bongo321 Posted December 10, 2018 Share Posted December 10, 2018 Hi i want a bit of extra security so i want to fit an isolate switch on the battery box . Do i switch the poss or neg . i can fit a jumper fuse to keep the radio presets Is there a simple way to not fry the alternator If it was ever switched with engine running . If so how please . thanks gerry Quote Link to comment Share on other sites More sharing options...
western Posted December 10, 2018 Share Posted December 10, 2018 one of these will allow your radio to remain powered while isolating the starter circuit https://www.12voltplanet.co.uk/battery-isolator-switch-removeable-key-with-ignition-isolation.html Quote Link to comment Share on other sites More sharing options...
bongo321 Posted December 11, 2018 Author Share Posted December 11, 2018 Looks good , not sure how to wire it up , do I just miss out the coil bit . Quote Link to comment Share on other sites More sharing options...
miketomcat Posted December 11, 2018 Share Posted December 11, 2018 You need to move the supply from the alternator from the starter motor to the battery side of the switch. This will require a longer cable. Personally I switch the positive with small fuse jumped across the switch to keep the permanent live. Mike Quote Link to comment Share on other sites More sharing options...
Escape Posted December 12, 2018 Share Posted December 12, 2018 What exactly do you want to achieve by installing a battery switch? Prevent battery drain, emergency shut down of the engine, theft protection (battery key), ... ? If it's just to isolate the battery, I'd use the negative. This will offer the best safety when working on the car, as you don't have a (short) live section from battery + to switch. But that would make it impossible to keep the radio (at least I can't think of a good solution). To cut the engine, you need to do some rewiring or use a suitable switch to prevent the alternator from keeping the engine (a)live. As discussed. For the radio I'd use a dedicated wire (with fuse) from battery + to the radio (and possibly interior lights, central locking, alarm etc while you're at it). Depending on the car, this could become rather complex. Filip Quote Link to comment Share on other sites More sharing options...
Flash17 Posted December 15, 2018 Share Posted December 15, 2018 (edited) Hi, If all you want is very simple additional security with a isolator switch and removable key the you can place on either the positive to the starter motor or the negative to the chassis. For additional security hide the switch. At work we have twin battery set ups on boats and each positive lead from each battery needs its own switch.....expensive On the works trucks we have twin batteries (one for starting & one to run equipment) with both battery negatives using the same cable to the chassis with a single isolator swich to kill the whole system, cheeper and effective. If you place your switch on the negative and upgrade to a twin battery set up in the future you wont need to place a second swich when you do so. A word of caution if you have accessories such as extra lights etc wired direct to your battery, ensure that they are wired to the none battery side of the switch, this ensures if the fuse blows power can't be routed though them when you try and start therefor potentially damaging them. Edited December 15, 2018 by Flash17 Quote Link to comment Share on other sites More sharing options...
Eightpot Posted December 15, 2018 Share Posted December 15, 2018 If it's for security I'd avoid the standard issue red plastic key ones - would be the first thing I'd buy if I were a landy thief, along with a piece of wire to defeat a hidden fuel solenoid switch. Quote Link to comment Share on other sites More sharing options...
mmgemini Posted December 15, 2018 Share Posted December 15, 2018 The only way to isolate the battery and not allowing it to run on the alternator is to fot an FIA battery master switch. You can also fit a series hasp to the battery box lid. The last time I returned from our trip. The shippers asked if they could drive the car out the box. I said yeas and gave instructions as where the battery switch was and how to use the key. On arrival at the docks. The box was open, car still inside. Even with my instructions they had been unable to find the master switch. Would that be good Quote Link to comment Share on other sites More sharing options...
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