24v vehicle with 12v accessories

[pinzpwr]

Hey everyone,

I'm in need of a solution to power my 12v devices off a vehicle that is based on a 24v system. Currently I have a converter to reduce the voltage from 24 to 12 for my accessories but I'm adding a ham radio and 12v winch (it was cheap) to the system. I'm running a CB with mods, laptop, gps, stereo, fan and 1K mini inverter all off the converter. Not sure what the new Yeasu 8800r requires for power but the winch (warn 8274) can use up to 450amps and a converter that size is BIG $$$.

The only idea I've been able to come with is adding a dedicated 12v gell battery to power the winch and mini inverter. But how would I charge this other battery?

Does anyone have a better solution?

Ed

 

[ntsqd]

Any reason that you're staying with the 24VDC system? Might be easier to have 12 volt fields put in the starter and convert to 12.

Other than that I'd suggest one of the small hot rod alternators (usually a Geo Metro 80 amp unit) and another battery to create a separate 12 VDC system.

 

[CanuckMariner/Nomad]

I, along with others with 70 series TLCs, have also got the 24V system. Most use a product called a Solar Converter Charge Controller as your system alternator doesn't know what is happening to either battery. Get one that puts out approximately the most amperage that you anticipate at one time. Not total as you won't have all on at the same time or will you?

This unit has a small computer in it that reads the voltage of each battery every second and uses the higher of the two batteries. This way each battery is used about the same (+/- 0.1 V diff.) and are charged the same. You should try to have both batteries the same make and age or at least charge them to within 0.1 V when they have been off the charger for about an hour or so. If you measure their voltage right after you charge them then they will read high. Your batteries will love you for this and last much longer.

Hope this helps. Remember the 24-12 inverter is using power all the time it is on and if you turn it off, your stereo will loose its memory. A quality one with a 30 AMP capability will cost quite a bit so keep this in mind when you here the price of the solar converter +/- $200 Kanuk buks as it is made by those really innovative Kanuks!

 

[pinzpwr]

Any reason that you're staying with the 24VDC system? Might be easier to have 12 volt fields put in the starter and convert to 12.

Other than that I'd suggest one of the small hot rod alternators (usually a Geo Metro 80 amp unit) and another battery to create a separate 12 VDC system.

Changing from 24v to 12v wouldn't be very practical as all my factory circuit breakers (not fuses) are designed for 24v, plus changing gauges, ignition, and the starter just too much work.

 

[pinzpwr]

CanuckMariner, using a charge controller is a good point and I have considered getting one. I currently have two matching deep cycle bats in series creating the 24v but I need a high output 12v source.

Is it feasible to pull 12v (up to 450amps) from just one of the batteries that are in series and let a charge controller make a slow compensation.

Or by adding a independent 3rd battery could I use a 24v solar charger from the two main batteries to charge the new battery?

 

[SunTzuNephew]

Just set up a 12vdc buss (using a Blue Sea fuse block, rigrunner, whatever) and wire your 12vdc items to it off one of the batteries. Unless you're running a winch or refrigerator off 12v the added draw won't matter much.

I used to have a military M1009 CUCV Blazer with a truly weird electrical system (military stock) and I ran my accessories this way, no (added) problems.

 

[proto]

Have you considered converting the winch to 24 Volts? The 24 V units draw about half the current (275 Amps?) so your winch wiring wouldn't have to be quite so beefy. And the 24 V motors run a might faster, too.

It's a straightforward motor swap. The 12 V motors are in demand because people run those winches hard and burn 'em up. You could yank the motor now before you mount the winch, sell it and use the proceeds to finance the 24 V motor.

As for 12V accessories: I like ntsqd's solution of a small, separate 12V batt and alternator! Clean, safe, gives you some redundancy.

There's a potential problem if you connect loads to your existing batteries asymmetrically; you risk unbalancing the cells. (Maybe a problem, maybe not -- depends on your usage pattern and your charging system -- could work just fine for you.) There are devices available designed to minimized unbalanced 12V loads in 24V systems. But, I don't think you can use them with ham gear because of grounding conflicts.

Good luck with this! Sounds like a fun project!

EDIT: If you do go with a 24 V motor conversion, be sure to check the rating on the solenoids. They used to all work for either 12 V or 24 V, but that may have changed.

 

[CanuckMariner/Nomad]

Just set up a 12vdc buss (using a Blue Sea fuse block, rigrunner, whatever) and wire your 12vdc items to it off one of the batteries. Unless you're running a winch or refrigerator off 12v the added draw won't matter much.

I used to have a military M1009 CUCV Blazer with a truly weird electrical system (military stock) and I ran my accessories this way, no (added) problems.

You should really get a 24V winch, much better and less draw in amps. A fridge (Engel, ARB, Waeco, et al.) do not draw much amps (+/- 2-3 amps max). All applications that can be 24V (fridges) should be as it draws on both batteries equally. Putting that much draw using a 12V winch will ruin your batteries and your alternator can not compensate for the one battery being drawn lower than the other. Proto is quite right in the lesser amps drawn and winch running a bit faster, besides as I said, the batteries will be drawn the same.

Have you considered converting the winch to 24 Volts? The 24 V units draw about half the current (275 Amps?) so your winch wiring wouldn't have to be quite so beefy. And the 24 V motors run a might faster, too.

It's a straightforward motor swap. The 12 V motors are in demand because people run those winches hard and burn 'em up. You could yank the motor now before you mount the winch, sell it and use the proceeds to finance the 24 V motor.

As for 12V accessories: I like ntsqd's solution of a small, separate 12V batt and alternator! Clean, safe, gives you some redundancy.

There's a potential problem if you connect loads to your existing batteries asymmetrically; you risk unbalancing the cells. (Maybe a problem, maybe not -- depends on your usage pattern and your charging system -- could work just fine for you.) There are devices available designed to minimized unbalanced 12V loads in 24V systems. But, I don't think you can use them with ham gear because of grounding conflicts.

Good luck with this! Sounds like a fun project!

EDIT: If you do go with a 24 V motor conversion, be sure to check the rating on the solenoids. They used to all work for either 12 V or 24 V, but that may have changed.

There is also the added weight, where to put it and expense of the third battery to consider. Everyone I know that has a 24V system uses the solar converter system and works fine.

 

[the dude]

I am running a solar converter and charging a third 12V bat in my system. I am running a 1000W inverter, CB, HAM, and a radio off the 12V.

Check your equipment. My Blackberry, Garmin GPS and dell laptop all plug into 24V

as others have suggested, find yourself a 24V motor for your winch.

here is a diagram of my setup:

 

[Wagontrain]

I would run the winch on 24V, I know a few guys that do with no long term repercussions. Just make sure the winch is simple, as in no overheating technology, like an 8274.
I bought a 30A 24->12V battery charger from the UK. It draws nothing from the 24V side, and a trickle charge from the 12V side. I used it to charge an Optima Blue Top, which in turn powered all my 12V stuff, including a 9500# Warn PowerPlant (winch/air compressor combo). The PowerPlant has all kinds of overload/heat protection, which when tripped cannot be easily reset, hence not running it on 24V. 30A isn't enough to keep up with the draw of a winch, but a good battery will take the brunt of the draw and a good charger will replenish it over time. These units are expandable, they come in 15A blocks. You could have a charger capable of +90A. These are real chargers, not convertors, so there is no fear of overcharging. The drawback is they are expensive. I paid around $300.00CAD for the 30A model.
http://www.eurogroup.gb.com/24v_12v_battery_chargers.htm