Member Since: 15 Feb 2010
Location: Germany
Posts: 167
Hello!
Drivesafe: Your explanation sounds very good. The BMS has some logic that it compares the voltage of the battery before start to adjust charging. So if the voltage changes by starting the engine and relaying the two batteries together, the BMS will be "worried" I think.
So I think I will try your system - after the winter...
The solution "disabling the BMS" does not sound very good, but because I have a fautmate I will give it a test - but sure not for permanent.
Greetings
gseumDiscovery 4/LR4 HSE 5.0 V8 MY2010 // Volvo XC60 II T8 Inscription Fusion Red MY2020 // Hyundai Kona Electric Trend MY2020 // Bürstner TravelVan 620G MY2020
14th Nov 2012 7:47 pm
DiscoDunc
Member Since: 08 May 2006
Location: Bristol
Posts: 16390
well, drained the yellow top last night and test the charging today.
before opening the car the aux batt was below 11v and the main battery at just over 12v
opened the car and main battery dropped as usual. started engine and main battery rose to 13v then after 1 min the solenoid kicked in and aux started charging.
voltage of alternator stayed at 14-16v for quite a while (got fed up of keep checking it) but then dropped to approx 14v. solenoid stayed connected for the full 90mile 1.5 hour journed and charge never dropped below 13v
on way home this evening, charge remained at over 13v for about 1/2 hour and then, assuming the aux battery was fully charged, the voltage dropped back to 12v on the alternator and repeated its varied charging. So, on the face of it , it seems that it recognises the aux battery combined with main battery and charges the aux battery just fine..
more testing required to make absolutly sure !!Duncan
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If I'd known I was going to be so thirsty this morning I'd have drunk more beer last night.
FFRR Autobiography 4.4 SDV8 MY17
D4 HSE MY13 SOLD
FFRR 3.6 Vogue TDV8 SOLD
D4 HSE MY10 SOLD
D4 SE TECH MY15 SOLD
D4 XS MY12 SOLD
D4 HSE MY10 SOLD
D3 HSE MY06 - Re-Cycled Worldwide
14th Nov 2012 8:21 pm
Splitpin
Member Since: 30 Dec 2010
Location: At the toolbox
Posts: 535
That's good news, I thought it would do that with the aux discharged.
At the end of the day it does not know its a second battery it thinks the first needs more charge.
Worst case if in an emergency, all smart alternators can revert to normal charging if the smart input is disconnected.
14th Nov 2012 8:29 pm
drivesafe
Member Since: 23 Feb 2006
Location: Gold Coast, Australia
Posts: 867
Hi Duncan and as I posted, you would be surprised at what these alternators ( and D4s ) can do.
What happens is the D4 monitors a high current draw, it actually has no idea that there is a second ( or more ) battery fitted to the D4, it just “sees†the high current load and works accordingly to cater for it.
Your Optima was at about 5% State of Charge ( SoC ) when you started and within the first hour of driving, it would have easily reached 90% and then by the time you got home, it would have been well over the 95%.
Your cranking battery is a different case and at 12v for normal use, this is too low.
Your 3 hour drive combined with the high operating voltage during that drive, should have your cranking battery back up in the 90% SoC, but Calcium/Calcium batteries are a bit finicky and can take some time to reach a fully charged state.
To fully charge a low Ca/Ca battery can take up to 8 to 10 hours of charging with a battery charger.
With or with out a standard split charge set up, it would pay to put your cranking battery on a boost charge once every month or so with a good battery charger but NOT a high current one.
You can measure your batteries voltage to get a rough idea of how well they are charged after they have been sitting with the motor off for at least 10 hours using the chart below.
Click image to enlarge
2008 TDV8 RR Lux + 2009 D4 2.7
14th Nov 2012 9:53 pm
cecilh
Member Since: 17 Jul 2012
Location: Johannesburg
Posts: 13
Thought I'd open subject up again. I have a MY13 D4 fitted with a NL dual battery monitor and a NL solenoid modified for the D4. I am having endless problems with the 2nd battery not being charged with this system and the problem is that the solenoid simply does not engage for long enough for the 2nd battery to charge. This is where I have some concerns - having recently been on a road trip and observing the monitor closely what happens is :
a) on start-up the monitor shows charging at 14.2v. After about a minute the solenoid closes and the 2nd battery also shows 14.2v
b) after about an hour (sometimes less) the voltage drops to 12.6v where it stays for anything from 15 - 30 minutes
c) quite quickly thereafter this drops to 12.2v and stays there for hours, occasionally kicking up to 12.6v. At the drop to 12.3v the solenoid disengages and the 2nd battery starts to discharge (fridge connected).
d) as the charging system is of the re-generative type when coasting in gear the charging voltage goes up to >13.2v but drops again to 12.2v the moment the accelerator is pressed. This usually does not last long enough for the solenoid to engage
e) on switch-off the voltage tends to stay around 12.2v
f) next morning on start-up voltage may get to 14.2 but typically goes to about 13.2 for a while before repeating what happened from (b) above.
Having now read all the previous posts I assume the charging system is working correctly in Land Rover spec terms? I am however concerned that the cranking battery is receiving a marginal at best charge and that I am going to be left with an undercharged cranking battery at some stage - I have been assured by some knowlegable people that this is not the case but the thought is still there. Is there perhaps a software solution for this situation? Alternatively perhaps a simple manual switch to force the batteries to parrallel when driving and the manually disconnect them when stopped (risk of course is that I forget to disconnect batteries and run both batteries flat. Anyone had success with DC/DC chargers like the CTEK? Any and all input much appreciated.
Last edited by cecilh on 29th Oct 2014 1:02 pm. Edited 1 time in total
28th Oct 2014 7:50 pm
DiscoDunc
Member Since: 08 May 2006
Location: Bristol
Posts: 16390
I have a NL battery pack with the modified D4 circuit board.
the charge system works fine and ive not had any problems.
the D4 alternator can reduce its output to 12v, but ive only noticed this happen when both batteries are fully charged.
mine runs for several weeks at a time running an engel freezer and the NL battery pack has always charged up.
hope that helpsDuncan
-----------------------------------------------------
If I'd known I was going to be so thirsty this morning I'd have drunk more beer last night.
FFRR Autobiography 4.4 SDV8 MY17
D4 HSE MY13 SOLD
FFRR 3.6 Vogue TDV8 SOLD
D4 HSE MY10 SOLD
D4 SE TECH MY15 SOLD
D4 XS MY12 SOLD
D4 HSE MY10 SOLD
D3 HSE MY06 - Re-Cycled Worldwide
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