# I want a 12V DC car charger for my 8.4V Li-Ion batteries



## ewarnerusa (Jun 8, 2004)

Does anyone know of a 12V car charger for 8.4V li-ion batteries (magicshine plug)?


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## Cat-man-do (May 16, 2004)

ewarnerusa said:


> Does anyone know of a 12V car charger for 8.4V li-ion batteries (magicshine plug)?


I believe Action LED sells one but probably the better option is to buy a small ( cigarette plug type ) DC to AC inverter for your car. With inverter you can then plug in any of your small ( low power ) AC chargers and you're good for on the go. I think the one I bought was about $30 with an output power limit of 40-50 watts. Mine I bought at Radio Shack. Sadly RS went out of business but you should still be able to buy one somewhere on the web.

( edit: the nice thing about having one of these is that it can be used for car camping and for when you have a power outage in your home. )


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## ewarnerusa (Jun 8, 2004)

My desired usage is for use in my camper. I do have an inverter for use in the camper and that's how I do it now. But it would be nice to eliminate the need for the inverter.


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## ewarnerusa (Jun 8, 2004)

I found one on the Action LED site, thanks for the suggestion!


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## ewarnerusa (Jun 8, 2004)

I see that the car charger charges at half the current as the 120 V AC charger. So my motivation of eliminating the inefficiency of converting 12V DC to 120V AC prior to charging may very well be negated by twice the charging time. Although it will be at half the current... Won't Peukart's Law say that this will mean net less energy required to use half the current for twice the time? 
Whatever the case, I bought one anyway since I want one! $12.27 with shipping.
http://www.action-led-lights.com/collections/batteries/products/battery-car-charger


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## find_bruce (May 8, 2011)

Your other option is to use a hobby charger - most run directly from 12v, my accucel 6 does but there are plenty of others


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## Cat-man-do (May 16, 2004)

ewarnerusa said:


> I see that the car charger charges at half the current as the 120 V AC charger. So my motivation of eliminating the inefficiency of converting 12V DC to 120V AC prior to charging may very well be negated by twice the charging time. Although it will be at half the current... Won't Peukart's Law say that this will mean net less energy required to use half the current for twice the time?
> Whatever the case, I bought one anyway since I want one! $12.27 with shipping.
> Action-LED-Lights ? Battery Car Charger


I wouldn't worry about the inefficiency because it's working off the car battery. The real question is would the inverter operate the charger properly and give you the listed output of the AC charger ( 2000ma ). I figure that depends on the circuit it is hooked up to. If your cigarette plug can supply the needed output than it should work as long as you have an inverter spec'd to operate in the needed power zone. I wish I had a better answer. I know the one I have works ( because I tested it ) but truthfully I've never actually tried to charge a completely discharged battery with it.

Anyway, I'm thinking that the reason the car charger is lower output is because the sellers want to make sure the charger doesn't overload the cigarette plug circuit and blow the fuse in the car ( or perhaps start melting something with the heat ). Now that I think about it , that might not be such a bad idea but with all the devices out there now that use car chargers I would think most modern car cigarette plugs should be able to charge something like a bike battery without too much problem. Laptop vs. bike battery....pretty much the same thing.

The idea of a hobby charger would be a good idea if you want faster charging but if used on a car battery it would likely be a good idea to hook it directly to the battery with some heavier cables ( assuming the hobby charger has a protection circuit ) and then maybe with the car running maybe 20 min or so every 2hrs just to make sure it doesn't kill the car battery.


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## scar (Jun 2, 2005)

I offer these to my customers, they are listed as 1.0A output - Smart DC Charger For any 7.4V Li-ion Battery Pack

****


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## patski (Dec 12, 2005)

Cat-man-do said:


> I believe Action LED sells one but probably the better option is to buy a small ( cigarette plug type ) DC to AC inverter for your car.


I use this inverter with dual 120V outputs, http://goo.gl/eny13b

Also keeps my laptop/phone charged on the road.


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## Cat-man-do (May 16, 2004)

patski said:


> I use this inverter with dual 120V outputs, Amazon.com: Rally 7413 200W Cup Holder Power Inverter with USB Port: Automotive
> 
> Also keeps my laptop/phone charged on the road.


That looks pretty good. As usual Amazon to the rescue. At least the one you have has the automatic shut-down protection to protect the car battery from over discharging.


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## ewarnerusa (Jun 8, 2004)

My inverters in my camper are both pure sine wave. One is rated at 300 watts continuous load and the other at 1500 watts continuous load. I rarely ever need the power that the big one can provide, so I usually just use the smaller one for efficiency. Camper has a solar charging system, so really my bike light charging efficiency losses are a moot point. But it's fun to geek out about this stuff. Plus if i can eliminate the need for the inverter for this, it's one less thing to have to remember tho turn on and off.


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## Cat-man-do (May 16, 2004)

ewarnerusa said:


> ...But it's fun to geek out about this stuff. Plus if i can eliminate the need for the inverter for this, it's one less thing to have to remember tho turn on and off.


I use the 12volt voltage ( step-down ) converters everyday for my phones and other USB type stuff. They work fine but you never leave them plugged in when not being used ( or if the car is turned off ) because the step circuit is always on ( if you have a car that leaves the cigarette socket hot when the car is not running. ) The one in my car is always hot whether the car is on or not. The one in my work car is not hot when not running... which is sort of a PITA. Anyway, just unplug it if you are finished charging. If you leave them plugged in, even though the power drain is minute, left on all night in cold weather might not be a good idea.


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## tigris99 (Aug 26, 2012)

I have my ac/dc smart charger atm which works fine but before camping this summer I need to come up with something more convenient.


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