Rippoff by design???

I was hauling manure for a friend with my '16 Duramax and 14k dump trailer today. On the 3rd load the battery in the trailer was getting weak already, so I went home and put the big charger on it and check the charge fuse on the truck. Sure enough, it had blown. It was a little square "micro" 30 amp female type like I had never seen before. Walmart didn't carry them, so had to go further into town to the auto parts store. They had it...$4.97 each! Nothing special about it, except the price...no reason the little spade fuses could not have been used at a much lower cost. I suppose some engineer got taken out to lunch by the manufacturer of that fuse, so that is what he used. I'm thinking of "re-engineering" it to use the cheaper fuse. If I forget to unplug the trailer every time I dump it seems it can blow the fuse...did it with my Dodge also. You would think they would have something to guard against this....

I tow every day with my 2016 duramax. My full size, deep cell battery(option)also ran low in my trailer. I charged it back up. Now wondering if I have a blown fuse. Where is this fuse?

It is #2 on the main fuse cover under the hood. I think it is called "trailer charge" fuse.

You should be able to replace it with a circuit breaker, I'm pretty sure our boat has a 30 amp breaker for the trolling motor. If my wife runs it wide open for too long it will trip. I bought a 15 amp last summer for <$10.

(quoted from post at 18:33:43 11/28/17) You should be able to replace it with a circuit breaker, I'm pretty sure our boat has a 30 amp breaker for the trolling motor. If my wife runs it wide open for too long it will trip. I bought a 15 amp last summer for &lt;$10.

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I need to look into that....maybe I can use a blown fuse and solder one to it. It is ridiculous to have an expensive 30 amp fuse in this application.....

Eldon quick deal and will solve your problem. Go back on the trailer tong before the plug and install a 10 amp circuit breaker like is the dash of the big over the road trucks. Can get one from NAPA if you forget and use the dump with the trailer it will trip the breaker but resets itself and charging will continue. Have this set up on our electric winches on gooseneck trailers, keeps the draw off the truck when we use the winch then goes back to charge afterwards.

We run late model FORDS but they have a fuse in the trailer live wire and that circuit breaker on the charge wire there before it goes to the trailer battery as solved that problem for us. Soon as you hit the winch or the battery begins to pull that charge wire the breaker trips and resets latter.

(quoted from post at 18:50:23 11/28/17) Eldon quick deal and will solve your problem. Go back on the trailer tong before the plug and install a 10 amp circuit breaker like is the dash of the big over the road trucks. Can get one from NAPA if you forget and use the dump with the trailer it will trip the breaker but resets itself and charging will continue. Have this set up on our electric winches on gooseneck trailers, keeps the draw off the truck when we use the winch then goes back to charge afterwards.

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Thanks, looking at them on the internet I wonder why they are not setup with these from the factory as cheap as they are.....

Here is what I did to remedy the expensive fuse problem I bought a fuse holder for the standard blade type fuses crimped on a couple of
insulated female ends slid them onto the terminals where that big expensive fuse was and it works great.

(quoted from post at 20:14:18 11/28/17) Here is what I did to remedy the expensive fuse problem I bought a fuse holder for the standard blade type fuses crimped on a couple of
insulated female ends slid them onto the terminals where that big expensive fuse was and it works great.

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That is what I would like to do, but this fuse is a smaller "micro" fuse....they probably heard that people were doing what you did, so they had to make it more difficult to "re-engineer" :x

You got a 60K truck and complain about $5 fuse, much more expensive things to fail.

(quoted from post at 18:33:43 11/28/17) You should be able to replace it with a circuit breaker, I'm pretty sure our boat has a 30 amp breaker for the trolling motor. If my wife runs it wide open for too long it will trip. I bought a 15 amp last summer for &lt;$10.

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You wife is the only one to run it wide open for too long?

You can buy an assortment on internet, brings it down to about $.50 each, if Ford uses same fuses I will get some.

Thanks for making me look so I get some.

It's not some diabolical plot. The engineer's challenge is to squeeze ten pounds of potatoes in a five-pound bag. Each year, the electrical content of vehicles goes up, while the room for it stays the same or gets smaller. Whoever designed that fuse panel was told how big it could be, how many circuits it would have and how much current each of those circuits must carry. Given those constraints, the engineer is forced to use fuses small enough that they'll all fit. The likelihood of the trailer fuse blowing was most likely not a consideration at all. And let's not forget that those fuses aren't cheap for the manufacturer, either, even though they're buying a hundred thousand at a time. (The panel is most likely designed and built by a supplier; they pass their cost on to the OEM, but suppliers are always under pressure to bring their component prices down.)

If it's any consolation, the price of those fuses will come down over time as they become more common.

