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Small DC to DC charger options?

boondox

Chief Engineer, RedNeckTech Industries
Joined
Mar 1, 2020
Messages
788
Hi All,

I am looking for a small DC to DC charger. I am putting a VHF radio in a 2020 Subaru Crosstrek. To avoid running wires up to the starter battery and to isolate the radio from the battery powered systems I want to put a small battery under the seat and charge it from the cigarette lighter. (Showing my age, I guess they have another name for it now) There don't seem to be too many options for low current chargers that one might run from the cigarette plug, those are generally limited to 120 watts. I did find this one but the reviews seem sketchy:


Anyone with a better quality option? I am thinking of going with AGM as the battery will be kept at float most of the time and LFP doesn't like that much.

Thanks!
 
Take a look at the Renogy 20A dc/dc converter - you'd have to either hardwire it in or add a cable with 12V plug. Costs about $115. I plan to use one to charge a boat house battery (lifepo) from alternator / shore power on a boat.
 
@flboater That pulls way too much for a cigarette outlet, it would pop the fuse.

@Boondock Saint That isn't a proper charger. I will be charging a battery. It is too low output to power the radio directly when transmitting as the radio pulls somewhere around 180 watts when transmitting.

But thanks!
 
Not familiar with Subaru but check the fuse size to see capacity.

My Ford has 15a x 12 v= 180w.

If you need more power, you might as well run an 8 or 10 awg wire to power the charger or battery.

That lets you use 30A fuse = 360 w.

Should be able to pull wire through one of existing wire grommets without drilling any new holes. I ran a wire to my trunk that way. No damage to car and lots of power

Then you could use a battery isolator for $50. The FET isolators let you charge both batteries with your alternator but will cut your auxiliary battery from the starter battery at 12.8 volts so your starter battery is not drained.
 
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ohhhh b a t t e r y . . . righto. Lost track of the fine print :D

Ya Rich585 has the idea.
 
Yeah, maybe I should suck it up and run a wire to the battery. It is such a pain in those newer cars and I need to keep it all hidden. While my wife wants the radio installed (we live in the sticks where cell phone coverage sucks) it is the first new car she has ever bought and so I want it neat. Also if I did that it would make it easier to add trailer lights. Since it is a plug in hybrid they usual trailer light plug isn't accessible! Grr.
 
I went that route with 2 big honkin deep cycle batteries in the front floorboard when I used to primitive camp. I needed a lot of juice so I used the alternator to charge them as I drove to the boonies. The mft engineer said it would be fine, and it worked fine for me.
 
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