Member Since: 05 Aug 2020
Location: Sutton Coldfield
Posts: 1278
Electrical mod question
Hey all, I’ve currently got a full auxiliary battery setup on the D3 with the aux battery in the “spare” battery compartment under the bonnet linked to the starter via a DcDc split charger. There’s a 100amp cable then feeding a fuse box at the rear for further aux fittings and sockets in the boot.
It’s getting pretty full under the bonnet now, and I want to look at upgrading the dcdc charger to a renogy full solar /battery charger but there’s no space so I’m looking at moving the aux battery to the rear with the minimum of re cabling.
Silly question but if I use the existing 100amp cable to link the dcdc to the aux battery in its new home, can I tee into it at the front to continue feeding the existing front aux fuse box? Or would it require a fresh feed cable? I think the former as there’s no different to me if you think both would attaché to the same terminal anyway?
Diagram of the setups below.
Click image to enlarge
2008 HSE Stornoway Grey
My Wife thinks the D3 is a hobby, The D3 thinks the wife is 💕
1st Jul 2024 9:27 am
Sidestick
Member Since: 22 Apr 2012
Location: Rome
Posts: 2335
First of all i can suggest to fit the dc/dc charger as close as you can to the leisure battery in order to limit the voltage drop at the line from the front to the rear end.
If you want to feed the "front" aux fuse box from the leisure battery you will need a new line or the front aux fuse box will be fed from the starter battery.
I do not know what model of dc/dc charger have you currently installed, but usually they need a feed line for no more than 40 amps, so the idea is to run a second (thinner) feeding cable from main battery to the rear end (to power the dc/dc charger) and leave the 100A cable for the front aux box connected to the leisure batt by a 100A resectable fuse.- Easy-Lift suspension module 4.0
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1st Jul 2024 11:36 am
KevinD3
Member Since: 05 Aug 2020
Location: Sutton Coldfield
Posts: 1278
Cheers sidekick. It’s a basic split charger at the moment hence wanting to upgrade it but no space under the bonnet the 100amp is there as I played it safe and didn’t want to end up running new lines as I added equipment, current max amperage use at the back at the moment is around 60amp all on (fridge lights etc) front fuse box mainly powers spots, Amber beacons, front six cabin sockets and roof power (all LED so low amps). Not realistic to tie off the existing 100amp then? Seemed that if it has capacity and it’s always live from the aux then there wouldn’t be an issue. If I run another cable I’ll probably run another 100amp on the “bigger is better” basis.
Although just compared the cost of 100amp v 50amp cable. 50amp may be ok 👀2008 HSE Stornoway Grey
My Wife thinks the D3 is a hobby, The D3 thinks the wife is 💕
1st Jul 2024 11:44 am
Sidestick
Member Since: 22 Apr 2012
Location: Rome
Posts: 2335
This changes everything...
you talk about a dc/dc charger, something a bit different to a split charger
In this case your scheme is good enough and more simple.
The only thing you could experience is that the leisure battery won't reach the 100% state of charge due to voltage drop, especially if it's about an AGM or GEL battery, so you will loose a bit of total battery range.
Anyway i suggest you a resectable breaker close to leisure battery in order to stay on the safe side - Easy-Lift suspension module 4.0
- GoodWinch 9500 lb
- Full underbody protections
- Tree/Rock sidebars
- Prospeed roofrack & ladder
- Compressor guard
- Raised Air Intake
- Driving lights (2+4)
- 50 mm Waffle boards
- Altox Heater control
- Overland Rooftop Tent
- Rear seats entertainment
- Front & Rear camera
- GVIF
- Removable tow bar
- Cubby box fridge
- BFG KO2 265/65R17
- iidTool BT
1st Jul 2024 1:12 pm
KevinD3
Member Since: 05 Aug 2020
Location: Sutton Coldfield
Posts: 1278
Brill, and yes, there’s already a reselectable breaker just before the aux battery, so it will move to the rear with the battery and there’s also one at the main battery end also which will stay in line.
Thanks Sidestick2008 HSE Stornoway Grey
My Wife thinks the D3 is a hobby, The D3 thinks the wife is 💕
1st Jul 2024 1:20 pm
Bird_2112
Member Since: 27 Aug 2020
Location: SWANSEA
Posts: 71
A few years ago I bought a 18amp Victron DC-DC charger and cable kit which I think is 16mm 110amp cable to put the battery in the back of a D2 using a 110ah AGM and it worked great. Vehicle written off so used the kit in the D3. Charger in the rear wheel arch space and decided on a battery box for the 100ah LifePo4. Check websites for wiring kits to confirm what cable sizes are and check what you have used. From my limited knowledge thicker is better! Only thing is have you run both cables to the rear or used an earth at the rear as you will need both ?
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the 100amp is there as I played it safe and didn’t want to end up running new lines as I added equipment, current max amperage use at the back at the moment is around 60amp all on (fridge lights etc) front fuse box mainly powers spots, Amber beacons, front six cabin sockets and roof power (all LED so low amps). Not realistic to tie off the existing 100amp then? Seemed that if it has capacity and it’s always live from the aux then there wouldn’t be an issue. If I run another cable I’ll probably run another 100amp on the “bigger is better” basis.
and yes, there’s already a reselectable breaker just before the aux battery, so it will move to the rear with the battery and there’s also one at the main battery end also which will stay in line.
