LMTV Alternator replacement 24 volt

[GeneralDisorder]

As a contrary to Ronmar - no disrespect intended or implied because there's plenty of ways to skin this cat and it's down to what you are personally comfortable with - I would point out that the 260A is the standard alternator used on all A1P2 trucks and I have no reason to believe it's any different on the new A2 trucks (still running the C7 - heck maybe they all got the 300!) so surplus is not going to be an issue in my lifetime anyway. And if the world ends in nuclear holocaust and despite all odds and beyond reason you happen to still be driving your FMTV and need one...... There will be plenty of them laying around for the taking.

 

[Ronmar]

yep, lots of ways to do this! But by my observations, surplus supply has always been hit and miss, and not nearly as good a deal as it used to be especially as more people(hike the HumVee) have gotten into the LMTV arena. This is especially true when it comes to alternators it seems. In line with my personal experience, Alternators are consumables... with few exceptions(diesel tractor and a Mitsubishi EclipsE GSX I ran for 11 years) I have put an alternator on every vehicle i have ever owned at some point...

Can running these trucks be expensive? yes! Does it have to be? not necessarily... Cost not being an object is all well and good, but isn't it nicer when it doesn't cost?

Any plan involving power should always involve a power study. There is often a huge gap between what people actually need and what they think they need.

IMO 100A@24V/2800W is a LOT of power, but then again my home emergency generator is 3KW but I harvest waste heat from it also In my case, my service batts need 25A worst case. The truck may use another 25A max with everything turned on. That leaves me 50A to play with or <50% loaded. 50A@24V is the equivalent of 1200W of solar on the roof. If my service batts are charged, they won't need the 25A I have allotted to them, that's now 75A to play with or comparable to 1800W of solar on the roof... 100A@24V alts are pretty common, and not horribly expensive.

Just my take on something that should be simple and robust...

 

[GeneralDisorder]

Agreed. Power study suggests you could get away with a 100A alternator that is at times pretty close to running at capacity.....

On the other hand, the 260A in the same circumstances, will only be running at 1/3 to 1/2 it's rated capacity. Meaning it will run cooler and easily tolerate sending 68A to my house batteries even at idle. Remember that the 100A literally *isn't* 100A at idle. That rating is only if you rev it up. It's lucky to provide 60A at idle IIRC. Now I have to go drive the truck if I want anything decent from the alternator for house charging since I clearly can't turn on 68A of Victron Orion's at idle......

Sure I could run fewer of them. Charging will just take longer. But I don't wanna!

And I want 4 batteries for redundancy. 4 can be reconfigured to two. Two cannot be reconfigured to one. Not with 12v batteries and a 24v starter.

 

[Ronmar]

Well that additional alt load is only a backup for the 1600W solar on the roof anyway. I don’t expect it will be used much… Backup? we don’t need no stinking backup Thats what the house batteries are for, same as in many RV and marine configurations…

My main point is that 2800W is actually a LOT of power, and obtainable at not a horrific cost…

 

[serpico760]

I found I had picked up this brochure at a local truck store

 

[MatthewWBailey]

I found I had picked up this brochure at a local truck storeView attachment 936204View attachment 936205View attachment 936206

According to the cross ref shown, the 40SI will fit in place of a CAT 272-1889, which is the Denso unit I bought. 160A excellent!

 

[GeneralDisorder]

But at what duty cycle?

Also they are over $1k. Not really much cheaper per-amp than the Niehoff 260A in the surplus channels. Which tend to be about $2,500 on a Wednesday. And can find them a little cheaper if you look around and message some forum members, etc.

 

[MatthewWBailey]

But at what duty cycle?

Also they are over $1k. Not really much cheaper per-amp than the Niehoff 260A in the surplus channels. Which tend to be about $2,500 on a Wednesday. And can find them a little cheaper if you look around and message some forum members, etc.

Logical, and why I deferred to the $170 delco.

I'll be selling the 260 I bought nos and keeping the 300 as a future j180 alternative with your bracket. Once I get the 100a neihoff back from rebuild I'll sell that too. Starting to collect too many niehoff electrical devices. I have two 570A units but those are for a science project.

 

[Gunny 0369]

if you are only drawing 24v out of it, it would be no more overloaded than any other 24v alt. The Neihoff‘s Achilles heel rears its ugly head when you start pulling 14v out of it. The alt is rated 100A combined load, and since the 14 is pulled from the first half of the windings, it can only deliver ~60A max at 12v. An incandescent light load is ~25A, if you have the lights on and are pulling that, the alt can only deliver ~75A @24. The truck needs perhaps 15+ of that, you are now at 60 or less available. A 240A wet cell needs that if its discharged, and if they are really flat we are talking hours at max load to recharge.

At straight 24, you have 100A. Well thats 12.5 A for the lights, another 15 for the truck loads, that leaves you 70A. The batts are looking for 60A(25% AH), so <90% load. A much more favorable situation if you have several hours of charging ahead. Not an issue if you keep the batteries topped(float charger or run a lot of hours)

Of course AGM batts blow this situation up with their 45% of AH current draw(108A for a 240AH bank). Thats was probably a big factor in the 260A alt changeup.

now pick a vehicle, any vehicle. The daily in your driveway perhaps. Total loads, total battery demand(25 or45% of batt AH capacity based on batt type) and compare it against the alternator rating. I would be surprised if you find a worst case combination much above 50-60% of the alternators rating, and the batts will most likely NOT require hours to recharge.

