Alternate Alternator Selection

[GeneralDisorder]

Just another data point, my 2 6tl flooded (770ca) didn't have enough juice to start my C7 at about -10F. Supposedly agm are better cca at over 1000 for most brands. I may end up with 4x agm 6tl to deal with WI winter.

Yes the AGM's are 1150 CCA each. And they aren't nearly as affected by cold temps as the flooded batteries or the lithium batteries. The FMTV's had arctic battery heating kits as optional accessories - basically unnecessary with the AGM's.

 

[aw113sgte]

Looking around at similar alternators to ours, price really isn't that different when everything taken in. Then have to deal with different mounting, the converter for 12V and then have the LBCD. If you don't need high output it can be done cheap it looks like (under $1K)

 

[MatthewWBailey]

Well you guessed the alternator I'm running. The difficulty is the availability, the horrendous price from Niehoff, and the bracket situation. A few of them have turned up in the surplus world - mostly attached to HIMARS crate engines - but that supply has dried up for the time being along with the M-ATV 370HP engines, and a lot of other stuff since we started giving away every spare HIMARS and MRAP to Europe.

The 260's have had bracket failures according to my sources and the 300 is 28 lbs heavier. So I'm not satisfied that my current solution is going to be suitable long term and as such I'm not going to show what I did or recommend anyone copy me.

That said - unless you have a late model A1R C7 truck - fitment is going to be a real headache. The 300 is 1/4" from the turbo compressor housing, and about an index finger's width from the coil-over shock mount. It's obvious what happened here - Someone asked Niehoff to fill the entire available space with alternator and the 300 was designed specifically for that purpose - probably first with the Buffalo A2 MRAP - but that ran a C13 engine. Force Protection produced about 450 of those trucks. Lockheed's production volume of the HIMARS that shares our C7 and chassis in 2022 was 48 units per year, giving a rough estimate of ~576 units having been produced since 2010 and it's actually less than that since early year production volume was much lower. Considering spare parts acquired to support the fleet, and production volume - it's no wonder that we don't see high serial numbers on these alternators. They are very specialized, very expensive, and only used for trucks with a lot of electronics.

You can buy one from Niehoff - just fill out the EUC and give them $7,450 or so. Plus tax and shipping.

Funny I bought one of these N1313-6 300A's last February off eBay for $500 + $130 shipping from FL. Seemed like maybe a good deal at the time as I was considering an upgrade. Looks brand shiny new. Date on reg says 2018. It was a purchase on spec. When it arrived I took it out and pondered my sanity after measuring. Seems like it's an act of God to fit it in there?

 

[Ronmar]

Even 100A @28V is a LOT of power. 2.8KW. The issue with the 100A dual volts is that the load on the 12v side reduces its output by 1/3, to ~1950W when both sides are fully loaded. If S&S would have put in a straight 24v alt and a converter/equalizer, these trucks would have been bulletproof electrically until they fielded AGM batteries. At straight 28V a 4 battery 240AH wet cell bank is only looking for 60A out of the alt. I would be surprised if the truck 28V load is over 10A and the 12v loads converted to 24V are under 15A@28v max, so 85% alt load worst case hell a 140A alt would support four 6T AGMs reasonably well at ~95% load worst case/dead battery…

Worst case my group 31’s want 25A(AGMs 45A), but if they are charged, being smaller, they should peak fairly quickly after a start, so should stay at a higher state of charge even if only driven low hours. With my 100A alt, and charged batts, I am left with the 25A@28V of peak truck load when everything is turned on. That means I have 50+A@28V(1400W) available to throw at house battery charging and still only be at 75% alt load… If I covered my habitat roof with solar, i might could get 1500W peak…

Going over 150A@28V is crazy talk IMHO. Unless you are doing something really off the wall, The truck simply does not need it...

 

[GeneralDisorder]

Funny I bought one of these N1313-6 300A's last February off eBay for $500 + $130 shipping from FL. Seemed like maybe a good deal at the time as I was considering an upgrade. Looks brand shiny new. Date on reg says 2010. It was a purchase on spec. When it arrived I took it out and pondered my sanity after measuring. Seems like it's an act of God to fit it in there?

It's quite the job on the 3116 and 3126b trucks - cutting huck bolts and upgrading a bunch of wiring and mounting hardware. Not impossible but there's probably easier ways to go about getting more alternator. Definitely cheaper if you are considering what Niehoff wants for one. It's not so difficult for the C7 A1R trucks - serial number 101,906 and higher trucks with the coil-over front shock mounts and factory 260A alternator (even higher in the serial number range). For us the world is a much more accommodating place. And our trucks can have 370 HP and a whole array of other benefits that make them worth the entry price once you have experienced the sum total of their benefits. When I drive an A0 or older A1 truck now it really feels like the those trucks are just "mushy" in many respects. My 2008 A1R is tight and crisp and just that last bit more refined that really sets it apart. But most people don't experience it and don't understand what I mean.

 

[hike]

The more I read the more I think 100 to 150a 24v alternator is all that is needed for cab and chassis only, even with a 24v HVAC system for the cab.

