[Guide] DC-DC Charger (for leisure battery) -- How I Done It --

[Bigsidavies]

Does anyone have knowledge of the relay adaptor that @travelvolts used to supply which was used to allow a dc-dc charger to be connected to the factory second battery wiring?
@Dellmassive?
My issue is this:-
My ctek 250se is not charging my Renogy LiFePo battery.
All the lights on the ctek behave as though it’s working perfectly. I start the engine I get the green and the two bottom yellows to show it’s charging from the alternator. I also get the top orange to show it’s charging from solar. Without the engine in I get the green light and the two diagonal orange to show its charging from solar.
No flashing fault lights etc.
However-it is not charging the LB.
All fuses are good. All wiring looks ok.
I’m in Spain touring around.
Is it possible to just remove the wire from the battery output of the ctek that at the moment goes into the travel bolts relay and replace it with a normal fuses 75a lead direct to the battery this elimination that as a possible problem.
Also, if the internal fuse in the ctek had failed would the ctek still be showing all the correct lights or would it flash an error does anyone know?

 

[Dellmassive]

Does anyone have knowledge of the relay adaptor that @travelvolts used to supply which was used to allow a dc-dc charger to be connected to the factory second battery wiring?
@Dellmassive?
My issue is this:-
My ctek 250se is not charging my Renogy LiFePo battery.
All the lights on the ctek behave as though it’s working perfectly. I start the engine I get the green and the two bottom yellows to show it’s charging from the alternator. I also get the top orange to show it’s charging from solar. Without the engine in I get the green light and the two diagonal orange to show its charging from solar.
No flashing fault lights etc.
However-it is not charging the LB.
All fuses are good. All wiring looks ok.
I’m in Spain touring around.
Is it possible to just remove the wire from the battery output of the ctek that at the moment goes into the travel bolts relay and replace it with a normal fuses 75a lead direct to the battery this elimination that as a possible problem.
Also, if the internal fuse in the ctek had failed would the ctek still be showing all the correct lights or would it flash an error does anyone know?

post some voltage pics. . . assuming you got a multimeter now?

the Travel volts relay wire is just a plug and play way of getting to the starter and LB POS connections (plus the Engine run signal)

you can omit the relay by cutting and joining the wires. ( thats what i done )

those ctek d250s are known for going bad.

so its time to start testing voltages to see whats going on.


.

assuming you have this setup?




+++++++++++

using the multimeter you should have 3 voltage readings . . .

YELLOW - the starter battery voltage (10-15v)

GREEN - the LB voltage (10-15v)

BLUE - the solar panel voltage (10-25v)





post some screen shots of the renogy APP when the engine is running with the main headlights ON. (or HEATED SEATS ON)

 

[Bigsidavies]

I don’t have a multimeter with me. I’ll try to buy one as I go along and then test those 3.
My Renogy app with everything on and the ctek showing all lights charging just shows 0v incoming.

 

[TallPaul_S]

I don’t have a multimeter with me. I’ll try to buy one as I go along and then test those 3.
My Renogy app with everything on and the ctek showing all lights charging just shows 0v incoming.

Might be a stupid suggestion, but the LB isn't fully charged, is it?

Actually, what is the SOC? So we know what you should be expecting to see.

Also, might be worth checking you haven't accidentally pressed something in the ctek app to disable charging or similar.

 

[Bigsidavies]

Might be a stupid suggestion, but the LB isn't fully charged, is it?

Actually, what is the SOC? So we know what you should be expecting to see.

Also, might be worth checking you haven't accidentally pressed something in the ctek app to disable charging or similar.

LB at time of faffing was 39%. Been used for 3 days since last EHU. Purposely didn’t get EHU in the site so it would be needing a charge.

Ctek doesn’t have an app. Is a dumb unit so to speak.

Soc of Lb will be 100% now as I’ve put it EHU coz we move on tomorrow towards an aire near Cartagena.

My plan was just to buy a Victron mppt 75/15 wire it in and live off the solar. But finding a place that sells those is driving me daft. Except for a place in the harbour at Denia that was asking €200 for a £52 unit. Them boat owners are obviously wadded lol.

 

[Bigsidavies]

@Dellmassive pack your voltmeter I’ll see you in Portugal lol.

 

[n10n]

My plan was just to buy a Victron mppt 75/15 wire it in and live off the solar. But finding a place that sells those is driving me daft.

Sorry to hear about the issues. Tech always fails at the wrong time doesn’t it?

How about amazon.es? I’ve used it with Chrome translation just fine. There also seems to be Amazon lockers in Cartagena so should be able to get what you need in some days, don’t know how fast their domestic deliveries are.

 

[Bigsidavies]

Sorry to hear about the issues. Tech always fails at the wrong time doesn’t it?

