Easy way to install a 12v radio?

[george walker]

although it sounds straightfoward it will cause a charging problem. When u tap off one battery for the 12v you will also take all the power to utilize that item from the one battery, and yes eventually the alt will see a drop in the overall 24v of the combined batteries. It will start to increase output to recharge them however only one battery is in need of additional charging the other is just being overcharged. How much overcharged depends on the 12v draw, however the result is likely just shortened battery life for at least one battery.

[Barrman]

As pointed out above, tapping into one battery will cause you problems down the road. Install a seperate 12V alternator and 12 V battery for any permanent needs. But, for something needed "right now" like a cell phone charge, go ahead and hook up to one battery.

[randyscycle]

As pointed out above, tapping into one battery will cause you problems down the road. Install a seperate 12V alternator and 12 V battery for any permanent needs. But, for something needed "right now" like a cell phone charge, go ahead and hook up to one battery.

I could see a problem, if you had a higher draw unit atttached to one battery, but just a radio?

I don't know exactly what a head unit draws, but it can't be enough to make much difference. I know mine has played for hours on end in the truck when I have been working or outdoors and it never drained the battery so that the truck wouldn't start.

If the regulator only sees a drop in the overall 24 volts, and ramps up the output, when it comes back to normal, it should cut back out, so I don't see how it would overcharge anything really.....That is unless there is a regulator issue....True one battery may be getting a bit more charge than the other.

Battery isolators allow one alternator to charge 2 batteries, and I have been using that set up for 3 years now in my Bronco. One battery is used exclusively for the winch and rooftop lights, and the other for the truck systems. The winch pulls the auxilary battery down a lot in serious winching situations, and that means the alternator has to crank up output to replenish it. In doing so, it charges both batteries, and the main battery has never suffered yet.

[countcv61]

How do you mount the 12v alternator, any pictures.

[rboltz]

I agree with RANDYSCYCLE. A low current device, like an AM/FM radio will do no harm. The tolerances between batteries is probably greater then the unballanced load you will create. If we are talking about high current, above maybe 10 amps, you should explore other options.

[kwai]

Get a 24v to 12v converter. It's what the FD's use for their equipment.

[brute4c]

Years ago when this first came up, I found a page online by electrical engineers that stated anything over a 2-3 amps draw would cause charging problems in 24 voltsystems where one battery is tapped. There may still be post in the archives copying that info...the original page is gone from the net. It actually was for other vehicles that use 24 volts not mil vehicles, but there really is no difference as long as all are 24volts.

The big problem is that when one battery is slowly reduced more than the other, imaging 2 containers of water and one has a slow leak, when the alternator charges, it puts equal amounts in both contaiers as it only puts in 24 volts...so a pitcher pouring a given number of fluid ounces in each container.
So one is either low when the other is full and the charging (filling) stops OR one is overcharged (overfilled) to get the other one full.
Neither scenario is good. If one is chronically lower than the other, it will eventually have less to startthe vehicle and will fail in time. Overcharging chronically will cause internal problems that will make that battery fail.

I do know that I ran a 5 amp draw off one battery and had to replace one battery every year...until I got smart and put in a converter that leaves me with 2 good batteries AND 12 volt power.

2 batteries replaced cost more than my converter did...

Being stranded and unable to get a 24 volt jump start really sucks...happened to me 3 times before I wised up.

[rboltz]

It's been over a 18 months now that I run a 12 volt ignition system with the 24 volt batteries. I just tap off the grounded battery with an ignition relay, connected the the master switch. Before I connected my battery maintainer for winter storage I checked both batteries with a digital meter. The battery that taps off the 12 volts was only .2 volts lower then the other one. One was 13.2 and the lower one was 13.0, well within tolerance. Now, I do NOT advocate drawing huge amperage loads at the 12 volt side as this will create problems. But as some have mentioned in this thread, as well as me, a small 12 volt load like a radio or ignition will not have much impact. Probably best to limit the load to 4 amps or less.

[ldj1002]

This is different but maybe the same. For years I flew airplane with 1 24v battery. I had to have business band radio and I got a 12v one. I cut the top off and old battery so I could see how and where the cells were connected together. I just used a big wood screw and screwed down thorough top of battery. I put the screw so it would screw into the conections between the 12 and 14v cell. Got my 13 volts and never noticed that the battery died any sooner than than the other planes that didn't need the business radio. Of course I don't think feds would have liked it so I just removed the screw and wire going to radio when in for annual inspection. Actually a 12v battery is 6 2v batteries and the 24 is 12 2v batteries. Sooo does that mean that half of my 24v battery would be under charged while the other half was over charged? If so it never hurt anything. Maybe because amp draw was so low?

[countcv61]

Please how do you mount the 12v alternator with pictures.
Dan