Will I do damage if I put 15v through the ECU socket under the dash?

To change the battery whilst keeping power in the system (to avoid losing functions / stereo etc,) I've bought a jump starter pack and a lead to connect it via the ECU socket. This I believe will be easier than trying to keep clamps on the leads in the engine bay. The trouble is the dedicated outlet on the pack (cigarette lighter type) is 15v. Is that a problem?

Last edited by Flanagan on 4th Apr 2020 4:42 pm. Edited 1 time in total

It will read 15Volts ...... but under load will be nearer 12Volts.

Hi - thanks.

When I changed my battery recently the only things that needed reset were the electric windows - the work of a moment.

This is also a frugal solution that could avoid any potential issues:

https://www.amazon.ca/gp/product/B07M6JZXD...&psc=1

You just need another 12 volt backup battery.

Simon J - did you not lose the radio, or did you have the code (I don't)?

MotionInc - thanks - I don't have a spare battery, just a power pack plus a cable like you show except it has a cigarette lighter style plug instead of crocodile clips.




The jump pack unit has an adaptor that adds a female cigarette lighter socket to the 15v outlet.

^^^IMO, the jump starter pack connected through the lighter (always live) lighter socket/OBII port should work just as well. Plan ahead and be efficient with the time the vehicle is on the auxiliary power supply.

I have made the assumption that OBII connection came with the Power pack? Maybe someone can chime in here or you can test this assumption with a meter on the OBII pins? You should be able to use the 12V lighter output port as well on the live lighter socket.

Flanagan wrote:

Will I do damage if I put 15v through the ECU socket under the dash?

No radio code might loose stations

No radio code might loose stations

MotionInc wrote:

^^^IMO, the jump starter pack connected through the lighter (always live) lighter socket/OBII port should work just as well. Plan ahead and be efficient with the time the vehicle is on the auxiliary power supply.

I have made the assumption that OBII connection came with the Power pack? Maybe someone can chime in here or you can test this assumption with a meter on the OBII pins? You should be able to use the 12V lighter output port as well on the live lighter socket.

Are you saying I can provide a 12-15v supply to the vehicle while the battery is removed via the cars lighter socket (rear centre console) instead of the ECU socket? If so, does this have an advantage over using the OBII port? I'd have to get another adaptor from somewhere as I'd need male to male. The power pack has a female plug.


The OBII plug did not come with the power pack - and it looks cheaper than the photo, though I haven't tried plugging it in yet..

Joedenise wrote:

No radio code might loose stations

I only listen to radios 3 ad 4 so that's not a problem but on another car I had I had to pay someone £50 (10 years ago) to get the radio code so I could use it at all.

Yes, read Alex's post. Your power pak has a side port labeled in your pic as 15V/10A Cig lighter OUTPUT. Find that adapter that came with the power pak and plug that into the live/rear center console lighter receptacle and turn the Power Pak ON then change your main battery.

EDIT: make sure that the power pak is fully charged b4 you do anything!

alex_pescaru wrote:

Flanagan wrote:

Will I do damage if I put 15v through the ECU socket under the dash?

A "woke-up" FL2 could draw several amps. The wires used on the OBD2 connector for power are too thin for that.
This is why the starter pack has an outlet designed to fit into a cigarette lighter.
The rear cigarette lighter socket (the one between the back of the seats) has a permanent 12V, so connect there the starter pack.
But you could read your owner manual at page 169 and you'll see, as Simon J said, that there is no need for an additional power supply during battery change.

Thanks. The power pack comes with a female adaptor for use with things like tyre and airbed inflators. There's no mention of using it for the purpose I want.

I didn't know the rear console socket could receive power from an external source. That would indeed feel safer if I can get a suitable lead.

Thanks for the OM reference which seems to back up the first reply that I can have the car powerless for a while and all I'd need to do afterwards is recalibrate the windows (no doubt there will also be an instruction somewhere). "If all else fails, read the manual"! Of course, in that case all the rest about voltages and cables is unnecessary.

MotionInc wrote:

Yes, read Alex's post. Your power pak has a side port labeled in your pic as 15V/10A Cig lighter OUTPUT. Find that adapter that came with the power pak and plug that into the live/rear center console lighter receptacle and turn the Power Pak ON then change your main battery.

EDIT: make sure that the power pak is fully charged b4 you do anything!