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davew

Member Since: 02 Jan 2012
Location: North Yorkshire
Posts: 888

1990 Defender 90 V8 Petrol PU Auto Rioja Red

The Devon4x4 ones linked are fine. If you compare the rating of the heavy duty Albright winch solenoid and the HD isolator solenoid, the isolator is actually higher rated than the winch solenoid that is being used in competition by a LOT of vehicles without a problem.

The current rating is a bit misleading really, firstly the solenoids' specs show the switching current, not the sustained current and secondly the current draw figures on most winch motors at 12v are VERY optimistic. You haven't a hope in hell of getting a normal 12v vehicle battery and electrical system to provide a continuous 350A to a winch motor. That's why many competitors use 24v electrics with 12v motors as it's the only way of getting anywhere near the theoretical maximum performance of the motor.

As soon as the motor starts rotating the current drops and the faster it moves the less current goes through it. If you add together the limitations of 12v cabling, the effective "resistance" that induction creates when the winch motor is moving and the plethora of joints in the circuit (normally at least 10 stud connections and 6 pairs of contacts before you add an isolator) then to get 350A all of those added together need to come to less that 0.04 ohm even if your vehicle system could sustain 13.8 volts in those circumstances. In reality most systems drop to less than 12v when winching commences so 0.03 ohm is more realistic.

I've used those isolators on my vehicles for a number of years and never had one fail even when the solenoid at the winch has failed. I use them for isolating winches on my competition vehicle and also for switching in the auxiliary battery and isolating the winch on our overland vehicle. I've used both the HD version and the SU280, both of which have worked fine isolating Warn 8274s with upgraded motors in competition and a Goldfish on the overland motor. http://www.yorkshireoffroadclub.net/

29th Aug 2014 11:27pm

Anderzander

Member Since: 08 Feb 2011
Location: Lancashire
Posts: 1000

Great post - thank you.

30th Aug 2014 6:06am

Waldo

Member Since: 18 Jul 2010
Location: Bit South of Manchester
Posts: 240

Excellent info

Defender 90 XS TD5 (03 Reg)

30th Aug 2014 7:34am

SupraAyf

Member Since: 08 Sep 2014
Location: Durham
Posts: 142

2011 Defender 90 Puma 2.4 HT Orkney Grey

Go Beyond wrote:
Frowned upon by a lot of clubs as they insist on a 'physical' means of disconnection as above these solenoids can 'stick' on, just as winch solenoids 'stick' on which is why you want a means of disconnection.

I'm with you on this one GB. I have 1 x Isolator on each of the winches on my trayback and a 3rd on the main battery tray right next to the seat. I wouldn't change it as I know it's a very safe combo. - Andrew -

15th Sep 2014 9:43pm

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