H.O. alternators
Fleet Owner
Joined: Jun 2004
Posts: 25,090
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From: Rio Rico, AZ.
At the very least run a separate wire to the charge wire for the trailer plug
and install a shunt between the positive post of the alternator and the positive post on the driver's side battery.
That will off load the current from the truck's main wiring harness and all it has to do is to run the truck.
Senior User
Joined: Sep 2004
Posts: 329
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From: Carroll County, MD
Dan
Good thought on the wiring between alt and batt. I would suggest add a ground wire as well, also large gauge. I have seen on alot of the big alts that there is a neg terminal as well as a pos terminal, so might as well use them both.
Correct me if I am wrong, but if the 7-pin trailer plug is stock, or at least tied into the stock wiring, there should be a fuse in the circuit for the charge pin, as well as a relay so the pin is dead when the truck is not running. Here is an interesting thought, though - is there something on the trailer that is sending a surge or spike back to the truck to zap the alt.
Good thought on the wiring between alt and batt. I would suggest add a ground wire as well, also large gauge. I have seen on alot of the big alts that there is a neg terminal as well as a pos terminal, so might as well use them both.
Correct me if I am wrong, but if the 7-pin trailer plug is stock, or at least tied into the stock wiring, there should be a fuse in the circuit for the charge pin, as well as a relay so the pin is dead when the truck is not running. Here is an interesting thought, though - is there something on the trailer that is sending a surge or spike back to the truck to zap the alt.
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Post Fiend
Joined: Sep 2006
Posts: 5,584
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From: Millbrook Alabama
the other problem with alts is heat dissipation. them electron pushing thingeys hate being hot.
I'm guessing that you have a load problem with shore power towing the trailer. Mine will charge the trailer battery and I see a definate 20 amp spike which with the A/c and lights on doesn't leave much room for capacity on the 100 amp alt I have in my truck.
perhaps starting the truck 15 minutes before towing to top off the onboard battery set?
I'm guessing that you have a load problem with shore power towing the trailer. Mine will charge the trailer battery and I see a definate 20 amp spike which with the A/c and lights on doesn't leave much room for capacity on the 100 amp alt I have in my truck.
perhaps starting the truck 15 minutes before towing to top off the onboard battery set?
The other thing you could do is install a circuit breaker on the charge wire going to the 7 way plug.
They are those little rectangle boxes with two posts on them.
NAPA has them in (I think) 15, 25, 50 amp ratings.
They are self resetting so you don't have to worry about keep flipping a switch, but the downside is they will take a very long time to recharge a dead battery.
And the trailer brakes rely on that same battery in a break-away situation.
I don't know if they use the battery during normal driving or if the trailer gets electric brake power from the truck when it is being towed. Not familiar with that part of the trailer design.
They are those little rectangle boxes with two posts on them.
NAPA has them in (I think) 15, 25, 50 amp ratings.
They are self resetting so you don't have to worry about keep flipping a switch, but the downside is they will take a very long time to recharge a dead battery.
And the trailer brakes rely on that same battery in a break-away situation.
I don't know if they use the battery during normal driving or if the trailer gets electric brake power from the truck when it is being towed. Not familiar with that part of the trailer design.
Brandon, are you leaving something ON in the TT that might be draining that battery way down or perhaps the TT battery has a shorted cell? You could and probably should charge the TT off shore power before towing. Actually that is probably good advice for all of us. 
With that being said, if you go with the 220 you have an alternator that doesn't have to work as hard and that has plenty of reserve if needed. Electrically speaking, bigger is usually better.....
With that being said, if you go with the 220 you have an alternator that doesn't have to work as hard and that has plenty of reserve if needed. Electrically speaking, bigger is usually better.....
Camper is charged on shore power for at least 3 days before truck is ever backed under it. I need to check the cells in the camper batt.
The thought occurred to me reading this post, is that if you put in a mondo alternator like that, you also need to upgrade the wiring on the truck.
At the very least run a separate wire to the charge wire for the trailer plug
and install a shunt between the positive post of the alternator and the positive post on the driver's side battery.
That will off load the current from the truck's main wiring harness and all it has to do is to run the truck.
At the very least run a separate wire to the charge wire for the trailer plug
and install a shunt between the positive post of the alternator and the positive post on the driver's side battery.
That will off load the current from the truck's main wiring harness and all it has to do is to run the truck.
