brunnhilde said no to trailer winch battery

 

Brunnhilde is known to haul all sort of thing, including a car trailer fully loaded across the Continental US. For most street cars converted into track cars, I have no problem driving the cars up and down the trailer with the ramps. However, with radical race cars they are next to impossible to do so because of the aggressive racing clutches, and non-existent flywheel mass due to sequential gearboxes.

I have resisted installing a winch on the trailer until I acquired my full blown race car. In order to keep the trailer weight and impart the least possible tongue weight on Brunnhilde I first use a good manual winch. That got old fast when the race cars require the loading ramps with approach angle in the order of 5-7 degrees, which resulted in 35' of winch cable. It takes a long time and cranks to reel in that much length.

manual winch at work on my sloped gravel surface

the best things about a good manual winch is it is extremely light, and few things to go wrong; the down side is it takes forever to pull in the loaded line even in the high speed setting; also I have to unzip the fabric fairing of the trailer which causes wear and tear

this is my track buddy's trailer with a high quality winch and a full size battery to power it; the combo easily adds 100 lb to the front end of the trailer

Using the manual winch to load and unload a car takes a lot of cranking. I don't mind it so much in cool days, but you work out to a sweat in the sun is most unpleasant experience as loading/unloading the car is not the only exerting labor. I want to install a power winch but do not want to add the tongue weight of the trailer incur by a average size battery.

the circa 13,500 lb road train

I continue to be amazed how versatile Brunnhilde is in her small package and efficiency; even to carry a nitrogen gas bottle for the race car's built in air jacks, and up to two full sets of wheels

Since loading and unloading my race cars involves very low ramp angles taking into account my sloped gravel surface at the ranch, I knew I can get away with an ATV winch, as long as I carry the manual one as an emergency spare should the ATV winch burns up from overloading. I set out to plot a contrarian solution. I want to have the cake and eat it too so to speak. That is to have a good solution and incur the minimum tongue weight as well as the entire Sprinter plus loaded car trailer roadtrain aggregate weight.

I swapped the steel cable with this synthetic line on the cheap ATV winch but finding a line long enough without overfill the spool wheel was a challenge

I first tried to use a small AGM battery that I carry in a rear compartment in Brunnhilde. It is one smaller than the one in Miata. To pull my cars up the ramp I use a 10A battery charger to supplement the diminutive battery and give it a few seconds of rest after a long winching, allowing the battery to be recharged.

as the battery is not carried on the trailer I needed a mean of electrical disconnect

I chose a pair of Anderson SB50 low voltage high current connectors

the battery weighs around 15 lb and is carried in the water boiler compartment to avoid the tongue weight capacity reduction; the short cable pig tail on the battery side is undersized as I didn't want to waste money until I finalize the design

This setup works satisfactorily and I have use it for three events. I know I can do better by refining the design.