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Discussion Starter #1 (Edited)
A guy I know told me he keeps his car battery plugged into one of these all winter , that they make a great trickle charger.
Its a charger for a Motorola two way radio.
This one says 13.8 volt output @ 0.9 amps.
He splices in small clamps like the ones on your batt. charger and its ready to go.

Any input ?
 

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I have 5 battery maintainers I bought at Harbor Freight for $4.99 ea. I have one on each of my cars. One of my vehicles is only started ~ twice a year & it has a 5 year old Napa gell filled battery. Anyways, all my cars start right up. Never have a dead or low battery. They work great! (the harbor freight battery maintainers). They will NOT charge a battery. They will maintain a charged battery though.
 

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I couldn't say for sure. The Harbor Freight ones have a little electronic black box inline with the charging leads. I think the box "pulsates" the voltage to prevent battery sulfation?
 

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Even though it looks the same, your and your buddy are taking a chance. The battery maintainers are not wired the same as a typical wall-wart. It would be quite easy to exceed the 0.9A rating you said your wall-wart has and melt it down. A wall-wart is essentially a voltage regulated power supply. You need current regulation also.
 

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Buy a trickle charger for a battery. The trickle charger will shut off at a predetermined level (say 12.9v), and won't re-engage until the battery drops off to ~12.3v. (these v+ are approximate and vary from make to make)

12.6v is a fully charged battery (2.1v/ cell)


A universal power supply will just sit there and cook the battery over time.
 

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I'd use the Motorola charger if I had or needed one. You're not going to harm the battery with less than an amp charging current, and if the power supply crowbars you aren't going to hurt anything. What's the difference between the 13-14 volts your alternator charges the battery with and the 13-14 volts this Motorola device puts out, other than the alternator can put out 50 times as much current?
 

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I'd use the Motorola charger if I had or needed one. You're not going to harm the battery with less than an amp charging current, ...?
It's not the battery you need to worry about, it's the charger. It may be rated for 1Amp, but you can try to pull more and see what happens. How much current it attempts to deliver is a function of the battery. I've seen plenty of wall warts melt down. You'd hate to have a fire or damage to you stuff because you were too cheap to buy a proper charger.
 

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If you're worried about burning up the charger, put a current limiter in series with it.
 

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Discussion Starter #11
You'd hate to have a fire or damage to you stuff because you were too cheap to buy a proper charger.
I wouldn't say I'm too cheap to buy a proper charger I only thought it would be a slick little outfit to trickle a little juice into my dormant battery during the winter , and wanted to run it by you guys cuz I knew there were a whole bunch of guys here who knew way more than I do about electricity. :(
 

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I wouldn't say I'm too cheap to buy a proper charger I only thought it would be a slick little outfit to trickle a little juice into my dormant battery during the winter , and wanted to run it by you guys cuz I knew there were a whole bunch of guys here who knew way more than I do about electricity. :(
No offense meant. Typed words sound harsh. Just trying to point out a not so obvious possibility.
 

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I wouldn't say I'm too cheap to buy a proper charger I only thought it would be a slick little outfit to trickle a little juice into my dormant battery during the winter , and wanted to run it by you guys cuz I knew there were a whole bunch of guys here who knew way more than I do about electricity. :(
That type of charger is meant for that use. Its better and safer to use the correct type of charger. I use this one http://batterytender.com/product_info.php?products_id=2

dnult said:
It's not the battery you need to worry about, it's the charger.
Correct. Even with the battery just a little low, the charger would be at max output for a very long time, which it was not designed for.
 
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