Winch efficiency: line speed, amperage, and heat factor

[aardvarcus]

RoyJ,

Thank you very much for your thorough analysis and for taking your time to answer my question. You have effectively saved me from a several hundred dollar mistake on an overgeared model that would not have met my needs.

I hope you overlook the discouraging comments in this thread, I think knowing where a winch performs and where it doesn't is a very important factor to consider prior to purchase and when doing longer/more difficult recoveries. Why create heat for no reason?

 

[aardvarcus]

Figured I would stop being lazy and do the calculations myself.

I am now looking at a Superwinch 1145220 Terra 45. Note I did my power graph in HP not watts.





Looks like this has higher power output than the Vantage 4000.

1.6HP motor, 191:1 gearing.

 

[RoyJ]

RoyJ,

Thank you very much for your thorough analysis and for taking your time to answer my question. You have effectively saved me from a several hundred dollar mistake on an overgeared model that would not have met my needs.

I hope you overlook the discouraging comments in this thread, I think knowing where a winch performs and where it doesn't is a very important factor to consider prior to purchase and when doing longer/more difficult recoveries. Why create heat for no reason?

You're very welcome. And thank you for the feedback and calculations, appreciate it!

I'm not discouraged at all, just been very busy with work lately to make any progress on this study. I knew very well what I was getting into starting this thread - it won't be everyone's cup of tea, or be as sexy and catch as much attention as fabbing up portal axles to run 44s in a 100 series...

But as I've mentioned before - information is power. It allows us consumers to make wiser decisions and forces manufacturers to be more honest with their products and / or develop better ones. When this info comes free, and the creator gets a kick out of doing it, what's there to lose!?

Yes, for most of us off roaders, it may not matter that much (I leak oil reminded me many times by now...). The beauty of the internet though, is you never know who's reading it and putting it to use. There may be guys out there doing dedicated recovery, or amateur crane builders, and for them, power and efficiency may matter very much, as well as power vs gearing.

The other day, I read on a forestry forum about a guy skidding logs using his mini dozer (Cat D3 I think). And guess what he used for a winch - a Warn, because his dozer was never equipped with a hydraulic unit. So now we have a guy dragging out freshly fallen timber, 3 at a time, from morning to afternoon. Power, heat, and efficiency matters VERY much in this application!

 

[RoyJ]

True, but we are getting out on the fringe again. What is the likelihood that anyone would be in that situation.....

If I need to winch more than a pull or two, I am likely going to spend some time scouting ahead to see what things looks like.
There is always the option to turn yourself around and go back the way you came.

I don't know how you would run the numbers, but my gut says that during multiple long pulls, it is going to take you enough time to re-rig the winch anchor after every pull, that the battery would charge and the winch motor would cool down.

On the ultimate adventure trip this year, we 'had' to winch everyone up this really long muddy hill. It was steep and slick enough that the vehicles would not 'stay' on the hill unassisted. It took me re-rigging 4 times with something like 300-400 feet of winching to get to the top. I did this as fast as we could rig the different winch points. I didn't overheat the winch or flat the battery. We had a few people out of the group of 20+ that had issues, but everyone made it to the top. I can only remember 2-3 vehicles that where having battery voltage problems.

I've done a lot of lead acid battery research over the years and can tell you this - while a deep momentary discharge on a STARTING OPTIMIZED battery may not show immediate effects, it will affect its lifespan. Even at 50% DOD (depth of discharge), high amp (thin plate) starting batteries can lose 10 times as many cycles as a 20% DOD.

Deep cycles fair much better. On long trips, I have my golf cart Trojans (very good at deep cycling), and a buddy has an Odyssey, so we're not concerned at all running a winch even with no engine power.

But on shorter day trip, with an aging starting battery alone, I would go out of my way to extract every bit of efficiency to preserve its life. Again, not telling everyone to do it, but when I see the number of batteries toasted on various off road forums, it makes me wonder if my approach would have helped just a little bit...

 

[RoyJ]

Yeah, a PS pump driven hydro winch won't outperform an electric (and will probably be slower). But provided you run a nice, big cooler in the fluid return line, the advantage comes in being able to keep winching until you're out of gas without worrying about sucking down the batteries or running into duty cycle limits for the winch motor.

I've been into tractors a lot lately (one of my billion hobbies), and ran into a very interesting class of tractors - industrial tractors.

These are farm utility tractors, modified at the factory into a very sturdy industrial platform to run a loader at industrial duty cycle. Whereas a farm tractor with loader is fairly weak and slow, and wears out quick. These brutes can lift 4000 lbs all day all its life.

