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Discussion Starter #1
Hi all,

Those of you who have seen my previous posts might already know that I've been having problems that seem to BeCM or battery related. So... I've finally got round to doing the tests (the battery had been charging from pretty dead for only 20 minutes, so I'm not sure if the battery is dud, although I doubt it):

1. Engine off, all accessories on for 30 seconds, then off. What voltage 12.3V
2. Voltage across battery at idle (no electrical load) 14.12V
3. Voltage across battery at 2000rpm (no electrical load) 14.14V
4. Voltage across battery at 2000rpm (everything electrical switched on) 13.85V
5. Voltage at ALTERNATOR at 2000rpm (everything switched on) 14.05V
6. Voltage drop between alternator body and battery negative (YES negative). Measure at max electrical load and 2000rpm 50mV
7. Voltage drop between alternator positive and battery positive. 2000rpm, max electrical load 90mV
8. Check Voltage drop from Battery Negative terminal to 1st groundpoint on vehicle 20mV
9. Check voltage drop from 1st ground point to block 30mV
10. Check voltage drop from Alternator Housing to block none measurable
11. Voltage from alternator positive to alternator housing 14.12V

What are your symptoms

My symptoms have been many:
First there was an issue where the battery was dead one morning. After a 24 hour charge with a pretty good charger, the engine would turn over but with no fuel being pumped, or spark; this turned out to be BeCM and alarm unit being out of sync. Also, at this time, the sunroof and trip computer stopped working.
I eventually got the above sorted by way of complete BeCM reset (Autologic - thanks Keith Gott), but fist I didn't notice the sunroof or trip computer so only had the security code re-synced. Between the resync and the full solution, all indicators came on solid (hazards on permanently), and the battery went flat again within a couple of hours. A simple jump start got it going again, and it was absolutely problem free for about 2 weeks.
Where I park at work, sometimes I am unable to lock the car using the remote, although unlocking is always fine and locking is mostly fine elsewhere.
The day I had a full BeCM reset (whatever that is), on a 10 mile journey the passenger door locked and unlocked itself multiple times.
This morning I came out to a very wet passenger seat: It appears that the window opened itself (I don't recall leaving it open...). Also there were multiple faults and the battery was pretty dead.

What have you done to fix it so far

As above: security sync and BeCM reset.

Could my BeCM be on its way out? Is it just that I should disconnect my alarm receiver antenna? Any help would be appreciated. :)
 

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jimbohotpants said:
1. Engine off, all accessories on for 30 seconds, then off. What voltage 12.3V
2. Voltage across battery at idle (no electrical load) 14.12V
3. Voltage across battery at 2000rpm (no electrical load) 14.14V
4. Voltage across battery at 2000rpm (everything electrical switched on) 13.85V
5. Voltage at ALTERNATOR at 2000rpm (everything switched on) 14.05V
6. Voltage drop between alternator body and battery negative (YES negative). Measure at max electrical load and 2000rpm 50mV
7. Voltage drop between alternator positive and battery positive. 2000rpm, max electrical load 90mV
8. Check Voltage drop from Battery Negative terminal to 1st groundpoint on vehicle 20mV
9. Check voltage drop from 1st ground point to block 30mV
10. Check voltage drop from Alternator Housing to block none measurable
11. Voltage from alternator positive to alternator housing 14.12V
Firstly you need to get your battery onto a GOOD 3 stage or better battery charger for 24 hours and rerun the tests. 12.3 volts is unacceptable and will cause blinkers etc to lock on and flatten the battery. Why I don't know but it can and sometimes does.

Your numbers do not quite add up. You have 140mv of voltage drop shown from tests 6+7 but 200mv of shown from test 4+5

My guess is that your alternator etc is OK and your problem is elsewhere. Try disconnecting the alarm antenna. And or first, rerun the tests after properly charging your battery. You should be seeing 12.7 or so volts in test 1 if your battery is "strong" or 12.5 if it is "marginal". 12.3 is no good.
 

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Discussion Starter #3
I thought the numbers weren't quite right either. I took a look inside the battery today (there's no window) and it was rather black, so bought a new one (550A rather than the current 315A too). I'll redo the tests with a better DMM as well, since the one I used was a tad crap. stay tuned :)
 

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what is a 550a battery? Hopefully not a 550CCA battery. Mine is an an 850 or a 950cca from memory.

You want the best standard type battery you can fit in there. I wouldn't use Optima brand, they are overhyped and I've not been impressed with mine. Just the best "mid range", large size lead acid that will fit.
 

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Discussion Starter #5
the 550A refers to "starting power", which I presume is the maximum current available at 12V for engine start. This could be cca, but it doesn't state that on the battery itself. The previous battery had a similar "starting power" rated as 315A. I'm not sure of the manufacturer of the new battery (it's branded as Halfords), but I do know it's Calcium-Calcium.

I've just redone the tests with the new battery and the results are as follows:

1. Engine off, all accessories on for 30 seconds, then off. What voltage 12.3V (still low it seems, even though the battery is brand new)
2. Voltage across battery at idle (no electrical load) 14.33V
3. Voltage across battery at 2000rpm (no electrical load) 14.33V
4. Voltage across battery at 2000rpm (everything electrical switched on) 14.12V
5. Voltage at ALTERNATOR at 2000rpm (everything switched on) 14.19V
6. Voltage drop between alternator body and battery negative (YES negative). Measure at max electrical load and 2000rpm 74.3mV
7. Voltage drop between alternator positive and battery positive. 2000rpm, max electrical load 60.1mV
8. Check Voltage drop from Battery Negative terminal to 1st groundpoint on vehicle 30mV
9. Check voltage drop from 1st ground point to block 40.3mV
10. Check voltage drop from Alternator Housing to block 0.7mV
11. Voltage from alternator positive to alternator housing 14.10V
 

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2010-2012 Range Rover MkIII / L322
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If the battery cost less than £80, take it back. That's the first thing to look at.

Ideally, you need to fit a Genuine Part diesel battery which is a 664 type battery with 107Amp Hours. That's the bare minimum really. The standard V8 came with a 072 model 72Amp Hours battery which was pretty useless.

viewtopic.php?f=3&t=7223&start=0
 

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Discussion Starter #9
OK, I've noticed something that won't help with battery discharging problem: The previous owner fitted a pair of headrest screens/dvd players and I noticed today that he tapped into the permanent power line rather than the ignition power. These will therefore constantly be draining the batt.

I also now have another problem :x in that I parked up earlier, left her for around 4 hours, then when I came back the locks wouldn't operate using either the main or spare keyfob. The locks DO operate fine with the key, however, when trying to start the engine, I get "Engine Disabled - press remote". I've tried disconnecting the battery, both keyfobs and the EKA procedure, but no joy. When either key is in the ignition at position 2, the LED flashes on them. The immobiliser/alarm LED on the dash doesn't come on at all when the door has been unlocked, but does when the locked, as usual.

My first thought was that it could be to do with BeCM-alarm sync, so tried the Sync-Mate I had kindly returned to me today (coincidence!), but unfortunately all I get from it is blue LED followed by single red flash, which apparently indicates that the ECU is not responding.

So.... does any of this make any sense to anyone? Does anyone have the faintest clue what I can do to get the car running again? This is becoming a serious pain in the arse.
 
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