We are thinking of splitting to a system of two 2-12vAGM's in series (first set to the starter; second set to the PDP @h X1, with a 24/12 70a dc2dc converter between X1 and X2), and replacing the LBCD with a Victron Cyrix-ct 225a 12/24v battery combiner. At the same time it looks like we can drop the polarity protection, too?

If I am thinking about this right the starter batteries would be charged 'first' and maintained. The alternator will drive the PDP and it's second battery set would only need be maintained as needed, and charged after running accessories that we may run while parked without the engine running. The Cyrix also allows the PDP set to back up the starter set if needed.

This will also work when we replace the dual Niehoff with a straight 24v '150a' alternator when that time comes.

Batteries, new alternator, and battery isolator/combiner all off the shelf, available overnight for a reasonable cost without reconfiguring the whole system: Cyrix replaces LBCD, polarity disconnect comes out (or not), 24/12v 70a added at the PDP, 4- batteries likely maintained with existing alternator running 24v only—

 

[Ronmar]

That sounds a little complex. Now a second set of batts isnt a bad idea especially if you are in VERY cold(below zero) temps. But that can be done with a simple BIRD relay either on a timer or a current sense control. Allows time for first batt to charge then connects second, or waits till current to first batt decreases enough to connect second set.

Or a fixed dc-dc charge controller that only connects and charges the second set when the engine is running. That along with a manually controlled contactor to tie the two batts together for start assist and you are good.

I work on an emergency vehicle so configured tgat ties service and house batts onto the alt when the alt is online. It has a manual switch to connect them as needed so house batts can help start the engine.

The LBCD has polarity protection in it, but the sole purpose of its control is to disconnect a too large battery from a too small alt if it overloads the alt. If the batts cannot overload the alt, it becomes unnecessary...

 

[hike]

That sounds a little complex. Now a second set of batts isnt a bad idea especially if you are in VERY cold(below zero) temps. But that can be done with a simple BIRD relay either on a timer or a current sense control. Allows time for first batt to charge then connects second, or waits till current to first batt decreases enough to connect second set.

Or a fixed dc-dc charge controller that only connects and charges the second set when the engine is running. That along with a manually controlled contactor to tie the two batts together for start assist and you are good.

I work on an emergency vehicle so configured tgat ties service and house batts onto the alt when the alt is online. It has a manual switch to connect them as needed so house batts can help start the engine.

The LBCD has polarity protection in it, but the sole purpose of its control is to disconnect a too large battery from a too small alt if it overloads the alt. If the batts cannot overload the alt, it becomes unnecessary...

Is it complex?

Use a Victron 24/12 70a to power the PDP's 12v side utilizing the full 24v side of the Niehoff alternator while the engine is running; charge 2 batteries in series maintained by the alternator's 24v side for starting, eliminating over charging, alternator over heating, and need for LBCD.

Add the Victron Cyrix (24v 230a about $120 smart battery combiner) set to first maintain the first (starter) 2 batteries in series and once charged maintain a second (PDP) 2 batteries in series.

The separate wiring to starter and PDP already exists, add wiring for the seperate battery banks. This eliminates the LBCD, keeps most the existing wiring and components while using your 2 battery idea with the existing Niehoff 100a alternator at 24v to manage two 2 battery banks; one bank at a time with readily available bits and pieces

This creates two 2- battery systems maintained by a battery combiner instead of an LBCD—

 

[coachgeo]

Is it complex?

Use a Victron 24/12 70a to power the PDP's 12v side utilizing the full 24v side of the Niehoff alternator while the engine is running; charge 2 batteries in series maintained by the alternator's 24v side for starting, eliminating over charging, alternator over heating, and need for LBCD.

Add the Victron Cyrix set to first maintain the first (starter) 2 batteries in series and once charged maintain a second (PDP) 2 batteries in series.

The separate wiring to starter and PDP already exists, add wiring for the seperate battery banks. This eliminates the LBCD, keeps most the existing wiring and components while using your 2 battery idea with the existing Niehoff 100a alternator at 24v to manage two 2 battery banks; one bank at a time with readily available bits and pieces

This creates two 2- battery systems maintained by a battery combiner instead of an LBCD—

the Neihoff dual alt does not function well with both sides still being used... and keep in mind..... the 100 amp Niefoff is only 50-ish amp on 24 side.

 

[hike]

the Neihoff dual alt does not function well with both sides still being used... and keep in mind..... the 100 amp Niefoff is only 50-ish amp on 24 side.

The Victron 24/12v 70a connecyed at PDP X1 supplies 12v to the PDP X2. Leave a 12v feed to keep dual alternator happy. Only load on alternator is 24v. 28v 100a should be 2.8kW—

 

[Ronmar]

But it sounds like you are dividing your power system, one for starter, one for pdp? I dont personally see a need for this...

The alt must see both 12 and 24v connections to a series battery string to regulate correctly. Beyond that you should be able to pull 2.8KW@28v. Mine does...

 

[Lostchain]

Hey as long as your coming up with outlandish solutions, what about this one:

Take a set of lawn mower batteries like here and connect the alternator directly to them. Then, have a 12v and a 24v DC to DC pair of chargers to connect to the 4 6TLs in the stock location. Those DC to DC chargers are turned on/off by tapping into the E wire of the alt VR. The alternator will never be overloaded, and if you somehow drain the 6TLs with your RV, you could get a couple of jumps to the truck out of the lawnmower batteries, lol.

