P38A Flat battery

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Duncanincapable

Active Member
Posts
99
Location
Barnoldswick lancashire
4 litre 1998 p38. Over Christmas didn't use the car and when I came to use it the battery was flat no power at all.jumped with leads and it started. Started it next morning and ran it to work about 5 miles and battery was flat again. Read about disconnecting the rf box and all that did was disable the engine so had to reconnect. Brand new battery fitted and after 3 days sat outside battery is discharged again. I am now assuming the altenator is at fault. The question is when I park up I disconnect the battery positive will this stop the altenactor discharging it and will it doing this do any damage to the rest of the electrics. Money is tight and can't afford a new alternator just yet. Hope someone has the knowledge to help. Thanks happy new year to you all.
 
Duncanincapable said:
4 litre 1998 p38. Over Christmas didn't use the car and when I came to use it the battery was flat no power at all.jumped with leads and it started. Started it next morning and ran it to work about 5 miles and battery was flat again. Read about disconnecting the rf box and all that did was disable the engine so had to reconnect. Brand new battery fitted and after 3 days sat outside battery is discharged again. I am now assuming the altenator is at fault. The question is when I park up I disconnect the battery positive will this stop the altenactor discharging it and will it doing this do any damage to the rest of the electrics. Money is tight and can't afford a new alternator just yet. Hope someone has the knowledge to help. Thanks happy new year to you all.
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A new battery should hold a charge for more than 3 days without use.
It sounds like there’s a drain such as an internal light not switching off or something else drawing a current to flatten the battery.
 
Try disconnecting the wire to the battery from the back of the alternator tape it up and see if the battery goes flat again if it does look else were
if its the rf receiver keeping the BECM awake I can point you in the cheep fix direction.
 
Last edited:
If it is the alternator it is normally the regulator pack at the back which can be replaced quite cheaply, if it is that go for one with a set point of 14.4v as early ones were 13.8v.
 
Duncanincapable said:
4 litre 1998 p38. Over Christmas didn't use the car and when I came to use it the battery was flat no power at all.jumped with leads and it started. Started it next morning and ran it to work about 5 miles and battery was flat again. Read about disconnecting the rf box and all that did was disable the engine so had to reconnect. Brand new battery fitted and after 3 days sat outside battery is discharged again. I am now assuming the altenator is at fault. The question is when I park up I disconnect the battery positive will this stop the altenactor discharging it and will it doing this do any damage to the rest of the electrics. Money is tight and can't afford a new alternator just yet. Hope someone has the knowledge to help. Thanks happy new year to you all.
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Take the battery off, charge it and see if it holds a charge. They do sell duff ones sometimes.

Do you have the wash/wipes on the lights? Check they'e properly parked. Also, aftermarket stereos can be an issue.
 
To answer your question, no, disconnecting the battery will do no harm at all and will stop the battery discharging.
However, if the alternator is at fault, it could kill your new battery.
Also, if you have to disconnect the battery every day, then it's going to need the eka entering every day which is great until one of the door microswithes fails.
 
Duncanincapable said:
What is an eka had flat battery over Christmas it was that flat no lights at all anywhere it was if the battery wasn't connected jump started it with out a problem.
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It is possible on some to disable the immobiliser and if that's been done it's probably had battery drain issues in the past. Eka is emergency key access which is a series of turns of the key to reset the immobiliser.
For battery drain issues from the rf module you only disconnect the aerial wire, not the entire rf unit.
 
Saint.V8 said:
A properly disconnected battery shouldnt require the eka code to be entered. Only needs the key re-synced.
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+1 I've had my battery off quite a lot over the years and all seems fine when reconnected. Sometimes even the keys still work. :D
 
I know the siren is disconnected when the key wouldn't do anything and the message engine disabled showed on the dash I got out locked then unlocked the car and all was back to normal. Also when I tried to start the car with the disabled message the lights were flashing so I don't know what's going on there and to be honest probably don't want to know.
 
After much consideration and reading of all your replies for such a massive power drain I'm drawn to the alternator to be at fault. The battery I replaced which is knackered was not the correct battery I've seen bigger ones in remote control cars to be honest the new one is huge. The car since buying it has sat in the same place and usually stays still from Friday to tuesay and never had a problem with starting so on that basis we can rule out bcm involvement. Will check alternator I know it produces 14 volts when running but I don't know how to check for a "leak" can somebody advise I do have a multimeter.
 
With a normal multimeter you can put it in series with the battery and lead but if you draw more than the multimeter can cope with you could pop it (some better ones have a fuse to protect them but be certain before you try it)
Better option is to see if you can borrow a dc clamp meter.
 
Wazzajnr said:
With a normal multimeter you can put it in series with the battery and lead but if you draw more than the multimeter can cope with you could pop it (some better ones have a fuse to protect them but be certain before you try it)
Better option is to see if you can borrow a dc clamp meter.
Click to expand...
I bought the multimeter from the local cheap shop and it is probably cheaper to buy another than change the battery all in all if it pops it pops thanks will do that when son turns up with his car and get it started again.
 
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