Winch Size

[Crispin]

Based on the current winch group buy thread...


What is a good guesstimate way to work out how big your winch must be? Forgetting about bigger is better (wife says it is over rated anyway), what is a good size? Obviously the rolling resistance of a LC is nowhere near a winch's limits. One stuck in mud? I recall LB pulling Ryan out of some horrible mud and while the winch was working it's backside off and not sounding happy, it did it.

If you ever caught short, snatch blocks would be the answer but not ideal due to speed and distance.

 

[Chris]

Crispin, winches seldom sound happy when under extreme load. Except Ian's which hums show tunes whilst pulling him up a rock face. LB never really struggled when I had it, but I do think that the main battery was starting to fail and I don't think that Tony has replaced that yet, so you have no 'reservoir ' of power there.

I know that Jon went for the 12k version, but honestly, the 9.5 should be enough for anyone. You can go to the trouble of some complicated maths, but it boils down to the fact that you can really have 8k, 9.5k of 12k There are some 10k too. But the Goldfish 9.5 will do you. I went for the 12k and when I got to David's place they actually talked me out of it. They know their onions those guys.

It's your own choice really. Pay the extra have a 12k and you'll never have to question whether you did the right thing, except they are slower.

Chris

 

[Crispin]

If you say LB has the 9.5 (I think you did?) then that is fine for me. What it did at Piccadilly wood was admirable. Like I said, if wound wanting, a block could be called upon.

 

[pugwash]

The calculation (an approximation of which should be used on any off road recovery):

Take the total weight of the vehicle, mulitply by the slope angle (ie a 1 in 1 slope is 45degrees etc), and divide by 60.

This gives you the pull of a winch on a clean smooth surface.

You then add on the ground effect on that slope- so take the figure above, multiply by the ground effect (typical value below) and then add back to the original figure.

(in the following calcas i'll use Lbs as that's wht winch draw is calculated at)

Example 1- you have an laden 80 series on flat tarmac:

typical weight 7,260lb (3,300kg x 2.2),
Multiply by slope of 1degree = 7,260
then Divide 7260 by 60= 121.

Tarmac effect is 3% ish= 121 * 0.03 = 3.63

Total load is 121 + 3.63 = 124lb-

A bit light but probably not a million miles off once you've got over rolling resistance.

So what about off road:

Take a heavily laden 80, on a steep slope (one you struggle to walk up) in deep claggy mud.

Typical Weight 7260lb (3200KG)
Multiply by degree of slope (say 50degrees)- 363,000lb
Divid by 60= 363,000/60= 6050

So on a 50 degree smooth tarmac slope you'd need a 6050lb winch just to move the vehicle.

then add ground effect

6050 * 60% (typical value for heavy deep mud)= 3630lb

Add ground effect to slope calculation= 3,630 + 6,050= 9,680lb

Note in choosing a winch you also need to add overhead-

Electrical effiency- most people don't run their winches at max efficienc-mainly due to cable loss etc. You can happily knock off 10% from a winch capacity (or add 10% to the winch calc)

Speed of motor- if you are operating near the winches calculated load speed the motor will very rapidly slow down (its where hydros are the real winner- they either work at the rated speed, or they stall- they do not slow down)- as it slows down it loses torque due to heat build up. hence you want at least another 10% so you aren't overheating the winch.

On some winches they will have thermal cutouts- and you can take a VERY long time to winch up a hil- very annoying.

So if you have a heavy truck which you use offroad, then a 12klb winch may be a better option- it may be slower, but it will be quicker than double lining a smaller winch! In the second example above you would easily need a 12k winch to pull you out

In my experience these calculations are always a bit light!

typical ground effects:

Ground Effects Percentages

Ground Condition *Effort Required
Tarmac 2-4 percent
Grass 8-14 percent
Hard Packed Sand 10-17 percent
Wet Sand 15-20 percent
Gravel 10-20 percent
Soft, Dry Sand 25-30 percent
Shallow Mud 30-35 percent
Deep Mud 40-60 percent
Deep Claggy Mud 50-70 percent
* as a percentage of total vehicle weight

 

[pugwash]

There are more calculations than this-

for example you need to consider the torque curve of the winch as it slows- at 85% load an 8274 is still pulling strong (and its only rated to something silly like 9k lb), but a crappy X5 will have stalled at that point.

The efficiency of the motor is key, as is the wiring and solenoids. ALbright solenoids are well known for a reason- they are efficient and thermally stable. The thermal stability of the motor is also important- once a motor starts to heat up it can do some funny things.

You're health of both batteries and alternator is also key. if you have an 80 with twin 90ah batteries AND an aux battery connected by thick fat cable, then you will be able to supply a huge amount of current- you'll need 300amp welding cable, but it will keep the winch happy.

