What's a good way to charge my 12v battery box?

[Sputnik]

OP: how complicated do you want to make this project? The simplest would be an inexpensive solar charge controller and a 50 to 100 watt panel to use solar to keep your battery topped.

The trouble is that you’ll likely find more and more uses for that battery and 12aH is pretty small. You may want to consider possible future needs and research accordingly.

I built my system to be enough for a fridge should I decide to get one as well as being able to charge stuff and run camp lights, etc.

 

[M Rose]

This place claims they make a 370amp unit for Imprezas and a few others.

I was referencing stock alternators, I know I can have an electrical motor repair shop wind one up to 500 amps if I really wanted to pay the money (depending on application).... I just bought a stock 195 amp alternator from a 1998 Ford E-250 with a 5.8L to be rewound to 350 amps for my 1989 Bronco. Now that I think about it, I’m probably going to have the guy wind it for 500 amps because I plan on adding an onboard DC welder and plasma cutter some time down the road... but for most people 200-230 amps is all they really need for added accessories...

 

[M Rose]

OP: how complicated do you want to make this project? The simplest would be an inexpensive solar charge controller and a 50 to 100 watt panel to use solar to keep your battery topped.

The trouble is that you’ll likely find more and more uses for that battery and 12aH is pretty small. You may want to consider possible future needs and research accordingly.

I built my system to be enough for a fridge should I decide to get one as well as being able to charge stuff and run camp lights, etc.

On to the dollar charge controllers... if you get a Zamp 60 amp controller you can use it as a DC-DC charger as well. Then all you have to do is add wires from stock battery to wherever you want to hook up the charge controller... that would be the best route to go... start with getting the solar charge controller, then upgrade from there.

 

[Viking1204]

On to the dollar charge controllers... if you get a Zamp 60 amp controller you can use it as a DC-DC charger as well. Then all you have to do is add wires from stock battery to wherever you want to hook up the charge controller... that would be the best route to go... start with getting the solar charge controller, then upgrade from there.

So I wonder how many amps a truck alternator puts out? I never thought of using a solar charge controller as the DC-DC charger but I guess that would work if your charge controller handles the amount of amps your alternator puts out.

 

[Viking1204]

I've left my solar behind, due to not staying anywhere that long.. A good DC/DC unit will service you nicely. As you grow in power needs (which you will), it will still be there for you. I have a 20amp Renogy (Renogy 20a).

Now it does kinda make me think a bit of only a 12ah battery, draw only to 75% (so it will last) and how you get by on 3 amps for two days...

I guess I'm missing something. I quick Google search brings up several links suggesting most late model alternators put out over 120 amps so how does a 20 amp DC-DC charger work? I guess I have a lot more research to do before I charge second batter from the truck. I have a 138ah lithium battery box that I built and I'd like the ability to charge it while driving but also charge it with solar when I'm in camp for a few days.

Edit: After some research I decided to go with this battery isolator, seems simple enough, has good reviews, and wasn't too expensive.

 

[M Rose]

So I wonder how many amps a truck alternator puts out? I never thought of using a solar charge controller as the DC-DC charger but I guess that would work if your charge controller handles the amount of amps your alternator puts out.

My Bronco has a stock 35 amp alternator, but in the late 90’s most automotive manufacturers started putting in 65-230 amp alternators to handle the demands of OBDII electrical loads.

 

[old_man]

Hi, You can not directly charge a small 12v 12Ah battery direct from your vehicle unless a charge controller is fitted inline. An option to consider is a small solar panel (40w max) with solar charge controller. Regards Dave G

I'm an electrical engineer and a battery specialist. I would like you to explain your reasoning.

 

[Downs]

I'm an electrical engineer and a battery specialist. I would like you to explain your reasoning.

I run a double ended male cigarette lighter port plug to charge my box while "underway". I've seen no issues with this but I"m far from an expert on it. As long as I don't leave it plugged in when the Jeep is off for extended periods of time I shouldn't have any "dueling" battery issues but I'm willing to be schooled on this subject.

 

[M Rose]

I'm an electrical engineer and a battery specialist. I would like you to explain your reasoning.

I think he is referring to Life4pro batteries and other new battery technologies that need a charge protection circuit with the ability to monitor heat dissipation due to the way their chemistry works.

 

[RJ Howell]

I guess I'm missing something. I quick Google search brings up several links suggesting most late model alternators put out over 120 amps so how does a 20 amp DC-DC charger work? I guess I have a lot more research to do before I charge second batter from the truck. I have a 138ah lithium battery box that I built and I'd like the ability to charge it while driving but also charge it with solar when I'm in camp for a few days.

Edit: After some research I decided to go with this battery isolator, seems simple enough, has good reviews, and wasn't too expensive.

Sorry I've be out scout runs with no internet... May stock alternator is about a 110 amp (maybe a bit less). May LiPo4 is only a 60ah unit and I have now determined my usage (24hr period) to be 14-16amps. I felt I need nothing greater than a 20amp unit to replace those used amps in an hour's time driving. Sizing the unit according to your need/time spent driving is important so you don't by something way too strong. Controlling the charge is very important to the longevity of the battery itself.

My DC/DC Charger is wired from the Battery (DC sourced) and set for LiPo4 charging. Once the battery is at charge, it shuts down, as it should.

I've read about battery isolators.. Good because it won't draw from the Truck battery (as the DC/DC isolates), yet I'm not so sure they control charging.. Control is really needed.

Hope that answered your question.