24 volt battery bank?

What kind of vehicle?

You don't need to convert 24 volts to 12 volts, you just use an equalizer http://www.vanner.com/manuals/EQUALIZER-70M-SERIES.pdf- it splits the battery banks in to 12 volt banks, and draws from the equally-

The Vanner VANN-Guard Power Management System is an efficient and highly reliable method of
obtaining a 12 volt DC power source from a 24 volt DC electrical system. The VANN-Guard makes the
batteries look like they are in series and parallel at the same time. In addition to providing regulated 12
volt power, the system ensures that battery voltages remain equal which significantly extends battery life.
Ideally suited for vehicle and alternate energy applications, the VANN-Guard is designed to save your
batteries and the money you would spend replacing them. Users of the Vanner VANN-Guard know that it
is the most cost effective and dependable solution for dual voltage systems.

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Should be much more efficient than converting 24 to 12.

2oldman wrote:
Probably best to ignore the sarcasm above. 24 is fine, as long as you use a 24-12 converter of sufficient amperage. I use a 25a victron.

Sorry for the sarcasm.... I overlooked the original poster's admission that he would need a 24-12 converter. In my world of some boon-docking I appreciate the efficiency of powering my coach directly off the battery bank. Perhaps the original poster's needs are different than mine and he can sufficiently operate with the inherent losses of a DC-DC converter ..

What voltage is (usually)used, in aircraft applications? If, say 24 volts, could that be a ready supply of components? Or, marine apps?

MEXICOWANDERER wrote:
Problem is with the cost of an extremely dependable DC Bucker..

$100

MEXICOWANDERER wrote:
But it's that bopping down the road recharging that's perhaps the biggest challenge.

solar

I tried a 24v bank with solar as a test. Worked great. The MPPT controller was more efficient doing 24-24 instead of 24-12 and it also allowed the PWM controller (no buck converter in those) to run a 24v panel which is a lot cheaper per watt than the 12v panels.

Since usually, the PWM controller is much cheaper than the MPPT, the advantage in money was to go 24v panels and PWM controller, but this requires a 24v battery bank. You have to offset that by the cost of your 24-12 converter, unless you use your existing converter as PT suggests, from that big inverter the OP wants.

In another test, running the existing converter from an inverter had about a 4 to 6 amp draw (at 12v not 24v) so that would need some solar to keep up with. AFAIK, the simpler kind of buck converter you can get for that job would be more efficient by using the 24v battery bank as source instead of 120v from inverter.

mlts22 wrote:
Other than needing to use a DC-DC converter for the 12 volt system, what problems would there be in going with a 24 volt battery bank for a custom rig?

Edit: Oops, I missed the part about using a 24-12 converter to maintain a 12V supply for the existing stuff BUT......
What are you trying to accomplish here ?? I think there probably is a better way regardless of what your objective IS.

(Original comments deleted)

You already have a converter. Run that from an inverter or shore power for the 12 volt needs.

It's done all the time on bus conversions. Some I have worked on have no over the road air conditioners, rather they use the 4kw 24v inverters to run the roof air conditioners, along with a high output alternator.

You just need an equalizer-http://www.vanner.com/brochures/Battery-Equalizer-PB-6-01.pdf, and a heavy duty alternator like this 270 amp model, or this 450 amp unit- both oil cooled alternators.

Problem is with the cost of an extremely dependable DC Bucker. My bus is 24 volt and I have zero appliances that require electricity. What folks here seem to not touched on is when you are cruising down Route 66, what battery recharging system will be working? My interior lights are LED in series configuration. I robbed the Trace 4024 for use in low hour outages. It also helps with 110 amps battery recharging. Drok seems to make a decent Bucker. Mine is a custom unit made by an electronics engineer as a favor and the parts cost was close to 600 dollars 20 some odd years ago.

A towed rig clad with solar would be a heck of a lot easier to do than a motorhome. But mine can charge batteries at a 400 amp rate.

There are lots of ways to go including foregoing all 12-volt and going AC with the lighting. At the time Shur Flo wanted 300 dollars for a 24 volt water pump.

But it's that bopping down the road recharging that's perhaps the biggest challenge.