You could also install a battery isolator like is used for a second battery on campers. It would let the trailer battery
charge but stop the electrical load from back feeding the charging circuit when you dump the trailer. That way you
wouldn't need to disconnect the wiring each time.

Your fuse blew because the alternator was trying to charge the depleted trailer battery through the inadequate factory wiring. That circuit was meant to keep RV trailer batteries topped off between campgrounds, not to charge a deeply discharged battery. It's only 12ga wire, at best.

You need to run a 2ga dedicated charge line with an appropriate circuit breaker back to the trailer if you want to have any hope of keeping the battery charged between loads. Lots of RV "boondockers" do this because they're trying to charge their trailer batteries on the road too.

Farm tractors are the worst for that sort of thing.Take hydraulics on most farm tractor hydraulics crazy complicated for no good reason,a crankshaft driven pump with a set of valves and tank would be better than most were ever built with a mounted on hydraulic 3pt with external cylinders.But it'd be too easy to repair for the farmer,also designing the whole hydraulic system around plowing
when most users plowing was a very small part of the use of the tractor.

(quoted from post at 00:34:56 11/29/17) You got a 60K truck and complain about $5 fuse, much more expensive things to fail.

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I was thinking the same thing!
:lol:

Well I have a winch on a hydraulic tilt flatbed and a dump trailer I pull with my 99 Ford 550 and never have had any issues with charging the battery back up after using either.

It?s actually the opposite, 2 gauge wire would ensure the fuse
blows. Smaller wire self limits the charge rate by its
resistance.

Likely you have a very good battery on your trailer with good leads to the winch so it doesn?t have to suck on the trucks battery very heavily.

If your local battery is too small or old the voltage drop under load will cause a large draw from the charge circuit. A small charge wire can limit the current by acting as a resistor. A large wire allows more current to flow in the charge circuit.

As mentioned a self resetting breaker is a great idea.

(quoted from post at 05:18:19 11/29/17) Your fuse blew because the alternator was trying to charge the depleted trailer battery through the inadequate factory wiring. That circuit was meant to keep RV trailer batteries topped off between campgrounds, not to charge a deeply discharged battery. It's only 12ga wire, at best.

You need to run a 2ga dedicated charge line with an appropriate circuit breaker back to the trailer if you want to have any hope of keeping the battery charged between loads. Lots of RV "boondockers" do this because they're trying to charge their trailer batteries on the road too.

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I know why the fuse blew...I was hoping a new truck would have a mechanism to prevent blowing the fuse. If they are only thinking RV's someone is not doing their job. As for space constraints, the small flat fuses take up less space than this square fuse.
I hauled two 5 ton loads per hour after replacing the fuse, 12 total and still had some juice left when I got done, not bad for starting with a low battery. I can live with that, it's having to unhook the power cord each dump that is ridiculous.

you could prevent this by putting in a switch on the trailer in to disconnect the truck from the trailer motor when in use so it doesn't draw from the truck. then switch it back when you're done. or have it wired so the power switch automatically disconnects the truck when on and reconnects the truck when off.

I just glanced over this subject yesterday as I am not a truck person. Today, read it and replies and finally realized what you are talking about. You have a trailer with it's own battery on it to operate a dump operation. Along with that you have a factory hookup that provides a system to keep that trailer battery charged. So, when you use the dump that voltage on that trailer battery is going to fall below normal alternator charging voltage , thus, the alternator goes to a high rate of charge to maintain charging voltage. I don't know how much current that dump draws when activated but it could very well put that alternator into a charge rate of 50 amperes or more. No way a 30 amp fuse set up sufficient. I would hook a relay up so that anytime you power up the dump the relay disconnects the circuit to that fuse. It would be rare that your trailer battery would require more than the fused 30 amp circuit to recharge it and in that case, that fuse would protect your wiring so you could alternately recharge battery or replace it.
Then, as far as a different style fuse, you would have to make sure it's contact points were sufficient and also, I would bet that original style fuse is a slow blow designed to take a over flow for an instant before it blows.

Charging the battery is not blowing the fuse. Running the dump motor with the charge line connected is what's over-current on that fused line.

The internal resistance of the battery will keep the charge current down below 30A. That's why there's a 30A fuse in the line, to protect against shorts from the wire, not because the battery will draw that much from the alternator. The alternator has a voltage regulator that limits the voltage applied to all batteries so that the plates will not warp under very high charge current.

The simple way to do this is to find an automotive relay with a set of normally closed terminals.

http://catalog.delcity.net/app.php?RelId=6.10.6.0.3

PN 73980 or equivalent can be found at your local auto parts store. Insure it has a terminal labelled '87a', which is the normally closed terminal from pin 30, the supply pin.

