Wiring idea for charging house batteries

Kiltym

Active member
I have drawn up the original westy wiring, and two options I see as viable, however one is starting to appear as the better option.

One general issue, Air Co and converter charging should not happen simultaneously. Not sure an easy way to idiot-proof this, so might just need to be something one has to pay attention to and make sure both don't run at the same time to avoid overloading the converter.


Option 1: Switch near converter and re-use existing starter cables from relay.

Issues:
- Onemanvan reports significant voltage drop.
- Have to add a relay to prevent Air Co from running via Start Battery when alternator is not running. (see: https://groups.yahoo.com/neo/groups/sprinter_westfalia/conversations/messages/9958)
- Switch is in back of van, so a bit inconvenient.


Option 2: Run new wire from converter to house batteries.

Issues:
- Have to run a cable. Unsure how to best get cable from converter to house battery? Under van? Or through internal spaces?


One general question/issue also. When AC power is applied (either by generator or shore power), both the Westy AC-DC charger and the converter DC-DC charger could be applying power to the batteries at the same time. I don't think this is a problem, but maybe someone knows something I am missing.

So, based on the above, and the drawings, it seems the new cable is the better way to go. Eliminates some of the issues of running the AirCo when it should not be because of the dc-dc charger. And provides a switch (probably near existing switch) to change between alternator or converter for charging source. Because of the dc-dc charger, no "bad states" could occur (except simultaneous running of AirCo and charger). I do not think any additional diodes or other items would need to be installed.

Any additional feedback and comments is very welcome.
 

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Kiltym

Active member
Also, another dc-dc charger that is looking appealing to me: http://www.enerdrive.com.au/product/epower-dc-to-dc-battery-charger-40a-plus/

Good things is it is fully programmable, so will work with any batteries. Most of the chargers "lock" you into one of their pre-programmed settings, which often don't actually match the batteries. Having full control over it is a big plus.

Does battery isolation, and high voltage MPPT solar controller.

With this unit can also control charging amps, so depending on size/type of battery bank it can be adjusted also.
 

OldWest

2004 T1N Westfalia
1. No AC and Charging at Same Time

I thought OneManVan replaced Kissling Relay so Meanwell converters could power air conditioner or batteries, not both?

If one does not turn on air conditioner, then no problem? So install some type of failsafe like extra cover over air conditioner on/off button? And another one over the circuit breaker, as a reminder?

2. Remote Switch

On OneManVan's lithium battery setup, he described a remote lightweight switch which then caused a heavy duty switch to activate (or something like that).

Is there something similar for your proposed setup? An electronic signal switch and the heavy duty switch in the rear?

3. Cable Runs

A..Neatest

Run cable from converter area, then underneath bathroom floor behind the metal cover panel (lots of other wires.there), then along side graywater tank/driver side body, then near battery charger to batteries.

Note: You'll see the wires in the closet run down through the floor, then behind the metal panel under the bathroom floor to get to driver side. The 120v wires run from circuit breakers, behind metal cover under bathroom floor, then to converters.

So the main wire/cable raceway is behind the metal cover. When you look under the bathroom floor (rear doors open), the metal cover is right above the tunnel (behind black tank).

In this Discus photo, he removed black tank and added the white HepVo drain to shower drain. You can see a bunch of PEX water hoses and wires behind where black tank would be (which to the right of the photo area above the tunnel are concealed.by the metal.cover).

https://sprinter-source.com/forum/showpost.php?p=286268&postcount=17

B. Quick and Dirty

There is a hole in the battery compartment which runs through the fresh water tank. Run cables under vehicle and up through hole.

C..Generator Cables

Run under van and then follow generator.cables to batteries???

4. Multiple Concurrent Charging Sources

If one of the charging sources is smart and reads voltage put out by another source, may interpret as fully charged and turn off or go to another phase????

If that's the case, need way to turn off whatever extra source. For.Westy battery charger, disconnect cord or turn circuit breaker off (some outlets, like microwave, also are on same circuit).

