4.2 battery drain rates
Discussion
Sorry for the questions, I'm slightly new to the world of TVR
After a flat battery the day after a long drive I've been going through the charging system. I've changed the battery as a starting point which has given me about 15% more capacity (55AH to 63AH)
I would have liked to put an 096 in as that would have had 74AH and the right height but just to wide at 278mm which would have meant modifying the scuttle.
I've checked the alternator, and as expected at idle there isn't much power but the minute it moves above c1000 rpm its pumping out 14v with the lights on and the fans etc etc
I put an ammeter in the circuit to measure what kind of background drain was in the system.
Strangely with the car unlocked with all the doors and windows closed lights off etc the car was still drawing 90ma with the unique key on or off. However once locked and alarmed it was only drawing 50ma.
IMHO This is still too high and wouldn't take long to take the punch out of the battery, I would appreciate any oppinions as to the best place to start hunting down the drain. Or should I just fit a batt cut off switch and be done with it?
After a flat battery the day after a long drive I've been going through the charging system. I've changed the battery as a starting point which has given me about 15% more capacity (55AH to 63AH)
I would have liked to put an 096 in as that would have had 74AH and the right height but just to wide at 278mm which would have meant modifying the scuttle.
I've checked the alternator, and as expected at idle there isn't much power but the minute it moves above c1000 rpm its pumping out 14v with the lights on and the fans etc etc
I put an ammeter in the circuit to measure what kind of background drain was in the system.
Strangely with the car unlocked with all the doors and windows closed lights off etc the car was still drawing 90ma with the unique key on or off. However once locked and alarmed it was only drawing 50ma.
IMHO This is still too high and wouldn't take long to take the punch out of the battery, I would appreciate any oppinions as to the best place to start hunting down the drain. Or should I just fit a batt cut off switch and be done with it?
Dont fit a battery cut off switch.
Your Alarm/ECU wont like it and you ll end up with more problems than you started with.
My 4.2 will stand 3 weeks untill the battery starts to go flat, but i dont leave it that long before i attach the optimate.
it might be money well spent getting it checked out by an auto electrican
Your Alarm/ECU wont like it and you ll end up with more problems than you started with.
My 4.2 will stand 3 weeks untill the battery starts to go flat, but i dont leave it that long before i attach the optimate.
it might be money well spent getting it checked out by an auto electrican
Edited by Gray_101 on Tuesday 3rd April 08:39
just one little thing to add here it came to my attention recently that the engine earth strap can be tight both ends,but the washers can corrode causing what appears to be a flattening battery ie turns over a little slower,thought my battery was on its way out,cleaned washers up and now she turns over really well.windows seem a tad faster too
Hi Spongy thanks for that tip I will check connections tonight.
In terms of the auto electrician I don't think this would be money well spent as it appears 50mA is typical for our cars so I might be looking for a problem that doesn't exist.
The garage where the car is stored doesn't have power so sadly a trickle charger isn't a viable option.
I understand the alarm will be running off it's own power when not connected but will it really do any damage to the ECU. Surely the low voltage it experiences from a deep cycled (knackered) battery is potentially more harmful?
In terms of the auto electrician I don't think this would be money well spent as it appears 50mA is typical for our cars so I might be looking for a problem that doesn't exist.
The garage where the car is stored doesn't have power so sadly a trickle charger isn't a viable option.
I understand the alarm will be running off it's own power when not connected but will it really do any damage to the ECU. Surely the low voltage it experiences from a deep cycled (knackered) battery is potentially more harmful?
Check out this thread before fitting the battery isolate switch
http://mobile.pistonheads.com/gassing/topic.asp?h=...
http://mobile.pistonheads.com/gassing/topic.asp?h=...
Right update. . . .
All interior lights checked including climbing in the boot and no sign of any issues.
Next up is the earth strap check and then on to pulling fuses, I'm changing the alternator fuse shortly so I may test with that removed to check it's not diode breakdown on the alternator.
Considering the groupings on each fuse I imagine even that is going to be of little help.
Theoretically what value should we be getting with the flashing L.E.D's, ECU memory and alarm draw?
All interior lights checked including climbing in the boot and no sign of any issues.
Next up is the earth strap check and then on to pulling fuses, I'm changing the alternator fuse shortly so I may test with that removed to check it's not diode breakdown on the alternator.
Considering the groupings on each fuse I imagine even that is going to be of little help.
Theoretically what value should we be getting with the flashing L.E.D's, ECU memory and alarm draw?
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