12V winch power from DS controller?

[808Pants]

(1999 DS)

I'd like to get some feedback on my tentative plan to test the use of my existing cart's controller to run an external (fixed-location) automotive 12VDC winch - safely, that is, with no fire-related drama, nor small puffs of plasticky smoke. I should mention that my winch current is WAY above the rating of any garden-variety accessory DC-DC convertors (I think they're typically rated only about 30A, while my winch starts at about 3X that rating.)

But I think there's no need for any new controller, anyway. Since I won't want to move the cart once it's in a position near enough to connect to the winch, I am thinking I could simply run a new, auxiliary set of heavy, short-as-possible leads from the controller's B+ and M- terminals, to my winch's 12V +/- terminals. I envision I would simply keep the cart's FWD/REV switch in 'neutral' while using the winch, so the cart wouldn't go anywhere, (though I'd prefer some kind of lockout). For now, I'd be using the winch's stock fwd/reverse ("in/out") controls. I don't really need to vary the winch speed while in use (though maybe later).

With those basics, it looks like I'd also need to
a) hot-wire the cart's solenoid (maybe just via a new toggle-switch - eg 'on' to allow winch operation), and
b) install an external potentiometer (?) to preset the controller speed to something that seems right for my "slope-lift" system.

Does this sound reasonable so far?

If so, then the big question on my mind is how well the controller is protected against overload. The rating chart for the winch shows that it will (theoretically) draw some 400A at max load - though I think that's going to be a very brief condition during snags or other eff-ups. So is the controller protected? And is that protection 'internal,' such that I don't need to provide it with any new external input from my winch aux connections?

Maybe someone's already been down this path?

Thanks for any wisdom...

Dave

[jdunmyer]

Dave,
One problem that I foresee is that many (most) controllers have a function that prevents any output until the accelerator pedal has been lifted to "zero" speed. This means that you can't simply throw a switch and have the controller provide a preset output for the winch.

[Sergio]

I think it is pretty feasible, You will need some safety features, specially if the winch is going to be connected at all times.

At the very minimum you will need a DPDT switch. All the connections would be available at the FNR switch.

One side (pole) of the switch would by-pass the anti-arc micro-switch at the FNR, White/Black and Green/White wires.

You would wire so it would be OFF when in Drive mode, and short the anti-arc switch when in Which mode.

The other side (pole) would provide a reducing resistor in line with the 1/2 speed reverse micro-switch.

You would wire a 15kΩ resistor (1/2 watt) in series with the Green wire at the reverse speed switch.

The switch would short out the resistor when in Drive Mode (so it has no effect), the switch would be open in Winch mode inserting the resistor in line.

You need to play with the Resistor value, but 15kΩ should be close, the smaller the value the higher the maximum voltage You would get at the Controller.

That way You would put the FNR in Neutral, flip the toggle switch to Winch and just use the pedal to output a variable voltage from 0-12v at the controller.

If the Winch is going to be permanently connected to the Controller, You would also need a solenoid or a disconnect switch so the Winch does not get +48v when you are driving around.

By the way, a 400 amp 12v load would only be 100 amps at the battery pack side.

[Revolution]

Dave,

I like the way your thinking. Ive had plans for a while now to build some electric tools to be powered from my golf cart batteries and controller.

Things like a high power electric chainsaw, garden tiller, pole saw, fence post auger, water pump and a winch like you want.

Safety will be an issue, you will need some kind of interlock setup.

Ideally you would want to pick motors in a close voltage range to the carts voltage.

I think with a potentiometer with a limit of some kind would allow you to power the winch.

I am looking forward to see how this works out.

[Revolution]

Way to go Sergio! I was still trying to work out resistor values.

Thats why I like this forum, good smart people here!

[808Pants]

Revolution - <gulp>...I guess I stepped up to guinea-pig myself, then...of course I will keep obsessively updating...

