Does the PPD do more than reverse polarity protect ? Modern replacement for PPD ?

[MatthewWBailey]

Found all of your 28SI alternator posts here:

Alternate Alternator Selection

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...

www.steelsoldiers.com

Pretty much the exact setup I was searching for. I will be knocking that off completely if/when my 100A Neehoff dies. Hoping to extend its life a bit by running a 24v setup only, but I am getting some voltage spikes on the trans currently as I mentioned in first post...

I tried searching your posts but didn't see any reference, what year/make is your truck ? A1 or A1R ?

'04 A1. I also had a few over voltage codes on the trans. It All began when the starter shorted. I still have to take the pulled Neihoff to the repair shop.

if you do this swap double check the existing belt length before ordering a shorter one. I used the wrong length at first. So my initial replacement was barely able to fit.

 

[InvictusDecretum]

WTF is this ? Is this normal ? I tried searching the forums and using google with "site:" prefix and not sure what to make of this... It was attached to the top lug of the PPD (fed directly from batts or alt). Is this normal ?








I know what this cable is for (INLET AIR HEATER), but not why it becomes what looks like a 10AWG or 12AWG cable, and then back to 4AWG... Is this some kind of strange "fuse" ? I don't get it. Not sure I've seen anything like it before.




I pulled this snip from one of Helicools videos... I also don't have the shunt and no evidence it's ever been installed on my '02 A1

 

[GeneralDisorder]

That's a fusible link. It is designed that way on purpose to burn through if the rated amperage draw of the heater exceeds it's rating. A "fusible link" is simply a section of wire that is intentionally several wire gauges smaller to contain the failure to a specific location. It's just like the various colored fusible links that feed high draw accesories and fuse panels on any old Chevy - you generally see them attached to the lug on the starter solenoid, etc. And yes that is the correct location - it should be on the battery 24v lug on the PPD/LBCD.

A1+ trucks don't have the shunt - they don't have the analog diagnostic plug that it was designed to feed. A1+ diagnostic kits use an inductive clamp rather than an on-board shunt and have only full digital diagnostic ports.

 

[MatthewWBailey]

WTF is this ? Is this normal ? I tried searching the forums and using google with "site:" prefix and not sure what to make of this... It was attached to the top lug of the PPD (fed directly from batts or alt). Is this normal ?


View attachment 922696


View attachment 922697
View attachment 922698

I know what this cable is for (INLET AIR HEATER), but not why it becomes what looks like a 10AWG or 12AWG cable, and then back to 4AWG... Is this some kind of strange "fuse" ? I don't get it. Not sure I've seen anything like it before.


View attachment 922695

I pulled this snip from one of Helicools videos... I also don't have the shunt and no evidence it's ever been installed on my '02 A1
View attachment 922699

I believe that is the inline fuse F3. My AIH lead has the same transition portion. F3 on the schematic has to be there since that cable only goes from LBCD to AIH.

 

[Ronmar]

Yea, he has an A0.5…

 

[InvictusDecretum]

That's a fusible link. It is designed that way on purpose to burn through if the rated amperage draw of the heater exceeds it's rating. A "fusible link" is simply a section of wire that is intentionally several wire gauges smaller to contain the failure to a specific location. It's just like the various colored fusible links that feed high draw accesories and fuse panels on any old Chevy - you generally see them attached to the lug on the starter solenoid, etc. And yes that is the correct location - it should be on the battery 24v lug on the PPD/LBCD.

A1+ trucks don't have the shunt - they don't have the analog diagnostic plug that it was designed to feed. A1+ diagnostic kits use an inductive clamp rather than an on-board shunt and have only full digital diagnostic ports.

Interesting, thanks for confirming what I thought its purpose was. I guess my question is, why not use a replaceable fuse ? Not a "critical" system and can confine the failure to a fairly open area (near the PPD) ?

I believe that is the inline fuse F3. My AIH lead has the same transition portion. F3 on the schematic has to be there since that cable only goes from LBCD to AIH.

View attachment 922700

Ahh, thanks. I'm an aspiring schematic reader and not quite there yet. This appears to confirm what you say:




And yeah... as Ronmar says, I have an early A1 truck so it is somewhere between an A0 and an A1. It's a fun challenge haha. Near as I can tell, this is how the truck was wired to/from the PPD. I've made this by looking at the A0 schematics, the A1 schematics, and then looking at my truck to see what is there and what size the cabling is (in case anyone needs/wants to do this in the future, I've also tried to include links to exactly what I'm using component wise).



So, I think I'm going to fuse that just like anything else off of the 24V 600A busbar with a 100A MRBF Fuse in a Block Terminal.



1892W @ 24V = ~78A
If my voltage drops to 22V, it'll draw 86A.


To pass 90-100A across 10' with a voltage drop of 3% or less I need 4AWG (Which it already is, so I'll hydraulic crimp splice it with some Ancor Marine Grade Primary Wire 4AWG from the PPD area to the battery box.

 

[MatthewWBailey]

If my voltage drops to 22V, it'll draw 86A

Your ohms law is not obeying your command. Wattage is not constant, resistance is. If the full
Load is 1892/24=78.8A, then V/I=R is 24/78.8=0.3044=R. At 22v, V/R=I = 72.3A

only with motors (induction) will current go up when voltage drops.

 

[Ronmar]

Thems fuses and holders cost good money boy…

 

[InvictusDecretum]

Your ohms law is not obeying your command. Wattage is not constant, resistance is. If the full
Load is 1892/24=78.8A, then V/I=R is 24/78.8=0.3044=R. At 22v, V/R=I = 72.3A

only with motors (induction) will current go up when voltage drops.

Thanks, appreciate that correction. Quite familiar with ohms and kirchoffs laws and shouldnt have made such a rookie error ! I mostly deal with micro controllers and stepper motors kind of stuff.

Thems fuses and holders cost good money boy…

Haha you're telling me... I feel like a fire would be more costly though. Not sure that's ever happened, but I would be the unlucky one to experience it. Especially with removing the PPD.

They're pretty common in boat, RV, and offroad builds. Blue Sea makes good stuff. I bought the MRBFs for this but I already have the 285 series and two of the 3 bus bars from previous builds.