Alternator Suggestions?

[Ronmar]

Thanks Ronmar. I just got done watching and reviewing some material on Lizard Skin products. Very impressive stuff. Just ordered the application kit and buckets of the sound dampening stuff and ceramic heat stuff. I think it will work well in conjunction with some of the other stuff we got. Thank you!

Kevin

Well Thanks, but it was General that suggested it... I have not had a chance to play with it yet

 

[jmak]

Stick with the 260.

What year is your truck? The 260 requires the older trucks to change the mounting of the shock as they have the mounting slung a little farther out. If you cut the huck bolts and make two copies of the spacer plate behind the shock mount out of 1/2" plate you can bolt the shock bracket back in place and it will clear the 260 or the 300.

Don't worry about potential failures - carry a spare VR. The 260 is dead reliable and I've yet to see a confirmed winding or diode failure, etc. Even the VR's are very reliable. In any case if you stick with the 6TL/6TAGM setup you can drive through a whole tank of fuel on just battery if you observe some electrical discipline. And as an overland truck you'll have a secondary solar/generator system that can be shunted over to charge the truck batteries - this gives redundancy so carrying spares or sourcing them during the mission is irrelevant.

Carry a spare starter instead. You aren't push starting this garbage so without a starter you are HOSED. Without an alternator you are just mildly inconvenienced.

Not sure where the concern about the shock tower thing on older trucks is coming from- I have a 98 1078 A0 (3116) and the n1224 dual voltage 260a alt fit with no modifications except creating a new bracket

 

[jmak]

Not sure where the concern about the shock tower thing on older trucks is coming from- I have a 98 1078 A0 and the 260a alt fit with no modifications except creating a new bracket

Here are pics. It was a very easy upgrade from the 100a alt. Only gotcha is the 260a alt seems to use metric for everything- the spindle nut was M20-1.5, not 3/4 like the 100a. They are very close, like a millimeter different. Not an issue if your 260a has a pullly/nut with it

 

[Kevin Means]

Wow! That's a big help jmak. Thank you. I see your 260 is right up against that "boot" that connects to the exhaust. I unbolted mine and moved it over as far as I could, and it looks like it will be OK, but just barely. I'm assuming you've experienced no problems?

The voltage regulator on my 260 has a completely different plug than the stock 100. I'd love to see some details on how you wired it.

Kevin

 

[jmak]

Wow! That's a big help jmak. Thank you. I see your 260 is right up against that "boot" that connects to the exhaust. I unbolted mine and moved it over as far as I could, and it looks like it will be OK, but just barely. I'm assuming you've experienced no problems?

The voltage regulator on my 260 has a completely different plug than the stock 100. I'd love to see some details on how you wired it.

Kevin

It's not touching the boot, but even if it was it's just the protective shroud around the fan blade so should be fine.. been a few hundred miles since install and no issues so far.

The reg shouldn't be an issue- I was worried for a second too, but it only connects to the alternator itself aside from the two wires that go to studs, so no prob. I didn't have to relocate the reg either, just had to remove it to tighten down the alternator then bolt it back on.

Very easy install! Worst part was taking things apart to do the water pump belt at the same time, and that really wasn't bad either.

Oh- I did have to cut and re-terminate some of the original smaller wires because their eyelets were too small for the larger bolts of the 260a alt. 3/8 eyelets and a metric bolt kit that has m6/M8/m10 and you should be good

 

[jmak]

Chatting with OP a bit in dms, looks like we had some confusion.. he has a n1243-6 260a 28v only alternator. Mine is the n1224 260a dual voltage that is used in newer fmtvs/mraps. I have no idea which vehicles use the n1243 or if it will fit

 

[GeneralDisorder]

Ah yes the 1224 is the FMTV 260A dual-volt. A single voltage 260 would be significantly smaller and likely easier to fit.

 

[jmak]

Ah yes the 1224 is the FMTV 260A dual-volt. A single voltage 260 would be significantly smaller and likely easier to fit.

