94 6.5 Dual Alternator Conversion

[Kick Ass Matt]

94 6.5 Dual Alternator Conversion
What I have:
94 6.5TD w/single alternator.
What I want:
Dual alternator setup
What do I need is my question.
I know the 95/96's and up have the AMB (ambulance) option that gives them dual alternators. I also know that you can go and buy brackets, belt, harness, belt-tensioners and such to retro fit a single alternator 95/96 and up into a dual alternator setup.
By the notion that they have the same block and working up stream from the belt. This is what I see that I need.
-96 p/s, A/C, Vac pumps
-96 idler pulley
-96 belt
Up stream from the pumps, what brackets would I need?
I don't want to go for a re-wound that gives me 250amps because if it ever fries on me then the truck will be down to wait for another re-wound. I rather have off-the-shelf stuff that I can get locally.

Why am I doing this you ask? I am planning to put in 2 5000W inverters under the back seat; wired in w/ batteries under the 2nd row seats the number of batteries would depending on the amount of space I have and the size of batteries; gel cells will be used.

Thanks
Matt

[Nobby]

Sorry I cannot help you with regard to the second mounting setup as I have no experience there although I am currently trying to figure out an onboard air compressor in the same location. The one issue that I am trying to figure out is that the installation of a pulley in that spare location makes for a poor quadrant of contact on the AC pulley. I am seeing the need for an intermediate idler between the AC pulley and the secondary location pulley to improve this issue.

Where I can help you is on the alternator/electrical side. You are going to want to steer clear of automotive units even the higher output ones and go with a Hot Rated unit. One that is designed for continuous high output at high temperatures. These will require an external regulator which is good because with dual alts you will want to control them from one regulator to ensure proper output. This is what I am installing/supplying in the marine field and can get you an output anywhere from 100-300A. These are rugged units that are in some cases specifically designed for emergency vehicles. In fact it may well be that you could fit/shoehorn one of the larger units into the existing location and stick with a single alt setup. Now are you planning dual alts to keep the vehicle 12V and the inverter 12V separate or are you going dual for higher output? Because what I am beginning to think with regard to the 5kW inverters that you stay separate and for easier wiring consider a 24VDC inverter.
Need to know though your intended style of operation for this setup how many batteries their sizing etc because there are many permutations here on doing this.

Gotta ask what are you up to needing 2 5000W inverters? Also do you intend to slave them together as their are many ways to do the inverter thing also.

[Craig M]

2 each 5000 watt inverters run from storage batteries? 120 volt systems are sometimes run directly from engine driven inverters, but rarely from auxiliarly car storage batteries. Run time may not be to long.

[Nobby]

Yep 2 x 5kW inverters at full load will be around 1000A on the 12 VDC side, this will be at least 5-6 8D batteries for only a 1/2 an hour of run time if we follow a 50% discharge floor rule. Not to mention recharge time and cable sizing.
Also 5kW at 12 VDC is not really an off the shelf item, can be had though.

Does sound initially kind of crazy need to find out what he is up to I guess.

cheers
Nobby

[Kick Ass Matt]

Yep 2 x 5kW inverters at full load will be around 1000A on the 12 VDC side, this will be at least 5-6 8D batteries for only a 1/2 an hour of run time if we follow a 50% discharge floor rule. Not to mention recharge time and cable sizing.
Also 5kW at 12 VDC is not really an off the shelf item, can be had though.

Does sound initially kind of crazy need to find out what he is up to I guess.

cheers
Nobby

Yeah I know it sounds crazy but here's what my train of thought.

I need to run a computer in my truck; not a laptop but a full blown computer housed in a mini-tower case under the front seat. It'll have a 12" touch screen output on a mount on the floor so I can have GPS tracking, 5.1 speakers, a music system that plays CD's (not tapes that the truck's got now), watch a movie on long trips, and charge my in-truck real time traffic cam which saved my butt a couple of times, too many idoits on the road in Toronto.

Why not a laptop? Theft magnet, you see a laptop in a truck you're asking to have it ripped off of you when you park it in a mall.

On top of that I'll have a mobil UHF, VHF scanner, and CB radio on the DC side of things.

Now I am contemplating in buying a crappy off the shelf gas/diesel generator, take the generator off, slap a pulley on it and have the engine drive it to give me AC power. As for the alternator I'll go single 140 from the crappy 105 that's on their now. But that opens new cans of worms because it means I can't have AC at crusing speed because those generators are only designed to operate at 1 speed, how would I solve that?

Also the draw back of an engine driven AC source is my truck has to be clacking away in order for me to have AC.

Keep the ideals coming...

[JohnC]

So, how do you come up with 2 x 5000 watts? Heck, with that you could also run an air conditioner, hot water heater, freezer, stove...

I run my whole house, barns and well (less the electric stove) on a 7500 watt generator.

[Nobby]

Yep the AC generator will not really work, as you already noted you need fixed speed and anyways those small gas AC units operate at 3600 rpm. The only real way to do vari-speed shaft driven AC is hydraulically and I am sure you do not want to go there.
You could construct an MG set 12 VDC motor driving an AC generator (the old fashioned inverter), seems to me tho that the inverter is the route as you are already happy to accept the addition of more batteries and a higher output alternator.
Now for your next issue Gel/AGM batteries have a different charging specification to flooded and will need an externally regulated alternator with temperature compensation. Problem here is that this will not match your start battery if it is a flooded unit. This is where things start to get complicated because we have to establish whether your actual vehicle systems and your inverter system stay separate or not. I do not like lumping in house and starter batteries together as you run the risk of not being able to start the engine. There are several ways around this too tho.

Now what you are listing I am not seeing 10kW of load.
So the first step is for you in building an inverter system is to calculate your current draw everything on. The size of the inverter plus your extra DC draws will dictate sizing everything else. Now I could just pull educated figures out of my rear, seems to me that you should be able to get away with 2kW inverter tho.

cheers
Nobby

[Craig M]

Do the inveters really give 120 AC or is it 120 DC? I recall many years ago that automotive inverters were really 120 DC. There may be better inverters now.

[DmaxMaverick]

Do the inveters really give 120 AC or is it 120 DC? I recall many years ago that automotive inverters were really 120 DC. There may be better inverters now.

The difference between transformer and inverter, in simple terms.

Transformer -- Alters the voltage.

Inverter -- Alternates the altered voltage. The inverter(s) being discussed have a transformer and inverter in one. Converts DC to AC.

Rectifier -- Un-alternates the current. AKA: converter. Converts AC to DC.