Should High Line Chassis's Be 24 Volt?

[Lug_Nut]

Automobiles and motor homes have a 12 volt electrical system. Conversion buses have a 24 volt system. Maybe high line rigs like the LADB, KADB, EXDP and MADP should be 24 volts. I realize this is more a chassis issue, so K-2 or at very least K-3 Spartan chassis's.
As this is a topic I'm going to write on in early August, I thought it would be great if I could get some helpful input on the subject.

Especially the K-3 with its soon to be 650 HP. The starters would operate at half the amperage and the cables would only be again half the size. After all, large engines generally come with 24 volt starters for that reason. My boat, for example is 24 volt. The engines and starters only come that way, it's 24 volt or pneumatic driven, no 12 volt choice at all.

So what are the advantages?

* All the wiring for the DC equipment is generally half the size.
* Inverting only requires half the DC amp input. (pretty substantial 150 amps 12 DC input to drive the microwave. 75 amps for the 24 volt.)
* Onboard equipment could be more specialized (a bonus for the manufacturer)
* Possibly better cold weather starts.
* Cooler running altenator for high amp loads.

Disadvatages

* Need more or bigger batteries for substantial amp hrs.

So, can anybody add to this or have any ideas?



Peter

[Lug_Nut]

Automobiles and motor homes have a 12 volt electrical system. Conversion buses have a 24 volt system. Maybe high line rigs like the LADB, KADB, EXDP and MADP should be 24 volts. I realize this is more a chassis issue, so K-2 or at very least K-3 Spartan chassis's.
As this is a topic I'm going to write on in early August, I thought it would be great if I could get some helpful input on the subject.

Especially the K-3 with its soon to be 650 HP. The starters would operate at half the amperage and the cables would only be again half the size. After all, large engines generally come with 24 volt starters for that reason. My boat, for example is 24 volt. The engines and starters only come that way, it's 24 volt or pneumatic driven, no 12 volt choice at all.

So what are the advantages?

* All the wiring for the DC equipment is generally half the size.
* Inverting only requires half the DC amp input. (pretty substantial 150 amps 12 DC input to drive the microwave. 75 amps for the 24 volt.)
* Onboard equipment could be more specialized (a bonus for the manufacturer)
* Possibly better cold weather starts.
* Cooler running altenator for high amp loads.

Disadvatages

* Need more or bigger batteries for substantial amp hrs.

So, can anybody add to this or have any ideas?



Peter

[AFChap]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">LADB, KADB, EXDP and MADP </div></BLOCKQUOTE>
Since your ID lists you as a member of the Newmar forum, this is Newmar code I suspect??
The 24 volt write-up might be an interesting read for some, but unless talking to an exclusive audience it would be helpful if you didn't talk in code other folks can't easily decipher.

[BryanL]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">* Need more or bigger batteries for substantial amp hrs. </div></BLOCKQUOTE>
not really.

Just running a higher voltage system does not by itself change the energy storage requirement nor the power draw requirement.

Batteries have about 10 watt hours per pound energy capacity. Power draw will depend upon battery and bank design.

What I am waiting for is the 42 volt automotive standard to start getting common. See ASTM- 42 v standard under way (some good pro/con in that) or EE Times. Note that the 42v is charging voltage like 14v for a 12v system.

[Route 66]

It's not really code, but Newmar's designation for their models. Well, I guess it's Newmar's code.

LADB-London Aire Diesel Bus
KADB, actually it's KGDB-King Aire Diesel Bus
EXDP-Essex Diesel Pusher
MADP-Mountain Aire Diesel Pusher

All are Newmar's highline coaches.

[FlyingDiver]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Route 66:
It's not really code, but Newmar's designation for their models. Well, I guess it's Newmar's code.

LADB-London Aire Diesel Bus
KADB, actually it's KGDB-King Aire Diesel Bus
EXDP-Essex Diesel Pusher
MADP-Mountain Aire Diesel Pusher

All are Newmar's highline coaches. </div></BLOCKQUOTE>

Actually, the list should be DADP, MADP, EXDP, KGDB. The London Aire is not currently being produced, and the Dutch Aire Diesel Pusher is new for 2009.

joe

[Cruzer]

Actually the disadvantage of needing bigger batteries isn't true. When you double yopur voltage, you cut your amperage in half. Amps times volts equals watts and watts are true power so that's all that really matters. A given load, say at 1,000 watts, won't change if it's convertred to a 24 volt device. As the volts double, it's amperage needs will be less. Therefore your battery bank can decrease in amp-hours as long as the voltage increases accordingly.

To me the only disadvantages are that most of the third party components are 12 volt and it could be tough to add a new toy to your coach if it was a 24 volt system. Also, finding 24 volt replacement light bulbs at your local auto parts store isn't going to be easy either.

The biggest advantage is the ability to pass large amounts of current through smaller diameter wires. Many coaches have long runs of battery cable to connect the generator set cranking motor to the batteries at the rear of the coach. Inverters require a fairly hefty chunk of cable to allow them to output higher wattages. A 24 volt system would be a huge benefit in getting all this stuff to operate with the current flow it needs. We already have #4/0 cable in some runs on my coach. You can only go so far.

[Route 66]

I didn't include the Dutch Aire as it's not a highline coach.

[Lug_Nut]

AFChap, You are correct, I should have spelled out the models and in addition add Monaco Signature and many more. I originally posted it on the Newmar site, but as I then realized it really is a chassis specification rather than a MH builder, I posted a copy on the Spartan section. This double posting was done in the past by the admin if it applied there also. I guess that does not happen anymore.

Peter

[Lug_Nut]

Cruzer, Actually the battery size will be the same to be power equal I believe. Power equal would be 50% lower amp hour than that of the 12.
I just wonder what the weight difference would be with 50% smaller diameter wire. I don't know if motors, like starter motors would be lighter due to the lower amperage.

Peter

[FlyingDiver]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Route 66:
I didn't include the Dutch Aire as it's not a highline coach. </div></BLOCKQUOTE>

You sure? It's listed in the "Luxury Motorhomes" section of the Newmar website.

http://www.newmarcorp.com/luxury

joe

[Route 66]

The DADP has only a 1 year warranty.

I'll confirm it's status Monday.

[Cruzer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Lug_Nut:
Cruzer, Actually the battery size will be the same to be power equal I believe. Power equal would be 50% lower amp hour than that of the 12.
I just wonder what the weight difference would be with 50% smaller diameter wire. I don't know if motors, like starter motors would be lighter due to the lower amperage.

Peter </div></BLOCKQUOTE>

When I hooked up "stuff" before I bought 100' reels of welding cable rather than battery cable because it's more flexible. The #2 cable isn't that bad but the #2/0 cable is just plain heavy. When you go to the #4/0 it's just plain ridiculous. I'm sure there'd be a substantial weight savings if you plumbed the entire coach with lighter cable. Although, in some instances I'd keep the same size just to rectify an issue with not being big enough in the first place.

[Lug_Nut]

There must be advantages, if not, why would Prevost coaches and the likes use 24 volt. I also noticed many aircraft opt for 24 or 36 volt dc power. Could it be that much better weight wise or reliability wise?

Peter