Whats the easiest and best way to check for a drain on the battery? Had a couple of starting issues this winter, 1 i know was from the mrs using it for lots of short journeys with every bloody thing on, heater,seats, stereo blah blah, got it started and put some life back in but wouldnt start last week again. Mr AA suggested checking for any drain, whats the best way to do this? And does it need to be parked and off for a while before doing it, to make sure all the PC's/etc have shut down fully? Think he said leave it 30 mins?
Datatek
Well-Known Member
Just as likely to be a duff battery. To check drain the safest way is with a clamp meter that goes round the battery cable, then you don't have to disconnect the battery. With a normal meter you set it to amps, remove one battery lead and connect one meter lead to the battery and the other to the lead you have removed from the battery.
Clamp around DC ammeter over the negative lead.
Datatek
Well-Known Member
That's wot I said
Cheers guys
Data it was a new battery last winter, cost about £150 wanted the best I could get at the time, so hoping its not that already? Mr AA said alternator is charging OK so its not that, just seems to be after 5 or 6 days of not being used, especially on these cold mornings...... used it for loads of short journeys summer just gone (3 or 4 trips a day), no problem, just had couple of problems since the cold arrived
Is there a minimum or max reading I should be looking for on the clamp meter around the neg cable?
Data it was a new battery last winter, cost about £150 wanted the best I could get at the time, so hoping its not that already? Mr AA said alternator is charging OK so its not that, just seems to be after 5 or 6 days of not being used, especially on these cold mornings...... used it for loads of short journeys summer just gone (3 or 4 trips a day), no problem, just had couple of problems since the cold arrived
Is there a minimum or max reading I should be looking for on the clamp meter around the neg cable?
Check your alternator belt. Make sure its not all craked and decaying. Thats the first place i'd start. Second to that i would have someone check the alternator itself. The belt is usually the culprit, followed by the alternator. I would say the battery is the usaul culprit but you say its fairly new so...
2.0_hippo
Well-Known Member
might also need a fault code reader so you can clear any faults that may arise from pulling random fuses
No. You put the fuse you have pulled back into the end of the test plug before you plug it into the fuse holder so it shouldn't come up with a fault. It has minimal effect on circuitry.
I have used one without problems and they are widely used on other cars.
Really useful piece of kit.
No - i asked why yu would want to disconnect the battery with a clamp on ammeter?
eightinavee
Well-Known Member
Things to consider;
1, Current drain on an L322 is 20-30mA,same as a P38.
2,They take 16-18 mins to shut down to sleep,during which time there are several surges as different ECU's do their thing.
3,taking out fuses one by one and replacing them with a plug in will just take forever as plugging the unit in will in most cases wake it all up again.
4,An ordinary current clamp cant measure accurately down low enough,for this kind of measurement you need something like this; K Clamp Series AC/DC, 3.9mm ID, Cat. II 300V - Chauvin Arnoux | Chauvin Arnoux But the only problem,(Besides its cost) is that the clamp will only go around a small wire.I get areound this by using a suitable lead with a croc clip on either end and carefully connecting it into the circuit without losing contact - helps on L322's and is even more help on P38's as you dont have to set windows/sunroof etc.
5, Common drain issues on L322's are the final stage resistor for the fan motors keeping the HEVAC ecu awake,headlight lowering ecu's being full of water,LPG ecu's,old phone kits,dead tracker batteries and water in just about any loom or other ecu.
1, Current drain on an L322 is 20-30mA,same as a P38.
2,They take 16-18 mins to shut down to sleep,during which time there are several surges as different ECU's do their thing.
3,taking out fuses one by one and replacing them with a plug in will just take forever as plugging the unit in will in most cases wake it all up again.
4,An ordinary current clamp cant measure accurately down low enough,for this kind of measurement you need something like this; K Clamp Series AC/DC, 3.9mm ID, Cat. II 300V - Chauvin Arnoux | Chauvin Arnoux But the only problem,(Besides its cost) is that the clamp will only go around a small wire.I get areound this by using a suitable lead with a croc clip on either end and carefully connecting it into the circuit without losing contact - helps on L322's and is even more help on P38's as you dont have to set windows/sunroof etc.
5, Common drain issues on L322's are the final stage resistor for the fan motors keeping the HEVAC ecu awake,headlight lowering ecu's being full of water,LPG ecu's,old phone kits,dead tracker batteries and water in just about any loom or other ecu.
eightinavee
Well-Known Member
I have some factory data on P38 BECM's and nowhere does it mention sending one to sleep - only monitoring current draw whilst it goes through its shutdown checks to hopefully get down to 20-30 mA.Cant remember what they are,but its in 3 steps from last activity.
L322 is a nightmare on going to sleep,I stood and watched a scope trace one day all the way through till if slept,after about 16mins.... There is alot going on.
