I have two screw type lifts for my engine cover and they operate extremely slow. I was thinking the current is limited by the switch at the helm, so I thought a relay with direct connection to batteries would help the speed and not have the resistance created by the switch. Have any others tried this or was your boat originally set up in this manner. thanks Roger

Mine always had the power wire ran all the way to the helm switch. Never had an issue. You could test your idea to see if you're right by hot wiring it directly to the battery manually for short periods to see if the motor is bad. Would save some work if the wiring is not the problem.

BTW, do you ever have issues of the electric screws not being at the same level, or do they seem to track well?

I did it on an old boat with one slow lift-you only need the realy for "up" since down has help from the hatch-it did speed mine up, but the wiring was really thin on the boat. You could also just rewire with heftier wire-might help.

Stryker,

You are on the right track. My hatch lift gets slow and when I replace the switch it is OK for another year. The switch tends to go bad over time. Even though it is rated at 20 amps they do lose current carrying ability over time. The relay would solve that problem.
Tim T.

I have a problem with mine as well. When closing the hatch, I have to let of the button just as the hatch closes or it gets so tight it wont go back up. The screw in the lift screws itself down tight. I took it apart and greased verything but it still does it ocasionally. Luckily I have an access hole behind my rear bech to reach through and unhook the cotter pin.

I remember seeing a relay in one of the catalogs (Eddie Marine, CP Performance etc) about a relay you mounted back near the screw to increase speed. Sort of like a fuel pump relay. Increases the voltage back up that you lose from the long wire run I think.

Craig

Brad Perry- Yes I do have issues with the tracking. One will bottom out and then the other will follow.I hope this relay setup would possibly help.


Thanks guys for your input: I have connected a small jet-ski battery to the lift and it ran 50% faster. So this may work very well, I'll post when finished.

Stryker,

I was afraid of this happening with me putting a second actuator on the other side of my hatch. The factory actuator just comes to a stop with the motor still spinning-no stall. This would solve the problem as with every complete hatch raise, they would in effect be re-syncronized. I would not pay the high price to Baja for another cheap actuator and decided to buy two new Danas (warner) from eddie marine. Nice units but I was shocked to find that they stall at the end of stroke and want to rotate the shaft. That sucks! I knew this would cause problems, so I am in the process of building a current (torque) limit motor driver that will cause the motors to stop at a desired pull (torque). When I get it together, I will post some pics.

Brad,
The lift mechanism has an over torque clutch that when reached it makes a very loud ratchetting sound. And yes they will try to turn. If you detatch the top end and apply power the shaft will just spin and not change height. That's the way they work.

I like the relay idea.
My lift is slow going up too and it's currently jammed in the down position. I know how to release it. I had to do it last year too.
I have an idea for a limit switch that, when tripped, will cut the power when the hatch is closed preventing you from jamming the screw jack. Guess it's time I got started on it.

[ 01-29-2002: Message edited by: Iggy ]

Iggy,

The one that came with my boat did not stall at the top. The motor continued to run, but nothing else happened. Like the threads got to the end. A graceful way to do it, but the major makers don't do it that way, like you said.

We once used one of these on a company product to deploy a sign trailer. Used a fet motor controller and measured the average current through the motor. When the motor hit the end (or the upholstry when lowering), the current trip limit was hit and motor was stopped. Very fast and repeatable with no mechanical stuff visible. I hope to get my own running in a week or so. Waiting on the microcontroller to come in.