Dan
Good thought on the wiring between alt and batt. I would suggest add a ground wire as well, also large gauge. I have seen on alot of the big alts that there is a neg terminal as well as a pos terminal, so might as well use them both.
Correct me if I am wrong, but if the 7-pin trailer plug is stock, or at least tied into the stock wiring, there should be a fuse in the circuit for the charge pin, as well as a relay so the pin is dead when the truck is not running. Here is an interesting thought, though - is there something on the trailer that is sending a surge or spike back to the truck to zap the alt.
Good thought on the wiring between alt and batt. I would suggest add a ground wire as well, also large gauge. I have seen on alot of the big alts that there is a neg terminal as well as a pos terminal, so might as well use them both.
Correct me if I am wrong, but if the 7-pin trailer plug is stock, or at least tied into the stock wiring, there should be a fuse in the circuit for the charge pin, as well as a relay so the pin is dead when the truck is not running. Here is an interesting thought, though - is there something on the trailer that is sending a surge or spike back to the truck to zap the alt.
Senior User
Joined: Sep 2004
Posts: 329
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From: Carroll County, MD
Well, if nothing is on in the trailer while towing, then there is nothing to do the zapping - I was thinking maybe an inverter or a fridge, but you have that covered.
Does the trailer have a seperate battery for the breakaway brakes? I am not familiar with 5ers, so I am not even sure if they have them. If so, check both electrical systems (main and emerg) on the trailer.
If you want to unhook the charge circuit, and you are working with stock, you can pull the fuse or relay (forget the number of each off the top of my head, but they are there)
Does the trailer have a seperate battery for the breakaway brakes? I am not familiar with 5ers, so I am not even sure if they have them. If so, check both electrical systems (main and emerg) on the trailer.
If you want to unhook the charge circuit, and you are working with stock, you can pull the fuse or relay (forget the number of each off the top of my head, but they are there)
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Post Fiend
Joined: Sep 2006
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From: Millbrook Alabama
Spinge, the 5er only has one batt, and the brakes are wired into it. I think the trailer brake system is designed to use the power from the truck for the brakes, unless the breakaway is pulled, and then it operates off the camper batt, so I guess the idea of putting a disconnect in the center pin is out. I dont think I would like the idea of a batt with no recharge operating my trailer brakes for a whole trip.
backtracking to the back surge idea, Chris mentioned to me one time that maybe I blew my diodes by plugging the tralier connection into the truck while shore power was still attached(or plugging in shore power at the campsite before truck is disconnected). I have tried to make a conscience effort to make sure this doesnt happen, but sometimes you have little helpers, and I cannot say for sure that this hasnt happened. thoughts?
backtracking to the back surge idea, Chris mentioned to me one time that maybe I blew my diodes by plugging the tralier connection into the truck while shore power was still attached(or plugging in shore power at the campsite before truck is disconnected). I have tried to make a conscience effort to make sure this doesnt happen, but sometimes you have little helpers, and I cannot say for sure that this hasnt happened. thoughts?
Senior User
Joined: Sep 2004
Posts: 329
Likes: 0
From: Carroll County, MD
Very good thought (I have little helpers too). If there is a battery charger on the trailer, and the shore power is plugged in while the trailer is still connected and truck running, it could very well happen.
Thoughts to solve the problem would be:
1) Some type of battery isolation device (a fancy name for a diode) to prevent trailer power from heading back into the truck.
2) Some type of relay in the power supply to the charger (on the shore power side) that is connected to the battery charge circuit from the truck. The relay would only allow the charger to come on once the truck was disconnected or shut off.
Thoughts to solve the problem would be:
1) Some type of battery isolation device (a fancy name for a diode) to prevent trailer power from heading back into the truck.
2) Some type of relay in the power supply to the charger (on the shore power side) that is connected to the battery charge circuit from the truck. The relay would only allow the charger to come on once the truck was disconnected or shut off.
Senior User
Joined: Sep 2004
Posts: 329
Likes: 0
From: Carroll County, MD
Ya can't keep kids from doing what they do, you can only protect your stuff so they don't hurt it too bad - LOL
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Post Fiend
Joined: Jul 2005
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From: 21791
I didnt read much of the post, but while you are at it, get a three or four foot long 4 gauge red cable, put two ring ends on it, attach one end to the driver's side battery and the other to the output post on the alternator. That's alot of amperage when full-fielded to be going through the stock 4 ga cable in the harness that goes to the PASSENGER side battery. Dont worry about a ground, it's already grounded twice.
