Ade Ray Posted January 31, 2003 Share Posted January 31, 2003 I have been reading some of the threads re installing a push start and it has raised a few questions: My push start has four terminals on the back, most of the threads I have been reading SEEM to indicate two terminals on the back of the button. Am I wrong or am I wrong? The threads also say to use fairly high ampage connectors but the connectors on the back of the push start are quite small and the only female connectors I can find that would fit are 2amp. Can anyone just confirm whether I am worrying over nothing or not. I am always a bit twitchy when it comes to electrics. Ade Make the world a better place, hug an estate agent Link to comment Share on other sites More sharing options...
oilyhands Posted January 31, 2003 Share Posted January 31, 2003 You only need a 2 pole button and you are only energising a solenoid, the amperage for a starter solenoid is quite low. I'd have thought 2 A too low though, I'm guessing 5 amp would do it. Oily Link to comment Share on other sites More sharing options...
StewartG Posted January 31, 2003 Share Posted January 31, 2003 I've just done mine using the RS switch and some 5 amp mains lighting cable soldered to the switch terminals, fed from the redundant wiper feed and feeding into the white/red wire that goes from the ignition switch to the solenoid. This puts the new button in parellel with the ignition switch so I can use either. Seems to work. Link to comment Share on other sites More sharing options...
Chris W Posted January 31, 2003 Share Posted January 31, 2003 Your switch is probably a "double-pole-single-throw" (dpst) in the jargon. That means it has two totally separate switches in it which are both simple ON/OFF types operated by a single button. You can check this out easily with a battery and a bulb if you don't have a meter or a 12v tester. Once you have ascertained the layout, simply use a pair of terminals that give ON/OFF when the button is pushed regardless of what else they do in the other position. The current to the solenoid is fairly low and since the solenoid is only energised for at most a few seconds on starting, I am sure your 2 amp terminals will be sufficient. The more important thing, if the switch has very small terminals, is to ascertain what the current rating of the switch is, although in general it's unlikely to be less than the 2 amps. (This is not a warranty of course!!!) rgds Chris Link to comment Share on other sites More sharing options...
Colin Grundy Posted January 31, 2003 Share Posted January 31, 2003 I'm glad you raised this as I have fitted a push button but am about to wire it up. FWIW I have read, and you can check the archives that 25amp is the recommended wire, but I take your point, the spade terminal would be too big for the terminal on the back of the button. Apparently there is a wiring diagram on the 7Register somewhere. I've got an idea............. wire it up with 2/5amp and let me know how you get on 😬 I think I'll do mine when the firemen aren'y on strike Link to comment Share on other sites More sharing options...
Ade Ray Posted January 31, 2003 Author Share Posted January 31, 2003 Further investigation is obviously required. What are the issues for me using a higher ampage wire than I may need? Ade Make the world a better place, hug an estate agent Link to comment Share on other sites More sharing options...
philwaters Posted January 31, 2003 Share Posted January 31, 2003 Just means you have something to lighten later on Phil Waters You mean you can drive these? I thought it was just there to polish 😬 Link to comment Share on other sites More sharing options...
Graham Sewell Posted January 31, 2003 Share Posted January 31, 2003 So why not pull the existing cable off the back of the key switch, put an ammeter in series and test it. If it runs higher than a couple of amps, then you know that the 25A cable is required. Otherwise, give yourself at least 50% contingency on the max current drawn. Else, put a relay in the circuit next to the starter and this will then draw about 100mA max and you can have the high current wire locally. However, judging by the thickness of the wire at the solenoid, it cannot be that much current. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
Chris W Posted January 31, 2003 Share Posted January 31, 2003 None - other than the wire will be thicker and therefore possibly less easy to route. Checking on the web, it would appear a general figure for starter solenoid current is somwhere in the range 5-10 amps. Chris Link to comment Share on other sites More sharing options...
chris a Posted January 31, 2003 Share Posted January 31, 2003 FWIW, I fitted one a couple of weeks ago, and took the advice regarding 25A wire as the only safe way to go. It certainly seemed to match the thickness of the wires I was messing with at the back of the ignition key, and gives me additional peace of mind. But the problem is that with this thickness wire it is a bugger to do anything with, let alone connect it to the spade terminals that you need to. I am surprised that no-one has the definitive answer yet!! Chris a Link to comment Share on other sites More sharing options...
Chris W Posted January 31, 2003 Share Posted January 31, 2003 Graham's suggestion above of fitting a relay would solve the issue as you can then use thin wire to the relay. On my new SV, I have just fitted an aircaft style starting switch and the red/white wire that goes off to the solenoid is the thinnest of all the wires connected to the original ignition switch. Chris Link to comment Share on other sites More sharing options...
