What are the benefits, if any, of having a 28 volt electrical system over the standard 14 volt system?

Mainly, from an electrical standpoint, higher voltage = lower current requirements. Lower current requirements = smaller wire size. Smaller wire size = lower weight.

Power (W) = Voltage (E) x Current (I)

~Chris

Cost of the battery

I don't think that the cost of a 28 volt system is worth it on a Maule. The reason that a 28 volt system might be used instead of a 14 volt system is to deliver more power for heavy current drain loads. As Chris pointed out, P=E*I. If you have a device that consumes 100 watts of power, the electrical system needs to deliver 7.14 amps of current at 14 volts but only 3.57 amps of current at 28 volts. To deliver more current, wire has to be lower resistance (thicker) or it will overheat and perhaps catch fire. Heavier wire = heavier weight in the airplane.

These days, the trend in modern electronics is to reduce current consumption so the higher power producing 28 volt systems aren't needed in most light aircraft.

Another cost factor besides the expensive 28 volt battery is the more expensive 28 volt alternator.

Thanks, guys. 'preciate it.

Do you Fellers think that there is an advantage to the 28V battery in spooling up a hot IO 540 ? If it doesn't help in that situation, then there's not much utility to be gained. What would you need to convert to 12V ? Battery, Starter, Alternator, Bendix, and what ? Mags ? Avionics ? (some of my equipment is 12-28)

The new light weight starters turn way faster than the old starters. I put a Lamar on an IO540 and now it starts hot like it never did before. No need for 24 volts.

The new light weight starters turn way faster than the old starters. I put a Lamar on an IO540 and now it starts hot like it never did before. No need for 24 volts.

The little 16 amp 12 volt Odyssey battery and a lightweight starter pretty well gets the job done these days.

My little Odyssey has been cranking cold or hot for over 5yrs now. Showing no signs of slowing down.

I had a VERY slow cranking engine with a totally fresh battery.

IA ran load tests and we ended up running all new battery cables from battery in rear to front. In the process corrected some potential grounding issues.

Result is my lightweight starter now spins the prop on my O-540 like a bandit, hot or cold engine.

Just throwing this out there for those having cranking issues.

Tom

SO . . . what would one have to do to ditch the 24v and go to 12v (besides avionics). replace the Starter, Alternator, Bendix, Mags . . what am I forgetting ? Starting to get pricey !

It's not worth the effort or cost to convert a 12 volt system to 24 volt or vice versa. Some of the avionics might need to be replaced in addition to the starter, alternator, alternator control unit, etc. Some newer avionics can handle either 12 or 24 volt but most of the older stuff cannot.

The lightweight starter and Odyssey battery sound like the way to go. When I did a major overhaul on my O-360-C14 in 2004, they didn't have a lightweight starter for that engine or I would have gone with it. My Concorde RG35AXC battery isn't as light as the Odyssey but it works fine in hot and cold weather but next time I have to replace the battery, I'm going to go with the Odyssey to lighten up a bit. How do folks in Alaska like the Odyssey in cold weather?

Thanks for your comments. It looks like the only real practical avenue is to look at each of the heavy components, Starter, Alternator, Battery, Prop, Etc. and see if a legal and lighter replacement is available. For the 24-28V battery, it seems like that's a big no, unless you have $6000.00 to spend on a battery to save 14lbs (https://www.truebluepowerusa.com/aviati ... a-a36-stc/). Talk about being made of pure unobtanium !