Ok I will bare it in mind, thanks for the advice
No continuity between main battery +ve and OEM split charge relay. Could it be this cable?
- Thread starter matt_ew
- Start date
Just looking at DC to DC chargers I guess you’d take the feed from the alternator to the split charger relay that’s there now and repurpose it?
Yep just put it in place of the relay, that gives you a high current feed from the starter battery and a charge signal.
Hi mate, back home and looking into this now. All Rac stuff removed and that battery still charges from the alternator so happy days.
Do you know where the ignition signal is or which cable im looking for?
Cheers
Do you know where the ignition signal is or which cable im looking for?
Cheers
Did you have the '100' split charge relay under the passenger seat?
There's 4x connections on this, 1. From starter battery 2. To aux battery 3. Ground 4. Engine signal.
I believe the engine signal wire is brown but I might be wrong. It'll be one of the 2 small wires. One will go to the chassis ground under the passenger seat.
Yeah I have that relay, should be easy to spot then, I know first 3 are there.
Thanks mate, will go test now.
Thanks mate, will go test now.
You have VIP Membership so the wiring diagram is here:
Ahh yes, thanks - so the engine signal wire to the relay is black, chassis ground is brown.
On my previous van, a T5.1, it had the factory second battery & split charge relay. I left the relay in place & used the output from the relay to feed the B2B, basically putting the B2B in series with the relay & the second battery. Worked a treat & when I sold the van, it was a simple job to put it "back to factory".
Just an option to consider.
What are you using the run signal from the alternator for? I had a little look at a couple of DC-DC chargers and not sure where you would put it?
Some don't need it or have an option to use it, some need it and others can either use the signal wire or use voltage detection.
All depends on the DC-DC as to whether it's required/optional/not required.
BillyBobHyx
New Member
Hey guys, a little late to the party trying to work out the same thing.
Is the Split charge relay the 100 in my attached photo? This is one of two sets of OEM cables and fuses under the seat with the aux battery. Have included photos of both for reference.
Is the Split charge relay the 100 in my attached photo? This is one of two sets of OEM cables and fuses under the seat with the aux battery. Have included photos of both for reference.
SouthieDave
New Member
Hello, ex rac van owner as well. Enjoying the info on the forum but it's definitely confirmed that i'm out of my depth with van electrics, I think I'll leave it to a professional, but can someone explain the difference, or reason, between the current split charger and installing a dc-dc charger? Thanks
I’ll take a stab.
OEM split charge relay just connects the two batteries together when the engine is running, so leisure battery charge tracs main battery charge. There’s two issues with this:
- T6 has ”smart” charging which tries to keep starter battery only 80% full. This is done to leave some room for brake energy harvesting. Hence leisure battery won’t ever be full either.
- If the leisure battery is actually used when the van is not running, the batteries may have significantly different charge. This results in large currents flowing in between batteries when the van is started as the batteries try to even each other out. This may not be a huge problem in itself but may result in starter battery being in unexpectedly low charge if the drive is not long enough to recharge both batteries back to near 80% limit.
EDIT: Also, with split charge relay, starter and leisure batteries have to be as identical as possible in terms of capacity, chemistry and age. With DC-DC this is not mandatory at all - eg many people swap the leisure battery for a lithium one to have greater capacity/weight ratio.
Last edited:
Fully agree with @n10n here.
The split charge relay isn't a charger at all, it just connects the 2 batteries in a bank so suddenly the alternator is charging them both.
Battery banks need to be carefully managed otherwise the weakest battery will drag the health of all the others down.
Randomly connecting the bank every time the engine starts and then heavily draining one half of it when the engine is off is a very long way from "carefully managed"
The only advantages of split charge is it's cheap (for the manufacturer) and simple. It's not very effective at all, will give you the worst possible charge for the leisure side and prematurely age both batteries (resulting in more cost for the owner)
It was fine 20 years ago when your leisure needs were a few lights and the fridge ran off the gas, it's totally unsuitable for modern power expectations and charging systems.
