Mark Posted June 9, 2006 Share Posted June 9, 2006 Hi All Stupid moment again :shock: I want to fit a master disconnect switch to stop any chance of the battery draining, my question is, what side of the battery does it go on, the live or earth side :?: it will also act as a deterrent for other people to drive away with it. Quote Link to comment Share on other sites More sharing options...
ArtistsRifles Posted June 9, 2006 Share Posted June 9, 2006 I would have thought it went in the live side of the circuit - otherwise it could by-passed either by something shorting to earth or, if talking security, by simply earthing the battery terminal elsewhere........ But I'm not an electrician so could be talking a load of <censored> here!! Quote Link to comment Share on other sites More sharing options...
Jessie The Jeep Posted June 9, 2006 Share Posted June 9, 2006 On my Hotchkiss, the circuit breaker is on the negative side of the battery, with a key to complete the circuit inside the drivers compartment. The positive side goes straight to the starter motor. Steve Quote Link to comment Share on other sites More sharing options...
andrewroberts.1953 Posted June 9, 2006 Share Posted June 9, 2006 All the vehicles that we have fitted in work have the "kill" switch in the chassis line. So negative if that is your chassis connection. This is done so that you don't have a live end floating about should the wire come off the switch. I know it sounds a bit odd, but it works fine that way. Try to keep all the wire short and as heavy as possible. It's possible to lose a lot of volts across a 10m/m cable a foot long when starting. Quote Link to comment Share on other sites More sharing options...
Mark Posted June 9, 2006 Author Share Posted June 9, 2006 Cheers Does it have to be connected as close as possible to the battery, or can I mount it in the cab as such :?: Quote Link to comment Share on other sites More sharing options...
sean101ryan Posted June 9, 2006 Share Posted June 9, 2006 If you look on ebay in Land Rover spares or military spares there are usually several military battery isolators with leads attached. One end has a battery terminal for the negative post and the other a post which fits in the connector on the end of the existing negative lead. The leads are about 18" long so plenty of scope to put the isolator where you like with no connectons to crimp up. Price is about £7 - 10 plus postage. Quote Link to comment Share on other sites More sharing options...
fv1609 Posted June 9, 2006 Share Posted June 9, 2006 Just one word of caution. This doesn't matter if you have a dynamo but if you have an alternaor make sure there is no liklihood of the battery being isolated with the engine running. The battery acts as a load & a sort of smoothing condenser. If the battery is not connected the voltage output from the alternator will rise & may destroy its diodes or other semiconductor equipment you have connected. Quote Link to comment Share on other sites More sharing options...
Degsy Posted June 9, 2006 Share Posted June 9, 2006 For some strange reason Jeeps don't seem to like one of these switches being fitted, I have seen numerous problems caused but as soon as the switch is removed things are back to normal. Quote Link to comment Share on other sites More sharing options...
Mark Posted June 9, 2006 Author Share Posted June 9, 2006 Mmmmm! me thinks it may be worth having second thoughts then, so how do landrovers cope with these switches and boats, do they have the same problems :?: Quote Link to comment Share on other sites More sharing options...
Degsy Posted June 10, 2006 Share Posted June 10, 2006 In my experience Land Rovers seemto be OK it only seems to happen with Jeeps but this is not too surprising as the electrics were not their strongest point. Quote Link to comment Share on other sites More sharing options...
andrewroberts.1953 Posted June 13, 2006 Share Posted June 13, 2006 Hi The problem is that if you have a 6 volt vehicle, you don't need to lose much to stop things working! What you can do is use a switch which is at the battery terminal, or a quick disconnect terminal. These can be found in caravan and camping shops, or in some car supply factors. The other thing is to be 110% sure that the electrics are righ on the vehicle. make sure the regulator is set righ, and that all the connections are clean and tight. Don't forget any braids from the chassis to the engine/gearbox. If in any doubt replace with bigger ones! I have got 6 volt vehicles to work ok with remote kill switches, but it's a lot of work. Quote Link to comment Share on other sites More sharing options...
rambo1969 Posted June 13, 2006 Share Posted June 13, 2006 Iv'e had a few of these on different landy's, bloody good they are to, mine were in the positve side, the good thing about them is if the wiring starts burning you can stop it by pulling out the switch/key, very useful on an old landy were the wiring has been played about with. Quote Link to comment Share on other sites More sharing options...
rambo1969 Posted June 13, 2006 Share Posted June 13, 2006 Another good tip; I have always put a heavy duty on/off switch on the coil side of the circuit and hidden the switch under the dash so that if someone try's to nick it, it will turn over but never start. On a diesel wire it to the fuel pump, it will start, but only run for about 2 minute's before it conk's out. My mate had a mini cooper and someone cut the stearing lock off, forced the ignition barrel but could not get it started because of the secret switch. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted January 9, 2009 Share Posted January 9, 2009 For some strange reason Jeeps don't seem to like one of these switches being fitted, I have seen numerous problems caused but as soon as the switch is removed things are back to normal. Just been reading this thread as a result of the recent question 'which side to put the switch on a landrover'. I had the same problem with a jeep, in good electrical order - had to bypass the isolator switch in the end. I measured quite a voltage drop over the new switch. GMC is fine with same switch on +ve side. Now - is this possibly more of a problem when the switch goes on the +ve side I wonder? Perhaps if the isolator is on -ve side of battery the voltage drop might not affect the starter so much due to the already significant drop through the starter....?? :confused::confused::confused: Quote Link to comment Share on other sites More sharing options...
