Member Since: 27 Dec 2009
Location: Liverpool
Posts: 6551
What split charge?
Going to fit a split charge system in my 15 plate D4. Was going to go with a simple VSR but have been told these could throw up some faults due to the D4 having a smart alternator. I’ve already got the VSR kit so any information of what to use not to use would be great. Also any recommendations. I’ve been looking at the C Tek ones but they are mega money.
Cheers AndyD4 MY15 SE TECH
D3 gone but never forgotten.
1st Sep 2019 5:37 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13629
Hi buddy
Would a T max be suitable , Have one in mine but don’t know how ur setup differs
Plus if u haven’t seen it, this web site has some good info
Member Since: 21 Oct 2016
Location: kent
Posts: 13629
Just seen this , ref, important section
Battery-To-Battery (DC-DC) Chargers
Battery-To-Battery chargers (also commonly know as DC-DC chargers) allow you to charge an auxiliary / leisure battery from your alternator whilst driving.
They are installed in-line between the positive terminals of two batteries (one of which is connected to an alternator, typically a starter battery) and offer several benefits when compared with traditional split charge systems that utilise a Voltage Sensitive Relay (VSR) or heavy duty, alternator-triggered relay.
Direct alternator charging used in a traditional split charge system with a VSR will only achieve around an 80% charge state. VSRs simply allow charge to pass directly from the alternator to the auxiliary battery whereas Battery-To-Battery chargers take the alternator output and boost or reduce it to provide a stable voltage output according to a multi-stage charging profile.
This provides a 100% re-charge for your leisure battery in a controlled way and typically achieves it faster than with direct alternator charging.
Current flow is limited by the charger's current rating, eliminating potentially damaging high in-rush currents and often allowing the use of smaller connecting cable than with VSR-based split charge systems.
Using a battery-to-battery charger is the only reliable solution if you intend to re-charge a second battery in a modern vehicle that has an ECU-controlled 'smart' alternator (generally Euro 5/6 compliant engines onward). These have a highly variable voltage output that is often too low to provide a charge or (in the case of regenerative braking systems) so high that it can damage some battery types.
*********Due to this highly variable voltage VSRs are not suitable for use with 'smart' alternators.*****
Battery-to-battery chargers are simple to install and will engage/disengage automatically on engine start/stop, ensuring the batteries are isolated and cannot discharge one another.
1st Sep 2019 6:47 pm
Andy Foster
Member Since: 27 Dec 2009
Location: Liverpool
Posts: 6551
Cheers pale
Looks like I’ll be getting a dc-dc charger then
Now to find one that’s not stupid money.D4 MY15 SE TECH
D3 gone but never forgotten.
1st Sep 2019 7:56 pm
gstuart
Member Since: 21 Oct 2016
Location: kent
Posts: 13629
Ur very welcome and glad it was some use
Hopefully others can advice u what to use
Last edited by gstuart on 1st Sep 2019 9:16 pm. Edited 1 time in total
1st Sep 2019 9:16 pm
stiff
Member Since: 17 Jul 2017
Location: Either cashpoint or garage...
Posts: 293
DC to DC charger. For the moment I wouldn’t go for the National Luna one. They have recently recalled their system.
But also take a look at Traxide - Tim does a kit for the D4. Different approach than the traditional solenoid/charge system in that it balances available power between cranking and aux battery. Comes with pre-cut cables and easy to install. I am using a Traxide DT-90 kit in a D4 which manages two Optima YT’s and the main battery.MY2008 D3 - It got me hooked...gone
MY2012 D4 - It kept me hooked...gone
MY2007 D3 - Mid-Life crisis toy continues driving me to bankruptcy...
MY2018 "D5" Si6 - But is it a "true" LR...discuss...but now gone
Back in a D4 with a lot of extras....
1st Sep 2019 9:16 pm
John P
Member Since: 12 Aug 2011
Location: West Sussex
Posts: 1275
"Stiff" Have you got any information regarding the National Luna recall, as I cannot see anything on their website?
1st Sep 2019 9:27 pm
Kelvo
Member Since: 07 Aug 2015
Location: Perth WA
Posts: 264
Andy Foster wrote:
Cheers pale
Looks like I’ll be getting a dc-dc charger then
Now to find one that’s not stupid money.
You do not need (or want) a DC-DC charger with a D4 or D3 if using a ‘normal’ lead-acid, calcium or AGM second battery. The only time you need a DC-DC charger is if you use a lithium battery as your second battery.
The VSR setup will be fine. I use a Traxide USI-160 smart VSR but generally run it in the 12.7V cutout voltage as opposed to the 12.0V setting without any issues. My D4 charges my 60Ah second battery and 130Ah battery in my camper trailer with no error codes.
IMHO DC-DC chargers are a solution to a problem that doesn’t exist.MY14 TDV6
1st Sep 2019 11:43 pm
stiff
Member Since: 17 Jul 2017
Location: Either cashpoint or garage...
Posts: 293
John P wrote:
"Stiff" Have you got any information regarding the National Luna recall, as I cannot see anything on their website?
I don’t have info I can point you to on the internet. My info source is the Benelux supplier. I wanted to purchase the NL system but the local dealer couldn’t get stock or delivery info for a couple of weeks. I was with him when he called the distributor again and got the message they had sent back stock and no news in resupply.
Maybe “recall” was not quite the right wording as it’s not a user recall
But either way the units were back in South Africa in July MY2008 D3 - It got me hooked...gone
MY2012 D4 - It kept me hooked...gone
MY2007 D3 - Mid-Life crisis toy continues driving me to bankruptcy...
MY2018 "D5" Si6 - But is it a "true" LR...discuss...but now gone
Back in a D4 with a lot of extras....
2nd Sep 2019 6:44 am
Davethegeo
Member Since: 01 Oct 2015
Location: Edinburgh
Posts: 879
Kelvo wrote:
You do not need (or want) a DC-DC charger with a D4 or D3 if using a ‘normal’ lead-acid, calcium or AGM second battery.
..............
The VSR setup will be fine.
IMHO DC-DC chargers are a solution to a problem that doesn’t exist.
Well I'm glad to hear you say that. I must say that was my understanding of the situation.
I'm keen to fit a split charge system when I can work out what I would use it for!D1 300Tdi - gone
D2 Td5 ES (Alive remapped...mmm) - sadly gone
D4 2012 SDV6 XS - Stolen
D4 2014 SDV6 HSE - Shiny
2nd Sep 2019 8:40 am
Andy Foster
Member Since: 27 Dec 2009
Location: Liverpool
Posts: 6551
Seeing as I’ve got the VSR kit I think I’ll fit it and take it from there. Could always swap when funds allow
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