The split charge relay isn't a charger at all, it just connects the 2 batteries in a bank so suddenly the alternator is charging them both.
Battery banks need to be carefully managed otherwise the weakest battery will drag the health of all the others down.
Randomly connecting the bank every time the engine starts and then heavily draining one half of it when the engine is off is a very long way from "carefully managed"
The only advantages of split charge is it's cheap (for the manufacturer) and simple. It's not very effective at all, will give you the worst possible charge for the leisure side and prematurely age both batteries (resulting in more cost for the owner)
It was fine 20 years ago when your leisure needs were a few lights and the fridge ran off the gas, it's totally unsuitable for modern power expectations and charging systems.
SouthieDave
New Member
Brilliant, thank you, makes sense to me, which is a good sign.
Hi. I’ve been reading loads and loads of these threads at the moment (often till the early hours ) getting my head around the SCR and retro fitting a DC to DC instead ( I have ‘22 plate T6.1 with OEM LB fitted under passenger seat). I’m planning in next few weeks to swap out my SCR too.
Info is great . However quick question and clarification of my understanding. (I have read. LOADS of post and searched to death but probably missed it). Or tied myself in knots.
1. If occasionally a solar is fitted direct into the DC to DC (say parked up on drive for period) as I understand this will trickle charge both SB AND the LB? ( I’m thinking of adding a panel to roof bars just to top up/use when van is idle and plug in on a couple of Anderson or similar connectors). Just like this great post from r00ps ( thanks… just what I need to do mine).
www.t6forum.com
2. With the DC to DC module fitted in place of SCR with OEM wiring, will ‘priority’ be given to charging SB or LB with engine running (or does alternator just feed both in parallel).
3. From what I’ve read DC to DC will allow LB to charge to 100% instead of capped 80%, so will ditching SCR for DC then also allow SB to charge to 100% (either by solar or driving) or is this 80% ceiling for SB governed by A/N other bit of kit?
Honestly my sincere apologies if this has been asked (somewhere) I have searched and read and read but it might be a case of ‘can’t see wood for trees’. Also apologies if I’ve misunderstood.
Thanks in advance.
Rob
Info is great . However quick question and clarification of my understanding. (I have read. LOADS of post and searched to death but probably missed it). Or tied myself in knots.
1. If occasionally a solar is fitted direct into the DC to DC (say parked up on drive for period) as I understand this will trickle charge both SB AND the LB? ( I’m thinking of adding a panel to roof bars just to top up/use when van is idle and plug in on a couple of Anderson or similar connectors). Just like this great post from r00ps ( thanks… just what I need to do mine).
T6.1 factory aux battery split charge relay upgrade & solar panel install.
Hi, I had the factory fitted aux battery ( under a single seat with swivel base ) fitted to my T6.1 with the intention of using it as a camper leisure battery. After getting less than impressive performance and reading about how the split charge relay is a pretty bad charging method I wanted to...
2. With the DC to DC module fitted in place of SCR with OEM wiring, will ‘priority’ be given to charging SB or LB with engine running (or does alternator just feed both in parallel).
3. From what I’ve read DC to DC will allow LB to charge to 100% instead of capped 80%, so will ditching SCR for DC then also allow SB to charge to 100% (either by solar or driving) or is this 80% ceiling for SB governed by A/N other bit of kit?
Honestly my sincere apologies if this has been asked (somewhere) I have searched and read and read but it might be a case of ‘can’t see wood for trees’. Also apologies if I’ve misunderstood.
Thanks in advance.
Rob
1. Personally, I would connect my solar to the LB side of the DC-DC & fit something like an Ablemail AMt-12 to keep the SB topped up. Plenty of folk use this method & it works well. Fitting the solar to the SB side might fool the DC-DC into thinking that the engine is running (Depending on how you've configured the DC-DC), this could result in the DC-DC draining the SB.Hi. I’ve been reading loads and loads of these threads at the moment (often till the early hours ) getting my head around the SCR and retro fitting a DC to DC instead ( I have ‘22 plate T6.1 with OEM LB fitted under passenger seat). I’m planning in next few weeks to swap out my SCR too.
