Simple way to keep second batt charged?

I installed a second battery that I got for free in the pass side back seat floor board.I am trying to do this as cheap and easy as possible so I made a battery tray that is bolted to the floor and plan to run a welding cable from the positive post through the firwall and up to the primary battery.I plan on grounding it directly to the back seat floor to save on the cost of cable.See any problems so far???I don't....does the ground to the second battery have to physically go to the primary battery post?

NOTE:aux battery will not be attached to the primary battery all the time because they are different types and I won't be using an isolator or solenoid.I will be using one of those forklift battery connectors to connect the batteries when needed,disco'd when not.
I plan to use the second battery during winching only,or as a way to self jump in an emergency.

Now the real question:How to keep aux. battery charged since it won't be hooked up to the primary all the time?Can I use the cigarette lighter to charge the battery?Wouldn't that essentially connect the two batteries together and cause one to drain th other???

Thought about solar chargers but have no first hand experience with them.The only other option is to remove the battery when it needs charged and charging it on the house charger.Problem with this is there would be a potential for sulfation because the aux battery will sit without current running to it all the time untill it needs charged.

What do ya think???

you really need an isolator to charge both batteries. problem with isolators is they usually drop 1/2 a volt when current is passed thru them lowering your charge capibility. you can fix this by putting the sense wire after the isolator but this might get a little tricky with a system the uses the pcm as the regulator. a solenoid that connects when the engine is running is prob your cheepest way to go you can also use this solenoid to switch on when your winching or jump starting and is most likely going to be about the same cost as the quick connect you speek of. the quick connect although it will prob work is not designed to make a high load contact like when hooking it together to jump start and may wear the contacts prematurly where a solenoid is designed for this.

solar chargers are junk huh?And the cigarette lighter won't work either?
Keep in mind that this dual battery system is only for occasional use.....maybe once a month if that,so I can't really justify spending alot of money/time on it.

If you really can't afford a two-battery isolator, you could use a single pole-double throw switch rated at 100+amps (also expensive) to switch the alternator output between the batteries. But I'd guess the switch would cost damn near the same as a dual-diode isolator. AND, I would not recommend doing this--it's a good way to blow the diodes internal to the alternator if the engine is running when you make the switch. Also, your battery is only being charged when it's switched. So if it drains while in "reserve", it won't be much good when needed, without charging first, which is a slow process with a standard voltage regulator.
Another way would be a battery switch, such as used in marine applications, that "make-before-break", insuring the the alternator is always connected, even when switching from one battery to the other.

I'd save up for the isolator--save you bucks and frustration in the future. example:
http://www.westmarine.com/webapp/wc...rue&storeNum=5002&subdeptNum=9&classNum=12106

I second the Isolator.....

I have seen to many wierd things that people have done here at the beach to hook a second battery. Many have resulted in a vehicle burning to the ground....

I am using this for more than 2 years with 0 problems!!! Install it and forget it.

http://www.yandina.com/c150Info.htm

There are less costly solutions out there like using a continous energized solonoid wired into the ignition.

got a link to a solenoid?

look here
http://www.carolinaclassictrucks.co...de=wiring-harness-accessories&Store_Code=CCTI

Ok one more question and I'll let this get burried.
I have a regular battery behind the passengers seat,any worry about gasses comming out of the battery into the cab?

outlander said:

Ok one more question and I'll let this get burried.
I have a regular battery behind the passengers seat,any worry about gasses comming out of the battery into the cab?

Click to expand...

Any conventional lead-acid cell ("wet", "gel" or "AGM") should be vented to the outside if it's mounted in the passenger cabin. It should be in a box, and the box should be somewhat sealed WRT the cabin, and there should be a vent passing to the atmosphere.

Batteries, when charged, tend to release hydrogen gas. Gel cells and AGM batteries reduce this considerably, but it's still a possibility.

does it only happen when the battery is being charged?How dangerous is it and will you immediately know if there is gas in the cab.....does it have an odor?

Typically, only when charging (when voltage applied to the battery - there's always a "trickle" when you're running.)

Odour? The gas is hydrogen, and I don't recall if it has an odour (my honker don't work so good anymore. It would take too long to go into why...) I think hydrogen by itself is odourless, but hydrogen sulphide (H2S) is also generated, and that has the characteristic "rotten eggs" smell that you are probably familiar with.

Safest to just vent the thing. Hydrogen is lighter than air, so you can get away with having a window open until you get around to venting - but do get the thing vented properly when you get a chance.

(Also note that hydrogen is highly flammable. Hindenberg, anyone? Don't smoke!)

thanks for the info.I'll probably be ordering a solenoid from you soon.

This is a description of someone elses batt set up.This is basicly what I want:

(quote)
I set up a dual battery system using a 200 amp continuous duty solenoid set up with a 3 pos switch.
-Normal position was connected only when ignition on for charging.
-Pos 2 was disconnected all time.
-Pos 3 was connected all time (for jump starting)

I was using an Optima Red Top for standard and a Yellow Top for aux (winch, lights, compressor, inverter, etc)
After early replacement of the Red Top I found out that Optima (and everyone else, it turns out) strongly recommends NOT using two different types of batteries in a parallel system unless an isolator or "smart solenoid" system is used.
Apparently if there is any difference in the two batteries, charging them together is a problem.
(end quote)

So If I run this setup with a solenoid I can't use my optima red top as my regular battery and use the free duralast battery as a backup or during winching because when it comes to charging they'll take charges differently?

5-90:You have a diagram on your site that shows how to wire a three position switch to the solenoids you sell to make a system like described above,no?
__________________