While.driving, sun hitting solar pushes voltage to 14.4. When driving away from sun, voltage drops to 13.9-14.0 (presumably alternator only). Reading voltages off central computer console.and voltages will vary by temperature.

Maybe highest voltage charging source wins out, even if lowest amperage???

5. Safety

Need big fuses, extra strong crimps on cables, etc.

Please take lots of photos.when you start taking things apart. Thanks.
 
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Kiltym

Active member
"I thought OneManVan replaced Kissling Relay so Meanwell converters could power air conditioner or batteries, not both?"

When his switch is connected to the start battery, theoretically the A/C could be (attempted) powered off just the start battery (even when the alternator is not running). His concern (and why he added a relay), was that if he was running the AirCo with the car running (which is fine), and then turns the car off, the AirCo will try to pull from the start battery still, with no alternator, which will create a dead start battery pretty quickly.

The Kisslinger relay prevents this, but a manual switch (alone) does not.

So the manual suggestions are ok to prevent you from turning the A/C on when his switch is on the start battery, but if the A/C is already on, then the issue appears, so the added relay cuts out the A/C when the car stops running, even though there is still power available via the start battery. Basically reproducing the function of the Kiss relay.

"Is there something similar for your proposed setup? An electronic signal switch and the heavy duty switch in the rear?"

With the running of a new cable, a new switch would be added near the existing battery switch to change between start/alternator and converter. No switch is needed or added in the rear.


Thanks for the cable runs tips, all good info!
 

Kiltym

Active member
I don't have the time to fully read all of these posts carefully, so pardon me if it's already in here somewhere, but here's another DC to DC Dual input charging option
Very nice find. It actually appears to be the same exact charger as I had posted a bit above from Australia, but in the U.S, and much cheaper.... The user manuals are virtually identical. Thanks!

The 50Amp version is what I posted, but nice to see a cheaper 30A version available.
 

onemanvan

Active member
I found it difficult to snake wire along the driver side - maybe an easier path would be parallel to the 'tunnel'...

1) to the rear of the wtr htr closet along the wtr lines
2) from the wtr lines through the louvers in the tunnel wall
3) remove kick panel in kitchen to pull wires up
4) along top of wtr tank to where ever...
 

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OldWest

2004 T1N Westfalia
Interesting re your photo of the fresh water tank. I think Westfalia must have changed the design a bit and made a much larger hatch door.

I think that on mine (too much storage junk there currently so didn't verify), the hatchdoor does not cover the screw inserts on the passenger side. Instead, the screw inserts are covered.by the cabinet floor, and there are three holes.directly above to access those inserts, each hole with a plastic cap (one cap now mysteriously floating somewhere in those recesses).

The screw inserts may be for NAFTA Westies for the screwed down black plastic cover with glued on foam gaskets. Each screw-in bolt came with lots of washers so a nightmare not to drop them. In addition, Airstream added the generator which added more thick battery cables so black plastic cover did not lay flat.

I just use a couple of the little bolts as such a pain to insert.

European James Cook versions may not have.those screw inserts.

The kitchen cabinet was probably installed after all the wiring was done, so easier access to run wires and stuff.
 
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OldWest

2004 T1N Westfalia
On the gray screwed in rounded metal kickplate on bottom of kitchen cabinet, it looks like ripples from the screws. It could be the protective film which you can peel off. If not, don't know why there'd be ripples.
 

Kiltym

Active member
Posting an updated wiring diagram for the "run new wire" option.

Another thing I realized (and another advantage of running a new cable), is that there is no need to change the K52 relay under the seat. It can be left as-is.

When car is running, relay is engaged, dc-dc charger sees power, and starts charging. Car is turned off, relay disengaged, and dc-dc charger drops out.

This is getting pretty simply to implement, which is great.

Re: dc-dc chargers, I spoke with Kisae, and they are the same as Enerdrive in Australia. Only issue is in N. America only the 30A charger is available right now until sometime in 2018. I am interested in having at least a 40A charger available for the dc-dc, so I may order from Australia. Will keep this thread posted as I make progress.

