How can I drive both extra alternator and A/C compressor with engine?

belfert · April 17, 2009, 02:15:52 AM

I would like to add both an extra alternator and an A/C compressor to my engine. Any ideas how to power both if I only have one pully on the driveshaft available?

Maybe I would be better off just using the big 50DN to power my house needs too, but then I really can't add a three stage regulator.

busnut104 · April 17, 2009, 02:49:02 AM

Hi: On my MC8 I run a welsh a/c compressor off the pulley on the squirrel cage blower gear box, Welsh has a pulley that bolts on and the compressor sets above the box. This is a small auto type compressor.

belfert · April 17, 2009, 02:58:06 AM

I have a Dina, so no blower box. I'm not real familiar with all the options for driving belt driven stuff on vehicles.

NewbeeMC9 · April 17, 2009, 04:37:03 AM

There are tree stage voltage regulators for the 50DN

Would have to find it in the archives. May be on old board.

gumpy · April 17, 2009, 04:57:39 AM

I've been charging my house batteries off my 50DN for 4 or 5 years now with no problems. All I use is the standard bus regulator.
I connect the bus and house batteries using a 200 amp crossover relay.

I'm still on my first set of house batteries. I did have to change one of my starting batteries last week but it was in the bus when I
bought it 9 years ago.

luvrbus · April 17, 2009, 06:55:27 AM

Belfert, there are several locations on the 60 series you can add new accessory drives to the engine on the front and rear good luck

Utahclaimjumper · April 17, 2009, 07:07:05 AM

You could also drive a pulley with a pulley.>>>Dan

belfert · April 17, 2009, 07:50:42 AM

Just using the 50DN is probably the best option, but won't I have to worry about possibly overcharging the house batteries since the regulator is only monitoring the starting batteries?

A three stage regulator for the 50DN is also not a bad idea, but then don't I have the opposite issue of the starting batteries maybe not getting charged properly?

I'll have to see if I can find the A/C selenoid to see if that would work to pull power off of.

FloridaCliff · April 17, 2009, 08:07:49 AM

Quote from: belfert on April 17, 2009, 07:50:42 AM
Just using the 50DN is probably the best option, but won't I have to worry about possibly overcharging the house batteries since the regulator is only monitoring the starting batteries?

No, I have a similar setup to Craig, when the engine is running the start and house batteries are paralleled together, so the regulator is measuring the combined charge on all the batteries. I also have a separate switch up on the dash where I can put the batterties in parallel when the engine is off. This allows me to charge the start batteries when on shore power and to use the house set to start the engine. That is if something was wrong with the start batteries such as one of them failed or were somehow discharged.

Cliff

gumpy · April 17, 2009, 09:11:22 AM

Quote from: belfert on April 17, 2009, 07:50:42 AM
Just using the 50DN is probably the best option, but won't I have to worry about possibly overcharging the house batteries since the regulator is only monitoring the starting batteries?

A three stage regulator for the 50DN is also not a bad idea, but then don't I have the opposite issue of the starting batteries maybe not getting charged properly?

I'll have to see if I can find the A/C selenoid to see if that would work to pull power off of.

Cliff is correct. When you combine the two strings of batteries in parallel, current begins flowing from the bank with more charge to the bank with less (from the starting batteries to the house batteries in the typical situation). The voltage becomes the average between the two sets of batteries. If the start batteries were, say 26 volts, and the house batteries were 24 volts, the combined voltage will be around 25 volts. The alternator regulator sees 25 volts on the coach bank and set the output of the alternator accordingly. The charge is trickling down to the house bank from the starting bank which causes the starting bank voltage to drop, which is then compensated for by the regulator. The house bank will only suck off what charge it can take and only as fast as it can absorb it on it's own.

I seldom see over 100 amps going into my house bank off my engine alternator, and then only for a very short time when I first connect the two banks. The charge current then drops quickly and considerably and I see it charging in the 20-30 amp range. If I run my house bank down to 50%, it will take 8-10 hours of full time driving to bring them back to full capacity (as opposed to my inverter charger which would charge them in about 3 hours). It's a slow but steady charge.

boogiethecat · April 17, 2009, 10:39:34 AM

I did it the hard way on my Crown... very different bus but the idea applies... I took the old single belt pulley off of my power steering pump and on my lathe I manufactured a double groove pulley for it. Then I drove my AC compressor with that second groove. You could do the same with any belt driven device...alternator, etc. It works really well. For the AC belt I used one of the thinner/newer V belts that is quite a bit smaller than the rest of my belts in the engine compartment... it matches the AC compressor's pulley. The compressor has two grooves in it's pulley but using only one belt has not been a problem.
The one thing that was a bit hasslesome was that the only way I could mount the AC compressor, it'd have to spin backwards. I eventually found that there are compressors out there that are rated for rotation in either direction. Not many, but Sanden makes a few...

Here's a writeup including a lot of photos...

http://www.heartmagic.com/engineACdays/EngineDrivenACdays.html

Cheers

JohnEd · April 17, 2009, 03:09:06 PM

boogie,

I don't want to hijack this thread. I will start another but it is mostly to you but not exclusively. See AC compressor question in topic.

Thanks john