As for loads like the AIH, still not thinking this is terrible. Again only fairly brief periods, and surely not as bad as say a winch Their voltage drawdown when on basically cuts off feed to the battery. The alt and batt are a team, so as the alt goes to full output and voltage drops, the battery steps in and makes up the rest, then the alt replaces it when the AIH cuts off. if your batts are kept up, not much of an issue IMO, and not thinking it is an alt killer. Lots of vehicles use them…

Ronmars comment answers alot- DRIVE the truck often, and plug in batt. maintainers EVERY day.

"" Not an issue if you keep the batteries topped(float charger or run a lot of hours)""

We went through 8 batteries until we changed to 24v float charging EVERY time we stopped. utilizing 5500w Generator when not plugged in.
2.5 years now, no issues. We do rotate the batteries regularly, and keep water topped off.
this is on an A0 with a 2008 100a alt. running a quadzillion amps in LED bar lights, and drive lights, in addition to HAB power-borrowing from the truck batteries when 600AH house batteries are down.
a spare 50# 100 amp alternator is easy to haul.

good info guys.
knowing keith, he will build a small reactor to power his truck AND the town he will visit.. he has the talent to.
OH!! we need a minigun update?

 

[MatthewWBailey]

@Keith Knight can you do a similar "Battery Options" thread to curate all the battery swap recommendations and knowledge base? There's too many threads with various titles.

 

[Keith Knight]

Ronmars comment answers alot- DRIVE the truck often, and plug in batt. maintainers EVERY day.

"" Not an issue if you keep the batteries topped(float charger or run a lot of hours)""

We went through 8 batteries until we changed to 24v float charging EVERY time we stopped. utilizing 5500w Generator when not plugged in.
2.5 years now, no issues. We do rotate the batteries regularly, and keep water topped off.
this is on an A0 with a 2008 100a alt. running a quadzillion amps in LED bar lights, and drive lights, in addition to HAB power-borrowing from the truck batteries when 600AH house batteries are down.
a spare 50# 100 amp alternator is easy to haul.

good info guys.
knowing keith, he will build a small reactor to power his truck AND the town he will visit.. he has the talent to.
OH!! we need a minigun update?

I’ve finished it. Put haven’t published part 3 of the finished project here is part 2.

Pt 2 MiniGun on a LMTV Nerf Style Gun Turret Overland 4x4 Expedition Vehicle Military RV

 

[Keith Knight]

@Keith Knight can you do a similar "Battery Options" thread to curate all the battery swap recommendations and knowledge base? There's too many threads with various titles.

Like battery options for the truck or habitat/house battery options.
I’ve got a couple other projects I’m working on currently. Like fabricating a Gun Port that will go in the back door.
We are heading out West early January and going to be full time Overlanding for the next 2 years. Not having access to my shop I’m trying to finish all the silly projects that I dream up while traveling. Going to miss not being able to make what I want or need. But certainly going to enjoy western America for the next 2 years.

 

[Gunny 0369]

Like battery options for the truck or habitat/house battery options.
I’ve got a couple other projects I’m working on currently. Like fabricating a Gun Port that will go in the back door.
We are heading out West early January and going to be full time Overlanding for the next 2 years. Not having access to my shop I’m trying to finish all the silly projects that I dream up while traveling. Going to miss not being able to make what I want or need. But certainly going to enjoy western America for the next 2 years.

Awesome-
See, I don’t feel all that unusual with my 9J shock system on the lower body panels..
“ bear” repellent.
Can’t wait to meet up with you on the road Keith.

 

[Keith Knight]

ImTell me more about 9J shock system!

 

[Gunny 0369]

ImTell me more about 9J shock system!

You can go all the way up to 32 Joules
Check out these-
(Disclaimer, to pass inspection these cannot be attached to the truck)

 

[Keith Knight]

You should start a thread on the subject. I’ve often thought of doing something like that but didn’t want to fry the trucks electronics.

 

[MatthewWBailey]

battery options for the truck

Battery options for the truck.

 

[coachgeo]

You should start a thread on the subject. I’ve often thought of doing something like that but didn’t want to fry the trucks electronics.

Me too. My understanding you need to ground the truck. I thought about a spring loaded (or just heavy weighted) Rebar made into a spike. Pull a lever and it stabs into ground. Before leaving you crank a handle orrr?? to pull it back up.

 

[Gunny 0369]

Me too. My understanding you need to ground the truck. I thought about a spring loaded Rebar made into a spike. Pull a lever and it stabs into ground. Before leaving you crank a handle orrr?? to pull it back up.

The rebar could double as an anchor, for those without a pacbrake.

No need for full ground,
Energize the panel's/ parts/ or handles in pos and neg ground, separated by nylon sheet or washers.
When the part is touched, the “ bear” gets knocked on its butt.
You can use the same principle utilizing cable or “ grab” handles or ladders or, best a modified bumper-
When driving slowly through large “herds” of wildebeast it’s more useful on the bumper.

 

[Keith Knight]

Seriously please start a thread and let’s get into more details.