Electric over hydraulic actuator

[pennstaterv]

Looking for anyone who has installed an electric over hydraulic actuator... I am finishing up my disc brake conversion but have a question about the actuator wiring..

I have a Hydrastar actuator with 4 wires ---

yellow wire goes to cold side of breakaway switch
white to ground
blue to brake controller
and black is 12v power for the electric pump

Now, instructions require a 25-40amp 12v source for the black wire... my F350, however, is only fused at 20amps for the trailer plug. I talked with the folks at etrailer and they were surprised to have never heard this issue before.... especially considering I have a very common truck.

Anyone used this set-up without a problem? I am guessing my only other options would be to replace the truck wiring or add a second 12v wire fused higher and run back to my trailer....

[pennstaterv]

Just finished up my first trip with the new brakes & actuator (about 400 mile round-trip).

Brakes worked great, no problems. Truck fuse didn't blow, and I monitored the battery voltage the whole time (Edge insight) and it never moved below 13.4v even while braking --- so it couldn't have been pulling too many amps from the truck. I know when I run my blow that voltage drops into the 12's.

I had no problem wiring up the yellow breakaway switch either, the only wire I had to fish was from the front storage compartment to the main pin box... pretty simple.

Will keep monitoring, but I think I am good to go...thanks for the help!

[C_Schomer]

I have the same actuator and I ran 10ga to the rv battery and used a auto reset breaker from napa. Every rv I've had has the breakaway sw. wired to the blue. I didn't use the yellow on the actuator. The instructions say there is a slight delay if activated by the blue but the yellow is quicker. I wasn't going to tear the rv apart to run another wire just for a slightly quicker breakaway circuit. If I'm in that much trouble that I need the breakaway... that little delay won't ruin my day any worse! Craig

[BurbMan]

Chris is our resident RV tech and has experience with these systems, so I'd be inclined to follow his recommendations.

To really answer this question, you need more detailed specs on the unit...how many amps does the pump draw and how many minutes per hour does it run in a severe duty cycle? If you know the amp/hours used by the pump then you could compare that to the amp hours that the Ford can deliver through the trailer plug.

If I understand your concern here it's that the Hydrastar unit will consume more power than the Ford can deliver through the trailer plug and deplete the battery in the process. Here's how you can check this to see if that is the case:

Before you leave for camping, measure the battery voltage with the trailer unplugged from both shore power and the Ford. Do the same again when you get to your destination. If the HS unit has been drawing more power than the Ford can deliver, you will see a lower battery voltage meaning that the battery has been partially depleted.

Use this chart as a reference:



If the voltage is the same when you arrive as when you left, then I think it's safe to assume that the battery has not been depleted and the Ford is supplying all the current the HS needs.

As I said your other option is to run a separate, heavier charge line right from the Ford battery and splice it into the 7-pin in place of the factory feed.

[pennstaterv]

Chris Bryant wrote:
It depends on the resistance- it will draw from the higher voltage source until the resistance in the circuit gets high enough the voltage drops to equal the battery voltage.
I believe you're over thinking this, and that the instructions are not very good- they spec a "25 to 40 amp" feed, and recommend using #12 wire. 25 amp would call for #10, and 40 amp would call for #8 minimum, purely on load carrying capacity (ignoring voltage drop).
I wouldn't sweat it- just make sure the factory circuit is in good shape, the plug is clean, and all connection tight.

so am I over thinking it, or are the instructions not very good 😉 ?

i hear you. the guy at e-trailer seemed to think I was the first one who read the instructions and thought of this. i'll see if I blow the fuse....

Thanks again for all the thoughts. Taking it out this weekend, I will update...

[Chris_Bryant]

It depends on the resistance- it will draw from the higher voltage source until the resistance in the circuit gets high enough the voltage drops to equal the battery voltage.
I believe you're over thinking this, and that the instructions are not very good- they spec a "25 to 40 amp" feed, and recommend using #12 wire. 25 amp would call for #10, and 40 amp would call for #8 minimum, purely on load carrying capacity (ignoring voltage drop).
I wouldn't sweat it- just make sure the factory circuit is in good shape, the plug is clean, and all connection tight.

[pennstaterv]

Question though.... If the battery is say, at 13volts, but the truck 12v that us topping it off, which is connected to the alternator, is putting out 13.6 or 14v, when the pump kicks on, It's gonna be pulling from the alternator voltage and not the battery, no?

[Chris_Bryant]

The pump does not run all the time- only on demand. As a matter of fact, running it for more than 2 minutes will burn it out.

Because of how the unit *has* to be wired, the battery will always be in the circuit, unless you install a dedicated breakaway battery, with a separate charge line. The it will always be in the circuit.

[pennstaterv]

Thanks--- I'm with you burbman. Manual shows 20amp fuse....

We dry camp a lot, so our trailer batteries are usually low by the time we pull out which is another reason why I don't want to run the actuator directly off of that.

[BurbMan]

OK, thanks for that, I see what you are talking about now. The black wire runs the hyd pump all the time, and the blue from the brake controller activates the solenoid that sends pressure to the wheel cylinders as needed. Agreed you wouldn't want to rely on your battery to keep the pump running if it draws more amps than your truck is putting in there..

When you say the circuit in the truck is fused at 20, is that what the owners manual calls for or is that the fuse that's in there now? Most are fused at 30 or 40 from the factory, so is it possible a previous owner replaced with a smaller fuse than called for?

Maybe post over in Tow Vehicles and ask some owners of same year 350's to check their fuse sizes?

Assuming fuse size really is 20, then I would run a separate #10 wire off the truck battery, fuse it at 30 with an inline fuse under the hood, and connect it into the 7 pin connector at the back of the truck in place of the factory wire.

[Chris_Bryant]

You are not really going to get much better than 20 amps through that 7 way plug- if you really insist on that, you need a separate 2 pole plug, like a 75 amp power pole connector.

Personally, I believe the trailer battery/stock charging circuit will be plenty, and that the brakes themselves would give out before you run out of 12 volt power.

[houstonstroker]

My actuator was installed in the front compartment of my 5th wheel and 2 feet from my trailer deep cycle battery. I ran the main power wire directly to this battery.

[pennstaterv]

The 'trailer battery charge' circuit in my truck panel is fused at 20.

I attached the HBA16 wiring diagram. It shows connecting to a "25-40amp circuit from tow vehicle". I understand what you are saying, and the trailer battery is part of the circuit for the breakaway switch, but I wouldn't want to rely on the trailer battery for the brakes on a regular basis. Don't trust a trickle charge to keep up with the use of my braking... I believe it has to be powered from the truck alternator via my 7-pin plug.

[BurbMan]

Correct, the trailer battery(s) has to be in the circuit. The power from the truck is only to trickle charge the battery, if the breakaway switch is operated, the power to either drive the hydraulic pump or engage the electric brakes comes from the battery.

You do have a battery on the trailer, right? I would think the breakaway switch wiring would be wired into the battery today and would stay that way.

[ScottG]

I think the charge wire coming from your truck is fused at 40A.
The lighting circuits are fused at 15~20 amps.
You can wire the pump to the on-board battery and since the pump doesn't take that much power all the time, the trucks charge wire will keep the trailer battery happy.