StewartG Posted January 31, 2003 Share Posted January 31, 2003 The solenoid is a relay. How many relays do we need to daisy chain together? Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted January 31, 2003 Leadership Team Share Posted January 31, 2003 The problem with the K-series starters has been put down to there not being enough "juice" in the cable run by the time it gets to the starter relay. If you fit another relay next to the battery, the "higher" current cables are only needed on the short runs - then it doesn't matter what you use on the starter button, but 17amp is probably the easiest size to work with and fits in well. Use the outside to connections on the 4 connector switch. If you need more details on the method of wiring the starter button and a starter relay, let me know. Every K-Series 7 that has had the relay mod up this end no longer has a starter problem. Stu. Link to comment Share on other sites More sharing options...
Chris W Posted January 31, 2003 Share Posted January 31, 2003 Stewart Sure, the solenoid is a relay - you're right..... but it's a bloody big relay drawing a significant current (Amps), whereas what everyone else is suggesting is the use of an additional small current relay (milliamps) to operate the big b****r!! rgds Chris 1.8K SV 140hp V11CPW Ruby Red with Silver nose and stripe Link to comment Share on other sites More sharing options...
Tony C Posted January 31, 2003 Share Posted January 31, 2003 Two suitable "Big Red" wiring diagrams here The Farnell sourced "Big Red" is itself rated at 10 amps. The outer two contacts are OFF and the inner two contacts are ON with the switch 'at rest'. This reverses when you press the button. I guess, if you really wanted to (NOT a recomendation), wire-up your headlights the the inner two contacts so that you switch them off automatically when you push for a start, maximising 'electricity' available to the starter motor. As you let go the button, the headlights would come back on again This is only for those too lazy not to have their headlights switched on before going for a START. The 25 amp minimum wire spec. advice is a belt and braces approach. Not necessarily to prevent the wire burning out (if Oily says the solenoid only draws a few amps, that's good enough for me), but I've heard this number elsewhere too. (Don't forget the 10 amp switch rating). Thinwall cable is the type used on most modern cars and is more flexible than the older PVC insulated stuff. "Big" cable minimises voltage drop. Think of trying to blow down a hyperdermic needle or a garden hose - which is easier. Same for 'electricity'. The 'female' spade connecters that "nearly" fit the "Big Red" are 1.5 to 2.5 square mm in cross section, about the same as the 25 amp rated cable. These are 2.8mm blade width. They nearly fit and need a bit-of-a-squeeze to make a nice tight fit. Or solder if you prefer. I always hear sizzling noises from inside the switch when I do that, so personally prefer the spade connecters. Engine nearly ready to go in Colin? Waiting for my BRG SV kit. 😬 (Superior Version) - 9 weeks to go! Link to comment Share on other sites More sharing options...
Big Brother Posted January 31, 2003 Share Posted January 31, 2003 Make life simple! All the debate re the correct wire to use is irrelevant! Look at the size of the (red/white) wire that came from the original ignition switch. This is the size of wire you wil need to use 😬 Steve Se7en-Up! Less is more! Link to comment Share on other sites More sharing options...
Tony C Posted January 31, 2003 Share Posted January 31, 2003 I completely agree Steve 😬 - your opinion is just as worthy as mine (ours) Waiting for my BRG SV kit. 😬 (Superior Version) - 9 weeks to go! Link to comment Share on other sites More sharing options...
EFA Posted January 31, 2003 Share Posted January 31, 2003 Well I disagree.... The red white wire can easily withstand the nominal current draw by the relay, but fails to handle the instantaneous load when the button is first pressed. The effect of this is not until you have a battery which is a little weak. Then you will find the starter inertia is reduced causing the starter to fail to engage correctly. Result is the starter will not engage, perhaps when you most need it to. But thats why they have the AA perhaps...... Caterhams looms are perhaps not the best engineered in the world..... Strip the insulation off the grounds around the lighting (particularly on the non PTFE insulated looms) and you WILL see the cable discoloured through overloading..... Arnie Webb The Fat Bloke back @ 512k Link to comment Share on other sites More sharing options...
Tony C Posted January 31, 2003 Share Posted January 31, 2003 Irony anyone? Waiting for my BRG SV kit. 😬 (Superior Version) - 9 weeks to go! Link to comment Share on other sites More sharing options...
Big Brother Posted January 31, 2003 Share Posted January 31, 2003 😬 😬 😬 Steve Se7en-Up! Less is more! Link to comment Share on other sites More sharing options...
