Flat battery question

sednwol · 03-06-2008, 07:58 AM

I've done a search and still need help.

My AU XR8 S 3 has a flat battery. Can I just remove it and recharge it (takes 8 hours). Would there be a problem if I do this with the ECU etc?

I suppose (given that it is flat) I cant connect the battery charger to the terminals while it is still connected to the car and charge it that way

Also I have heard that sometimes you can use a 9 volt battery plugged into the cigarette lighter so that the radio code is not lost. How is this configured, wired etc?

james22 · 03-06-2008, 08:14 AM

Don't worry about the ECU, It will relearn over time with your freshly charged battery.

You can charge it while it's connected to the car. Positive lead onto positive battery terminal, Negative lead onto a good earth in your engine bay somewhere and you'll be set.

sednwol · 03-06-2008, 08:18 AM

Quote:

You can charge it while it's connected to the car. Positive lead onto positive battery terminal, Negative lead onto a good earth in your engine bay somewhere and you'll be se

Have you done this youself James 22? Sounds dangereous.

james22 · 03-06-2008, 08:21 AM

Quote:

Originally Posted by sednwol

Have you done this youself James 22? Sounds dangereous.

Yes mate. Nearly every month, cause I never drive my car. Not dangerous at all.

Just make sure you DON'T PUT the negative onto the battery, make sure it goes to a good earth, eg. Alternator bracket, Manifiold etc

sednwol · 03-06-2008, 08:31 AM

Quote:

Underpowered and Slow, Series III AU XR8 220 - 274rwhp

Got the same model as me I'll give it a try. What do you connect to when you earth the car?

james22 · 03-06-2008, 08:41 AM

1 - Positive lead onto positive terminal on battery

2 - Negative lead onto earth. In my XR I use the alternator bracket, or hook onto the manifold, or engine lift point thingmajig. Picture below

3 - Plug battery charger in, and away you go :-)

sednwol · 03-06-2008, 08:45 AM

I'll try connecting it to one of the brackets that hold the exhaust pipes in place.

james22 · 03-06-2008, 08:49 AM

Any solidly connected metal object under the bonnet will do just fine as a earth. so find one and take your pick

sednwol · 03-06-2008, 08:52 AM

Sorry to be a pain, what if I connect the negative to the bonnet, where the catch is. its all metal? Thanks for all your help

james22 · 03-06-2008, 08:57 AM

Nah probably not good enough. If the earth is crappy, it just won't charge.

Use the alternator bracket if you have one, or the top of your manifold, or that little thing in the picture above. Any solid unpainted metal will do fine.

sednwol · 03-06-2008, 08:58 AM

Thanks, I'll use the engine lift as you first suggested.

TOASTED · 03-06-2008, 08:59 AM

why cant you connect it to the negative terminal? i used to all the time on my ef and never had any troubles. also i grew up with batteries dads dad started the business, now dad and i run it, and i have never heard this.

james22 · 03-06-2008, 09:04 AM

Another piccy for ya

sednwol · 03-06-2008, 09:10 AM

Thanks James, I've connected it to the engine lift thingo and my battery charger is showing the battery flat and I have a good charge connection. Many thank again really appreciate you help mate!

BTW who signed the engine cowling?

james22 · 03-06-2008, 09:19 AM

Dick Johnson, hehe.
Glad to be some help. 8 - 10 hours and you'll be all good. Theres also a good chance you didn't lose ECU settings if you never disconnected your battery, unless it was REALLY dead. Either way though, it won't cause any probs for ya.

sednwol · 03-06-2008, 09:24 AM

She wasn't completly flat, everything working horn etc, just wouldn't turn that big baby over LOL.

james22 · 03-06-2008, 09:28 AM

Quote:

Originally Posted by craigosmoddedEF

why cant you connect it to the negative terminal? i used to all the time on my ef and never had any troubles. also i grew up with batteries dads dad started the business, now dad and i run it, and i have never heard this.