To be clear- I have the n1224 dual voltage and installed it on my 98 1078A0 with a 3116 engine. It fits great- no modifications needed. Someone on a Facebook post about it said if you get a full install kit with the official bracket that may be when you run into the shock tower issue. I have zero fitment issues with the cheap/easy bracket I made. My 260a was missing the pulley too- I was able to use the pulley from the 100a alt, it just needed a larger m20 spindle nut and a larger washer

 

[GeneralDisorder]

To be clear- I have the n1224 dual voltage and installed it on my 98 1078A0 with a 3116 engine. It fits great- no modifications needed. Someone on a Facebook post about it said if you get a full install kit with the official bracket that may be when you run into the shock tower issue. I have zero fitment issues with the cheap/easy bracket I made

The kit slings the alternator out further to get more belt wrap. The 260 and 300 when loaded can barely operate without belt slip as it is. Having the alt too close to the engine reduces wrap on the pulley and thus power transfer. They already slip when heavily loaded, or when the belt is old, or wet, or slightly loose - which all vee belts almost always are. The serpentine system is *better* but doesn't entirely solve it. The belt needs to be 2-3 ribs wider like it is on the 540A MRAP units, etc.

I would be concerned that my high amperage alternator isn't really all that high and won't really provide when needed due to slippage issues. There's typically a reason behind these decisions and it wasn't just a concern of fitting it in the space - the engine has to effectively spin it too.

 

[jmak]

The kit slings the alternator out further to get more belt wrap. The 260 and 300 when loaded can barely operate without belt slip as it is. Having the alt too close to the engine reduces wrap on the pulley and thus power transfer. They already slip when heavily loaded, or when the belt is old, or wet, or slightly loose - which all vee belts almost always are. The serpentine system is *better* but doesn't entirely solve it. The belt needs to be 2-3 ribs wider like it is on the 540A MRAP units, etc.

I would be concerned that my high amperage alternator isn't really all that high and won't really provide when needed due to slippage issues. There's typically a reason behind these decisions and it wasn't just a concern of fitting it in the space - the engine has to effectively spin it too.

Ah, gotcha. Someone else mentioned slippage concerns too. It's definitely slipping a bit as I noticed the belt labels were no longer aligned with each other after running it. I wasn't getting anything out of my original alternator likely due to a bad regulator, so I'm not super concerned.. maybe worth revisiting and trying to come up with a better tensioning system or different pulleys/belts if I ever add house batteries. It's working well enough to keep the output voltage high enough and keep four batteries charged, so I'm stoked to be saved from plugging into a trickle charger constantly for now.

 

[GeneralDisorder]

The truck itself draws very little power so I wouldn't expect it to be an issue at at the moment. It WILL present to you when the temp drops if you have a grid heater - those draw something like 90 amps at 28v and will load the cold alternator and belt that are both ~15 degrees and the belts will absolutely wake the dead with their protest.

Same thing happens if they are loaded down against a battery bank but you can somewhat better control when that occurs.

 

[ckouba]

Thanks Hike - interesting. General... I'd never even heard of Lizard Skin until it was mentioned here. I'll definitely check into it.

Kevin

Day late to the party but I'll give a recommendation to the Lizard Skin as well. Keeps our habitat quite manageable regardless of the temp outside- at least for heating inside. I don't have AC in the box yet but I imagine it'll perform comparably in that arena as well. Application is SUPER easy, although potentially messy. It's also a little spendy, but worth every dollar. I think about it every time it's cold outside and I am so happy I did it! Buy once, cry once, and then enjoy your creation.

We applied it to the entire interior of the habitat. I am seriously thinking of the underside of the doghouse and other cab sheetmetal.

 

[Kevin Means]

Our Lizard Skin stuff and spray applicator was delivered a couple of days ago. I still have to remove a few things from the cab before applying it, but it looks pretty straightforward. Funny... I'd never even heard of it before people here mentioned it. Now it seems like it's actually one of the more popular heat and soundproofing materials around. Thanks for the additional vote of confidence Ckouba.

