 | Home > Technical > Winching: theory vs real life |
 
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8578  
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Confusion here between current draw required at full load which will be measures in Ampere/Amps/A and battery capacity measured in Ampere Hr or Ah? Or a typo?
Which winch? A typical winch would draw between 300-500 Amps at full load Brendan |
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13th Jan 2015 6:51pm |
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| zone30 Member Since: 07 Sep 2012 Location: Gent Posts: 669  
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I base this on a goodwinch tds 9500lbs, but that really doesn't matter.
Do I need to know the available capacity to do the calculation, e.g. 900A. So in that case you will empty the battery in less than 3 minutes, wright? What's the 120Ah for then? |
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13th Jan 2015 7:15pm |
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| roel Member Since: 08 Aug 2009 Location: Lelystad Posts: 2039  
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Your alternator will probably deliver the first 100 Amps or maybe more for a Puma.
I don't belief in the 4 m max as I have been winching more in one go with one Optima yellow top with engine running off course. But I have found out that when I use a double line I never have problems with lack off electrical power and I probably have had that problem when I had to winch out a long stretch off deep mud were I needed to winch more than 2 cable lengths in a row. By that time the winch got very hot too. I had 2 Optima yellow tops in my Camel discovery and I am convinced that if you have 2 batteries parallel you will more then double your winching time and it is better for your winch too. Why? As I believe with 2 batteries your voltage drop will be lower so you will have a higher voltage on the winch and because off this your current draw will be lower at the same power requirement off the winch. In practise I think that the winch will be quicker and so your will drain the batteries less. Does this make sense? Roel 1984 90 2.5 na Diesel - RR V8 (1994-2001) 1997 Camel Trophy Discovery 300TDI (2001-2009) 2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts. 2003 90 Td5 (2009-now) |
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13th Jan 2015 7:32pm |
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| tobz102 Member Since: 07 Feb 2014 Location: Atherstone Posts: 134 
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I'm not an expert but isn't it something to do with energy lost through resistance and consequently heat??
Resistance = Voltage x Current So winch @ full load: 12 x 320 = 3840ohms of resistance An iphone charger @ full load: 12 x 2.1 = 25.2ohms of resistance Therefore when you're running your winch on full load, the resistance in the battery is huge. This increases the temperature of the battery, changing the internal chemical properties of the battery fluid - reducing efficiency. No doubt when battery manufacturers claim lets say 120Ah, they've tested that by drawing a really low current and not the sort of current draw you'd get from a winch. (infact quite often you see Ah quoted with a specific current.. e.g. 70Ah @ 3.5A - typical for auto batteries) |
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13th Jan 2015 8:09pm |
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| zone30 Member Since: 07 Sep 2012 Location: Gent Posts: 669
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Makes sence. Thx!
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13th Jan 2015 8:35pm |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8578
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At max load a winch draws say 300 amps.
Now assuming the engine is dead/switched off how long will a battery last at full load? This will depend on what type of battery, condition of the battery and its discharge curves. A typical AGM battery used in Defenders are Odyssey brand and a typical battery used is the PC1500. Now if you look at page 9 HERE which shows the current discharge curve. Now the PC 1500 will give 304 amps for 5 mins, whereas the PC1700 will give 337 amps for 5 minutes. So with a dead engine a PC 1500 will give a pull for 5 minutes. A battery of lesser performance will last even less. The battery capacity Ahr is normally calculated over a 10 hr discharge rate. Brendan |
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13th Jan 2015 8:36pm |
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| jst Member Since: 14 Jan 2008 Location: Taunton Posts: 7687 
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i would get the 9500, you can always double line to ease the load on the winch and reduce current draw.