Senior User
Joined: Sep 2004
Posts: 329
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From: Carroll County, MD
Kris,
The only reason I suggested the ground is because alot of times the alt manufacturer will put the terminal on there. That leads me to think that they don't trust the ground straps on the motor, or the mounting bolts and such. In my younger years I did a BUNCH (20 years) of work on fire trucks, and the biggest single cause of electrical problems was bad grounds. Especially for us - MD = salt on roads in winter = corrosion. It is amazing what .5 ohms can do to an electrical system
The only reason I suggested the ground is because alot of times the alt manufacturer will put the terminal on there. That leads me to think that they don't trust the ground straps on the motor, or the mounting bolts and such. In my younger years I did a BUNCH (20 years) of work on fire trucks, and the biggest single cause of electrical problems was bad grounds. Especially for us - MD = salt on roads in winter = corrosion. It is amazing what .5 ohms can do to an electrical system
Gone Fishin for Mark
Joined: Nov 2004
Posts: 1,354
Likes: 2
From: West of Houston
Wiring Code 7 way Car End # Color Gage Circuit Function connector interior
1 white 10 common ground
2 blue 12 electric brake
3 green 14 tail/running lights
4 black 10 battery charge (+)
5 red 14 left turn/stop
6 brown 14 right turn/stop
7 yellow 14 auxiliary/back up
NOTE: #7 is the center terminal and currently is most commonly used for backup lights.
The trailer brakes operate off of current sent from the brake controller. The trailer battery supplies current only if the break-away is pulled. If you are using the center pin for charging and the camper is using the # 4 pin, perhaps we are on to something. Also take note of the wire guage sizes.
Enjoy this day.
1 white 10 common ground
2 blue 12 electric brake
3 green 14 tail/running lights
4 black 10 battery charge (+)
5 red 14 left turn/stop
6 brown 14 right turn/stop
7 yellow 14 auxiliary/back up
NOTE: #7 is the center terminal and currently is most commonly used for backup lights.
The trailer brakes operate off of current sent from the brake controller. The trailer battery supplies current only if the break-away is pulled. If you are using the center pin for charging and the camper is using the # 4 pin, perhaps we are on to something. Also take note of the wire guage sizes.
Enjoy this day.
Senior User
Joined: Sep 2004
Posts: 329
Likes: 0
From: Carroll County, MD
Either with or without a ground wire, the point is make sure that there is a GOOD ground, as even minimal resistance can cause you headaches.
Joe may be on to something if there is a mis-wiring between the trailer and truck, but I would think that the problem would be instant with a fault like that.
Joe may be on to something if there is a mis-wiring between the trailer and truck, but I would think that the problem would be instant with a fault like that.
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Post Fiend
Joined: Sep 2006
Posts: 5,584
Likes: 0
From: Millbrook Alabama
Wiring Code 7 way Car End # Color Gage Circuit Function connector interior
1 white 10 common ground
2 blue 12 electric brake
3 green 14 tail/running lights
4 black 10 battery charge (+)
5 red 14 left turn/stop
6 brown 14 right turn/stop
7 yellow 14 auxiliary/back up
NOTE: #7 is the center terminal and currently is most commonly used for backup lights.
The trailer brakes operate off of current sent from the brake controller. The trailer battery supplies current only if the break-away is pulled. If you are using the center pin for charging and the camper is using the # 4 pin, perhaps we are on to something. Also take note of the wire guage sizes.
Enjoy this day.
1 white 10 common ground
2 blue 12 electric brake
3 green 14 tail/running lights
4 black 10 battery charge (+)
5 red 14 left turn/stop
6 brown 14 right turn/stop
7 yellow 14 auxiliary/back up
NOTE: #7 is the center terminal and currently is most commonly used for backup lights.
The trailer brakes operate off of current sent from the brake controller. The trailer battery supplies current only if the break-away is pulled. If you are using the center pin for charging and the camper is using the # 4 pin, perhaps we are on to something. Also take note of the wire guage sizes.
Enjoy this day.
Kris, yes I will be upgrading the wire directly from the alt. to the batt, the new one will come with it.
Here is the alt that I am ordering. eBay Motors: FORD F TRUCK 7.3L HIGH OUTPUT ALTERNATOR 98 99 00 01 (item 160273403505 end time Aug-24-08 11:19:37 PDT)
but I will call them in the morning to get it. it should be here wednesday