly appreciated! And yes, I could buy a charger from Batteries Plus, that was sitting on the shelf right next to the battery I bought.... But that would be WAY too easy and cost yet more money.


Thanks in advance, Fred

[frogman63]

Most cigarette lighter sockets are set up to provide 12v and 10 amps maximum current (i.e. 120 watts max). You can verify the current capacity by checking the fuse table in your owners manual. The current draw is not fixed at 10 amps; your device/load (or in this case, charger) will dictate the current draw.
I would be carefull in modifying a cell phone charger. It may have electronics in it that converts the 12v to what the phone requires. If you do not have a standard cigarette lighter male plug, you can purchase one at R.S.
Also, there are both "full charge" and "trickle charge" solar battery chargers available. The full charge systems have larger solar panels.
If you have any other questions, let me know.
Brian

[usddude]

Fred, the outlet throws the about same voltage as your car battery, 12 to 13.8 volts. The amperage will vary depending upon the device plugged in. For example a phone charger may only draw 300 milliamps while an actual cigarette lighter will draw several amps. Most outlets in cars have a 10 or 15 amp fuse, so the circuit could easily .5 amp (500 milliamp) battery draw. Do not use a phone charger. Use a direct wired plug. Truckstops sell them for $5 or so. Is the battery self contained or a container to prevent acid leakage in case of an accident? ie: dropped, kicked..etc

Steve

[Bryan]

Not sure if this will work for you or not but I put an inverter in the element and plug the DVD player into that. I got tired of messing around with the aux / cigarette outlet. Plus you can use it to charge batteries and power a lot of other AC items.

http://www.bestbuy.com/site/Wagan+-+400 ... Id=9890447

[antique diver]

Hi Fred,
Your post sounded like you might be considering just connecting your 12V 2.5 amp battery directly into your 12v. outlet to charge off your automobile alternator.
I may have misunderstood, (and I am certainly no electronics expert) but if you do that you might charge the small battery at too fast a rate. For your safety and that of the battery, please use a simple inverter like shown in the link, and then use a battery charger recommended for that type battery.

It will work fine. I keep an inverter in my truck all the time to run all kinds of small item chargers, from power tool batteries to dive lights. You will find it to be a handy item.

BTW, your cornbread skillet turned out a fine batch of Jalepeno Cornbread last night, thank you!

[USdiver]

Fred,

Why use a separate battery for the screen? Can't you just hard wire it into the car's electrical system and draw power directly from the alternator/car battery?

[usddude]

An inverter converts dc to ac. If your lcd runs 12v dc use a straight in wired male plug to an outlet. If its ac use the inverter, you can also plug a trickle charger into the inverter. I am concerned about plugging your smaller battery into the vehicle 12 volt system as well. Maybe just use it as a backup when the engine is not running.

Steve

[ebj]

If you can use an inverter as Brian suggested, you'll be better off. I'm running my hp tablet pc off one typing this reply. It stays plugged into the charger in my truck and and is also great for charging cell phones etc. I use about 10 hrs a day. I gave up on the 12v chargers. They just don't last. My inverter cost less than $30 and is over 4 yrs old and still works great.

[8dust]

So many fine ideas, I knew they'd be out there, thanks a bunch.

I may be wrong, but I think my truck, a 4-door, has 5 of those dam ports. Could be even more hiding somewhere I haven't noticed... I just feel compelled to plug something into them!!!!

Anyway, the object wasn't to run the LCD, it was to charge a 12v 2.3a/h battery, which then in turn runs the screen, far from the truck. I'm building a pole mounted video camera for recording my son's soccer games, to use as a training aid. An old 8mm video camera sits way the hell up on a fiberglass tree trimming pole I found out in somebody's weekly trash. The pole is just the ticket, once I took the rusty saw blade off and made up a threaded mount, and though old, the camera is perfect because it has video out ports and a remote for on/off and even zoom. The idea is I stick the thing way the hell up there, and then have another monitor down with me powered off its own source. Version 1.0 used an extended 12" bolt about chest-high that I lined up with the camera so I could point at the action with that similar to a hunting/target bow, sort of, and that worked OK, but I thought this would be the pro 2.0 upgrade. If it works well and proves useful, I may spring for a solar cell next season to power both the camera & monitor which if I stuck it on the very top somehow, would provide the extra benefit of some shade for the cammera on those blazing hot days. We'll see.

Long and short of it is, despite my urge to plug into my many random ports, I think I'm going with the inverter idea, (I never knew about those) as I can see plenty of other random stuff making it's way out to the truck once that power source is available. My local Batteries Plus even has one with 2 outlets, that for all the world looks just like a starbucks cup w/ lid, so it almost makes sense permanently riding up in the cup holder!

Thanks again! Fred

[Herman]

A couple of hints on the inverter for you Fred.
First off, decide how much power in watts you think you will need and AT LEAST double it, triple is better. All the inverters I have seen rate them in peak watts, which is the max they can provide for a short period, not continous duty which is what you are really interested in. Rated peak watts can be 50% or more than than rated continous watts. You will likely find the continous rating in small print somewhere on the package. Next realize that they eat a fair amount of power even at idle so they WILL KILL YOUR BATTERY in a few hours, so don't think you can plug it in and run all day without the truck running. I highly recommend you use them with the truck running and unplug them before turning the truck off. If you don't, sooner or later you will forget and leave it running- they are quiet. I also suggest you invest in a good set of jumper cables to go along with it....don't ask how I know.

If it were me, I think I would take a third option. I would buy a little larger (or use 2 or 3 in parallel or swapping them out) gel cell batteries and use them to power the camera. You can recharge them at home with a small car charger. The recharge time on the batteries is going to be at least a couple of hours so having 2 or 3 and charging them at home would keep your running longer......and reduce the need for jumper cables.

[spectrum]

You don't want that lead acid battery charging in the passenger compartment. Hydrogen gas will be released and history tells us what that can lead to. Cars that have the battery in a contained space have a battery with special vent ports to route the gas to the atmosphere. My daughter has one in her Saturn, I think the designation has a V suffix.

Pete

[8dust]

Ah ha!
Good details to add! Thank you, Both.
The inverter may be incarnation 2.1 then, as I had not picked it up yet, just a standard cheap wall charger I was going to plug in at home and on the road, if required. It may turn out to be something of a non-issue if the battery lasts for the afternoon. We'll see tomorrow. Tested all components last night and they all play together fine. Now just have to rig it up this afternoon, and we' be off to the fields!