And thanks for all the feedback and assistance.
 

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OldWest

2004 T1N Westfalia
Taking me awhile to figure this out so feel free to skip giving any more explanations.

1. Schematic

Don't know what protocol/rules for doing a schematic. Maybe this is just doing a shorthand version. [EDIT: Nevermind. Figured out schematic.]

EDIT--SKIP BELOW; Think I figured it out:

Should there be an 120v wire going to Kissling Relay and then a 12v wire going from Kissling Relay to Converters?

Then, a 12v wire from Converters to air conditioner and then the NEW 12v wire from Converters to House Batteries?

Converters are ALWAYS ON when plugged into shorepower/generator (Confirm?)

If the converters are always on when plugged into shorepower/generator, does the 12v power from the converters go to the Kissling Relay and then to air conditioner (versus 120v power to Kissling Relay and then to converters, and then 12v power from converters to air conditioner)?

(When plugged into shorepower/generator, there is noise which could be the converters' internal fans and/or the extra exhaust fan?)

EDIT: NEVERMIND. I think this is how things work?

The Kissling Relay chooses from 12v power from engine alternator OR 12v power from the Meanwell Converters. There are NO 120v wires to Kissling Relay.

Only 120v wires go to the Meanwell coverters.

When engine is on, a signal or something switches the Kissling Relay to the engjne alternator. Otherwise, default position is getting 12v power from Meanwell converters.

When shorepower/generator plugged in, converters must be ALWAYS on.

All 12v power to the air conditioner goes through the Kissling Relay.

2..Defective Kissling Relay

Questions:

If there is a defective Kissling Relay, no harm?

If Kissling Relay is stuck on engine 12v position, everything is as normal except air conditioner does not work on shorepower or generator, AND converters do or won't work to charge DC-DC charger???

The new Wire is before the Kissling Relay, so even if Kissling Relay is stuck on engine power, can still send power from Meanwell converters to DC-DC charger.

If Kissling relay is stuck on 120v Meanwell converters 12v power, then air conditioner won't work on engine power. But DC-DC charger works in all situations???

3. Engine on AND Shorepower/Generator Plugged In

What happens? No harm, no foul?

Kissling Relay can still choose only one position (presumably engine) and the NEW switch only chooses one source of power for the DC-DC charger.
 
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Kiltym

Active member
"Don't know what protocol/rules for doing a schematic. Maybe this is just doing a shorthand version."

Yes, just a sketch, nothing 100% formal as I am not an electrician :).

One thing to note is I made existing wiring bright red, and new wiring dark red.

"EDIT: NEVERMIND. I think this is how things work?"

Yes, all correct now.

"If there is a defective Kissling Relay, no harm?"

I don't think so. It would likely get stuck in converter mode from what I understand, so all will work fine, except could not run A/C from start/alternator. One thing to remember is to not run the dc-dc charger and A/C at the same time as it would likely overload the converters. Not sure how to failsafe this, or if it is worth the time.

"If Kissling Relay is stuck on engine 12v position, everything is as normal except air conditioner does not work on shorepower or generator, AND converters do or won't work to charge DC-DC charger???"

All that will happen is the A/C wont run on shore power. The charging would still work fine from the converter. The charging with a new wire is 100% independent of the Kiss relay.

"If Kissling relay is stuck on 120v Meanwell converters 12v power, then air conditioner won't work on engine power. But DC-DC charger works in all situations???"

Yes.

"3. Engine on AND Shorepower/Generator Plugged In
What happens? No harm, no foul?
Kissling Relay can still choose only one position (presumably engine) and the NEW switch only chooses one source of power for the DC-DC charger."

Also all correct. All should be fine, but house bank would be charged from both the dc-dc converter and the 10A AC Westy charger. In fact, this is the exact same as it would do now, except the alternator is going direct to the house batteries.

So when plugged in, or with generator, you have a few options:

Leave new switch to alternator, and Westy 10A charger does it's thing.
Put new switch to converter, and dc-dc charger and Westy 10A both charge.
Turn off breaker for Westy 10A, new switch on converter, and only charge from dc-dc charger.

