Thinking more about 12 volts from the 24 volt system...

[Flea]

What about using a speed controller from a golf cart? Theoretically speaking, you could use one designed for 24 volts and be able to get anywhere from 0-24 volts out of the controller. With ratings in the hundreds of amps, power supply wouldn't be a problem.

The downside is you would have to use a multimeter to get the exact voltage you need dialed in. Each time you wanted to change voltage, you would have to break out the multimeter and repeat the whole process...

I think this could be a workable solution to 12 volts, perhaps voltage could even be dialed up to charge a third battery without having to resort to adding a separate 12 volt alternator?

Thoughts?

 

[jwaller]

if you want 12 volts just hook your accessory to 1 battery.

 

[CCATLETT1984]

The issue with just hooking to one battery on a straight 24v system, is that you will imbalance the batteries. One will be under charged and one will be overcharged, shortening the lives of both. Its not worth it to mess with the system for the cost of batteries.

The golf cart idea would work, you could theoretically just wire up a multimeter and leave it in the system. Although around here its not like you can find free electric golf carts.

 

[Jake0147]

I could be mistaken, but I dont' think the speed controller in question will actually "set" a voltage. I think that varying the load will vary the voltage available through the controller to protect the electric motors at low speed... At least that's what I thought it was doing. I started to play with one of those controllers once, but didn't get very far because I found smoke and fire which caused me to skip several steps down the trouble tree to the "replace faulty motor" section.

 

[Flea]

The way I understand it, the resistance in the controller is varied by throttle input - when you step on the go-pedal, the resistance is reduced until the motors see full voltage. By setting this device at a constant throttle position, you could get a standard, steady voltage out.

At least, that's how I understand it?

I'm just trying to explore all options before I bite the bullet and put a one-wire alternator on my deuce. I want to see what can be the most reliable, which continues to be the alternator route -- probably the route I'll go. However, I have limited metalworking ability (no welders or torches), so fabbing up a mount and such is what I'm trying to avoid.

Unless someone makes a mount?

 

[tennmogger]

Not being an expert, I can offer 2c worth: Some of the older golf card speed controllers were nothing more than a series resistor to add resistance in series to slow the motor, and a big switch to turn it off. The newer ones use solid state devices to chop the voltage and send a lower "average" voltage to the motor, pulse width modulation to be specific. Neither of those methods would provide a steady 12 vdc for any load. A regulated supply, using transistors to dissipate the unwanted voltage in heat (aka any 12 v power supply with 24 v unregulated input) would work fine. All the "linear" power supplies worked this way, and many had about 24 v from the rectifiers.

One of the commercial 24 to 12 converters would be ideal. I use one of those to provide 12 v dc for radios, GPS, ham transceivers, etc, in my U-1300 Unimog. These are common to fire and maintenance equipment. There is no need for a third battery, so there's that much less maintenance. The one I use is rated at 35 amps continuous. The converter is overload protected, over heat protected, and over and under voltage protected. It turns on and off by a 24 v logic line from the key, or in my case from a dash switch.

Bob

 

[quarkz]

Yes it is a variable resistor that you push with your foot,
but it is part of a circuit that then reduces the current flow thru an IGBT,
a version of a high current transistor.

What about putting another 12V battery in parallel with the 12V battery(from the two that make up 24V) that has its negative terminal attached to ground? And then use a large current handling diode to attache the positive terminal to the point where the 24V batteries join together. I think this isolated the new 12V battery from the charging system.

 

[tennmogger]

Hi Tony,

Yes, the IGBT would soak up the unwanted voltage and dissipate it as heat, but that setup would give no regulation of 12 v at all.

IMHO, placing the second battery across the one above it in the drawing, with the diode, would share the series charging current intended for the two upper batteries, effectively starving the upper right battery of a portion of it's charge current and unbalancing the two batteries. The diode would be transparent in the charging direction to charge the 12 v battery (except for 0.6 -ish volts drop) but would certainly keep the added 12 v battery from discharging back through it's paralleled partner.

A good argument FOR using the extra 12 v battery is that it can be used with the truck off with no effect on the truck batteries. If the need is for power with the truck off, the extra battery is the way to go.