Wire the charge line from truck to relay pin 30, and the trailer battery + to pin 87a. Wire pin 85 to trailer chassis ground. wire pin 86 to the switch which activates your pump motor, if that pin is the +12V which engages the motor. If the motor is driven by a relay, wire pin 86 to the coil pick at that relay. The objective is for the charge line to remain connected to the battery at all times except when the motor is activated. Use a DMM to check that pin 86 is connected to the +12V for the motor. When the switch is operated, the motor will start, the relay will open, the charge line from the truck will be disconnected from the battery. When you release the motor switch, the relay will close, and charging voltage will be restored.

If the motor is switched by the ground side, you will wire pin 85 to the truck battery(same as pin 30 on the relay), and you will wire pin 86 to the ground activated side of the motor switch, so that when ground is applied to the motor, it is also applied to pin 86, thus activating the relay and opening the charge line circuit.

The hysteresis in the battery will provide sufficient buffering so that the fuse will not blow during the transition state from closed to open.

Oh, and do NOT use a smaller gauge wire as a self-limiting current device. when the cheap plastic insulation melts as the wire gets to ~300F it will short out on something somewhere and may cause serious damage to the truck primary. Wire in a loom, or even loose is not designed to be a fuseable link.

The charge fuse has always been an odd non-standard fuse on GM trucks since 1999. The old "Stud #1" fuse, which they didn't even include with the truck when it was new. There was just a plastic plug in the hole. You had to go buy your own fuse and install it to enable the charge line to the trailer!

Prior to the 1999 model year, though, you were running your own wires for things like charge lines and trailer brakes.

Frankly though, GM is hedging its bets. They figure 99% of the trucks they sell won't even use the charge line, let alone have a charge need exceeding the capacity of a 12ga wire and 30A fuse. Copper's expensive, and if you can cut copper use in 1/2 by running a 12ga instead of a 8ga wire, you can save a lot of money.

I had the same problem on out dump
trailer. My 16 Ford had same size
fuse.30. I just put a 30 amp breaker in
the little wire going to battery on
trailer then a 50 amp fuse in truck.
Hauled 10 loads one day.

> As for space constraints, the small flat fuses take up less space than this square fuse.

You can't compare the square fuses with the "micro" fuses. These fuses are time delay (aka "slo-blo"), and to get a comparable time delay blade-style fuse they would have to use a "maxi" fuse. Those are much larger than the square fuses. And I think you'll find they're nearly as expensive. (I just checked AutoZone, a MAX-30 is four bucks and an FMX-30LP is five.)

> was hoping a new truck would have a mechanism to prevent blowing the fuse.

There is a mechanism to prevent blowing the fuse. It's called the "ignition switch". I seriously doubt the fuse will blow if you only operate the hoist with the engine off.

The thing to remember about fuses is they exist solely to protect the vehicle's wiring. No fuse means you burn up a wiring harness, and that's a lot more expensive to repair than any fuse.

> It's only 12ga wire, at best.

No OEM would put a 30 amp slo-blo fuse on a 12 gauge conductor. The harness would be smoking long before the fuse blew.

> ...when you use the dump that voltage on that trailer battery is going to fall below normal alternator charging voltage , thus, the alternator goes to a high rate of charge to maintain charging voltage. I don't know how much current that dump draws when activated but it could very well put that alternator into a charge rate of 50 amperes or more...

Correct. His truck probably has a 180 amp alternator. It can easily supply all the current his hoist requires, and will try to do so if the motor is running when he raises the hoist.

> You could also install a battery isolator like is used for a second battery on campers. It would let the trailer battery charge but stop the electrical load from back feeding the charging circuit when you dump the trailer. That way you wouldn't need to disconnect the wiring each time.

I'm not aware of any battery isolator that works that way.

I disagree. When that voltage drops in trailer battery the alternator is going to try to maintain regulated voltage by increasing the current flow to trailer battery through that circuit. If the engine on truck is not running, I do not know how it is wired so cannot say if it would draw current from truck battery or not. Probably protected with a diode so it would not.

i have the same situation with my dump trailer. unplug the trailer when running the dump body. i have been toying with the idea of putting a
momentary contact switch in the tool box on the front of the trailer that holds the dump control cable , pump , resevoir and battery, and adding a
30 amp relay so when you open the tool box lid to get the control cable the switch cuts powerto the relay, then when you close the lid , the relay
closes and charges the battery. havent done it yet, but still thinkin bout it!!

This truck has a completely different set of wiring and controls for the trailer with its own fuse box etc,but I have pulled the battery on the tilt bed down pretty far with the winch
charged back up coming home no problem.

The 30 amp circuit on the truck was never intended to supply enough power to run a winch, or even to share part of that load. In this case I'd say the trailer manufacturer or the winch manufacturer/installer is the one that dropped the ball. They probably skipped isolating the truck when the winch is running to keep their cost attractive, or the charging circuit from the truck was added later.