Anyways, I went to see one model, a Ford 445A, and what Ford did is run a drive shaft straight out of the main crank pulley, and use that to turn a 22 GPM pump @ 2500 psi. Right above it sites a 10 gallon reservoir. The whole package is surprisingly compact, and fit in front of the radiator in the "nose piece" of the tractor:



I've seen these tractors being parted out for as low as $1000 Cdn, figure can probably get the pump and reservoir for $100 - $200. If a pulley can be fabbed up, it just might fit inside an engine bay, and you'll have an industrial duty setup that can run monster winches at full speed.

For guys with HD pickups that have PTO at the transfer case, this would be a piece of cake. I know the Aisin on the Ram Cummins, and maybe the Allison on the GMs. This would get rid of my concern about over stressing my expensive PS pump.

 

[Metcalf]

I've done a lot of lead acid battery research over the years and can tell you this - while a deep momentary discharge on a STARTING OPTIMIZED battery may not show immediate effects, it will affect its lifespan. Even at 50% DOD (depth of discharge), high amp (thin plate) starting batteries can lose 10 times as many cycles as a 20% DOD.

Deep cycles fair much better. On long trips, I have my golf cart Trojans (very good at deep cycling), and a buddy has an Odyssey, so we're not concerned at all running a winch even with no engine power.

But on shorter day trip, with an aging starting battery alone, I would go out of my way to extract every bit of efficiency to preserve its life. Again, not telling everyone to do it, but when I see the number of batteries toasted on various off road forums, it makes me wonder if my approach would have helped just a little bit...

Or we could just slow down the recovery.....are we in a race? I would rather just slow down the process slightly if needed, rather than have to rig a double line pull honestly. In my experience, I RARELY need that much help from the winch. I wish there was an easy way to have a 'load-o-meter' to actually know. I notice many more issues with the winch not being fast enough under almost no load, than I do with the winch being to slow when pulling 'harder'. With the vehicle helping, which in my opinion it should when it can, the winch is going to see a highly variable load.

I wonder if it would be possible to have a volt meter that would read JUST the battery voltage with the engine running. I think your likely going to see the alternator charging voltage....

I tend to default to the simplest system when I can. I don't want to have multiple batteries if I can help it. Decent automotive batteries are not THAT expensive. They should probably be replaced more often than most people do.

We can always end up going down the rabbit hole in any direction. Maybe running double line every time will induce more wear on the winch cable/line and cause it to need to be replaced more often. Synthetic winch line isn't cheap and it is much harder to find vs a battery.....

In the end, it's just a judgement call. Sometimes you are going to need a double line pull. Sometimes a quick single is all you need. Sometimes even a double line pull isn't going to be enough and your going to have to get out the shovel, axe, stack rocks, or whatever. There is no one size fits all solution to vehicle recovery.

 

[comptiger5000]

I wonder if it would be possible to have a volt meter that would read JUST the battery voltage with the engine running. I think your likely going to see the alternator charging voltage....

When the engine is running, battery voltage = alternator output voltage. Until you start drawing more power than the alternator can supply, at which point, voltage will fall as power is taken from the battery.

 

[Metcalf]

When the engine is running, battery voltage = alternator output voltage. Until you start drawing more power than the alternator can supply, at which point, voltage will fall as power is taken from the battery.

Right, I haven't been able to think of a way to sample JUST the battery voltage with the alternator charging.
There should be a way to turn off the alternator charging in some way....but would you want to do that while your trying to winch...probably not.

 

[ducktapeguy]

Right, I haven't been able to think of a way to sample JUST the battery voltage with the alternator charging.
There should be a way to turn off the alternator charging in some way....but would you want to do that while your trying to winch...probably not.

I've also had similar thoughts in using the battery voltage to estimate winch load. I don't think you'd really need to isolate the battery, even at no load most winches are pulling more than the alternator can produce at low rpm's, so all you'd need to know is the battery discharge curve and you'd have a general idea of the current draw. Couple that with the graphs on these pages (assuming the mfg data is accurate) and you'd have a rough estimation of the winch load. Wouldn't be that accurate, but probably good enough to tell you what ballpark you're in. Although if you have enough experience, just listening and/or watching the winch might tell you the same thing.

 

[RoyJ]

Right, I haven't been able to think of a way to sample JUST the battery voltage with the alternator charging.
There should be a way to turn off the alternator charging in some way....but would you want to do that while your trying to winch...probably not.

Comptiger is correct, the battery and alternator is essentially connect by a bus, and bus voltage is constant unless amperage demand exceeds alternator output, which can very well be the case under winching.

There's not such thing as "just battery voltage", under non-winching conditions, every plate inside battery is at the same electrical potential as the alternator / 6 (6 cells). The battery is receiving a net current input until the load exceeds the alternator, then it starts outputting.

If I were doing heavy winching, I'd have the winch connected to my golf batteries, and disconnect them from the alternator, so my alternator isn't hit with a huge 400 amp load. Once done, I'd then re-connect the switch and allow the alternator to charge. The charging load on the alternator is much lower than winch (essentially a short circuit from alternator's point of view).