It is important to note that hydrualic winches feel a LOT more powerful than eletrical winches- they suffer very very few losses- a 9.5k hydraulic winch WILL pull a true 9.5k all day long (so long as you have enough fluid and cooling capacity)- an with small tweaks can shoot well over that. A milemarker will happily pull 12k. If you do your calculations correctly then a under load hydro will beat a under load electric in many cases (i'm ignoring the monster twin 24v 8274 top housing gigglepin winches for a minute- they aren't really self recovery winches)- as well as some of the monster PTO Mech winches.

 

[Crispin]

Nice post! Thanks.

 

[Jon Wildsmith]

For any given situation the 12k is more likely to get the job done and is more likely to keep on going. I'm not in a hurry so I prefer that and will wait a bit longer to get there

 

[Crispin]

Thinking about the electrics to keep the winch happy....

The 120 has two 80AH batteries in parallel. + is via a cable from battery to battery but earth is via the chassis on one and starter on the other.

It would be a good idea to uprate the positive connection between the two as well as put in a proper negative strap between them.

So with the above extra and a 100A standard alternator, all should be well then for this?

 

[Chris]

Crispin, it's just pos to pos and neg to neg from winch to main starting battery. Forget the other battery.

Chris

 

[Crispin]

Why would I do that? i.e. forget it? Why not just help it out?

 

[Chris]

It's not necessary Crispin. If it were, then people would already be doing it. Motors draw the current that they need. Having more on tap doesn't mean that they get more. Connecting the winch across both batteries - ie pos of one battery and neg of the other isn't how you do it. In fact, could be wrong, but that wouldn't be the best use of the alternator either. If you get that wrong, you'd end up giving them 24v too.

Not a vehicle sparky, but never seen anyone try to do this. Your second battery will be in support anyway without connecting to it. Also you don't want two flat batteries!

Chris

 

[Crispin]

I don't mean connecting them in series. They are already connected in parallel, I just wanted to know if there is any benefit in getting bigger cable for the sake of a winch. If the winch (apparently) draws 300A, having them in parallel would share that. Having suitable cable between them helps.

having two batteries as the 120 does though, you will not have a spare to start from as they are in parallel anyway and will both drain.

I could put a split charge system between them. Where did I put my toy list.... Oh, there it is.

 

[Chris]

The winch comes with 35mm cable. I asked about upping that. They said that it wasn't necessary. That was the cable it needed. Unless you are in serious competitions, I wouldn't make it any harder than it needs to be. I appreciate that it's a question worth asking, but the answer is, just connect it to the main battery. That's all it needs. Most 4x4s only have one battery. They manage just fine. Remembering that some LRs have the batter under the seat too, so there are cable losses there.
I wasn't suggesting that you'd connect it in series Dear Boy, I was saying that you COULD end up connecting it in series. People read these posts and then go off and do weird things.

Using a snatch block is the best way to help the motor. It doesn't so much allow you to pull twice as much as halve the load on the motor. Making it grunt and banging a trillion amps down it is a recipe for heating it up more quickly and having it trip out.

Chris

 

[Crispin]

The winch comes with 35mm cable. I asked about upping that. They said that it wasn't necessary. That was the cable it needed.

With that then, if the cable I already have between batteries and batteries and chassis is the same or thinker, and there is no reason it would not be, then I shall leave it alone

 

[Chris]

same or 'thinker'. Hmm hedged your bets there then Crispin.

It's today's new word.

Cris

 

[Jon Wildsmith]

Using a snatch block is the best way to help the motor. It doesn't so much allow you to pull twice as much as halve the load on the motor. Making it grunt and banging a trillion amps down it is a recipe for heating it up more quickly and having it trip out.

This is why I choose the 12k, for the extra help the gearing gives the motor seeing as I have no faith in electric winches and still think they need all the help they can get

 

[pugwash]

The winch comes with 35mm cable. I asked about upping that. They said that it wasn't necessary. That was the cable it needed. Unless you are in serious competitions, I wouldn't make it any harder than it needs to be. I appreciate that it's a question worth asking, but the answer is, just connect it to the main battery. That's all it needs. Most 4x4s only have one battery. They manage just fine. Remembering that some LRs have the batter under the seat too, so there are cable losses there.
I wasn't suggesting that you'd connect it in series Dear Boy, I was saying that you COULD end up connecting it in series. People read these posts and then go off and do weird things.

Using a snatch block is the best way to help the motor. It doesn't so much allow you to pull twice as much as halve the load on the motor. Making it grunt and banging a trillion amps down it is a recipe for heating it up more quickly and having it trip out.

Chris

35mm is fine, but you will get cable losses- and if you have 2 batteries then upping the cable size between the two batteries is always a good idea. Problem with cabling only really occurs at max draw of the motor- you can seriously damage both the motor AND your batteries with underspecced cabling. Don't forget that a winch under full draw can easily pull 100amps!

Whilst it is of course true that a snatch block will more than double the winch speed and more than halve the amp draw, in marginal situations (where you just can't be arsed to setup a snatch blokc - which is most times), current spikes can easily load the winch up.

