no electrical power

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hoppington
Posts: 5
Joined: 15 Jun 2020, 09:05

no electrical power

Unread post by hoppington »

Hi
I have a charged up battery that sits under the passenger seat. When connect terminals there is no power to the car what so ever! The battery shows voltage so where next to look?

Thanks

wheeler
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Joined: 21 Sep 2002, 19:07
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Re: no electrical power

Unread post by wheeler »

Need a bit more info on this. First of what model, year & engine is in it?
Your profile says you have a Citroen Xhara?
Im guessing as you are talking about a battery under the seat you have a Xsara Picasso??
Also a bit more info about the fault, was it just dead one day after regular use? Has it been sitting unused for ages? Did it cut out whilst driving?

hoppington
Posts: 5
Joined: 15 Jun 2020, 09:05

Re: no electrical power

Unread post by hoppington »

wheeler wrote:
15 Jun 2020, 10:32
Need a bit more info on this. First of what model, year & engine is in it?
Your profile says you have a Citroen Xhara?
Im guessing as you are talking about a battery under the seat you have a Xsara Picasso??
Also a bit more info about the fault, was it just dead one day after regular use? Has it been sitting unused for ages? Did it cut out whilst driving?
Hi Wheeler
Yes its a Xsara Picasso 58 plate
engine is a 1560CC diesel
Its been sitting around for a while off the road so I do not really remember much before

wheeler
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Re: no electrical power

Unread post by wheeler »

So everything was working normally when it was last used? when you say sitting around for a while do you mean weeks or months?
What voltage do you have at the battery? Just because you have connected a charger to it doesn't mean the battery is accepting a charge. Also a battery can show 12.5v but not have any capacity to even light up the dash. Can you confirm nothing electrical whatsoever works? interior lights, dash lights central locking?
Have you tried jump starting it?
If the battery is good then you need to check if there is power at the under bonnet fusebox main bolted connection & check the main chassis earths.

hoppington
Posts: 5
Joined: 15 Jun 2020, 09:05

Re: no electrical power

Unread post by hoppington »

Its been sitting for months, don’t rely remember any problems with it
I think it was showing 10.5V on the battery or something (will have to recheck). But even still should there not be enough to power up stuff.

Yes there is absolutely no power to anything what so ever
wheeler wrote:
16 Jun 2020, 14:08
If the battery is good then you need to check if there is power at the under bonnet fusebox main bolted connection & check the main chassis earths.
where are these?

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xantia_v6
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Re: no electrical power

Unread post by xantia_v6 »

10.5 volts is not enough. You need to fit another battery, or connect a fully charged external battery with good quality jumper leads.

wheeler
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Re: no electrical power

Unread post by wheeler »

hoppington wrote:
17 Jun 2020, 17:52
wheeler wrote:
16 Jun 2020, 14:08
If the battery is good then you need to check if there is power at the under bonnet fusebox main bolted connection & check the main chassis earths.
where are these?
Forget about them for the moment, this sounds to me almost certainly just a battery problem. You really want a minimum of 12.2v and it shouldn't drop below 9.0v when attempting to start.
Get a set of jump leads on it for 10 minutes before you do anything else. How old is the battery?

civvie
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Re: no electrical power

Unread post by civvie »

hoppington wrote:
17 Jun 2020, 17:52
Its been sitting for months, don’t rely remember any problems with it
I think it was showing 10.5V on the battery or something (will have to recheck). But even still should there not be enough to power up stuff.
The days of just about managing to light up the oil light and the ign light are Long gone. so many computer modules need power these days just to get ready to go. Look at old posts here where most problems are due to iffy/old batteries.

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Hell Razor5543
NOT Alistair or Simon
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Re: no electrical power

Unread post by Hell Razor5543 »

In a PC (I know this is NOT about a PC, but this explanation may still be valid) the system board will not even start up if the power being supplied is +/- 10% of the expected values, so anything outside the range of 3.0volts/3.6volts on the 3.3volt rail (for example) will stop the PC from working. This is because good PSUs have a voltage monitoring system built in, and will hold the system board in a reset state until the PSU is supplying the expected voltages on all of the rails.

It should be safe to assume that modern day cars would have similar protection circuits so that delicate electronics are not damaged by receiving inappropriate voltages.

hoppington
Posts: 5
Joined: 15 Jun 2020, 09:05

Re: no electrical power

Unread post by hoppington »

I have had the battery on charge with a domestic battery charger
I will go out again and check what voltage it was
What do you think the optimum voltage of a 12v car battery should be?

wheeler
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Re: no electrical power

Unread post by wheeler »

Bare minimum should be 12.2v ideally 12.5v-12.8v, If you check the voltage immediately after disconnecting the charger there will be surface charge in the battery so you wont get an accurate reading, you want to leave it to stabilize for an hour before checking.
The issue is the voltage of a battery is not a good indication of battery health, a car battery can show 12.8v at rest but not have the power to light a bulb never mind turn a starter motor.
If it is over 12.2v try & start the engine with the meter connected, it shouldn't drop below 9.0v when the starter is operating.

hoppington
Posts: 5
Joined: 15 Jun 2020, 09:05

Re: no electrical power

Unread post by hoppington »

I got a battery charger out to the battery and car and had it on for 2 days


Now when I go to the car there is power!
I turn the ignition on and a relay near the dash flickers and the side lights and wippers come on but will not turn over

wheeler
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Joined: 21 Sep 2002, 19:07
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Re: no electrical power

Unread post by wheeler »

You could put a battery charger on it for 2 weeks but if the battery is faulty like I suspect then it wont hold any decent charge, it also does not matter what the voltage reading says, a completely knackered battery can show 12.5v at rest but not have the guts to even turn the headlamps on.
Have you tried jump starting it with jump leads?
If the voltage is over 12.2v attempt to start the car with your volt meter still connected, if the voltage drops below 9v when you attempt to start it replace the battery.