Markheliops Posted January 9, 2009 Share Posted January 9, 2009 Master switch is a good idea Mark. As I recall, the connection is down to if the vehicle is a negative or positive earth. It really doesn't matter which way round it is as long as the battery current is isolated but the majority of people fit them on the live side. Doesn't matter where they are fitted but take into acount the length of the cables. The longer the battery cables, the more resistance is created. Markheliops Quote Link to comment Share on other sites More sharing options...
Mark Posted January 9, 2009 Author Share Posted January 9, 2009 Thanks everyone Quote Link to comment Share on other sites More sharing options...
fv1609 Posted January 9, 2009 Share Posted January 9, 2009 If you have a 24v system it is better to switch the earth side. Once it is turned off it is nice to know it is relatively safe to work on the batteries. On any of the 4 terminals of the 2 batteries, if you are using a spanner to tighten or undo the terminals if the spanner touches the chassis or its box then it is quite safe. But if you have the switch in the 24v + lead & turn it off, it is not safe to work on the batteries. If you work on the terminals with a spanner, on 3 of the terminals they are 'live' with respect to earth. So the spanner touching earth or the case could cause a very nasty short circuit. Unlike a wire that may burn out, a spanner won't & may weld itself in place & the battery go into melt down. Whether you have two batteries or one there is a slightly greater risk with a switch in the supply line rather than earth. The switch terminals are at risk to coming undone & wires touching earth. Or if the terminals are not covered in insulation (I have never one that was) there is the risk of something falling on it & shorting to earth. Any of those things happening would have no dangerous consequences if the earthed side is switched. I have vehicles with both arrangements. The Pig is isolated in the earth lead as I chose to do that. The Shorland is switched in the supply lead which allows the switch to be placed in the circuit that is nearest the driver. Despite what I have said. Although I would prefer a switched earth, I would always chose the option that gave the switch as easy access to the driver as possible. I once have had a loom burn out & needed to switch off very quickly & would want the same facility in the event of an RTA. Quote Link to comment Share on other sites More sharing options...
Espressodude Posted January 9, 2009 Share Posted January 9, 2009 Earlier comment about marine/boats...Almost all boats in US have disconect on the + hot side. Many disconnects also have an alternator disconnect as an attempt to save the alternator if the switch is opened. It is general practice to put (rubber) covers on the battery cables to prevent the dropped spanner syndrome. I have seen disconnects placed in both battery leads to totally isolate the battery. Most disconnects do not have a wiping action of the contacts, just straight on push the contacts together, and hence do not wipe any corrosion build up from them. I have had to disassemble and clean contacts in order to start.:coffee: Quote Link to comment Share on other sites More sharing options...
Guest catweazle (Banned Member) Posted January 9, 2009 Share Posted January 9, 2009 Just put warning 24 volt on the windscreen,No one will steal it.:rofl: Quote Link to comment Share on other sites More sharing options...
gritineye Posted January 9, 2009 Share Posted January 9, 2009 Mark, one of the most reassuring things to fit to an older vehicle, as per previous posts fit to the earth side. Beware of the cheap ones with a red plastic bayonet fitting type of key, often sold by Landrover accessory outlets, these caused us so many problems on competition vehicles due to lack of robustness. Use a good quality nos MV one, good value at Beltring. PS agree with the wiping action comment Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted January 9, 2009 Share Posted January 9, 2009 . Use a good quality nos MV one, good value at Beltring. I've standardised on the heavy duty HELLA ones which are also excellent quality and good value, if a bit large. From truck components / auto elec suppliers. Having said that the jimmy one is still a Lucas red plastic key jobbie! Quote Link to comment Share on other sites More sharing options...
HotBed Posted January 9, 2009 Share Posted January 9, 2009 On my Hotchkiss, the circuit breaker is on the negative side of the battery, with a key to complete the circuit inside the drivers compartment. The positive side goes straight to the starter motor. Steve my m201 has the same system but after 3 to 4 weeks of inactivity the batteries have run down enough to hinder starting it so ive taken to disconnecting the batteries as well regards Quote Link to comment Share on other sites More sharing options...
Tony B Posted January 9, 2009 Share Posted January 9, 2009 Frost's do a lovley little piece of kit that replaces the positive battrey terminal. There is a screw in brass plug to make contact when you want to use it. No holes in the body, hiden nicley away. For modern vehicles there is a 10 amp fuse to keep things live. Quote Link to comment Share on other sites More sharing options...
Simon Daymond Posted January 10, 2009 Share Posted January 10, 2009 If I ever get around to it, I have a CAV master switch which were fitted to PSV's, they kill both the Pos & Neg, it's just getting around to wiring it up! For now, the one Tony posted looks a good bet. Quote Link to comment Share on other sites More sharing options...
gps Posted January 10, 2009 Share Posted January 10, 2009 on my scammell exploer the master isolater switch disconnects the + and the - on the starter lines and the charger field energise line ,and finally on the ignition. it is quite a large unit by todays standerd but it works well if any thing gose wrong it kills everything. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.