ostland
Member Since: 16 Jan 2009
Location: Capital!
Posts: 89
  
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| What is the Minimum Required Battery Voltage? |
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Somewhat belatedly, I managed to get into sat nav screen diagnostics using "753", and found an entry denoting current battery voltage.
I read somewhere in this forum that when battery starts to die, there will be more likelihood of faults occurring, so to avoid a christmas tree light ups you need to make sure the battery is charged.
I couldn't find a thread discussing this, but as most likely someone already has I apologise in advance for bringing it up again, what is the safe minimum voltage for D3 to operate? At what voltage should I start to get worried? At present, fiddling around with electronics my D3 had shown 11.0v.
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 27th Jan 2010 1:44 pm |
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heine
Member Since: 07 Feb 2007
Location: Midrand
Posts: 4054
 
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Most high cycle lead acid batteries are considered 50 % discharged at 11.6 (or is it 11.5 v) . With a "dead" battery being 10.5 V . So IMHO it's probably not very healthy . Disclaimer I'm no battery expert , just relaying what I've been told 
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| 27th Jan 2010 2:02 pm |
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ostland
Member Since: 16 Jan 2009
Location: Capital!
Posts: 89
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Thanks very much Heine - I refound the thread on voltage this morning and checked using the hidden access on the radio screen. It showed 11.7v before w/o engine on and 14.2v with engine running so it appears ok. Apparently the sat nav screen gives a very crude voltage whereas the one on radio seems to show upto 1decimal place.
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| 28th Jan 2010 2:16 pm |
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heine
Member Since: 07 Feb 2007
Location: Midrand
Posts: 4054
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Hmmm 11.7 is not a healthy battery . A fully charged battery should be at least 12.5 overnight
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| 1st Feb 2010 10:10 am |
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hensoni
Member Since: 01 Oct 2007
Location: Sleepy Somerset
Posts: 576
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14.2v simply means that your alternator is most likely working.
If you take a dead NiCd (i.e. knackered, not 'discharged') and plug it into a charger, it will immediately show 1.3 - 1.5v depending on the charger. Turn off the charger - you've still got a dead NiCd.
I would agree, 11.7 volts is not a healthy voltage.
You can measure the voltage at the trailer 12S socket so that you can see the difference between asleep and awake (pin 3 is a perm 12V, pin 4 is the return). When the vehicle wakes up, the battery will dip momentarily as the load comes on. It should then rise to a healthy 12.5V+.
With a steady state of 11.7V, you are walking on thin ice...
Provide a long, steady, low current charge to your battery to see if it is suffering from short journey syndrome. If not, change it!
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| 1st Feb 2010 10:37 am |
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Matty 2332
Member Since: 02 Dec 2008
Location: West Yorkshire
Posts: 670
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Ostland, how did you get into the 'hidden access screen' on the radio ? 
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| 1st Feb 2010 10:43 am |
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caterham
Member Since: 04 Feb 2006
Location: West Lothian
Posts: 23
 
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Matty 2332 - if you turn the radio on and then press and hold the rotary button on the right hand side of the radio it will eventually (about 20 seconds or so) change the radio display to show the vehicle VIN details. release the button and then press and hold it again. The display will change after a while and you can use the rotary knob to cycle through various pages. A lot of the pages don't mean anything but after 5 or 6 you will get some details about temperature and charging voltage. I was shown how to do this after I was having some 'funny' electrical problems and had been using a multi meter over the battery to check the voltage. This is obviously much easier - and you can see how the voltage changes as you drive.
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| 1st Feb 2010 10:08 pm |
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heine
Member Since: 07 Feb 2007
Location: Midrand
Posts: 4054
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Not sure exactly where this is measuring the voltage , its quite a bit lower than on the battery itself . Also not very useful for testing the battery for an "open voltage" , as the car needs to be awake to do this
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| 2nd Feb 2010 7:43 am |
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Matty 2332
Member Since: 02 Dec 2008
Location: West Yorkshire
Posts: 670
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Thanks Caterham, I will give it a go today 
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| 2nd Feb 2010 7:54 am |
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Matty 2332
Member Since: 02 Dec 2008
Location: West Yorkshire
Posts: 670
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Thanks guys, tried accessing the 'hidden screens' but alas mine will not do it. I presume its because mine is a base spec. Thanks anyway
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| 4th Feb 2010 3:51 pm |
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ostland
Member Since: 16 Jan 2009
Location: Capital!
Posts: 89
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Thanks guys, and sorry Matty 2332, I had a hectic week and didn't see your question until now. I did it the way Caterham described, and the key is to hold the right hand button for 10 secs immediately after turning the radio on, then when the screen changes, let go of the button and re-press the button for further 10 secs. It may be model specific though. The ones I have tried did not show the VIN. it was left blank.
hensoni, I think my trips these days were: one 10 mile /per way / weekend and one 100 mile / per way / month. Would these be too short to fully recharge the battery?
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| 7th Feb 2010 2:55 pm |
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hensoni
Member Since: 01 Oct 2007
Location: Sleepy Somerset
Posts: 576
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Hi Ostland,
It depends on what else you are running on those 10 mile trips (lights, heated screens, climate control, satnav screen, etc) but my immediate reaction to your question was: No.
To qualify that, the load of a single engine start in low temperature typically needs 15 - 20 minutes of engine running time to replenish a (healthy) battery. Your 2 x 10 mile trip every w/e is most likely consuming more power than the journey replenishes.
A fresh battery would cope with that sort of cranking load without too much complaining, but a 3 year old, tired battery will need a little more assistance.
TBH, your best option is to put your battery on a load tester (not a multimeter) and if shown to be worn out - replace it. My VW T4 Transporter battery is on it's last legs and boy, don't I know it when it coughs and splutters into life. The engine is lumpy, it smokes terribly and refuses to rev as the engine management system sits there and sulks until the alternator has forced some electrons back into a reluctant battery...
Ian H
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| 7th Feb 2010 3:50 pm |
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Matty 2332
Member Since: 02 Dec 2008
Location: West Yorkshire
Posts: 670
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Thanks Ostland, it must be radio / spec specific, as I still cannot access the screens, i'm presuming its because the radio is baseline, as is the car. Thanks all the same. 
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| 7th Feb 2010 5:02 pm |
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MikeS2005
Member Since: 13 Sep 2008
Location: Midlothian
Posts: 920
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Hi
The correct voltages for a discovery 3 is between 14.2 to 15.2 and thats from a LR technician the easy test is take a reading with the engine off then running then with everything switched on the alternators are bad for sectors going down inside the windings and it will still give you a healthy 12.? this isnt enough to charge the battery and certainly not enough to run the electrics.
It happened to me and Ive just replaced mine
cheers
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| 7th Feb 2010 5:35 pm |
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