Member Since: 03 Nov 2011
Location: Bristol
Posts: 47
Alternator charging
I was sad enough over the weekend to plug a voltmeter into the power sockets in the front but to my amazement found that a tick over and whilst throttling there is hardly any charge at all and the voltage stays around 12.6 but never drops no matter what you switch on but as soon as you free wheel or brake the voltage shoots staight up to over 14 volts!
I guess it must be to improve economy but my concern is that my second battery in the back for my fridge which Is being charged by the towing socket 15 amp charge output just isn't charging enough when idling or driving around especially on short runs.
I did wonder wether it was just a power socket thing but I put some jump leads onto another of my vehicles of mine with a volt metre and at tick over or reving the engine didn't rise the voltage over 12.6!
Any ideas on improving charging, is there a little box somewhere I can trick or bypass?
9th Apr 2012 9:16 pm
B16 KJR
Member Since: 10 Jul 2006
Location: Rosyth, Fife
Posts: 3005
To me it sounds as though there could be a problem with your altenator. When revving the engine the voltage should rise to about 13.6v
Full charge output should be upwards of 14.7 to 15 volts, it looks like your alternator could be failing.. But your rear battery should be the same as the front when charging.
I would look at your wiring for your rear socket, check that all the earths are good because if it alters when you are braking then making that circuit sounds like its helping to make proper contact somewhere.
Could even be your brake light switch..
Flack
Last edited by Flack on 10th Apr 2012 12:58 pm. Edited 1 time in total
10th Apr 2012 12:54 pm
DiscoDunc
Member Since: 08 May 2006
Location: Bristol
Posts: 16390
if the battery is fully charged, my alternator can only put out 12v-13v if there is little load on the electrical system, even when travelling at 70mph down the motorway - has always done that. doesnt sound anything wrong to me unless your battery is struggling to start the car. Try it again over a longer test period with some load
typically mine will start at a low voltage then after a minute of so increase to around 15v then drop back down after battery is charged. sometimes it appears that the alternator is not charging at all !!Duncan
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10th Apr 2012 12:58 pm
Russell
Member Since: 24 Aug 2007
Location: Kent
Posts: 10564
The D4 has an inteligent altenator that uses the best time to charge the battery unless it is very very low, there was a post about it somwhere and there is also blurb in the pulicity info. So as Dunc says there are no issues with it from what you have described.MY17 D5 1st Edition Namib Orange
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10th Apr 2012 10:52 pm
Rich Sims
Member Since: 03 Nov 2011
Location: Bristol
Posts: 47
Yeah I don't think there is anything wrong with it it's just when the battery on the car is up to full charge the trickle caravan charge output drops to nothing and doesn't charge the second battery as quick as you would like it.
11th Apr 2012 9:59 am
CUCO
Member Since: 27 May 2011
Location: Spain & Oleee!!!
Posts: 609
Nothing is wrong with your alternator or recharging system. the D4 have a special recharging method, i have studied it because i want to install a split charge to know the cut in and cut out voltages and yes, it boost the recharging voltage when coasting or braking, to left it in a nominal voltage when accelerating or starting.
11th Apr 2012 2:00 pm
CUCO
Member Since: 27 May 2011
Location: Spain & Oleee!!!
Posts: 609
ask drivesafe if you want more info, he is "the expert" in D3 and D4 battery recharging systems
11th Apr 2012 2:01 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
CUCO wrote:
ask drivesafe if you want more info, he is "the expert" in D3 and D4 battery recharging systems
Hi CUCO and I wish.
Hi Rich and if you have the nav display screen, enter the hidden screen and you can bring up the vehicle's voltage while you are driving.
The voltage reading is no more than about 0.1v out and this is well and truly accurate enough to see whats actually going on.
The voltage readings you get on the screen relate to the cranking battery’s voltage ONLY, and from what you’re posting, it sounds OK.
What is happening at your caravan battery is a totally different situation.
If you are using the vehicle’s wiring at the rear socket to get power to your caravan battery then you are pretty well wasting your time.
