O/T sort of

[wildcard]

At least it's electrical. I run a 155 Cat forklift with a 360 degree rollover. I want to hook up a 12 volt heater in it but it has a 24 volt system. How could I get 12 volts to tap into ? I have never been able to find a fuse box and it has no operators manual.

[FORDification]

Basically you have two choices: install a second alternator (12 volt one wire); or install a 24 to 12 volt converter. If you plan on many accessories, the second alternator would be best. If you just want to run a heater or radio, then a converter would work fine. There are two types of converters, high and low efficiency. The difference is that the low efficiency gets rid of the extra voltage by converting it to heat. This means the unit is larger, with a large heat sink, and that it wastes a lot of energy. A high efficiency unit is more expensive, but better.

[knightfire83]

I don't have experience with a 24 volt system, but wouldn't that mean there are two 12 volt batteries wired in series?

If so, couldn't you tap a 12v feed between the batteries?

[70_F100]

Wouldn't the system have 24 volts throughout?

[knightfire83]

Anything connected to the first battery in series would have 12v. Anything connected to the second battery would have 24v.

I'm not sure what the 155 Cat forklift configuration is. I assume that it is a propane or gasoline powered engine vehicle and not electric as some stand up forklifts.

Imagine a flashlight, a 1 D cell flashlight has a 1.5v lamp. A 2 D cell flashlight has a 3v lamp and so on because the batteries are used in series. - to + - to +

Now if you wire batteries in parallel as + to + - to - then the voltage remains constant, but the storage capacity increases.

A 2 D cell flashlight wired in parallel will have a 1.5v lamp, but shine twice as long as a 1 D cell flashlight.

Sounds more complicated than it is.....

[70_F100]

No, not complicated at all.

I've worked on many 24V systems in the past, and I know about parallel and series circuits.

I just thought that once the circuit was complete, it would have full 24V power throughout. You're taking your power source from the cable, and your ground would be common to all electrical system components.

That's different from your analogy of a flashlight. You've still got both batteries in the system, so system voltage would be 24V.

[FORDification]

The way I understand it: when two 12V batteries are hooked in series, you can't just hook up an accessory to one battery, because the two batteries themselves are connected. The ground on Battery 1 is hooked to the positive on Battery 2, so a single battery can't be isolated.

[70_F100]

Thanks, Keith.

That's exactly what I thought.

[knightfire83]

Battery 1 provides 0-12v, battery 2 would provide 13-24 volts to the system. It is exactly like the flashlight scenario.

Electrons in a D.C. circuit only flow one direction, negative to positive. To get 24 volts at the tap in my first diagram, electrons would have to flow backwards to the tap, positive to negative. Theoretically, this would cause several problems and is definitely not possible in a Direct Current system.

References:
http://www.tx4x4.com/unimog/12volttap.html
http://forums.lr4x4.com/index.php?showtopic=27665
http://www.boatdesign.net/forums/archive/t-6664.html
http://www.rare-earth-magnets.com/magne ... n_flow.htm

To be fair to you guys, doing further research today I found that tapping 12v between batteries isn't the best way to do things. Seems that one battery will be discharged more than the other, possibly causing problems when it comes time to recharge both of them together.

Referring to the original question asked in this post, the correct way to run a 12v heater on a 24 volt system, would be to get a voltage reducer available at any boat and RV store.

But none the less... my point stands as correct. You can get 12 volts, and it would work, from a tap between two series connected 12 volt batteries in a 24 volt system.

[wildcard]

Thanks for the replies. Looks like I will get a reducer to be on the safe side.
knightfire, it's a diesel powered forklift with a 2 battery system. Capable of over 15,000 lbs. of lift. The fork movements are all controlled by hydraulics. Except it can lift something and then flip it over 360 degrees. The forks spread out to 10 ft. and are about 6 ft. long. At the rear, they're 10" wide and 2-1/2" thick. Tapering to about 6" wide and 3/4" thick at the front. Guess I'm the biggest forker on the depot.

[Thunderfoot]

Battery 1 provides 0-12v, battery 2 would provide 13-24 volts to the system. It is exactly like the flashlight scenario.

Electrons in a D.C. circuit only flow one direction, negative to positive. To get 24 volts at the tap in my first diagram, electrons would have to flow backwards to the tap, positive to negative. Theoretically, this would cause several problems and is definitely not possible in a Direct Current system.

References:
http://www.tx4x4.com/unimog/12volttap.html
http://forums.lr4x4.com/index.php?showtopic=27665
http://www.boatdesign.net/forums/archive/t-6664.html
http://www.rare-earth-magnets.com/magne ... n_flow.htm

To be fair to you guys, doing further research today I found that tapping 12v between batteries isn't the best way to do things. Seems that one battery will be discharged more than the other, possibly causing problems when it comes time to recharge both of them together.

Referring to the original question asked in this post, the correct way to run a 12v heater on a 24 volt system, would be to get a voltage reducer available at any boat and RV store.

But none the less... my point stands as correct. You can get 12 volts, and it would work, from a tap between two series connected 12 volt batteries in a 24 volt system.

Just wanted to also confirm that knightfire83 is spot on with the voltage being 12V over each battery so yo could tap off of one battery for the 12V needed. I personally wouldn't be concerned to much about doing this as long as your not doing a large amperage draw, with it affecting the battery much.

[papabug71]

As far as I know, the only thing on 24 volt systems that are actually 24 volts are the starter & glow plugs, (if so equipped). At least that is how the old CUCV's are wired. Everything is knocked down to 12 volt via resistors. Look at the lights on it & see if they have 12 or 24 volt markings.

Is your lift diesel or gas ??

[wildcard]

Thanks guys. I think I'll take my volt meter and be sure before I screw something up.
Thunderfoot, I'll look when I buy a heater and check the amps. What would be considered too many amps ?
papabug, it's a diesel engine. I'll check the lights also. I know my humvee is 24 volt and the heater blowers and such are also 24 volt. But I just always figured a 24 volt system probably meant everything was 24 volt.

[70_F100]

One other thing I just thought of after reading papabug's post.

On older trucks (I'm talking big trucks, not pick-ups), lots of them were set up with a 24V starting system. The alternator and all other electrical components were 12V.

They accomplished the 12V/24V conversion using what was called a series-parallel switch. It was basically a relay that was wired into the battery circuit that, when energized, would switch the starting circuit from parallel (usually with four 6-V batteries) to a series circuit.

I know something like this wouldn't be of much use in this application, because it would be difficult to wire in, and those switches were not continuous duty. On the other hand, there may already be something similar on the lift, since, like papabug said, the only 24V components should be the starter and glowplugs (and possibly the alternator, like on other CAT equipment, i.e., 955, 977, D6, D7, etc).

[Thunderfoot]

Thanks guys. I think I'll take my volt meter and be sure before I screw something up.
Thunderfoot, I'll look when I buy a heater and check the amps. What would be considered too many amps ?

Just a guess... depending on how high of output the alternator is, I would keep it under 10-15amps for a low output alternator (35-45amp) you could go more with a higher output alternator. I'm guessing that that forklift will not have much as it probably don't have any electrical drain other then the starter.