Info is great . However quick question and clarification of my understanding. (I have read. LOADS of post and searched to death but probably missed it). Or tied myself in knots.
1. If occasionally a solar is fitted direct into the DC to DC (say parked up on drive for period) as I understand this will trickle charge both SB AND the LB? ( I’m thinking of adding a panel to roof bars just to top up/use when van is idle and plug in on a couple of Anderson or similar connectors). Just like this great post from r00ps ( thanks… just what I need to do mine).
T6.1 factory aux battery split charge relay upgrade & solar panel install.
Hi, I had the factory fitted aux battery ( under a single seat with swivel base ) fitted to my T6.1 with the intention of using it as a camper leisure battery. After getting less than impressive performance and reading about how the split charge relay is a pretty bad charging method I wanted to...
2. With the DC to DC module fitted in place of SCR with OEM wiring, will ‘priority’ be given to charging SB or LB with engine running (or does alternator just feed both in parallel).
3. From what I’ve read DC to DC will allow LB to charge to 100% instead of capped 80%, so will ditching SCR for DC then also allow SB to charge to 100% (either by solar or driving) or is this 80% ceiling for SB governed by A/N other bit of kit?
Honestly my sincere apologies if this has been asked (somewhere) I have searched and read and read but it might be a case of ‘can’t see wood for trees’. Also apologies if I’ve misunderstood.
Thanks in advance.
Rob
2. The batteries are charged in // (parallel) so they will sort themselves out, this is the beauty of a DC-DC charger over a SCR.
3. The SB will still only charge to around 80% for the reasons given in (2) above. Also another reason to connect the solar to the LB, The LB will be fully charged whilst the SB will be maintained by the AMT. Otherwise by connecting the solar to the SB side, the SB could feasibly be charged to 100%, which isn't a bad thing per-se, but might cause strange behaviour down the line.
Hi Salty.
That’s great advice, very much appreciated and good to know I’m not too far off the mark with my thinking. I don’t have a large power draw from the LB ( CRx50 compressor fridge and LED down lighters in the back only. (I’m using van as day van, with very occasionally off grid stop over come site work van). I’ve got no EHU or inverter as I use a Fossibot 2400 Power Bank for USB device charging and 230v for the coffee machine, charging drill batteries etc.
Just want to improve on the VW standard set up and have the ability to charge LB from solar in my back pocket should I need it.
Understand totally you saying not to connect on SB side as it could cause the Vehicle OEM regen/voltage sensing/charging system to throw a wobbly.
I’ve just been reading about the Ablemail you mentioned as not heard of it before but can see why you would use it, so I’ll deffo get one.
So I suppose final question ( given my usage above) is CTEK D250 DSE or REDARC BCDC CORE 25 A?
Cheers.
That’s great advice, very much appreciated and good to know I’m not too far off the mark with my thinking. I don’t have a large power draw from the LB ( CRx50 compressor fridge and LED down lighters in the back only. (I’m using van as day van, with very occasionally off grid stop over come site work van). I’ve got no EHU or inverter as I use a Fossibot 2400 Power Bank for USB device charging and 230v for the coffee machine, charging drill batteries etc.
Just want to improve on the VW standard set up and have the ability to charge LB from solar in my back pocket should I need it.
Understand totally you saying not to connect on SB side as it could cause the Vehicle OEM regen/voltage sensing/charging system to throw a wobbly.
I’ve just been reading about the Ablemail you mentioned as not heard of it before but can see why you would use it, so I’ll deffo get one.
So I suppose final question ( given my usage above) is CTEK D250 DSE or REDARC BCDC CORE 25 A?
Cheers.
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