If a third battery, for 12 v, is acceptable or even desired, a charging circuit off the total 28 vdc would be a good way to go. Set the charger to output 13.8 vdc full time, but current limited at a couple of amps above expected load on the 12 v battery. I use a cheap Samlex 24 to 12 converter, 8 amps, in series with a half Ohm resistor, to accomplish that. The regulator of the Samlex had to be adjusted to get the 13.8 output. Less voltage than that (like 12 v) will not keep the battery charged. The current limiting would be required in case the 12v battery got drained, and you started the truck. I have a setup like that in my 1965 Unimog radio truck and it works, but is rather involved.

In my experience with 24 v Jeeps and trucks, and using 12 v ham gear for many years, the extra battery and circuitry is a lot of effort. A heavy duty 24 to 12 converter is simple, relatively foolproof, and maintenance free. By the time the cost of batteries over the years is added to the cost of the charging circuitry, the converter doesn't sound too expensive.

BTW, the best 24 to 12 v converter I've used is a Wilmore which I picked up used out of a dismantled fire truck.

Bob

 

[tlm47201]

I run my 12 volt fire department equippment off one battery. The 12 volt truck acc. run off same battery with no problem. My plans are to pull the lead for the 24 v block behind passenger door on my M1009, off the 24 volt block under the hood, connect it to the front battery, making a 12 volt block inside for power to added accessories. Its how I have had the fire trucks for a while now, with no bad side effects.

 

[tmbrwolf]

I'm assuming we are talking about your Deuce, If you pull 12V from one battery as stated above it WILL cause a problem with both batteries, I have this problem with fire departments all the time in the 2 1/2 and 5 tons, we recommend that they use a 24v to 12v converter to run the radios etc. A converter can be had from most parts stores less than the cost of a battery replacement, thats of course if you can get them to actually look it up and order one, or get the guy that actually knows what your talking about!

 

[tlm47201]

My post was regarding the M1008/1009 series. The deuce system I wasnt aware of that. How about using diodes to create a voltage divider? My electrical skills are a bit rusty, but seems like I used to do that to split voltages.

 

[stampy]

Search ebay I bought my 15 amp transformer for 40 bucks it reduces 24 to 12v@ 15amps

 

[randyscycle]

Search ebay I bought my 15 amp transformer for 40 bucks it reduces 24 to 12v@ 15amps

Ditto that. I run a 10 amp unit for my pyro and GPS and it works fine for $30.

Unless you plan on huge amp draw stuff one of the cheaper reducers will work just fine. Mine is regulated and fuse protected and output is a constant 13.8 volts.

 

[Oldgrunt]

Hi Guys
I've been tring to 12 vdc hook up for my Deuce to run car charger ect... and I hope this doesn't sound too stupid, but what kind of a part store are you refering to, to purchase the 24v to 12v converter, NAPA, Auto Zone ect.... or a electronic parts store such as Radio Shack. Sorry again in advance, eletronics is not my strong suit.

Old Grunt

 

[stampy]

See above about ebay. Mine is an Opek model vr15 15amps @12vdc from 24vdc. You probably won't find 24v/12v transformers at any local parts store. Maybe a truck stop. Ebay was an easy buy for me.

 

[tennmogger]

Here's a good USA built converter company.
http://www.wilmoreelectronics.com/

Wilmore Electronics products are used in many commercial, railroad, and emergency services vehicles to provide 12 v (typically 13.6v) from 24 v system. You can order directly from them.

I personally use their model 1416-12-35 (35 amp, a 1416-12-15 (15 amp), and a newer 1640-12-15 (15 amp).

I've had trouble with imported converters (namely Samlex, China).

Bob

 

[AN/ARC186]

Hi Guys
I've been tring to 12 vdc hook up for my Deuce to run car charger ect... and I hope this doesn't sound too stupid, but what kind of a part store are you refering to, to purchase the 24v to 12v converter, NAPA, Auto Zone ect.... or a electronic parts store such as Radio Shack. Sorry again in advance, eletronics is not my strong suit.

Old Grunt

I set mine up with a separate 12 volt alternator feeding 2 deep cycle batteries. set up a couple of terminal strips to land connections on. This way I have plenty of amps for any 12 volt accessory.

 

[Blythewoodjoe]

For a deuce (the only thing I have ever owned) the dual voltage alternator with a deuce pulley drilled out is a great way to go if you want unlimited power. I put 3 car batteries in my battey box and used the third to run my dump hoist and what ever I wanted to run.

Used alternator, $200
Pulley, $35
Drill pulley by professional, $50

If your running small things the tranformer works great too. My alternator job is well documented on here somewhere. I for one can't find much with the search. And I still don't know what the WIKI is.

Joe