In a 10-15 year old vehicle it seems eminently sensible to keep the wiring up to scratch- or at least keep the connections clean etc

 

[Chris]

What is missing from the calculation is the effect that having all wheels locked, in low gear with mud terrain tyres turning on each corner, has. Theory is all very interesting, but the rope never lays down evenly on the drum, the media that you are winching through is never consistent etc etc. There are too many variables. I think we could turn this into something that to doesn't need to be. For typical self recovery, a 9.5 is more than up to the job in any circumstance that I have ever found my self and I have made a career out of getting hopelessly stuck.

From experience, I have never stalled a winch. I have never overheated the cables, I have never not had enough power from a single battery. Lil Blue, after being rolled that fateful weekend, got bellied at Tom's Farm. It was sitting on the bashplates with no wheels touching the bottom of the ruts. We had a 110 and a Discovery roped together on good ground and LB still reeled them in with their wheels turning. The winch never stopped. That was a single line pull. In the end, we strapped the two vehicles to an oak tree and LB pulled itself out. True it overheated about twice and cut out but other than that it got me out. Anymore stuck that that and I would have been part of the rock underneath. The day before I had to self recover off the hill, with no engine running as it was full of oil, on one battery and I got all the way to the camp site like that and there was still power to turn the engine over.

The other thing to consider is rope size too. The fatter the rope, the quicker the depth builds up on the drum and the faster you lose the best part of the pull. The Dyneema 9mm is rated at something phenomenal and I can believe it. I now have the 11mm but not sure it's really needed.

Lots to consider, all of it interesting and of course valid. But not necessarily, necessary.

Chris

 

[pugwash]

What is missing from the calculation is the effect that having all wheels locked, in low gear with mud terrain tyres turning on each corner, has. Theory is all very interesting, but the rope never lays down evenly on the drum, the media that you are winching through is never consistent etc etc. There are too many variables. I think we could turn this into something that to doesn't need to be. For typical self recovery, a 9.5 is more than up to the job in any circumstance that I have ever found my self and I have made a career out of getting hopelessly stuck.

From experience, I have never stalled a winch. I have never overheated the cables, I have never not had enough power from a single battery. Lil Blue, after being rolled that fateful weekend, got bellied at Tom's Farm. It was sitting on the bashplates with no wheels touching the bottom of the ruts. We had a 110 and a Discovery roped together on good ground and LB still reeled them in with their wheels turning. The winch never stopped. That was a single line pull. In the end, we strapped the two vehicles to an oak tree and LB pulled itself out. True it overheated about twice and cut out but other than that it got me out. Anymore stuck that that and I would have been part of the rock underneath. The day before I had to self recover off the hill, with no engine running as it was full of oil, on one battery and I got all the way to the camp site like that and there was still power to turn the engine over.

The other thing to consider is rope size too. The fatter the rope, the quicker the depth builds up on the drum and the faster you lose the best part of the pull. The Dyneema 9mm is rated at something phenomenal and I can believe it. I now have the 11mm but not sure it's really needed.

Lots to consider, all of it interesting and of course valid. But not necessarily, necessary.

Chris

Guess it depends what you do. In a competitive enviroment you will see winches stalling continuously.

Greenlaning you should never need a winch anyway- if you have a winch out it means you shoujldn't be there, or you've buggered up.

an 80 with lockers and MTs (or Simex smiliar) will get itself a very very very long way before it gets itself stuck- far further than any LR product on Simex will- the long wheelbase, lockers, and very strong drivetrain means you can get anywhere. Problem is on the occasions i've got myself properly stuck- ie no forward or rearward motion in the slightest, a 9.5k winch on a single line pull stalls immediately. Yes you can get a snatch blotkc out, but when you have mud most of the way up your door you don't really want to be arsing around outside more than you have to- you want to get the winch connnected up and pulled out ASAP before you start to settle into the clag even further.

having seeen the problems a 9.5k X9000i had in dragging a modeately laden colorado up a hill, then having the extra power can only be a good thing. Coupled to which, if you aren't in a competitve enviroment, then speed isn't an issue- but power and controlability is.

Personally i'd go crank driven Hyrdo (or PTO driven as on my last hybrid- not really an option on landcruiser though- unless you are very veryvery lucky to get a PTO driven winch) for endless power and speed, but to do it properly will happily cost £2k.

 

[Chris]

I think that the spec here was pretty clear. Self recovery, mostly pay and play and adverse weather such as now. Not competition. And even laning things can go wrong as we all saw last weekend in Wales where the winch was necessary to recover a stricken (mechanically stuffed) vehicle. Fully agree that in the simplest of terms you should not require a winch on what is a public road. 10" of snow sometimes changes things. Getting stuck is not necessarily a sign of poor driving. I deliberately get stuck so that I can explore the limits of the vehicle and practice recovery so that I know better what to do in a real situation. I call it preparation and practice. Yes, I have been stuck without intention before following a slight miscalculation. And that's when we buried the spare wheel!

Warn winch, struggling? No, really? That's why I have a TDS now.

Goodwinch do a twin motor set up too. Now that is interesting. I think that competition is a very different thing and if I did that, I'd probably go with hydraulic

Chris