eurocamper1 Posted December 25, 2014 Share Posted December 25, 2014 Hello i have a problem with my battery going completly dead sometimes after sitting overnight its 79 manta with fuel injection has any body had this problem and how did you fix it cheers Quote Link to comment Share on other sites More sharing options...
spiney_norman Posted December 25, 2014 Share Posted December 25, 2014 Tried a new battery? Quote Link to comment Share on other sites More sharing options...
mantadoc Posted December 25, 2014 Share Posted December 25, 2014 Battery Faulty alternator diode(s) After market wiring or things left on (e.g. interior light). Ignition switch. Use multimeter to check for drain. Quote Link to comment Share on other sites More sharing options...
Manta78 Posted December 26, 2014 Share Posted December 26, 2014 We always have batterys that going dead and most of the time its a light or something sitting on so check that. Quote Link to comment Share on other sites More sharing options...
dog321fish Posted December 26, 2014 Share Posted December 26, 2014 Light in boot ? Quote Link to comment Share on other sites More sharing options...
Kevin Abbott Posted December 26, 2014 Share Posted December 26, 2014 (edited) Light in boot ? Mine did the same. Boot light Change it for a led if you can't track it down Edited December 26, 2014 by Kevin Abbott Quote Link to comment Share on other sites More sharing options...
mantadoc Posted December 27, 2014 Share Posted December 27, 2014 Mine did the same. Boot light Change it for a led if you can't track it down The boot light has a switch operated by the boot lid hinge. You can't really say what it is just where to look and if it is the boot light on then better to fix the switch, it's only a push button like the door switches so unless bent should never fail closed. Anyway just pulling the bulb to test is one solution but easy enough to see if it is on. Changing the boot light for an LED if you have not established that as the cause is unlikely to sort the problem. Most cheap multimeters have a current facility up to 10A so with everything off you on the car you can pull fuses (up to 10A of course) and use it across the terminals to find which circuit the drain is on. If it is not on a fused circuit then slipping the earth terminal off the battery and putting it across the earth lead and battery earth terminal should show any drain not exceeding the multimeter's capability. If there is a drain you either unplug stuff till it goes away or for example reconnect the earth lead and try the same on the alternator leads to see if their is a leakage. However, do not exceed the capability of the tool being used or it may break ad of course all health and safety regulations should be observed as sparks near batteries or from thick leads touching to earth can be very dangerous. Basically do a risk assessment before starting and if in doubt seek expert help or assistance. Blown up car batteries full of acid are not fun. Generally the wiring is pretty good barring earths so also look to any after market additions such as stereo and amps (maybe not set to power down / incorrect use of trigger wire). Also think about any changes you made recently before the problem appeared. Typically fault follow a change whether deliberate or accidental no matter how unlikely Quote Link to comment Share on other sites More sharing options...
madmantamik Posted December 30, 2014 Share Posted December 30, 2014 what kevin abbot Is proposing is if the boot light is staying on, changing for an led lamp which has a very small current demand should not drain the battery overnight. you do not have to do any energised testing at all. disconnect the battery completely both pos and neg using a multimeter set on the ohms scale touch the leads of the meter onto the car body leads , on a healthy system with everything turned off you will get an infinite reading ie no load. no current. if you do get a reading with everything turned off pull the fuses out one at a time to see if the reading changes.if it does the fault is on that circuit. my suspicion is the power diodes in the alternator have failed you can verify this by using the multimeter as before then disconnect the alternator and the reading should go to infinite if you need it explaining further drop me a pm. Quote Link to comment Share on other sites More sharing options...
h0tr0dder_uk Posted December 31, 2014 Share Posted December 31, 2014 I had a boot lamp that would stay on and drain the battery. The garage that found the issue simply put someone in the boot and closed it lol 1 Quote Link to comment Share on other sites More sharing options...
mantadoc Posted January 1, 2015 Share Posted January 1, 2015 what kevin abbot Is proposing is if the boot light is staying on, changing for an led lamp which has a very small current demand should not drain the battery overnight.I know and what I said was just fix the switch lol it's quicker and easier and free 99% of the time. After all live goes to light and earths through switch. If you can't track that down in 2 mins the live must be earthing somewhere before the bulb and an LED won't help. on a healthy system with everything turned off you will get an infinite reading ie no load. no current.This is incorrect. For one the clock is a permanent drain on a standard Manta. As do all transistors so a GTE will also have a slight earth leakage from the EFI and diodes are 2/3 of a transistor so there may be a leakage there (not checked) plus any alarm or stereo permanent live for memory. If your battery terminal sparks slightly when connected there are some drains (often interior lights if doors open) but healthy cars are not necessarily infinite resistance / open circuit when checked. Quote Link to comment Share on other sites More sharing options...
Kevin Abbott Posted January 1, 2015 Share Posted January 1, 2015 Just remove the bulb. Job done if the battery stops going dead. If it does then delve deeper. If it doesn't then we are barking up the wrong tree and maybe alternator like said 1 Quote Link to comment Share on other sites More sharing options...
madmantamik Posted January 2, 2015 Share Posted January 2, 2015 thanks mantadoc for telling me I don't know my job 19 years as an electrician and 12 years as an auto electrician i really should know better, oh but wait a minute firstly I suggested uning a multimeter on the OHMS scale not on the milliohms scale, for the battery to deplete overnight it would need a resistance of at least 4 ohms which is far greater than any vehicles I.O.D.never mind a vehicle with a very basic wiring loom like the manta. basic ohms law that one. and secondly if a live was to earth out before the LAMP not the bulb would the fuseable link not blow.. please feel free to delete this as there is no way I can be right is there. 1 Quote Link to comment Share on other sites More sharing options...
mantadoc Posted January 2, 2015 Share Posted January 2, 2015 secondly if a live was to earth out before the LAMP not the bulb would the fuseable link not blow..Shorts aren't always a dead short, if they were a fuse would be gone / wire would be smoking and we wouldn't be debating it.I'm just trying to be comprehensive because anyone that see the earth terminal spark will know there is some load or leakage even if thy don't see it on the meter, plus they may choose their own scale. Quote Link to comment Share on other sites More sharing options...
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