A ghost in the machine?

Anyone else suffered/ cured this one?My Elise mk1 has a battery drain problem - sometimes it’ll sit unused and start after 2 weeks, sometimes it’ll be flat after 48 hrs!Can run it all day one day, and 2 days later it may be so flat, the starter relay just clacks, other times as I say it’ll last 2 weeks and burst into life first turn.It’s as though sometimes something is getting stuck in an on state and drawing � an amp, and other times, the ‘thing’ is switching off as it should. (no I’ve not yet measured the drain to see if it is the case yet). The battery is new (Any ideas/ experience of this?All ideas and help welcomeThanks

Do you have a face-off stereo ?It’s been known for those to draw a current with the face on.

Elises are renowned for killing batteries; I’ve known a brand new battery die after 3 months! It mainly happens with cars that aren’t used very regularly, but obviously I don’t know if this applies to you. If you do use you car all the time, you may have a duff battery, in which case you should be able to get it replaced under warranty (Lotus’ or the battery manufacturer’s, depending on the age of the car). Alternatively, as you say, you may have something draining the battery. Make sure that there is nothing in the battery area that could occasionally be shorting the battery to the metal chassis, as this has been know to cause problems. If you don’t use your car regularly, the battery may have suffered in the usual Elise way, in which case you should still be able to get it replaced under warranty.I strongly recommend battery conditioners for cars that are not in constant use; they significantly prolong the life of the battery, as well as ensuring that your car will start when you want it to! [image]http://www.exiges.com/ubb/NonCGI/images/icons/smile.gif[/image]

Battery conditioners - how that work and what do i do?

Check that the brake light switch isn’t sticking in the on position. This is a known problem with the Elise and can result in a flat battery after only a day or so. Worth a check…

quote:Battery conditioners - how that work and what do i do?They’re small mains-operated units that you connect to the battery when the car isn’t in use. They put the battery through a repeated charge / discharge cycle, which keeps the battery charged and prolongs its life. It also thereby prevents the damage caused by the battery going completely flat.Lotus sell them, but Lotus’ product ia actually a badged AirFlow units that is available much cheaper direct.

I had a car that used to kill the battery within days. It turns out the earth strap wasn’t connected properly (to the chassis), and it wasn’t holding the charge.Just a thought.

TT - Like the idea of the break light switch sticking on - that’s what I hope it’ll be 'cos that would fit the symptoms - sometime OK for weeks, and sometimes flat within a couple of days, and of course as I pull off the road, the break is the last think I touch.I’ll set to this weekend with a test meter and a tin of WD40.AGYNJO - Do you know which earth strap? I’m thinking not the engine one, perhaps the alternator (does it have one, or does it share the engine earth?) or the main battery earth. Thanks for the pointer, I’ll give them a waggle.Thanks for the ideas, I’ll let you know.(Off to Goodwood on Sat, if the car starts, that is)

Regarding the battery conditioner, Tony says (above) “They put the battery through a repeated charge / discharge cycle…”.Surely that can’t be quite right. If it discharges the battery as part of a cycle then what happens if I want to go somewhere?? It effectively means that half the time you have a flat or near flat battery.Does it simply mean a small occasional load, followed by a top up? Surely you would get this from an ordinary battery charger, since the alarm provides a constant load.

Ken, for long term use, ordinary battery chargers are too vicious, and most, if left on, will overcharge a battery, which is as harmful as the battery going completely flat. The units I’m referring to trickle charge the battery until it is fully charged, then apply a light load for a while. When the charge has fallen to a pre-set level, the unit starts trickle charging the battery again. However, the point to which the battery is allowed to discharges is still effectively fully charged. The units are designed to be left on a car for months at a time if required; doing this with a normal battery charger would almost certainly kill the battery. I hope this clarifies the situation� [image]http://www.exiges.com/ubb/NonCGI/images/icons/smile.gif[/image]

James,One way to trace the current drain is to disconnect the Positve (red) battery cable and insert an amp meter in series (one lead on the battery terminal and the other onto the lead you have just disconnected) DO NOT TRY TO SWITCH ANYTHING ON!!! THIS WILL CAUSE YOU IMMENSE GRIEF [image]http://www.exiges.com/ubb/NonCGI/images/icons/frown.gif[/image] Turn the meter to read current and switch it to on.Read of the current drain and then one at a time remove each fuse until the current drops to zero, this will narrow down your search to what is flattening the battery.You could also have a duff battery, record the battery voltage with a volt meter it should read around the 14 volt mark, if this is not the case it could be that you have a duff cell within the battery, this can occur in many ways but a common one is to try and start the engine on a flat or near flat battery.What happens is that the lowest voltage cell (of which there are twelve, each of 1.2volts in a car battery)is reverse polarised due to the current pulled from the starter motor (current goes up as voltage goes down!!)the only way to resolve this is to replace.Before the replacement is installed i would carry out the above check so you don’t cream cracker the replacement.It is good practice to replace a battery which has been totaly drained (i.e. starter just clicks, lights only dimly glow etc)as one cell is almost certainly been damaged and will drain the other good ones… You then enter the “what is draining my battery game!!!” when it is the battery draining it’s self!!!Hope this helps…

The simplest solutions are often the best… nice !

How did you get on James?

Hi Diggy - Oh, OK now you ask - I’ve not had time to look yet. Been using the toy fairly regularly this last 2 weeks, and it’s been OK - This just to lull me into a false sense of security, I’m sure.My worry about the fault, as manifest by the symptoms, is I’ve got an intermittent problem. e.g. the immobiliser or alarm or ignition system sometimes gets stuck in a high current state, and sometime rests in its low current state.I’ll of course run through the fuse checking routine as you suggest, if this does not find it first time round, I’m thinking what I need to fit is one of those ‘removable key’ devices on the battery lead - normally the key , which I guess is just a thick piece of copper allows the car to operate normally, when one departs, one removes the key and leaves just a 10 amp fuse across the ‘break’ which allows the alarm to function, but breaks if the car is started. I’d replace the fuse with the current meter, and therefore be able to check the quiescent drain at rest, regularly and easily until the fault reappears.Thanks for your help, I’ll let you know.

James, without wanting to teach you to suck eggs, just one word of warning: make sure that the meter can cope with the anticipated current before you connect it, and always start on the highest current rating and then work down. I’ve seen more than one meter fried while trying to measure a current that it wasn�t rated for! [image]http://www.exiges.com/ubb/NonCGI/images/icons/wink.gif[/image]

to prevent meter burning, just put a 20 amp fuse…just to be sure! [image]http://www.exiges.com/ubb/NonCGI/images/icons/smile.gif[/image]

Right easy way to do over a period of time, each time you park up for the night or exetended period remove a different fuse until it stops being drained, this may take sometime [image]http://www.exiges.com/ubb/NonCGI/images/icons/rolleyes.gif[/image] but is safe. Being that car battery is DC it will hurt alot as you will not be thrown off it (like Mains) but will grab hold off you, on;ly thing limiting the current is the internal resistance of the battery if you short it with a spanner etc so please be careful,if you are passing Reading on your travels let me know i will have a look at for you…As for fuses go, it is now a legal requirement under the Electricity at work act 1989 to provide all multimeters with GS38 test leads…ie they must be fused.