Jmaik... I really appreciate your help the other day. If you have a chance (no hurry) could you measure the length of your alternator's body? I'd like to stick with the 260 amp unit I bought, but I don't want to waste time building brackets for it if it ultimately won't fit. If yours is the same size as mine - mine should fit, then, all I have to figure out is the voltage regulator wiring.

General, you mentioned something that I was wondering about - that is, how much power the alternator will actually put out. Belt-slippage is something I hadn't considered, but I'm also wondering about how much power the alternator will put out after the Eco Hubs are installed. They drop the engine's RPM considerably, and alternators really only reach their rated output at higher RPM, Any issues there?

Kevin

 

[GeneralDisorder]

There is no voltage regulator wiring to "figure out" - it's just the E ring terminal that gets the K11 relay signal to start the alternator. Same as the 100. The wiring between the two is absolutely identical.

RPM is no issue. The alternator makes it's rated power by the time the engine is at about 1200 RPM.

 

[Kevin Means]

OK. That helps. So am I to assume that the 10 pin plug on the 260 amp unit's voltage regulator doesn't get used at all? There is no such plug on the 100 amp unit's VR. That's what's been confusing me. The rest of the wiring looks pretty straightforward.

BTW Jmaik, I took careful measurements and I believe that my 260 amp unit WILL fit, albeit right up against the rubber boot on the exhaust, and it doesn't appear that the boot will hinder any of the alternator's cooling. Thanks, but I don't need you to measure your alternator.

Kevin

 

[Ronmar]

OK. That helps. So am I to assume that the 10 pin plug on the 260 amp unit's voltage regulator doesn't get used at all? There is no such plug on the 100 amp unit's VR. That's what's been confusing me. The rest of the wiring looks pretty straightforward.

BTW Jmaik, I took careful measurements and I believe that my 260 amp unit WILL fit, albeit right up against the rubber boot on the exhaust, and it doesn't appear that the boot will hinder any of the alternator's cooling. Thanks, but I don't need you to measure your alternator.

Kevin

The cannon plug is between alternator chassis and regulator… There should only be 5 alternator connections to the truck an all these are:
+28
+24
Ground
E screw terminal on regulator. This receives 28v in from K11 to enable alt output after the engine is running.
F- or AC terminal on regulator. On the A0 this was a field drive pulse width signal to the STE plug to monitor how hard the alternator field was being driven by the regulator(Load state). On the later trucks it is an alternator RPM signal used by the LBCD to help determine overload and if the alternator is putting out rated voltage. The LBCD controls the battery disconnect relay and the charge system failure idiot light in the dash Using this signal, a voltage measurement and a stopwatch…

 

[GeneralDisorder]

That diag port usually has a cap on a chain covering it for use. That is a CANBUS and diagnostic port that is not used on the FMTV A1's. It can be hooked into the J1939 and the VR will report alternator RPM, temperature, both voltage outputs, load percentage, and likely a few more things that are only understood by the Niehoff diagnostic software. The above listed items are seen by Dearborn diagnostics as generic generator PID's. In any case you should insulate that or find the cap that's supposed to be on it. Looking at your pics..... That's interesting that it came with an N3271 reg. The FMTV version typically comes with an N3221 regulator. Looks like the N3271 has more pins on that diag port so it's probably for some other application that uses that plug and thus why there was no cap provided for it. Look at N3221 pics and you'll see the cap. In any case it's all optional stuff. The E terminal stud is the only connection that alternator needs to run. It gets the 24v turn on signal from the NC contacts of K11 and it's rocks and roll till it stops spinning. You can't shut it off without shutting down the engine. Pulling the E terminal wire won't shut it down once it starts.

 

[Kevin Means]

Great! That's what I had hoped to hear. I'll cap it off. And the description of the 5 hookups from Ronmar was also good news - simple. I think my stunted brain can wallow through the alternator installation now. As usual, thanks

Kevin