I feel this eliminates the need to install a better AC charger since the dc-dc will work on AC power because of the converter.
 

OldWest

2004 T1N Westfalia
Looking good.

1. If you store Westy for more than a month, might want a small smart.maintenance charger (Ctek, etc.).

While your new smart DC-DC charger can do maintenance float (and don't want Westy charger connected), would still be relying on Meanwell converters and related fans.

The DC wiring for a small maintenance charger would be thin so easy to do, and could plug into any available outlet.

2. As K52 relay does not have.the OneManVan activation switch, still need a way to charge engine battery off shorepower/generator.

The Westy charger does charge engine battery if engine battery voltage drops too low.but only for 3 hours for each plug-in (according to manual).

A Trik-L-Start might be an option.

https://sprinter-source.com/forum/showthread.php?t=55490

3. Cables

There are several places on the Internet for inverters which will make custom cables (presumably with fuses too). Have to measure carefully (never very clear about including or not including the clamps).

Lots of discussion re type of cable (thickness, strands, insulation, code, etc.) and best type.of crimping.

http://www.jackdanmayer.com/Wiring.html

4. Weird Alternator Voltage Readings

Did you ever figure out if weird or normal re voltage readings?

https://sprinter-source.com/forum/showthread.php?t=57949
 
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Kiltym

Active member
"Did you ever figure out if weird or normal re voltage readings?"

I think it had to do with being in 100F heat. It seems to be acting as I would expect now.
 

OldWest

2004 T1N Westfalia
Why couldn't new switch just be on new wire (move new switch on schematic an inch over to right so nothing between K52 and DC-DC charger? Switch (on/off type, not a choose power source switch) would be at end of the new wire only, right before the DC-DC charger.

So whenever engine is on, there is always power to DC-DC charger (never have to worry about forgetting to switch over to engine power).

Problem with Reverse current?

Engine on, Switch OFF: DC-DC charger powered.by engine alternator.. No power coming from Meanwell converters. No power going to Meanwell converters.

Engine on, Switch on, ShorepowerGenerator on: Two sources of power from engine alternator and Meanwell converters. Does this work or do two sources of power into DC-DC charger create a problem?

Engine Off, Switch On, Shorepower/Generator: Power from Meanwell.Converters.

Engine on, Switch on: PROBLEM? Does power from engine alternator go to DC-DC charger AND in reverse direction into Meanwell converters so a PROBLEM?

Is this where the diode comes into play?
 
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Old Crows

Calypso 2014 View Profile
Some alternative ideas for charging. Would even work while driving.... You have do do your own wiring....

RAT turbine generator F-104 Starfighter: https://encrypted-tbn0.gstatic.com/...1Du71f79IeVIuxBIKZ8QRdjDN0RJgZpTw4ga262c5ec4V

Wind generator J-3 Cub: https://www.pipercubforum.com/genfront.jpg

DeHavilland DH-4 (Old School) http://www.airminded.net/dh4/dh4_usafm_gen.jpg

DeHavilland/AIRCO DH-9* https://collections.museumvictoria.com.au/content/media/41/27141-small.jpg
*this is a LUCAS product - comes with a unopened package of instant sparks and large bottle of smoke.... use with extreme care...
 
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onemanvan

Active member
One thing leads to another... Yesterday I orderd one of these:

https://www.invertersupply.com/index.php?main_page=product_info&products_id=4472

And it's all your fault Kiltym - if I hadn't been following this thread I would have never done such a rash thing:)

Kidding aside - hopefully there is a method to my madness...

The reason I'm going to try and tie one of these into my system is somewhat off topic. So I'll be brief - the icharger 3010 I purchased for charging my lithium batteries worked OK during my summer travels but I found it requires more 'babysitting' than I would like. It's essentially a DC to DC converter - or B2B charger - with numerous bells and whistles - such a cell balancing - that can be useful for lithium batteries. The DMT1230 seems to be capable of performing the same basic functions for charging lithium batteries - minus the cell level capabilities - and hopefully without so much babysitting required!