Leadership Team SLR No.77 Posted January 31, 2003 Leadership Team Share Posted January 31, 2003 Look boys , sod the cable size 🤔 . If it's a K-Series, it's recognised that there are problems with the starter solenoid & wiring being cooked by the heat from the manifold. The tried and tested fix for this is a second relay before the starter solenoid, and I know from experience that not only does this fix the "click-click-click" problem, but the whole activity of starting is more positive. Once you've done this mod, the power needed to switch the solenoid is minimal, therefore the discusion becomes academic. the wires taken out of my Cat 7 Scalextric car would be enough to start it with the mod fitted! Honestly, don't even waste the time worrying about wire ratings and connector types for the starter button - add the solenoid and the whole discussion is as relavent as George Bush listening to the UN Stu. Link to comment Share on other sites More sharing options...
neilsjuke Posted January 31, 2003 Share Posted January 31, 2003 as the lot from Dartford seem to use motor bike wiring 14/0.012 in /or 14/0.3 rating 8.75amps for this use would be fine with the short distance ( lack of volt drop) or if you feel the need 28/0.012 in or 28/0.3 Met 17.5 amp rated will be over the top as is same as the alt output on some 7s i have seen.( I dont know what next with all this retro push start buttons like real Lotus 7s did you know the start button on the L7 is also a foot switch for the two tone horns on fire engines of the 70s Link to comment Share on other sites More sharing options...
Colin Grundy Posted February 1, 2003 Share Posted February 1, 2003 Tony Don't worry mate.........just wait for the call 😬 Link to comment Share on other sites More sharing options...
Tony C Posted February 1, 2003 Share Posted February 1, 2003 Oh God, its him again 😬 I've already told myself off for being flippant earlier. What stu is saying makes a lot of practical sense. As AMMO said on another recent thread, if a well thought-out modification works - go for it, or keep fiddling until it does. If several people have experienced a similar inability to start there probably exists an underlying fault, other than with the wiring from the key/button to the solenoid. My understanding of a starter solenoid is that it's a remote, electrically operated switch. Designed to minimise voltage drop in the wiring from the battery to the starter motor. The solenoid has two coils, a pull-in and a hold-in. These coils draw a relatively small current. When the solenoid is operated by the ignition key/button it closes a ‘chuffing-great' switch to connect the battery directly to the starter motor via an equally large wire. The starter motor itself draws a very large current, particularly immediately after switching it on (starting current), hence the need for big wires of short length. The initial spin of the starter motor throws the starter drive into engagement with the ring gear on the rim of the flywheel - or am I being old fashioned - and away you go. . If you turn the key, get one ‘click' and nothing else, I would think that the solenoid has operated correctly, but not enough current is going to the motor to spin it. If you get a series of ‘clicks', sounding more like a woodpecker, the pull-in coil is OK, but the hold-in coil isn't holding-in. The battery is able to supply 12 volts, but only when in peak condition and with minimum resistance in the circuit. The circuit just to the starter motor is going draw an enormous current from the battery. If there is any high resistance in the circuit or the battery is in less than peak condition there will be insufficient current 'left over' to hold-in the solenoid, which will then drop out and the starter motor will be disconnected from the battery before it can start spinning. There will then be enough current to operate the solenoid again, which repeats the above sequence until you let go the key in disgust. I've read previous threads on this subject and there seem to be several possible reasons for our starting problems. 1. Heat from the exhaust combined with vibration which messes with the electrical connections within the solenoid or the external wiring. 2. Dodgy or a poorly maintained battery, unable to give full voltage. 3. Dirty or loose electrical connections. 4. All of the above. Some people have gone for the Brise starter as a long term fix - high quality kit. Some have taken their solenoid to pieces and modified its internal electrical connections. Some have fitted a remote solenoid/relay, but IM Humble O, this fix is probably just sweeping the underlying problem(s) under the carpet - but if it works long term, who cares. There is nothing worse than a car that will not start reliably. I personally think the quality of the motor/solenoid is suspect and was considering going down the route of heat shielding held away from the solenoid/starter and using lightweight ducting to blow cool air into the gap. Electricity - a pain in the butt 🙆🏻 Waiting for my BRG SV kit. 😬 (Superior Version) - 9 weeks to go! Link to comment Share on other sites More sharing options...
Ade Ray Posted February 2, 2003 Author Share Posted February 2, 2003 Thanks for all the good advice. I am going to try and tackle the installation if I can get the bits I need. Tony, What amp rating ar the spade connecters you refer to in you earlier posts? Ade Make the world a better place, hug an estate agent Link to comment Share on other sites More sharing options...
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