Elise battery drain
Discussion
I've had my Elise for 12 years and it's never given any bother.
A few months ago, after using it, I forgot to hook it up to the trickle charger. A few days later, it was completely dead. The battery (Varta) was 7 years old so I presumed it was knackered and that the trickle charger had kept it on borrowed time for a while. I replaced it with a Yuasa Silver. Checked alternator output, 13.5v.
The next time I used it, I purposely didn't hook up the trickle charger just for peace of mind that everything was ok. Few days later, completely flat. Jump started it, alternator still 13.5v.
Obviously it had a drain somewhere but I didn't drop everything to sort it because I thought the trickle charger would keep it on the boil.
Fast forward a few months to this evening, I noticed that the trickle charger was quite warm when I unhooked it. Started the engine - it only just caught and went around to my parents to borrow the multimeter again. I left there after a couple of hours. Despite a near 15 mile drive, again it only just caught when I went to leave.
Put the car in the garage and left it running whilst I checked the alternator again. Alternator has now failed - output varying between 10.5v and 12.5v. This can be explained by a recent track day in hot weather. Normally leads to failure of a K series Elise alternator!
Now the slightly worrying part, I decided to disconnect the battery whilst it had some charge in it. The battery was just about too hot to touch. Very very hot! Surely this cannot be normal?
What's would cause such a drain on a battery that would drain it dead in 48hrs and leave it so warm when the car is in use? I can only think starter motor?
Where do I go from here! Help!
A few months ago, after using it, I forgot to hook it up to the trickle charger. A few days later, it was completely dead. The battery (Varta) was 7 years old so I presumed it was knackered and that the trickle charger had kept it on borrowed time for a while. I replaced it with a Yuasa Silver. Checked alternator output, 13.5v.
The next time I used it, I purposely didn't hook up the trickle charger just for peace of mind that everything was ok. Few days later, completely flat. Jump started it, alternator still 13.5v.
Obviously it had a drain somewhere but I didn't drop everything to sort it because I thought the trickle charger would keep it on the boil.
Fast forward a few months to this evening, I noticed that the trickle charger was quite warm when I unhooked it. Started the engine - it only just caught and went around to my parents to borrow the multimeter again. I left there after a couple of hours. Despite a near 15 mile drive, again it only just caught when I went to leave.
Put the car in the garage and left it running whilst I checked the alternator again. Alternator has now failed - output varying between 10.5v and 12.5v. This can be explained by a recent track day in hot weather. Normally leads to failure of a K series Elise alternator!
Now the slightly worrying part, I decided to disconnect the battery whilst it had some charge in it. The battery was just about too hot to touch. Very very hot! Surely this cannot be normal?
What's would cause such a drain on a battery that would drain it dead in 48hrs and leave it so warm when the car is in use? I can only think starter motor?
Where do I go from here! Help!
MJK 24 said:
I've had my Elise for 12 years and it's never given any bother.
A few months ago, after using it, I forgot to hook it up to the trickle charger. A few days later, it was completely dead. The battery (Varta) was 7 years old so I presumed it was knackered and that the trickle charger had kept it on borrowed time for a while. I replaced it with a Yuasa Silver. Checked alternator output, 13.5v.
The next time I used it, I purposely didn't hook up the trickle charger just for peace of mind that everything was ok. Few days later, completely flat. Jump started it, alternator still 13.5v.
Obviously it had a drain somewhere but I didn't drop everything to sort it because I thought the trickle charger would keep it on the boil.
Fast forward a few months to this evening, I noticed that the trickle charger was quite warm when I unhooked it. Started the engine - it only just caught and went around to my parents to borrow the multimeter again. I left there after a couple of hours. Despite a near 15 mile drive, again it only just caught when I went to leave.
Put the car in the garage and left it running whilst I checked the alternator again. Alternator has now failed - output varying between 10.5v and 12.5v. This can be explained by a recent track day in hot weather. Normally leads to failure of a K series Elise alternator!
Now the slightly worrying part, I decided to disconnect the battery whilst it had some charge in it. The battery was just about too hot to touch. Very very hot! Surely this cannot be normal?
What's would cause such a drain on a battery that would drain it dead in 48hrs and leave it so warm when the car is in use? I can only think starter motor?
Where do I go from here! Help!
In my experience batteries only get hot/smoky when they have been Overcharged (15v+) which is plausible seeing as the alternator has now failed on the same day and that's more than likely what's happened. If you measured a varying output of 10.5-12.5v, your battery is also now flat and will need testing to make sure it also hasn't been affected by an overcharging alternator.A few months ago, after using it, I forgot to hook it up to the trickle charger. A few days later, it was completely dead. The battery (Varta) was 7 years old so I presumed it was knackered and that the trickle charger had kept it on borrowed time for a while. I replaced it with a Yuasa Silver. Checked alternator output, 13.5v.