All I know is the instructions with nearly all battery chargers state, that if charging the battery while connected to the car. It should be connected Positive to positive and negative to earth.

If charging out of the car, they state Negative to negative of course, because theres no other way to get a circuit when its not connected.

Heres a link to a manual stating what I said above, and some text I have copied out.

http://209.85.173.104/search?q=cache...ient=firefox-a

STEP 2B - CONNECTION IN VEHICLE
Determine if the vehicle is Positively (+) or Negatively (-) earthed. Negatively earthed vehicles
have a cable (usually black) from the Negative battery terminal to the vehicle’s chassis.
Negatively earthed (Most Vehicles)
Connect the RED lead (battery clip) from the charger to the Positive (+) battery terminal.
Connect the BLACK lead (battery clip) from the charger to the vehicle’s chassis away from the
fuel line or moving parts.

james22 · 03-06-2008, 09:33 AM

P.S - Page 7 in that link above is where the info is.

You can clearly see that there is a different procedure for in car and out of car charging.

InfernoSR · 03-06-2008, 09:34 AM

woops... disreguard and delete please mods

sednwol · 03-06-2008, 09:39 AM

The way James describes works as I am getting a connection and therefore a charge.

james22 · 03-06-2008, 09:44 AM

read above lol

woops adam caught on lol

sednwol · 03-06-2008, 09:49 AM

James should it be connected to the battery post (if possible) or just onto the red lead fitted to the post.

james22 · 03-06-2008, 09:49 AM

Some for disconnecting, as you can see in car charging says remove from vehicle chasis

"Quote from page 9 above link'

STEP 6 - DISCONNECTION.
Turn the 240V mains power off.

Battery out of vehicle
Remove the BLACK lead (battery clip) from the battery.
Remove the RED lead (battery clip) from the battery.

Battery in vehicle
Remove the chassis connection.
Remove the battery terminal connection

james22 · 03-06-2008, 09:51 AM

Quote:

Originally Posted by sednwol

James should it be connected to the battery post (if possible) or just onto the red lead fitted to the post.

Doesn't matter mate. As long as its connected, and you have a circuit, it'll charge and work. Easy as

:

sednwol · 03-06-2008, 09:58 AM

Just wondering as Iam not hearing any battery "bubling" noise that I usually hear when charging...I'll just wait and see. My charger shows only lit boxes showing the state of charge ie flat, 25%, 50% etc, it doesn't actually tell me if it is charging. Still showing flat.

**Peuty** · 03-06-2008, 10:19 AM

Well if you only connected it half an hour ago, chances are the battery is still flat!

InfernoSR · 03-06-2008, 10:34 AM

Quote:

Originally Posted by sednwol

Just wondering as Iam not hearing any battery "bubling" noise that I usually hear when charging...I'll just wait and see. My charger shows only lit boxes showing the state of charge ie flat, 25%, 50% etc, it doesn't actually tell me if it is charging. Still showing flat.

You hear bubbling? i always thought that to be a bad sign of a bad battery... from what i know, they will bubble, but it should be rather faint...

TOASTED · 03-06-2008, 10:41 AM

dont worry bout battery bubbling

TOASTED · 03-06-2008, 10:43 AM

Quote:

Originally Posted by BLUEPRINT

You hear bubbling? i always thought that to be a bad sign of a bad battery... from what i know, they will bubble, but it should be rather faint...

exactly

if a battery bubbles only in one cell the chances are that cell has collapsed.

easy way to tell if battery has dropped a cell: each cell is rated at 2.0-2.2 volts thus if a cell drops in a 12 v battery the battery when charged will drop down to 10 volts approx

sednwol · 03-06-2008, 10:57 AM

Quote:

Well if you only connected it half an hour ago, chances are the battery is still flat!

Been two hours, I have charged many many times on my old XF, should be off the flat reading by now going from past recharges. I'll give it another hour to show signs of recieving a charge. Even with the power off on the BC it shows the same reading as two hours ago.