How about amazon.es? I’ve used it with Chrome translation just fine. There also seems to be Amazon lockers in Cartagena so should be able to get what you need in some days, don’t know how fast their domestic deliveries are.

View attachment 232012

Oooo never thought of that. I’ve never done Amazon but her indoors has an account. I’ll look into it tomorrow when the San Miguel wears off.
Thanks.

 

[stoic]

Ahh, I'm assuming LHD? So drivers seat for you is our (UK) passenger seat. Which is the standard location for a non California.

As above, the biggest battery you can get that will fit under the seat, is one of the 'seatbase' batteries, like the fogstar drift 230Ah:

SEAT BASE 12v 230Ah Lithium Leisure Battery

Our Drift 12v 230Ah SEAT BASE Lithium Leisure battery is 275 x 315 x 187.5, making it one of the most compact on the UK market. Priced at just £799.99 (include free shipping).

www.fogstar-drift.co.uk

With a 41v VOC on the solar panel you could use either of the Renogy units, or go for separate Victron units. All depends on cost, complexity, space etc.

What inverter do you have? Also what's the current AGM leisure battery, the 75ah std one?

Powering the factory heater from a portable system would be more complex than I'd like to consider, so best to avoid this, as you suggest. Running a separate portable alongside the factory set up might work, but I'm not sure on the limitations - if you've only got the diesel heater running off the factory LB then it could work, for sure. You'd then charge the portable system off the alternator and/or solar. The only issue might be if you're off grid for several days and using the heater a lot, with no way of topping up the factory LB (although a quick run of the engine for 20 minutes would charge it).

I more or less have the same setup on my T6, and planning to install the renogy 100 ah lithium and the DC to DC I purchased. One question: I think there are 2 batteries set up via Carista? Should I change the second one, seems to be EFB+ 70 ah on a panel van, and what should I add, or does the ECU/BCM even need to understand what the second battery is, in this case? Also, will the lithium battery discharge into the car electrics ever(how is the connection to OEM diesel heater achieved, if everything goes through DC to DC which acts as a battery isolator - or is there a fuse box connected to LB only from "after" the DC to DC)? Since there is no travelvolts relay, I will have to cut the wires and add midi type fuses, and connect D+ directly to renogy DC to DC.
Other idea, is to add some sort of bypass so I could connect the lithium LB to starter battery via a switch, only if needed to start the van one day - if starter battery is flat? Cheers to all of you outhere.

 

[roadtripper]

Lithium and Lead Acid have very different voltage profiles, never connect them directly.

If you want that kind of capability then look at the DC-DC chargers that offer a self jump start like the Sterling range.

It's probably easier to just carry a NoCo jump starter with you though.

 

[roadtripper]

Do you have a general T6 or a California?

If you have a general T6 and a factory second battery you should find that there is a small fuse/distribution box on the battery terminal, also some of the wiring moves across under that seat (generally 12v sockets but also one of the factory fit power lines to the towing socket)

If you have a California then you may also have a negative shunt on the battery like the main battery so the camping electronics can monitor the battery and do things like boost charge it when you aim to camp (overriding the stop start 80% limit) - as far as I know that's unique to the factory California's

 

[stoic]

Good info about battery profiles, thanks! I have a small, cheap battery starter I used to charge my phone with it, I guess that will suffice.
I have T6 "startline" plus airco, and oem engine heater (front webasto which heats also the water in the "normal" climatic system). I'll probably find out more when I take the driver seat out (LHD).

Carista shows I have a "towing module" installed, whatever that means. I have no towbar installed and no such electrics go to the back of the van afaik.

 

[stoic]

"The existing feed for the OEM relay was used as the ignition trigger for the new DC-DC."

The assumption is then this wire will not have any fancy logic behind it, ie, will just give a plus 12 when there are any kind of engine revs detected.

My concern was that at the last regular maintenance, I got a nice print with both batteries health information, starter battery almost gone, leisure/second battery half way through. Not sure if that was extracted from the ECU/BCM or they just hooked up some service tool to measure how well those 2 batteries hold a charge.

 

[roadtripper]

The assumption is then this wire will not have any fancy logic behind it, ie, will just give a plus 12 when there are any kind of engine revs detected.

It's not exactly engine revs - it's when the BCM thinks it's appropriate for a second battery to be charged so may be off for good reason even if engine revs are there. But what logic applies to a split charge relay should be valid for a DC-DC.

 

[roadtripper]

My concern was that at the last regular maintenance, I got a nice print with both batteries health information, starter battery almost gone, leisure/second battery half way through. Not sure if that was extracted from the ECU/BCM or they just hooked up some service tool to measure how well those 2 batteries hold a charge.

Likely just an independent test of voltage and how it reacted under a test load.