If your caravan battery is near full, this wiring will keep it topped off but if your caravan battery is low, because the D4’s wiring is so thin, the low caravan battery’s current load on that wiring will cause so much voltage drop, you would need to drive for 20 hours straight to charge your caravan battery.2008 TDV8 RR Lux + 2009 D4 2.7
11th Apr 2012 7:24 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26705
@Tim (Drivesafe)
Slight diversion from topic, but is the D3 standard tow wiring also too thin to be useful? I have always suspected that the car did not charge the caravan battery properly - usually because I have to use the 4wd motor mover to hitch up the van, and this drains the caravan battery very quickly. Usually when I arrive on site after a long drive, the caravan battery is still too flat to use the motor mover properly.
To get around this would it be acceptable to run a thicker wire from the back of one of the permanent 12v sockets in the back of my car (supplied by your good self, and connected directly to the auxiliary car battery, which is charged by a Traxide) and connect the other end to the charge pin on the 12S caravan socket?
This should have the effect of connecting the caravan and the aux battery in parallel, and I think the Traxide will handle this?
Hope this makes sense, and tell me if i'm talking rubbish!
11th Apr 2012 8:23 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Gareth, and it sounds like you have one of my TPSE kits fitted. This kit comes with a thicker twin main cable ( 8B&S Twin ) to the rear cargo area and then you would have branched off with the thinner cable, to the two power sockets.
If this is the kit, then the main twin cable is too thin yet is about the same size as the cable thats connected to the 12S plug in your D3.
We supply that size cable to power a few additional power sockets, so you can see how under sized the D3’s cable is for charging a battery.
Unfortunately Gareth, your need to run a new thicker twin cable ( 6B&S or 16mm2 ) from the auxiliary battery to a 50 amp Anderson plug set up, and then the same size cable from the Anderson plug set up to the battery in your caravan.
The 12S plug is not very good at handling the currents you can be required to charge a low battery and they are not good for Hot Make-N-Break connections.
Where as Anderson plugs are specifically designed for this sort of situation.
The diagram below shows what is needed in your D3.
PLEASE NOTE, Gareth, if you have the SC40-LR isolator, as this isolator is designed to control the charging of ONE auxiliary battery, you will need a bigger isolator, if you have the SC80-LR, as this isolator is specifically designed to charge multiple auxiliary/house batteries, you will only need the heaver cable and the Anderson plugs.
Click image to enlarge
Gareth if you decide to run the thicker cable, PM me your E-mail address and I can E-mail you back the full instructions to make it easier for you to see how to run the heavier cable through your D3, to the rear bumper.2008 TDV8 RR Lux + 2009 D4 2.7
12th Apr 2012 12:37 am
Rich Sims
Member Since: 03 Nov 2011
Location: Bristol
Posts: 47
Sorry its been a long time since I last posted on this subject but I did cure the problem with charging about 6 months ago and it works so well that I had forgotten about it until some one told me today about their charging problems...
Basically 6 months ago I connected a ballast resister to the brown wire going to the towing socket(side lights feed) to make the car think its towing a trailer or caravan and then it charges all the time which makes charging phones better and split charging other batteries on the car possible.
18th Jul 2013 1:13 pm
CUCO
Member Since: 27 May 2011
Location: Spain & Oleee!!!
Posts: 609
Rich Sims wrote:
Sorry its been a long time since I last posted on this subject but I did cure the problem with charging about 6 months ago and it works so well that I had forgotten about it until some one told me today about their charging problems...
Basically 6 months ago I connected a ballast resister to the brown wire going to the towing socket(side lights feed) to make the car think its towing a trailer or caravan and then it charges all the time which makes charging phones better and split charging other batteries on the car possible.
please, could you post a picture of the ballast? or tell us the specs and where to connect it?
many thanks!
18th Jul 2013 1:37 pm
Rich Sims
Member Since: 03 Nov 2011
Location: Bristol
Posts: 47
Its called a load resistor which are used when using LED lights and is half way down this page
you just need to connect it between the brown going to the towing socket and an earth point, I used a scotch lock to connect it to the brown wire and a 6mm ring terminal on the other end to the earth bolt next the wireing. The wireing for the trailer is located in the boot on the n/s behind the opening panel.
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