Topic: Flat battery, should I replace it? (Read 21413 times)

wpo750 · « **on:** April 25, 2009, 12:00:44 PM »

Hello all, the XJ is going really well and we took it on a 500 mile round trip to North Devon the other week where it did not skip a beat. All good.

I went to retrieve it from the car park last night where it has been laid up since Monday morning and the alarm fob seemed not to work. I unlocked it with the key and tried starting but no signs of life. All dash lights were out, interior lights too.

I got a set of jump leads on it and left it charging for about 10 minutes before turning it over. With hesitation and a dab of the throttle it kicked into life but as the revs dropped back down the jeep stalled. I left it to charge a bit longer and tried it again. This time it started at a turn of the key and idled OK if a little lumpy so I let it idle for a while. The battery gauge showed that it was fluctuating between 13v and 14v which didn't seem abnormal to me.

As soon as I come off the throttle the jeep stalls :-(

Does it sound like time for a new battery and if so are there any recommendations?

Thanks!

Panic mechanic! · « **Reply #1 on:** April 25, 2009, 12:05:13 PM »

if it keeps stalling at idle, its not the battery, altho you may have a duff battery as well. once an engine starts and runs it will draw current direct from the alternator, via the battery leads, so if it stalls back at idle it sounds like you got a fuel starvation problem to me.
when was the last time the fuel filter was changed?

Bubba · « **Reply #2 on:** April 25, 2009, 12:07:39 PM »

is the battery is fubar it may act like this have you got another car you can borrow the battery from

wpo750 · « **Reply #3 on:** April 25, 2009, 12:21:36 PM »

Quote from: "Panic mechanic!"

if it keeps stalling at idle, its not the battery, altho you may have a duff battery as well. once an engine starts and runs it will draw current direct from the alternator, via the battery leads, so if it stalls back at idle it sounds like you got a fuel starvation problem to me.
when was the last time the fuel filter was changed?

Hmmm, what you say makes sense and the battery gauge on the dash suggests that nothing is wildly wrong although it does seem to fluctuate a little.

The battery was absolutely dead when I went to start it last night though...

Fuel filter was changed early part of 2008 according to the SH.

@ V8 Bubba - Good plan, I'll see if I can remove one of the batteries from the 8. Annoyingly I have a couple of Bosch Silvers (one of which was never even used) sat in my parents garage but I think they'll be flat too. Considering this perhaps I should invest in a good quality charger???

Mike Pavelin · « **Reply #4 on:** April 25, 2009, 02:21:24 PM »

Charge the battery properly overnight.

If the Jeep has a flat battery it can forget how to idle. In order to re-learn, start her up using the throttle, slowly back off until the rpm drops to below idle speed and let the engine management take over. You may need several attempts for this to happen.

wpo750 · « **Reply #5 on:** April 25, 2009, 04:02:31 PM »

Quote from: "Mike Pavelin"

Charge the battery properly overnight.

If the Jeep has a flat battery it can forget how to idle. In order to re-learn, start her up using the throttle, slowly back off until the rpm drops to below idle speed and let the engine management take over. You may need several attempts for this to happen.

Interesting, last night I did notice an improvement in its idle over a period of about 10 minutes of charging and backing off the revs slowly did seem more stable than coming off abruptly.

I've gone and bought a CTEK charger from Costco and I'm in the process of charging up a spare Bosch 70aH battery (is that adequate?) so I'll let you know how I get on.

Dave69 · « **Reply #6 on:** April 25, 2009, 11:26:40 PM »

if the battery is literally dead and jump starting from another battery works then with the engine running at a fast idel the alternator will give out what it can for the duff battery. when the jeep then idles around 800rpm the alternator will not be kicking out as much as it would at 1500rpm. So what charge is going into a dead battery is going straight out to the spark plugs then the sensors will read a low voltage and stop the car. stick another battery on it and see what happens remember you are limited on battery size for an xj

wpo750 · « **Reply #7 on:** April 25, 2009, 11:47:46 PM »

Quote from: "Dave69"

if the battery is literally dead and jump starting from another battery works then with the engine running at a fast idel the alternator will give out what it can for the duff battery. when the jeep then idles around 800rpm the alternator will not be kicking out as much as it would at 1500rpm. So what charge is going into a dead battery is going straight out to the spark plugs then the sensors will read a low voltage and stop the car. stick another battery on it and see what happens remember you are limited on battery size for an xj

That makes sense to me, cheers! However, I'm not aware of the battery specs for the XJ...

Edit: I'm currently charging up a Bosch S3 - 008 which fits the space and has a capacity of 70ah and 640 CCA. Will that be enough?

Panic mechanic! · « **Reply #8 on:** April 26, 2009, 12:01:46 AM »

a good alternator will bump out 13.5-14 volts at idle....and also at 2000 rpm or 3000 or 5000, only dynamos vary.
if you look at the way a car wiring loom is made up the alternator kicks full voltage to the fusebox and engine management as its wired in parallel to the battery, but it is possible the battery plates have warped and fused togther giving a short circuit and thus draining a lot of the current to ground and causeing the poor running, funnily enough I have known things like that usually happen after a long days use travelling a few 100 miles.

wpo750 · « **Reply #9 on:** April 26, 2009, 12:17:26 AM »

Quote from: "Panic mechanic!"

it is possible the battery plates have warped and fused togther giving a short circuit and thus draining a lot of the current to ground and causeing the poor running, funnily enough I have known things like that usually happen after a long days use travelling a few 100 miles.

