Trailer battery charging for electric/hydraulic actuator
 

Electric drum brakes are powered solely from the 7 pin harness on the truck, except in a catastrophic case of trailer separation where the trailer battery will apply maximum voltage to the brakes if the emergency separation plug is pulled.

Electric/hydraulic disc brakes use an electronic pump/actuator every time the tow vehicle brakes are applied, and this power is sourced from the trailer battery, if I'm not mistaken. The actuator still uses the signal from the 7 pin to determine brake line pressure, but the power to run the pump comes from the onboard battery.

I've also read that, with the new smart trailer connectors, the truck doesn't provide enough amperage to actually charge the trailer battery. It will only maintain it if it's charged.

Herein lies the problem I'm asking about- would it be possible for an electric/hydraulic trailer brake actuator to drain the onboard battery enough that the trailer brakes would stop working, as the truck's 7 pin connector will not recharge the trailer battery while towing?

You would have to run the pump for a long time in order to drain the trailer battery. The battery is also being "topped up" even while it's being used to run the pump.

I'm not sure what kind of amps or wattage the hydraulic pump uses, but I've drained my entire freshwater tank into the dump tanks in my TT and that took almost 15 minutes of continuous running for my water pump. Battery hardly took a hit.

Does the E over Hydraulic pump use the coach battery or the breakaway battery . A cargo trailer has no coach battery and the E/H system works fine. Maybe the wiring allow both/either to be used?

The aftermarket brake system I'm considering comes with its own smaller battery, separate from the house battery, for the actuator. I'm not sure how long it will last. I suppose I could tie it in parallel to the house battery, but I'm not sure how that would work for charging on shore power with two batteries of vastly different capacities. I could see problems of a higher charging voltage for the house battery overcharging the small brake battery.

Right now, the house battery serves as the break away battery on my electric drum brakes. The electric/hydraulic system comes with its own, much smaller battery.

I wouldn't tie the two batteries together unless you use an isolator to charge them. Even then, you risk overcharging the smaller battery. Paul has a point though. Boat trailers with electric/hydraulic brakes don't have its own battery. The one I use definitely doesn't, and the breakaway feature is mechanical...

I'm wondering what this trailer is that you're towing? If it's a travel trailer, why are you adding a hydraulic brake system instead of traditional electric brakes? Electric brakes work fine. You usually only switch to hydraulic for boat trailers that will have the wheels submerged...

My rig is a flat bed car hauler . Disk brakes E/H setup the only battery does both functions emergency and conventional braking. THe battery is the typical small breakaway battery. Hard to believe that is not the standard setup - meaning no house battery is required. My research does not mention a connection to a house batt.
Boy I Guess I need some tech help to understand.

Yes, it's a travel trailer. It's near the max that my F150 can tow. 10K lbs fully loaded. The GVWR for the trailer is over 11K lbs, but it also lists over 3K lbs payload (just under 8K dry weight), so I don't ever use up all of that.

I've properly adjusted the drum brakes on the trailer, but would still prefer more brake power. I have the gain on my factory controller set to max (10) and it will not lock the trailer brakes at 20-25 MPH when I quickly pinch the controller. I checked my truck manual and it says this might happen with heavy trailers.

I would like the much improved brake power of hydraulic disc brakes on the trailer before I drive through any mountains. To be sure, I can feel the trailer brakes working, but in my opinion no electric drum brakes are adequate for a 10K lb trailer even if it were connected to a 1 ton truck. Electric/hydraulic disc brakes are simply a much better, more powerful option.

That's exactly how mine will be according to the kit I'm going to buy to retrofit my travel trailer. I'm just concerned about the truck passing enough current to the trailer battery to keep it charged during repeated brake applications, such as stop and go traffic. As I understand it, these new trucks with the smart trailer connector don't charge trailer batteries nearly as well as the older systems did.

VTX here is a Q for you. When you have the trailer hooked up truck engine on what is the voltage on your house battery. A full charging voltage would be 14.3+ whereas with the truck off the house battery should read 13.6+/- . What say you?
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Then to answer you Q we need to measure the current for real.
Here how. Trailer hooked up - truck motor on - Find the +12 wire and using your clamp on current meter get a reading then put a big load on the trailer and get another reading. Do it again but use the +12 for the small breakaway batt, but have some one push on the truck brakes to get a big reading. Report back.