So now I'm scratching my head - just as Kiltym probably is - trying to figure out how best to tie it into my system. Bearing in mind Iv'e already made numerous changes over the years. IE: swapped out Kissling relay with a battery switch, added an on-off-on switch to the coil of K52, added an inverter, added solar panels and charge controller, added a lithium battery system, etc...

I just read the back and forth discussion between Oldwest and Kiltym about the Kissling relay.

The Kissling relay is prone to failure - that's a whole other discussion... Anyway - I replaced it many years ago with a battery switch. Functionally it does the same thing as the Kissling relay. But it also has an A + B position - which allowed me to send current from the Mean Well converter to the Starter battery. I figured if I added one more switch to the coil of K52 I could manually latch the relay and thereby send current further down the line to the house batteries. I chose an on-off-on switch that allows one to energize the relay via the field coil of the alternator ( normal OEM operation ) or apply 12 volts manually to latch the relay. In the off position the starter battery and house battery are isolated. Iv'e found this off position to be useful when driving - IE: in the morning when I set out I flip the switch to normal and let the alternator perform a bulk charge. Once the central electronic console reads 14.1 - if I have good solar gain - I flip the switch to off. Then the solar charge controller raises the charge voltage to 14.4 and completes the absorption phase. After that it goes to float. When I want to run the microwave off the inverter - for example to bake a potato which takes some minutes - I flip the switch to normal position and start the engine. In this way I can avoid taking a big bite out of the house battery budget. When I want to charge the house battery - lead or lithium - via the Mean Well converter I flip the switch to manual. If the starter battery is dead I flip the switch to manual and charge the starter battery up from the house battery.

That's a lot of background discussion - but it's a prerequisite to an explanation of how I'm thinking of integrating the B2B charger into my existing system. And in so doing it might give Kiltym some food for thought.

I've attached a simple electrical diagram of the Kissling relay. The output of the relay goes to the roof A/C. I'm thinking - for my purposes anyway - it might be best to run a 6 awg wire from that point to the B2B charger alternator input. I'll probably put the B2B charger in the cubby hole under the drainboard in the kitchen. If I want the B2B charger to get it's power from the alternator I flip my battery switch to alternator. If I want the B2B charger to get it's power from the converter I flip my battery switch to converter. In both cases I flip the K52 switch to the off position. By doing it this way I don't have to reroute the existing alternator charge line that goes to the house battery. For me this is important as I want to retain the ability to power the inverter off a combination of the house battery and alternator output. If I reroute the alternator charge line to the B2B charger alternator input I lose that capability. And as already discussed this hopefully reduces the parasitic losses I've observed in the 'long way round' charging scenario. FWIW: with regards to the Abso DMT1230 - they recommend running a line from the alternator field coil to an input terminal they refer to as 'Ignition start'. I see no reason why one couldn't simply run a jumper from the DMT1230 Alternator plus input over to the 'Ignition start' terminal to realize the same functionality. In my case some manual intervention might be required as I have a manual battery switch in lieu of the Kissling relay. But with the Kissling relay in circuit the output of the Kissling relay would only go high if either the generator/shore power is in play or the engine/alternator is in play. Otherwise the B2B charger would revert to solar power input.

So - that was a long winded way of addressing a couple of things I wasn't sure about with regard to how you are proposing to integrate your B2B charger.

1) You have shorted across the terminals of K52
2) You have added a switch to toggle between converter/alternator

Not sure either of these are necessary or advisable - certainly not in my case - possibly not in your case either...

So consider:

As you were already planning to do - add a wire going from the output of the Kissling relay to the alternator input of the DMT1230. In this way you don't need to reroute the alternator charge line from the house battery up to the DMT1230. The Kissling relay does the switching between sources automagically:) So you don't have to add an additional switch.

When configured this way you wouldn't want to leave the existing alternator charge line the way it currently is. You'd just wind up with some bizarre round robin flow of current from the house battery to the start battery to the Kissling relay to the B2B charger and back to the house battery. