Dual Batteries

Has anyone installed a 2nd battery in a stock Ranger or Bronco 2? If so where did you install it, and did you use a battery isolator?

I've been thinking with the radios and future electrical needs about installing a 2nd battery somewhere but haven't figured out where to do so that it would fit. Also, thinking that since I'd use the 2nd battery to power the additional loads that it would be wise to install a deep cycle battery as the 2nd battery, and run all the radios, lights, etc. from that battery. Installed with an isolator so the load will never discharge the starting battery.

Since I plan on installing a power inverter I was thinking the 2nd battery would be a very wise choice to do before the inverter install.

Ideas, pictures? Any input would be great.

If you are just using it for electrics like lights and radios, not winch or other high amp draws then you don't have to use a full size car battery.

Figure out how many AMPs each current and future device will use
CB Radios pull less than 2amps transmitting
For lights take total wattage and divide by 12(volts), so 50watts of lights would be 4amps
Say you have 10amp total
A 12volt battery rated at 40 amp/hours could power 10 amps for 4 hours, 5 amps for 8 hours

Car batteries are usually rated by CCA, cold cranking amps, the amps they can deliver to starter motor for 30 seconds at 0deg temp
Deep cycle batteries are usually rated in amp/hours

Yes you would use an isolator, so alternator could charge both batteries AND power all the electrics when engine is running but when engine was off batteries power their loads separately.
So alternator does need to be rated high enough to power all the added electrics, when engine is running alternator provides 13.5-14.5volts, so whole electrical system is running at that voltage, batteries are only 12volts so not used at all while engine is running, they do smooth voltage, but are not being drained

With the power inverter thrown in I think a full size battery would be a must.

Only issue is trying to figure out where to install the 2nd battery LOL.

wildbill23c said:

Has anyone installed a 2nd battery in a stock Ranger or Bronco 2? If so where did you install it, and did you use a battery isolator?

I've been thinking with the radios and future electrical needs about installing a 2nd battery somewhere but haven't figured out where to do so that it would fit. Also, thinking that since I'd use the 2nd battery to power the additional loads that it would be wise to install a deep cycle battery as the 2nd battery, and run all the radios, lights, etc. from that battery. Installed with an isolator so the load will never discharge the starting battery.

Since I plan on installing a power inverter I was thinking the 2nd battery would be a very wise choice to do before the inverter install.

Ideas, pictures? Any input would be great.

Click to expand...

I am planning this job as well. You can either move the overflow/ window washer bottle back to clear the battery opposite the factory battery or go the the local junk yard and find a smaller one for the truck.

I think 2 batteries are a great idea. My '91 F-350 plow truck with 7.3 diesel came with dual batteries and with a plow that weighs at least 700 lbs. The plow pump is a Meyer T-5 from the 60's and really draws the amperage.

All my plowing is in low range and at speeds of only 5-10 mph(if that fast). Even with a 100amp alternator I need the second battery to smooth out the amperage draw and to keep from discharging the batteries while plowing.

I would imagine that you could put quite a load on your system also with the radio's. My 3000watt inverter is also in the truck with the dual batteries. Works really well.

I've been running dual batteries in both my rigs for many years. I don't use an isolator mostly because I wanted the full Ah capacity of both batteries to be available. Not using an isolator does require both batteries be of the same brand, type and age however (I run two grp-27 deep-cycle units in parallel for approx 200Ah).

I have found that with two or more batteries in parallel, things such as 2-way radios, inverters, and/or a camping refrigerator tend to lose performance or shut themselves off before the batteries reach a point where they're unable to turn the engine over, which eliminates some of the worry of being stranded with a dead battery (or having to push-start it). I also mounted a voltmeter inside to show how much charge remains as well.

As for placement, my Ranger has both batteries under the hood (I fabbed up a tray to fit it in the open slot that exists on the passengerside of '93 & '94 models). On a BII you would have to relocate the washer fluid/coolant recovery bottle as Terry mentions (my BII has the batteries under the rear floor board, something I did mostly to free up space for other items under the hood, but also reposition the CoG somewhat as well).

I'm leaning towards moving the overflow/washer fluid reservoir back, and finding a mount to install the 2nd battery there.

Since I have an automatic push starting is out of the question LOL. I'd rather have the isolator and be safe than sorry. An inverter can pull a lot of power and if the engine isn't running for a period of time it could drain both batteries to the point the vehicle won't start especially if its cold outside. Plus having dual batteries gives the option of having a backup battery if one fails, you could jump start the vehicle with the other battery.

Going to look into getting the battery tray, cables, and an isolator in the near future before I install my inverter, that way I can run the cables for the inverter and not have to mess with rerouting them later.

IMO the best type of isolator is one that uses a solenoid (heavy-duty relay) to switch the aux battery in & out of line. I've seen any number of different problems with solid-state isolators (both mosfet and diode types). With the solenoid type, all you have to do is energize the solenoid with a switch to jump-start yourself from your aux battery if needed.

This thread on another forum has some great discussion on building an isolator setup for ~$50:
http://www.expeditionportal.com/forum/threads/77503-How-to-make-a-cheap-isolated-dual-battery-setup-for-50


Just FYI,
most, if not all, inverters do have a built-in low-voltage shutdown (usually around 10.5V under load). After it shuts off, a healthy pair of batteries should bounce back up to around 11.5-11.8V, which normally should be plenty to turn the engine over, especially since the starting current is split between both batteries.
I can't recall once that I've ever HAD to push-start mine, though the lack of that option certainly would be of concern, so I can see where you're coming from.

Another option might be to carry a lithium-ion jump pack... These compact little gizmos weigh (I'm guessing) 2-3lbs but have more than plenty of current to jump-start your engine. Anyway, just another idea.

I already plan to carry a jump pack, but the solenoid sounds like a much better and easier solution...I should also add cheaper than a good isolator.

Haven't dug too much into this yet, too busy at work and other problems around the house that never seem to come at a good time.

wildbill23c said:

Has anyone installed a 2nd battery in a stock Ranger or Bronco 2? If so where did you install it, and did you use a battery isolator?

I've been thinking with the radios and future electrical needs about installing a 2nd battery somewhere but haven't figured out where to do so that it would fit. Also, thinking that since I'd use the 2nd battery to power the additional loads that it would be wise to install a deep cycle battery as the 2nd battery, and run all the radios, lights, etc. from that battery. Installed with an isolator so the load will never discharge the starting battery.

Since I plan on installing a power inverter I was thinking the 2nd battery would be a very wise choice to do before the inverter install.

Ideas, pictures? Any input would be great.

Click to expand...

Did you end up putting the 2nd battery in? I wanted to do this as well - thought about moving the reservoir...

cflowrider said:

Did you end up putting the 2nd battery in? I wanted to do this as well - thought about moving the reservoir...

Click to expand...

No, I never did, I just removed my radios prior to the engine replacement last year and never bothered putting them back in....seems here in Idaho nobody uses CB's, or Ham radios so never went any further with a 2nd battery install. I'd think moving the reservoir and mounting the 2nd battery there would be the best location though. Then mounting the isolator in a corner by the firewall somewhere maybe was my thought.

I haven't decided on a radio installation setup yet, my Bronco 2 is of course one of the many vehicles that were never used by emergency systems so there was never a console system made to mount radios in, which is what I would have liked to do...instead I found a nice console from a Ford Explorer and installed....I had a shelf-it shelf installed prior to the engine replacement which was mounted up on the ceiling where the sun visors mounted, but that thing was extremely heavy with the radios mounted in it and had it fall down a couple times on rough roads so I tore that out and haven't figured out a good place to install the ham radio and CB radio...I also have a Midland GMRS mini radio as well but trying to find easy to access places to mount them has proved far more of a difficult job than I have the brains for....I also have an auxiliary switch panel I need to get figured out too...what I have is a complete mess overall as well I apparently have ADD can't stay on any sort of project for more than an hour then never get back to it again LOL.

I'd love to see pics of the Explorer dash in there and how you have it set up. I'm making my own version of the Rugged Ridge Ram Bar system which I am mounting 1" over the dash. Those are solid connections - nothing giggling around. I'm using the iComm 7100 for AR so less weight/bulk to knock around. Everything is behind the dash except the screens. That also looks less enticing to thieves [I live in the city] nothing to see when they look in.