Separate 12 volt alternator

RickB · February 15, 2010, 06:40:37 AM

Clifford,

Would it make sense to run it off the camshaft pulley and mount the alternator to a truck a/c front mount? Something tells me this might actually work.

I would much rather do that than run it off the crank pulley.

FWIW I'm not trying to horn in on the thread for no reason, I am planning on adding a 12 volt alternator for my house batteries as well.

Rick

bevans6 · February 15, 2010, 07:19:24 AM

When I thought about adding an alternator to my MC-5C, my plan was to drop one of the four belts to the DN-50 off, and run the 12v alternator from the pulley on the DN-50. It would all depend on if the three belts remaining could run the DN-50 when the bus heater motor was on. Since I have a Vanner, the other idea is to charge the 12v house batteries from that. But the Vanner documentation really emphasizes the need to have balanced batteries in the 24v "stack" and obviously if you add say 240 amp/hours of deep discharge 12 volt battery in parallel with one of the 8D start batteries, you don't have much balance anymore... What will happen if you try that?

My Vanner is a 60 amp deal.

Brian

Ed Hackenbruch · February 15, 2010, 08:01:17 AM

Brian, my 12v alt. runs off of the 24v pulley and the heater motor works just fine. The only thing i would like to do a little differently is set it up so that the belt runs off of the first groove instead of the last. Makes it a lot easier to replace the belt for the 12v if you don't have to take off the other 3 first.

I had also kicked around the idea of moving the whole thing to the right corner and running off one of the pulleys there but i just don't have enough room there to be comfortable with it.

Lin · February 15, 2010, 10:10:33 AM

Thanks for all the info. Just to clarify, I should have mentioned that I do not have a 50 DN on the bus. It is a 45 amp, single wire set up on the left back running off 2 belts from on pulleys there. I actually have a rebuilt 50DN in the garage but do not see ny reason to install it. Since the OTR heat and air have been removed, I do not need all that power. I just need an over-the-road house battery charger, which a little 12v alternator would do fine.

Lin · February 15, 2010, 12:15:06 PM

Hey now, don't yell at me for asking this, but I am curious about whether I could charge the house batteries by center tapping the coach batteries with a manual switch. Does this seriously unbalance things?

JohnEd · February 15, 2010, 12:47:24 PM

Use the three wire system and sample at the bat post. Even the inverters sample at the post and they are the best bat chargers out there.

I don't agree about the 50 DN. I think it puts out 2 or 3 hundred amps and your inverter will gobble that up nicely running a roof top down the road. You may have coach air, and I hope you do, but if it fails you understand that in a hot climate you cannot tolerate the interior of a bus in the sun. That goes for running down the road/ also. Being able to run the roof tops anytime is a serious backup system. I think you need something like 120 amps to generate the 12 amps at 120 volts so you need a 50 DN or close.

John

Lin · February 15, 2010, 01:14:01 PM

John,

You are certainly right about having the option of running roof air on the road. Since we do not have dash air, we do that a lot using the generator. However, changing over to the 50DN would be a chore. We have a one wire system now, so we would have to re-establish that former system with a voltage regulator. We would also need to get a big enough 24volt inverter and a Vanner equalizer if the house bank would also be 24 volt. Aside from which, the current alternator is relatively easy to change should it go bad, but the 50N is a monster that I suffer to lift even the best of locations. I doubt I could handle the R&R of one alone if I had to. Therefore, I think that the current compromise situation is acceptable.

bevans6 · February 15, 2010, 01:38:40 PM

Quote from: Lin on February 15, 2010, 12:15:06 PM
Hey now, don't yell at me for asking this, but I am curious about whether I could charge the house batteries by center tapping the coach batteries with a manual switch. Does this seriously unbalance things?

Yes, it does. The amount of imbalance will depend on the particular batteries in question, and the importance of that will depend on how much you care about battery life. Basically one battery will get well over charged and the other (the "lower" battery with the house batteries paralleled off, I think) will be undercharged. The Vanner is, simplistically, a power supply that is powered by the 24v supply that forces the center tap to be exactly equal to half of the total supply, thus the batteries are forced to be equally charged. Now, the Vanner website specifies that there can be a "load" of up to 60 amps and that the batteries have to be identical. Obviously if you contemplate charging the house batteries as the "load", the batteries are no longer equal. I have found no one to tell me if using the Vanner to charge the house batteries is an "allowed and recommended" way to use a Vanner.

Brian

redbus · February 15, 2010, 05:54:50 PM

I have used a Vanner to charge my 12 v house Battery's (4 8D's) for 6 years and it works fine.

Lin · February 15, 2010, 06:18:03 PM

Terry,

How did you do that? Did you just connect the output of the equalizer to the house bank as if it were a battery charger? Did you have it on a manual switch or was it a fulltime connection? How large an equalizer did you use?

luvrbus · February 15, 2010, 07:13:48 PM

Lin, your better off with a 120 to 140 amp alternator than with a Vanner both price wise and charging time and I know you like price lol

good luck

Lin · February 15, 2010, 08:25:20 PM

Clifford, I don't know where you got that impression. Certainly not from my Rolex watch (or is it a Timex. I get those ex's mixed up). Anyway, it is interesting to check out the different possibilities. One thought is that the equalizer puts out 12 volts, so it would seem that it could only charge the batteries part way. Maybe someone that actually knows could help here.

Fred Mc · February 15, 2010, 10:09:13 PM

Since grounding seems to be a problem on our older busses is it advisable to run a separate ground wire on these one wire alternators? I presume the ground is through the engine and frame otherwise.

Fred Mc.

Pd4106

JohnEd · February 16, 2010, 01:00:36 AM

A single wire alt can be changed/modified to a remote sense alt. I think that they all can but of course?

? Any alt rebuild-er can confirm the '"if" part. Pack that 50DN up and stow it in the bus. In your travels you will find someone that will install it for a reasonable price. Some of the 50 were anemic in comparison to the biggies. Maybe 100 amps and that isn't worth reaching for with all the trouble. BUT, the difference between them is the armature(?) and that swaps out for $60 or 80 the new one is good for 250 amps or more. Don't hold me to this as it was an incidental conversation long ago and recently I have been having trouble with stuff like where I was married....just kidding but take the hint. I will post the number of a rebuild-er located here in Eugene that is not convenient to almost anyone but he is a good guy ad will most likely answer any questions youmight have abut auto electrics in general. Don't have the number on me at this time and no, we arenot related.

Good luck,
John