When my timing belt broke i winched the truck off two 110Ah, 900CCA batts over 400m of grassland up a 10deg gradient, once timing belt was fixed they still started the vehicle (husky winch 8000lb version and low current draw) The tds has really good low current draw, esp when comapred to something like an XD Warn. Cheers James 110 XS Utility 130 Puma Station wagon/camper (in the making) 90 Puma Hardtop |
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13th Jan 2015 10:40pm |
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| excossack Member Since: 22 Feb 2012 Location: North West Posts: 5744 
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I have had no issues with my 12000lbs Goodwinch when doing long winching with a standard battery and alternator 1999 Defender TD5 110
Regards John M0VAZ Econet Station 48 no clock |
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13th Jan 2015 11:09pm |
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| mikeh501 Member Since: 07 Jan 2013 Location: United Kingdom Posts: 1142
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The only difference between the goodwinch 9.5 and 12 is the gearing. Same motor. Id go with the 9.5. Will be much quicker.
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13th Jan 2015 11:52pm |
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| dgardel Member Since: 30 Nov 2008 Location: Veneto (Heart & Head) Posts: 3586 
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150A alternator on Puma Discovery 5 td6 HSE Stornoway Gray Outback Engineering Limited Edition 
IID Pro MV License |
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14th Jan 2015 12:53am |
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| 100inch Member Since: 15 May 2012 Location: Brunswick Posts: 407  
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I see a bigger problem than battery or alternator size whilst winching. Experienced drivers tend to use the winch way sooner once stuck, getting out with a light pull most the time whilst inexperienced drivers can often be seen trying to drive out, making the recovery a much bigger strain on the winch. Throwing all data about amps right out of the window, burning motors, draining batteries etc... just my observations. m
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14th Jan 2015 3:21am |
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| VeeTee Member Since: 06 Mar 2011 Location: Somewhere Posts: 1512
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Hmmm, not quite right... The calculations are: U = I x R, or R = U / I. So whinch: R = 12/320 = 0.0375 ohms and iPhone charger: R = 12 /2.1 = 5.71 ohms and resistance in battery (internal resistance) has nothing to do with the resistance in the calculation above....   Cheers, Vincent
1959 Polynorm 1/4 Ton Trailer, Olive Drab Green (sold) 1970 M416 Military Trailer (Camping Trailer Conversion), Epsom Green (sold) 1975 Series III 88 V6, Light Green (sadly sold) 1996 Defender 110 CSW 300 Tdi, Epsom Green (sold) 2000 Freelander 1 TD4 3-drs, Silver (sold) 2006 Freelander 1 TD4 5-drs Facelift Automatic, Tonga Green (sold) MySite |
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14th Jan 2015 7:45am |
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| leeds Member Since: 28 Dec 2009 Location: West Yorkshire Posts: 8578
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I think the OP Zone30 was asking how long you could winch with a dead engine and just on battery alone.
This would depend on many factors so there is no simple answer, but at maximum load where you could be drawing 300+ amps then most batteries will only last at best a few minutes. To get an idea of how long a battery will last under a certain current draw you need to consult the discharge curves of that battery. Double lining is a much safer way of winching, as it basically halves the load on each section of the winch rope which greatly reduces the chance of the winch line breaking.  The downside of double lining is increased time in setting up and it halves the effective line speed which means you double the time taken to winch a given distance.
However halving the winch load does not mean you halve the current being drawn. For instance TDS 9.5 draws 295 amps at 8,000lbs and 181 amps at 4,000 lbs Brendan |
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14th Jan 2015 10:15am |
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| roel Member Since: 08 Aug 2009 Location: Lelystad Posts: 2039
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A double line doesn't mean half the speed as a lower load on the winch means it will pull faster.
But you will anyway probably only spend 50% actual winching the rest off the time is getting the gear finding an anchor point and setting it all up. So the Winching speed isn't that important. So for me if I think it will be a heavy pull and I can reach the anchor point with a double cable I most off time do that. Roel 1984 90 2.5 na Diesel - RR V8 (1994-2001) 1997 Camel Trophy Discovery 300TDI (2001-2009) 2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts. 2003 90 Td5 (2009-now) |
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14th Jan 2015 10:46am |
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