 

[hike]

But it sounds like you are dividing your power system, one for starter, one for pdp? I dont personally see a need for this...

The alt must see both 12 and 24v connections to a series battery string to regulate correctly. Beyond that you should be able to pull 2.8KW@28v. Mine does...

We see it as a good path forward as we are adding 24v AC to the cab.

Another way to separate out the AC and non essential accessories would be to replace the Niehoff dual with a 28v 200a and reuse the 12v lines to run 24v for the AC and accessories straight off the second battery bank. Except for the cost of the new alternator this would be a better path:

Simply stated. 28v 200a alternator to Victron smart 24v battery combiner (Cyrix-ct 24v 230a) to: starter and PDP run by two batteries in series (~35a); added accessories and AC run by two batteries in series (>=70a)–

 

[hike]

Hey as long as your coming up with outlandish solutions, what about this one:

Take a set of lawn mower batteries like here and connect the alternator directly to them. Then, have a 12v and a 24v DC to DC pair of chargers to connect to the 4 6TLs in the stock location. Those DC to DC chargers are turned on/off by tapping into the E wire of the alt VR. The alternator will never be overloaded, and if you somehow drain the 6TLs with your RV, you could get a couple of jumps to the truck out of the lawnmower batteries, lol.

View attachment 915904

Your efforts paid off; thanks for the laugh.

Habitat will have a separate system–

 

[MatthewWBailey]

It's quite the job on the 3116 and 3126b trucks - cutting huck bolts and upgrading a bunch of wiring and mounting hardware. Not impossible but there's probably easier ways to go about getting more alternator. Definitely cheaper if you are considering what Niehoff wants for one. It's not so difficult for the C7 A1R trucks - serial number 101,906 and higher trucks with the coil-over front shock mounts and factory 260A alternator (even higher in the serial number range). For us the world is a much more accommodating place. And our trucks can have 370 HP and a whole array of other benefits that make them worth the entry price once you have experienced the sum total of their benefits. When I drive an A0 or older A1 truck now it really feels like the those trucks are just "mushy" in many respects. My 2008 A1R is tight and crisp and just that last bit more refined that really sets it apart. But most people don't experience it and don't understand what I mean.

After rummaging in my shop, Looks like I forgot that I bought a 260 after realizing the 300 would be impossible. Is the 260 a manageable retrofit? This one is definitely used so I'll have to test it but the seller said it came from Northern Pacific Repair in WA.

 

[GeneralDisorder]

After rummaging in my shop, Looks like I forgot that I bought a 260 after realizing the 300 would be impossible. Is the 260 a manageable retrofit? This one is definitely used so I'll have to test it but the seller said it came from Northern Pacific Repair in WA.

The 260A is several inches shorter and 26 lbs lighter and doesn't need as much clearance with the shock tower because it doesn't have the side mounted output. But it does still require the shock mount be spaced out due to it's diameter and it uses a different engine mount and longer belt.

 

[MatthewWBailey]

I figured I'd post the progress here instead of the starter thread, since others may look here first for alt options.

I got the delco-Remy aftermarket alt today and mocked it up with some 3/8 studs. I don't have any 4" long 3/8 bolts but I'll get them tomorrow. See photos. The unit fits perfectly in that mount with space behind. Seems peachy. My old pulley fits right on there. The shipping box had a test report in it. Says 130a max output. for $170, I'm hoping this'll be reliable. 110a is the nominal rating at 24v

The belt is obviously long. I measured a 4.5" closer pulley position from the old pulley centerline with the tensioner at half position. So that's 9" shorter belt I need.

the parts spreadsheet says the 3126 has a 78.25" long k8 belt. I wonder if Napa will have the shorter one. More research..

anyway, we'll see tomorrow if the hot test works. This delco Remy is a brush type alt and single voltage which accounts for the smaller size. Probably not as mil spec as the neihoff but I just need simplicity.

 

[coachgeo]

I figured I'd post the progress here instead of the starter thread, since others may look here first for alt options.

I got the delco-Remy aftermarket alt today and mocked it up ...

is that 25.x Volts; enough volts?? considering their is likely a reason OEM FMTV is 28.x volts.

 

[Ronmar]

The normal regulated voltage for 24v alts is typically ~27.5-27.7V. that works out to 13.75 per battery, which is a high float charge voltage for wet cells and a little friendlier on outgassing the batteries on vehicles that run long hours on the highway. Our 28v alts are a little hot for extended runtimes… That 25.48(12.74/battery) on the spec sheet is probably the voltage at full load and not the actual mean regulated voltage, as that would be just under 100% SOC on a battery and the point where a battery would start to really kick in to support a load test pile…

 

[MatthewWBailey]

Here's the literature from delco. This has remote sense so is supposed to maintain 14v (28v) at battery per the info.https://www.delcoremy.com/getmedia/...elco-28SI-Single-Page-Brochure-12-14.pdf.aspx