Problems after flat battery - Jump start

delmel · 16 Feb 2020

Hello on a Vauxhall Meriva B was jumped a few issues but the car functions fine apart from these.

Infotainment display completely Blank
Door warning light the one with the key symbol on a door is lit but central locking and rear door function as they should.
All audible warning sounds have stopped

Fuses seem to be intact and tested ok

I suspect it mat have had a flash on the battery but unsure of this or how it has created these issues.

Diver Fred · 16 Feb 2020

Disconnect the battery.
Put it on charge.
Get the handbook.
Make yourself a cup of tea.
Read the handbook instructions on what to do when the battery is replaced whilst drinking tea.
Take battery off charge.
Reconnect battery to car (live first then earth).
Follow instructions in handbook following battery replacement.

If that doesn't work it's main dealer and lots of money I'm afraid.

Munroast · 16 Feb 2020

is it a 'stop start' ? Don't think you can jump these in the tradition way, it can cause problems.

('stop start', being the name for cars that automatically switch engine off at traffic lights etc)

Burnerman · 16 Feb 2020

Its important not to jump start cars these days - unless the battery is only just below par.....the voltage spike crocks various ECU's, in this case possibly one of the body control modules.
That's also the reason why you don't connect the negative jump lead direct to the battery but rather to an earth post provided. I have to confess I'm not too sure why.
John

Keithmac · 16 Feb 2020

I would never jump our Kuga off, could possibly damage over £3000 worth of engine/ gearbox/ BCM/ Infotainment etc ECUs. Not worth the risk..

@Burnerman our car has a "shunt resistor" on the negative battery connection, this is to allow the Battery Management System to work our SOC and charging current to the battery.

I think the main reason for the earth post away from battery is in case of explosion from a failed gassing battery but could be wrong.

EFLImpudence · 16 Feb 2020

It seems like bad design to me to have all these possible consequences from people doing perfectly normal things.

What happens when a (possibly very poor) battery is changed for a new one? Is that different than a jump start?

Can you start with a flat battery by push-starting or running down hill?

Burnerman · 16 Feb 2020

In the 'good old days' if you had a flat battery, you could push start your car and all would be well, assuming you could spin the alternator past its cut in speed. (Circa 1200 rpm.)
With smart charging, apparently the various ECU's 'learn' what voltage they need, and anything different from that causes them to throw a wobbler......sometimes the ECU's fail, other times they have to learn what's required once more when the car gets going again.
With my own car (Yeti 2.0 diesel) if the battery voltage isn't exactly right then it won't even try to start, whereas years ago the engine would crank, albeit slowly. On the one occasion this happened to me, it wouldn't respond to a jump start either, I had to pop my smart charger on and wait until it indicated that the battery had enough juice in it

What a pain! Sure enough though, off it went.
Regarding the attaching of jump leads, a spark (spike) must be prevented.....by having a remote earth post this is prevented but I've no idea how or why.
As an aside, if you roll your car down hill to start, you'll crock the dual mass flywheel as well - eventually

John

EFLImpudence · 16 Feb 2020

Burnerman said:
Regarding the attaching of jump leads, a spark (spike) must be prevented.....by having a remote earth post this is prevented but I've no idea how or why.

I would think it bypasses any electronics mentioned above - diodes? - in the negative lead and so not registering those spikes.

Plus, of course, it better connects the negative directly to the starter motor metal (engine).

EFLImpudence · 16 Feb 2020

Having said that, (as before) it really is no different than connecting a new/replacement battery.

bernardgreen · 16 Feb 2020

With modern cars and large engines it is better to use a charger to re-charge the battery for long enough to get the engine to start and then use the vehicle alternator and charge regulator to fully charge the battery.

A possible reason for problems after using jump leads is that when the charged "help" battery is connected to the discharged battery the sudden change in voltage supply adversely affects the electronics in the vehicle. A charger ( properly used ) would be unlikely to cause a rapid change of voltage on the battery terminals.

Keithmac · 16 Feb 2020

EFLImpudence said:
Having said that, (as before) it really is no different than connecting a new/replacement battery.

When you connect a full battery to a flat one, the flat battery will "suck" an enormous amount of current. The CCA of a car battery probably around 500amps?. It's the current inrush spike that can cause havoc.

Correct way would be a controlled charge to the flat battery (if you can't remove it for any reason).

It's not the same as connecting a battery where there wasn't one before.

Quite a few manufacturers have a warning about jump starting iirc.

Not worth the risk on a modern car imho.

EFLImpudence · 16 Feb 2020

bernardgreen said:
With modern cars and large engines it is better to use a charger to re-charge the battery for long enough to get the engine to start and then use the vehicle alternator and charge regulator to fully charge the battery.

Could you do that by connecting jump leads and using the donor's alternator to charge the low battery.
I agree it would not be advisable with a completely dead or faulty battery.

A possible reason for problems after using jump leads is that when the charged "help" battery is connected to the discharged battery the sudden change in voltage supply adversely affects the electronics in the vehicle. A charger ( properly used ) would be unlikely to cause a rapid change of voltage on the battery terminals.

That's different than connecting a new battery, is it?

EFLImpudence · 16 Feb 2020

Keithmac said:
When you connect a full battery to a flat one, the flat battery will "suck" an enormous amount of current. The CCA of a car battery probably around 500amps?. It's the current inrush spike that can cause havoc.

It's still 12V or so.

Correct way would be a controlled charge to the flat battery (if you can't remove it for any reason).

Is using the donor car's alternator alright?

It's not the same as connecting a battery where there wasn't one before.

Why not?

Quite a few manufacturers have a warning about jump starting iirc.

Do you have an example of what they actually say?
It wouldn't be Main Dealers wanting a large fee, would it?

bernardgreen · 16 Feb 2020

EFLImpudence said:
That's different than connecting a new battery, is it?

Yes it is different. When connecting a new battery the ols battery is disconnected and everything has zero voltage and closes down.

The new battery is then connected and equipment powers up from closed down to full function.

If the old battery with a low voltage remains connected then some equipment may be in an undefined state between fully functional and closed down. When another battery is connected and the supply voltage rises ( almost ) instantly to 12 volts some of the equipment may not be able to recover from the undefined state.

Munroast · 16 Feb 2020

EFLImpudence said:
It seems like bad design to me to have all these possible consequences from people doing perfectly normal things.

What happens when a (possibly very poor) battery is changed for a new one? Is that different than a jump start?

Can you start with a flat battery by push-starting or running down hill?

Some batteries now are 'smart' they have some sort of chip in them so as to communicate with the cars ecu. So a new battery may involve a trip to the main stealers so as they can programme it in, £60 please

Problems after flat battery - Jump start

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