RangeRovers.net Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
151 Posts
Discussion Starter #1
It started off with the usual case of vehicle left for a few days and the result was a flat battery.
Battery at the time was 4+ years old and the alternator was testing ok so after checking the BECM for sleeping and it was i determined the battery was at fault and replaced it with the diesel version.
So all was happy for a month untill the dreaded phone call off the missus the *************** won't start.
I got home to a battery, reading 4 volts .
I rang the auto electricians who i bought it from and returned the battery to them they tested it yes it was flat but it was still serviceable.
They offered to put it on their charger and bring the specific gravity up but i said i will do it at home,so they advised an overnight charge which i did with a 10 amp charger.
12hrs later battery refitted and vehicle sprang into life.
Prob solved I thought untill 24 hrs later vehicle would not start.
Battery voltage across terminals 11v so i jump started the truck checked the voltage from the Alt and it was at 14v I switched everything on lights etc and still got 14v so I took the truck for a long run came back turned it off and went out a few hrs later and it started no problem.
Then came today it wouldn't start, voltage 10.5.
I rang the auto elecs who asked me if I could start it by jumping it again and drive it down to them and they would be happy to check out the charging circuit etc as everything was pointing to an Alternator going faulty .
I jumped the vehicle and drove it down the lads at the garage who checked the lot.
The alternator was fine and charing was good.
There was no backfeed
They then left the vehicle standing with multimeter attached and watched the amps drop off bit by bit as the different ECU's shut down the amps duly fell away to the point they were into the milliamps and dropping.
So everything was as it should be.
Then the hydrometer came out and the cells were individually checked and the battery was in a very poor state of charge.
The battery is currently with them being charged on their system.
But some good points have come from this,
Check your specific gravity before you blame the alternator as no alternator will be able to bring up a battery from such a flat state as they operate on voltage and battery voltages can rise rather quickly compared to amps and in which case the alternator will be switching on and off once the volts have been reached.
One question remains:
Just what did discharge the battery to such a low level the usual culprits lights etc have been eliminated?
The other point is the checking of my Range Rover has cost me nothing the company where more than happy to help
Just for the record the battery is a Varta pro motive (diesel spec)
Hope this info is off use to someone one day
I will update tommorrow as and when i get the battery back.
 

·
Registered
Joined
·
1,758 Posts
Thanks for the post. I'm always at a loss when it comes to proving a battery will no longer hold a charge or allow full charging based on alt shutting down when volts come up. Our battery now is a delco 950 cca, similar to original interstate 950. What I have found is that once an older battery has had a deep discharge it just does not recover. I don't know if this is because the lead plates oxidize or the battery acid fails or what you have just mentioned with the alt. shutting off as voltage comes up. Will look forward to hearing about a successful outcome .
 

·
Registered
Joined
·
151 Posts
Discussion Starter #3
Quick update:
Battery picked from Auto elecs specific gravity back up and showing fully charged (Test carried out while i was there)
Battery back in RR and all windows etc reset.
Vehicle started no probs.
I am now going to leave it for 24 hrs and see how it goes tomorrow.
Will keep an update going as and when
 

·
Registered
1995-2002 Range Rover P38A
Joined
·
865 Posts
Big batteries that are fitted to the rangies like a 110amp need a good charge rate of at least 5 to 7 amps on a battery charger for at least 24 hours with cables disconnected, this is where a spare is handy to maintain electronics etc.

If you do alot of stop go driving (a killer for the P38) then the alt will struggle to maintain it to a good state.
 

·
Registered
Joined
·
151 Posts
Discussion Starter #5
Well folks so far so good is all I can report no electrical issues since it was charged by the auto elecs.
When i get round to buying a hydrometer I will be able to put some figures up so you can see how the battery is performing
 

·
Registered
Joined
·
593 Posts
Is the BECM being kept awake? That will do it. For example, are you parking the car with the level in PARK? Are there lots of other cars nearby which have remote control locking? Lots of radio transmitters nearby?

And what are the results of the electrical sticky tests?
 

·
Registered
Joined
·
151 Posts
Discussion Starter #7
Hi mate as in the first post the BECM went to sleep over a period of 3 minutes approx.
The load went from 1.2 , .8,.5 ,0.1
All electrical loads where checked by the garage giving 14.2 -14.4 under varying load conditions.
The only other area that couldn't be tested is once the BECM had gone to sleep was it being activated by other radio waves,but now I know it does go into sleep mode I might have a play over the weekend to see what happens.
 

·
Registered
Joined
·
593 Posts
PAULBROM said:
All electrical loads where checked by the garage giving 14.2 -14.4 under varying load conditions.
Hi Paul it is important you do the tests exactly as specified and report every single result here. No exceptions. Time after time people tell me they've done the tests, it is all fine, you spend time helping them and then find it was there from the beginning in a test they didn't do.

I'm happy to help with what I can but I don't help without the tests being done and reported as specified first. That is why I wrote the sticky.

Greg
 

·
Registered
Joined
·
151 Posts
Discussion Starter #9
Ok Greg.
your help is much appreciated and i spoke too soon vehicle left for 2 days BATTERY flat. now on charge.
I will take it back to the auto elecs and when i get it back run the tests according to the sticky
Thanks for your input.
Paul
 

·
Registered
Joined
·
151 Posts
Discussion Starter #10
Well here we go.
After my return from the auto elecs with a new battery i decided to run my own tests to see if my electrics where shutting down.
As i have previously posted the auto elecs tested for battery drain when everything was shutdown and all was well.
Anyway back on my drive I connected the meter and watched the amps drop away from 1.1,0.8,0.56 and 0.02 but immediatley the amps climbed back to 0.56 this went on for about an hour.
So basically there was a permanent .6 amp drain on the system.
My first guess was the good old alarm and guess what after disconnecting the aerial from the reciever and 2mins 30 seconds later the system was sleeping like a baby and still is 4hrs later.
All I can summise from this is that there are no spurious signals floating around near the auto elecs waking the BECM up and outside my house must be signal junction.I must say when i look at networks on my laptop it has gone from 1(mine) to 4 so i will blame the neighbours for my problems.

One other mention must go to Greg (ghind) for his expertise and help in diagnosing other issues with my electrics. :thumb:

I hope I have laid this one to rest at last
 
1 - 10 of 10 Posts
Top