Battery woes

[Ralph]

Changed the alternatoron my 300tdi few months ago because for the last week of it life i had to rev it to about 2000rpm to get the light to go out! then it finally gave up and light would not go out at all.
Recently it started to get very sluggish turning over in the mornings and if it did not fire straight away the battery would die completely, so yesterday afternoon i went out and bought a new battery(£41 inc vat) Went out last night with the dogs after a few rabbits came home at 4 this morning and parked the truck up. Went out today at 3 pm flat battery!!! Put jumps leads on started straight away, been out and about in it and alternator is charging fine. Going to get the new batt tested in the morning but now i am begining to think that the old one was ok and there may be somthing drawing the power. If i take batt lead off and touch it on the terminal there is a small spark not much but a spark.
Does anyone know how much current roughly a totaly standard disco should draw with nothing turned on aprt from the clock and i presume the alarm which is factory fit??
Dont know yet exactly how much is being drawn as not got a meter till the morning.
Am really hoping it is just a dud battery!!!

[davidlandy]

I ll bet the battery is ok and something else is at fault

[Steve ray]

put a meter across your battery with say, headlights, blower and heat rear screen all ON .... see what output you're getting from the alternator.

[karlo]

Had similar syptoms on a ford some years ago, turned out to be the starter motor?

[Graham2]

I had a similar problem on my Range Rover a few years ago. It was the 'on it's last legs' starter moter. It was drawing so much from the battery to get it started, that it flattened the battery really quickly. When the AA guy put his booster thing on to get it going, smoke poured out of the starter! Got me to the garage that replaced it though. It might also be worth checking the earth straps as well. On the RR there are loads fixed to a bolt under the header tank on the off side inner wing, don't know if they're in the same position on the Discovery though.

[mark.yellow.series.3]

right,
first thing, its not a good idea to take the battery leads off when the3 engines running, this can blow certain types of alternator regulator.
second, dont touch the battery lead to earth as this can also blow the regulator.

to test your truck, test the battery voltage with nothing switched on, preferbibly when it hasnt been run (first thing in the morning). the voltage should be above 12vdc, idealy 12.2vdc or above. if it isnt the battery might be knackered.

next start up the engine, measure the voltage again, after about 5-10 mins of running it should come up to anywhere between 13-14.5 vdc.
if its not, ie the same voltage as it is not running or slightly lower the alternator is goosed, dont rely on the battery light on the dash, it doesnt tell you everything.

if the voltage of your battery in above 12volts first thing in the morning, and it still doesnt start, the starter might want reconditioning, or a bad earth or cable.

hope this helps
mark

[Ralph]

Well what do you know!! it started this morning no trouble, Had battery tested and that was fine alternator showing 14.3 volts.
Am waiting now till morn see if its ok.

[mark.yellow.series.3]

perhaps with the battery being discharged it just needs charging up properly.

fingers crossed it starts for you in the morning.

[Range Rover Blues]

I'm thinking an alternator past it's best.  Thing is our TDi is a slow starter, always fired up atraight away though but now it's stood a few days each week it's a PITA, new battery and all.  I'm watching with interest as I was thinking the starter might be goosed.  I tried adding an extra earth via my jump leads, no joy..  I measured the voltage drop between the battery terminals and th enegine during cranking and it's nearly a volt on both earth and positive :shock:

The rev counter is playing up too, so when I've time.........

Let us know the progress

[Ralph]

Started again today no probs. I put the old battery which has been out in the cold now for 2 days on my transit tipper today and it started that no probs so i dont think i needed a new batt afterall.
What i did find out yesterday with my newly aquired test meter!! was that the backup batteries in the alarm siren under bonnet were totaly knackered so i cut them out cos i was thinking that they are drawing current constantly from the battery trying to charge themselves. ps. siren stills works just dosent if the wires to it were cut or unplugged, which it didnt anyway as batteries were totaly shot.

[Mark2Disco]

ive got same sort of problem
i dont use car for a week or so the battery goes down to about 50 %
charged  then car doesent start
new battery and alternator
seems that something is draining battery
i was thinking the alternator may have a fault and shorting out
any help would be nice
thanks

[jsstevo]

Hi,

How do you take the backup batteries out of alarm on a 300TDI Disco?

Cheers!

[Mark2Disco]

mine just prizes apart
normally with kitchen knife

[jsstevo]

but what do i prise apart?