Oh wow, I was worried about the solar charger damaging the battery. It never occurred to me that the vehicle power might burn up the solar charger. Looks like I will have to unplug it when I am travelling with the trailer too. Thanks for the tip.
It never occurred to me either. Won't be sure till I can check things out this weekend.
Giving your thread a bump so you might get some responses to your Q's on hydraulics, and also to add to the info on the solar chargers.
I had a look through the manual for my 1.8 watt solar charger and it states that if the charger is less than 15 watts you do not need any type of charge controller, so it seems to be safe to leave it on all of the time and will not overcharge the battery.
You were right though about danger to the unit from leaving it on while driving. The manual is only two pages long and it was important enough for them to mention twice that it is not safe to leave the solar panel plugged in while driving the vehicle. I installed mine into my horse trailer on the weekend and am pleased with the results. From the outside you can't really see it because of the tinted window, but from the inside you can see what I did, placing it between the screen and the glass so I am not relying on just the suction cups to keep it in place.
I followed the path of the wiring that was already going from inside the gooseneck out to the battery box. I couldn't get it to thread through the multiple elbows in the tube so I just wrapped it around, and I had to splice in an extention to increase the length of the wire, but a test with the multimeter showed that the panel was putting out some current.
The panel has a jack that allows you to switch between alligator clamps on the pattery poles or just plugging it into a cig lighter. I am clamping directly to the poles, but I placed the jack in an easily assessible spot so I can easily disconnect the panel when the trailer is connected to the truck for travel, without having to open the locked battery box every time.
Hopefully this will mean I no longer have to periodically connect to the charger to keep the trailer lights working (or at least a lot less frequently) and also helps prolong battery life by keeping a trickle charge in the colder winter days.