The next time I used it, I purposely didn't hook up the trickle charger just for peace of mind that everything was ok. Few days later, completely flat. Jump started it, alternator still 13.5v.
Obviously it had a drain somewhere but I didn't drop everything to sort it because I thought the trickle charger would keep it on the boil.
Fast forward a few months to this evening, I noticed that the trickle charger was quite warm when I unhooked it. Started the engine - it only just caught and went around to my parents to borrow the multimeter again. I left there after a couple of hours. Despite a near 15 mile drive, again it only just caught when I went to leave.
Put the car in the garage and left it running whilst I checked the alternator again. Alternator has now failed - output varying between 10.5v and 12.5v. This can be explained by a recent track day in hot weather. Normally leads to failure of a K series Elise alternator!
Now the slightly worrying part, I decided to disconnect the battery whilst it had some charge in it. The battery was just about too hot to touch. Very very hot! Surely this cannot be normal?
What's would cause such a drain on a battery that would drain it dead in 48hrs and leave it so warm when the car is in use? I can only think starter motor?
Where do I go from here! Help!
In rare cases sticking diodes in the alternator can cause a drain on the battery, however I doubt you're lucky enough for the alternator to be causing both issues. Imagine it's more coincidence.
More than likely you have a electrical current drain - this could be essentially anything that requires electricity to function. And, as you've stated a good track day/sheer coincidence has subsequently killed the alternator.
Where to go.. get the alternator changed & battery tested to ensure they're ok. From there you're into fuse pulling territory to find your drain. Plenty of info on the net about setting up a meter to measure for current draw, my only advise would be to start with anything recently fitted before you had issues & retrofit (i.e radio, phone kits, tracker etc).
If this is a conventional alternator - not ECU controlled - then after a short run & with everything off & revs raised to around 2000 rpm I'd be expecting around 14.4 volts.
If the result was 13.6 volts then the voltage regulator in the alternator is defective.
Sounds like yours is completely knackered & you're wasting your time looking for other faults until you've replaced it.
If the result was 13.6 volts then the voltage regulator in the alternator is defective.
Sounds like yours is completely knackered & you're wasting your time looking for other faults until you've replaced it.
Edited by paintman on Monday 15th August 08:25
The K-series Elise has a tendency to cook its voltage regulator - it's mounted on the back of the alternator, too close to the exhaust manifold and the heat shield isn't sufficient. When mine failed I paid something like £10 for a second-hand alternator unit from a Rover 25 and fitted it myself... it's been fine ever since. 
kambites said:
The K-series Elise has a tendency to cook its voltage regulator - it's mounted on the back of the alternator, too close to the exhaust manifold and the heat shield isn't sufficient. When mine failed I paid something like £10 for a second-hand alternator unit from a Rover 25 and fitted it myself... it's been fine ever since.
If heat is the problem, I suggest that the regulator be modified and then bypassed, only use the regulator as a brush-box then fit and wire a external regulator well away from any heatPenelope Stopit said:
kambites said:
The K-series Elise has a tendency to cook its voltage regulator - it's mounted on the back of the alternator, too close to the exhaust manifold and the heat shield isn't sufficient. When mine failed I paid something like £10 for a second-hand alternator unit from a Rover 25 and fitted it myself... it's been fine ever since.
If heat is the problem, I suggest that the regulator be modified and then bypassed, only use the regulator as a brush-box then fit and wire a external regulator well away from any heatHow would I go about fitting a remote regulator?
MJK 24 said:
Penelope Stopit said:
kambites said:
The K-series Elise has a tendency to cook its voltage regulator - it's mounted on the back of the alternator, too close to the exhaust manifold and the heat shield isn't sufficient. When mine failed I paid something like £10 for a second-hand alternator unit from a Rover 25 and fitted it myself... it's been fine ever since.
If heat is the problem, I suggest that the regulator be modified and then bypassed, only use the regulator as a brush-box then fit and wire a external regulator well away from any heatHow would I go about fitting a remote regulator?
Have you insulated the exhaust with heat-shield tape?
Is there a heat-shield fitted between the alternator and exhaust?
Assuming it's standard, there's an aluminium (I think) heat shield there but that's all. Wrapping the manifold would probably require taking the rear clam off; it's a right arse to get at that area of the engine with it on.
ETA: Hmm, actually the OP's car isn't a 111S so the setup will be slightly different to mine due to the different manifold design. I think the standard manifold has a bit more clearance to the alternator but I don't know if they fitted extra shielding or it's just an air-gap.
ETA: Hmm, actually the OP's car isn't a 111S so the setup will be slightly different to mine due to the different manifold design. I think the standard manifold has a bit more clearance to the alternator but I don't know if they fitted extra shielding or it's just an air-gap.
Edited by kambites on Tuesday 23 August 16:22
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