Phil G Posted October 29, 2011 Share Posted October 29, 2011 I fitted a fully charged Banner battery last Saturday and went for a health blat which should have kept the thing topped up. I tried to start it today and had insufficient charge to even crank it over once. This is not the first battery to do this and I’m assuming at least one of them, if not both, is in good condition. Is it possible that the immobiliser can draw that much current over 7 days to drain the battery or should I be looking for another culprit? No power in lock-up so trickle charging not an option. No battery cut-out switch either. It starts first time on jump-leads. Link to comment Share on other sites More sharing options...
Chris Wells Posted October 29, 2011 Share Posted October 29, 2011 Hi I have had a similar experience. The battery will go flat quite quickly and have always put the problem down to the immobiliser light. ☹️ I'm lucky and can leave mine on a trickle charger, but you could try charging the battery and then disconnecting it. See what happens. It shouldn't go flat without a load of some sort. Chris Link to comment Share on other sites More sharing options...
richy Posted October 29, 2011 Share Posted October 29, 2011 If you have a multimeter, disconnect the battery and connect it in series (do not try to start the car!). You should be able to measure the current draw from the immobiliser. There have been other recent threads on this issue. richy Link to comment Share on other sites More sharing options...
millsn Posted October 29, 2011 Share Posted October 29, 2011 I once drove from Goodwood to Huntingdon on a battery that wasn't being charged at all. Would be worth checking if your alternator is fried, you should see 13. something volts once the car is running, if not, dead alternator Link to comment Share on other sites More sharing options...
Jason Plato Posted October 29, 2011 Share Posted October 29, 2011 you could use a discarnect try a google search Link to comment Share on other sites More sharing options...
JetSepter Posted October 29, 2011 Share Posted October 29, 2011 I gave up on the small Banner battery because of this problem. Fitted a bigger Powervamp and a cut-off switch some months ago and haven't had any problems since. Pictures on my.lotussevenclub.com/pictures under JetSepter. Link to comment Share on other sites More sharing options...
tbird Posted October 30, 2011 Share Posted October 30, 2011 Phil earlier thread here, with some figurers , as mentioned above Discarnectis a cheap and cheerful solution (obviously don't connect resistor) keep one on my Audi, which suffers a similar problem after around 13 days Tim Link to comment Share on other sites More sharing options...
Phil G Posted October 30, 2011 Author Share Posted October 30, 2011 Thanks for the advice guys. I'm going to do a hydrometer reading on both batteries as a starting point. I like the simple idea of a discarnect as a short term measure – I wonder if they do one with a bolt fixing rather than the tapered post mounting? Doh! Fitting will fit all types - Read the bl**dy blurb first Looking at all your links the best step appears to be………fit a cut-off switch. Electrics not being my forte can I ask a numpty question? Is it simply a matter of wiring it between the live feed? Edited by - Phil G on 30 Oct 2011 08:49:57 Link to comment Share on other sites More sharing options...
shn7 Posted October 30, 2011 Share Posted October 30, 2011 Phil, Note that the cut off switch can suffer from wear if the key is inserted/removed lots of times. It can get to the point where holding the key in the on position makes the difference between start and no start. Though this may be better than your current (pardon the pun) situation. Link to comment Share on other sites More sharing options...
tbird Posted October 30, 2011 Share Posted October 30, 2011 Is it simply a matter of wiring it between the live feed? Not quite, some info from 7 Faq Fitting Switch Tim Edited by - tbird on 30 Oct 2011 12:13:59 Link to comment Share on other sites More sharing options...
Phil G Posted October 30, 2011 Author Share Posted October 30, 2011 Ah! I see..........Thanks Tim. I'm guessing but are the other wires (Brown & Purple) feeds to the rest of the electrical systems? 😬 Edited by - Phil G on 30 Oct 2011 13:05:36 Link to comment Share on other sites More sharing options...
tbird Posted October 30, 2011 Share Posted October 30, 2011 I think the FIA switch open circuits, the main 12 battery feed, as well as the ignition cct to stop the Alternator keeping the engine running once battery disconnected, and a cct is added to dump the alternator current to earth via a resistor when switch used with engine running, this saves the regulator pack in alternator going bnag Tim Link to comment Share on other sites More sharing options...
Phil G Posted October 30, 2011 Author Share Posted October 30, 2011 Checked both batteries with hydrometer and all cells fine and charged after some time on the optimate. Stack telling me I have a good charge. Thanks again Tim.......Why do I feel such an ignoramus where electrics are concerned. If you can't hit it, screw it or tighten it with a spanner I'm buggered. Re: 7FAQ Fitting Switch. I appear to have 3 brown leads connected to the + side. One heavy gauge and two lighter ones crimped together onto one terminal Linky I have yet to locate the purple one - any pointers? Link to comment Share on other sites More sharing options...
fred_gustafsson Posted October 30, 2011 Share Posted October 30, 2011 I had similar issues so i installed an ammeter and voltmeter to be able to figure out what's going on. It turns out that the standard CC alternator doesn't charge the battery at all under 1700 RPM. The car will draw more then 15 amps when you are idling. If you are driving home with headlights on, the fan going and spend a lot of time in traffic jams (I live in London) you tend to come home with a battery that is almost empty and that won't be enough to start to a week later. I considering a smaller pulley wheel on the alternator to make it charge at lower revs but for now I just rev it for a few minutes before parking. (Duratec 175) Link to comment Share on other sites More sharing options...