Sergio - great details that I'd no clue about. Some followups on those:
1) I've little-to-no experience with controller mods. I think this is a PWM type, though, right? Anyway, I'd been given to understand that output voltage measurement from PWM-type controllers actually requires something more sophisticated than your average DVM. Thus, again, my impression that determining a safe cap on the output might not mean limiting to the "rated" voltage for my load (in this case the 12V winch, presumably OK for, say, 14V if powered off of a running internal-combustion-engine vehicle). Can you comment on the above (true/not true/...dumb...) WRT trying to limit the winch supply voltage to 12-14V? Is that indeed a reasonable limit? And can it actually be measured with a standard DVM?

More on that - I recall from one of my many haven't-quite-got-to-it projects that, up to a point, some DC motors will perform better in some or all aspects when given "too high" of a voltage - eg replacing a 36V pack in an EZ-Go with a 48V pack. Higher voltage means lower current, thus lower i2r resistance-heating in the motor, but apparently not so high of a voltage as to...what, burn through winding insulation? Anyway, you know what I'm getting at, probably. I have the idea that there's significant "overvoltage" headroom when running from a PWM power supply. How does one judge when it's too high?

2) Heat and 'duty cycle' in the winch motor: (is this the core concern in terms of preventing disaster?) I think most auto winches are nowhere near 100% duty-cycle; certainly mine are not. Spec charts says to rest it for FIVE MINUTES for every ONE minute of operation - even at ZERO load - which seems insanely conservative to me. But I tend to assume that this simply goes to preventing overheating. True? So I'm considering some kind of thermistor-based means of monitoring the winch-motor temp, and disabling the contacts when it exceeds, say, 105C, or some temp I'd guess at for the insulation rating. If it responded quick enough, maybe this would be a better determinant of max controller output than voltage?

4) re: "...By the way, a 400 amp 12v load would only be 100 amps at the battery pack side." I take it I can't count on any overcurrent protection built into the controller, then? (If it's all about heat or low-voltage problems, though, maybe I'd best look at other methods anyway?)

5) re: "...That way You would put the FNR in Neutral, flip the toggle switch to Winch and just use the pedal to output a variable voltage from 0-12v at the controller." I didn't adequately explain my intended use. I won't be anywhere near the winch or cart when the winch is in operation, that's why I was thinking about the potentiometer to be set somewhere, as a replacement for the pedal. (wait...doesn't that overlap with the 15K resistor's purpose, though? That is, when in "winch mode," could I "set and forget" a 5K (?) potentiometer that substitutes for the accel pedal's function, and not have a need for the 15K resistor?)

My typical use: I will be hiking around above the winch and cart with a keyfob remote, used to either winch in or out, somewhere up on a steep, irregular, jungly slope, along the hoisting path. This is something I've done in the past, but with a much cruder winch installation; remote seems to work up to several hundred feet away from the antenna before I lose too much transmitter strength to trigger the winch, and that's enough for now. My loads might be trash trees, bundled up and coming down to meet their doom in a chipper, or construction materials going UP the slope. So these loads often need 'supervision' via tag-line as they move, to keep them from snagging on trees, etc, and that'd be my job. Stuff will be suspended from a snatch-block-suspended carrier frame, which will ride up and down on a second, semi-fixed main cable, separate from this winched line.

Added thoughts?

Thanks - Dave

[Revolution]

Dave,

I can help with those questions, it won't be tonight, other members might have answers sooner.

Ill have some free time tomorrow and Ill address them as I have time. Its doable safely with a little work.

[Revolution]

I have consumed to much CH3CH2OH to reply in an acceptable manner.

[jdunmyer]

I like the way your thinking. Ive had plans for a while now to build some electric tools to be powered from my golf cart batteries and controller.

Things like a high power electric chainsaw, garden tiller, pole saw, fence post auger, water pump and a winch like you want.

You might look into tools meant for the GE Elec-Trak garden tractor. Available tools included chain saw, hedge trimmer, drill motor, lawn edger, and more, all powered from a 36-volt receptacle on the tractor. See: http://www.elec-trak.com/

[Revolution]

Originally Posted by jdunmyer

You might look into tools meant for the GE Elec-Trak garden tractor. Available tools included chain saw, hedge trimmer, drill motor, lawn edger, and more, all powered from a 36-volt receptacle on the tractor. See: http://www.elec-trak.com/

Those are cool little tractors. I almost forgot about them. Thanks for the reminder.