Mega problem?

[macey]

Hello, I have a 2013 Elise S (2ZR-FE engine). Glanced inside the other day and noticed that the immobiliser was not flashing, "strange" I thought. Battery flat? Only did 1,500 fault free fantastic miles in it two weeks ago. Took the front panel off today and jumped a fully charged battery to it. Nothing! Can't  open the door, can't get into the engine compartment either. Alslo noticed that the RPM counter is stuck at 2,500 rpm. Looks like a major ECU/computer failure to me. Any ideas here? What the fcuk am I going to do? Help much appreciated.

[Steve J]

You'll need to either charge the battery or replace the discharged one with a charged one. If I understand correctly just linking another battery with the dead one in place won't do much. 

[timbo]

As Steve J says, stick the battery on charge. If you can, check the voltage first to see what it's like.

If you have a flat battery and put a good one as a jump, all that will happen is the good one will simply lose charge to the flat one.

Assuming your original battery responds and you can charge it, then see if things improve.

[macey]

Hmm, interesting viewpoint, so "jump starting" is a fallacy? A fully charged battery connected to the same circuit as the main will effectively provide the energy required. A small percentage will leak to the dud (or flat) battery. An exception to this is if the resident battery is short circuit (very unlikely).

[matthewhaskins]

As has been said already, just replace the battery rather than trying to connect another in parallel - for that to work you would need to be generating more current, a running car might work but its far easier (and safer for the electronics) to just replace the battery - 9 out of 10 times its the battery...

[timbo]

1 hour ago, macey said:

Hmm, interesting viewpoint, so "jump starting" is a fallacy? A fully charged battery connected to the same circuit as the main will effectively provide the energy required. A small percentage will leak to the dud (or flat) battery. An exception to this is if the resident battery is short circuit (very unlikely).

Jump starting is not a fallacy; however if you connect a pair of batteries in parallel, where one has a higher voltage than the other then the higher voltage one will lose charge to the other until the emf of both is the same. Basically the process is like a battery charger; however the charger keeps supplying energy as it's plugged in to a supply, ie. the mains.

The difference with normal jump starting, from one car to another, is that the car being used to provide the 'jump' will have the engine running do the alternator is charging both batteries.

[macey]

I have jump started cars many times without the doner car engine running. The charge current to the flat battery is very low, milliamps, plenty of current left to, at least, open the door.In my case, with parallel battery connected, no response from the car at all, can't open door... Nothing. Forgot to mention, tried charging the battery via lugs under front panel.

[timbo]

What is the voltage of the battery? As I said earlier, I would check that before jumping, charging or anything else. Just because the charging current to it is low doesn't necessarily mean it's okay, just that it's not taking charge.

[The Cakes]

9 hours ago, macey said:

I have jump started cars many times without the doner car engine running. The charge current to the flat battery is very low, milliamps, plenty of current left to, at least, open the door.In my case, with parallel battery connected, no response from the car at all, can't open door... Nothing. Forgot to mention, tried charging the battery via lugs under front panel.

Won’t make any difference if your battery is knackered. As above check the voltage. Do some searches here and Seloc, people above and many before you have experienced this. If a new battery doesn’t solve it I’ll eat my hat! 

[Steve J]

You can get to the battery in the boot by using the manual release through the rear wheel arch. Then charge the battery. Check voltage when cranking as you can show 12v just sat there but drops when trying to turn the starter.

[macey]

I finally managed to get into the car, I jumped it with a fully charged battery via the two jump points under the front panel. Couldn't undo the driver door from outside, undid passenger door and removed roof. Only remaining problem is driver door only opens from inside. Tried key in lock, wont turn anticlockwise from vertical.

Door only opens from inside, hhelp appreciated.

[duncx]

If you have used a second battery to get into the passenger side I assume that your central locking has now 'unlocked' then? Does this mean that in previously attempting to open the driver's door you have in fact locked it with the key and you now cannot unlock using the key? If that's the case then it's just a case of getting a bit of wd40 into the key slot and wiggling the key a bit The keylocks certainly can be a bit temperamental

 

[macey]

 Sorted, found out how to unlock with key (even though never have locked it with the key). Key in lock, button in, turn to right. End of problem. To summarise, flat battery, jump lead not connected properly due to restricted access on car 'jump posts', Second attempt disabled immobiliser, opened passenger door, took roof off because couldn't get in via passenger door due to restricted access, got into car after opening driver door from inside, figured out how to unlock driver door with key.:)

[Steve J]

Result

[macey]