Phil G Posted October 30, 2011 Author Share Posted October 30, 2011 If I go the cut-off switch route I think I will also change to a gel battery. Link to comment Share on other sites More sharing options...
tbird Posted October 30, 2011 Share Posted October 30, 2011 Suspect 7faq was written some time ago, so wiring may have changed, I haven't actually fitted one just understand theory, hopefully someone may be around who has fitted one, as its fairly critical that you get it correct, maybe if, as you say, you are not electrically minded it may be one of the jobs you get your local 7 specialist to undertake, shouldn't be such an expensive job. Tim Link to comment Share on other sites More sharing options...
Phil G Posted October 31, 2011 Author Share Posted October 31, 2011 Wise words.......... Quite a bit on BC about the 'hard to find' purple wire - I'm not alone it would appear! I think I'll have a chat with the boys at Redline. Link to comment Share on other sites More sharing options...
Paul Deslandes Posted October 31, 2011 Share Posted October 31, 2011 It turns out that the standard CC alternator doesn't charge the battery at all under 1700 RPM. The car will draw more then 15 amps when you are idling. The problem is the ratio of the diameters of the crank and alternator pulleys and the alternator speed at max revs. To get a good charge at, or just above, idle requires a high ratio, ie large crank - small alternator pulleys. Trouble is, with the engine doing much above 6000rpm, you're in danger of over revving the alternator, so a larger alt pulley is often fitted to prevent its destruction. This, in turn, reduces at-idle alternator revs to the point at which the output voltage isn't high enough to push current through the battery. Turn your headlights on and watch them go dim when the revs drop below the charging level. Its a compromise. Link to comment Share on other sites More sharing options...
LazerBrain Posted October 31, 2011 Share Posted October 31, 2011 Phil - you haven't mentioned what engine you have. My EU2 K series engine's MEM ecu had a problem which caused it to flatten the battery. There's more information in the TechTalk thread Link to comment Share on other sites More sharing options...
MartinH Posted October 31, 2011 Share Posted October 31, 2011 Another slight hijack so apologies. The 7FAQ seems to imply that using the master switch as a security device or as a way to stop battery drain is not advisable on K series cars... On K Series cars it is not advisable to switch the engine off on the master switch except in emergencies as this will wipe the memory of the ECU. While no permanent damage will be done, it will result initial rough running until the ECU has been able to re-program itself. Is this also the case with Duratec cars? Cheers, Martin Link to comment Share on other sites More sharing options...
Phil G Posted October 31, 2011 Author Share Posted October 31, 2011 LazerBrain 1800 VVC Emerald K3. Link to comment Share on other sites More sharing options...
Jason Plato Posted October 31, 2011 Share Posted October 31, 2011 I have a fia cut off switch and would advide anyone NOT to fit one. They are unreliable and the scource of problems. I'm on my 4th in 12 years and carry a spare in my touring / trackday spares box. Link to comment Share on other sites More sharing options...
gundersen Posted October 31, 2011 Share Posted October 31, 2011 Quoting MartinH: On K Series cars it is not advisable to switch the engine off on the master switch except in emergencies as this will wipe the memory of the ECU. While no permanent damage will be done, it will result initial rough running until the ECU has been able to re-program itself. Is this also the case with Duratec cars? I would not do that on any car unless it was an emergency (as the wiki says). ECU's are fairly complicated bits of computer kit, and like any computer they should be shut down properly. However, I think there is a difference between "switch the engine off on the master switch" and "shutting down the car in the normal manner and THEN cutting the master switch". In the latter case, the ECU will have time to do its final bookkeeping before being shutdown. The above is of cause totally void of any factual knowledge of both the K and duratec ECUs, so take it appropriately 😬 Link to comment Share on other sites More sharing options...
LazerBrain Posted October 31, 2011 Share Posted October 31, 2011 Thanks Phil - I've only heard of the problem I experienced a couple of times, and only with the Rover MEMs. It's still worth measuring the current through the various fuses with the engine off to determine if you have got anything taking unexpected current from the battery. Link to comment Share on other sites More sharing options...
Phil G Posted October 31, 2011 Author Share Posted October 31, 2011 Good idea LaserBrian. Anyone in the Worthing area fancy helping me on this one (with meter and knowledge). Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now