I've never heard of this happening before but it would explain things. I'm entirely clear what you mean by the battery plates though(?)

Panic mechanic! · « **Reply #10 on:** April 26, 2009, 10:19:17 AM »

here's a simple pic of the internal side of a battery apart from the fact there are a lot more plates on a normal battery this just shows 2.
as an alternator charges it creates heat in the battery, if it overcharges it can in extreme circumstances warp the softer plates due to the heat so they actually touch and create a short circuit, thus it kills the battery.

Bubba · « **Reply #11 on:** April 26, 2009, 10:24:36 AM »

if a battery is fubar and wont take a charge throw you dont call ncis sorry panic you are helpfully confusing the isue almost all batterys the days are manitenance free sealed so what goes on inside has no litle or no merit you shoud treat it like a fuse if its had it throw it

Panic mechanic! · « **Reply #12 on:** April 26, 2009, 11:19:32 AM »

if i have confused someone ( usually me ) I apologise.

wpo750 · « **Reply #13 on:** April 26, 2009, 11:38:33 AM »

Having spent 19 hours charging up the Bosch battery I've just discovered that it's a tad too large to fit the compartment and the terminals are the other way round! :-?

The leads are not long enough reach the correct terminals either...

I've taken the old battery out of the Jeep and was surprised that it's only a 45ah 450 CCA unit. It was a Mopar battery but I was led to believe that the Cherokee needed a larger capacity one???

I'm off to Halfords to pick up another battery...

wpo750 · « **Reply #14 on:** April 26, 2009, 06:40:50 PM »

So, £97 later the Jeep is up and running again. The Halfords battery was a higher capacity than the Mopar unit that came out and the XJ started and idled perfectly once connected. All sorted? Not quite...

Thinking that everything was hunky dory, I packed away my tools and slammed the bonnet - half shut. It appears that the new battery is somewhat taller and fouls the bonnet along the reinforced section of the underside. I was strapped for choice in Halfords and picked up the only one on offer which had suitable power and the terminals the right way round.

I've left it in for now as the Jeep was parked up in an NCP car park and I'm not leaving in there for another week.

Looks like I'll have to order a new battery then. Does anyone have any recommendations?

scrw · « **Reply #15 on:** April 26, 2009, 07:09:25 PM »

Go to a decent motor factors and get a bog standard lead acid battery to fit the space. I have had loads of cheapys with no issues, soon as I have an Optima I have problems with it.
look for 550CCA or above

gazjeep · « **Reply #16 on:** April 26, 2009, 07:30:29 PM »

Bought one for my old XJ 12 months ago, proper Mopar jobby, £55 from jeep dealer job done, right size etc etc. Get hold of your local dealer, it may surprise you 8-)

Mike Pavelin · « **Reply #17 on:** April 26, 2009, 09:19:54 PM »

Bishops Finger · « **Reply #18 on:** April 26, 2009, 09:48:08 PM »

Change said replacement battery ASAP for one that fits......

wpo750 · « **Reply #19 on:** April 28, 2009, 04:58:14 PM »

Quote from: "gazjeep"

Bought one for my old XJ 12 months ago, proper Mopar jobby, £55 from jeep dealer job done, right size etc etc. Get hold of your local dealer, it may surprise you :lol:

Panic mechanic! · « **Reply #20 on:** April 28, 2009, 05:27:39 PM »

http://www.carbatteryshop.co.uk/i-096R- ... I1013.html

wpo750 · « **Reply #21 on:** April 28, 2009, 05:59:27 PM »

^^^ That's good bang for buck, cheers. Only problem with that one are the physical dimensions. The Bosch S3 008 I tried fitting on Sunday shares the same dimensions and that seemed to overhang the battery tray by about 5mm. :-?

gordy · « **Reply #22 on:** April 28, 2009, 07:13:16 PM »

Well guys, my Optima Red Top bit the dust sometime over the last couple of days. Went to start the truck this morning and dead, nothing, in fact the fob would'nt open the doors, the battery seems to have a short curcuit, as when I connect a charger to it, the charger cuts in/out fast exactly as if I touch the crocodile clips on the charger together. Lasted 3 years which is the same as a regular battery, dissapointing really considering what I paid for the friggin thing. They carry a 24 month guarantee so are obviously built to go tits up in their third year. Bloody shite. Got a Unipart battery for 55 quid from the garage down the road.

Bishops Finger · « **Reply #23 on:** April 28, 2009, 08:06:39 PM »

If the battery is too big and causes problems shutting the bonnet get rid of the battery ASAP if not sooner... :twisted:

.

A clued in independant auto electrical place should sort you out for £70-80 ish

captain cavalier · « **Reply #24 on:** April 28, 2009, 09:25:13 PM »

My battery has gone completely flat on 2 occasions

kids leaving interior lights on over weekend and both times I had the same symptoms ie stalling for the first 1/2 an hour then fine

Author Topic: Flat battery, should I replace it? (Read 21413 times)

wpo750

Panic mechanic!

wpo750

Mike Pavelin

wpo750

wpo750

Panic mechanic!

wpo750

Panic mechanic!

Panic mechanic!

wpo750

wpo750

scrw

Mike Pavelin

Bishops Finger

wpo750

Panic mechanic!

wpo750

gordy

Bishops Finger

captain cavalier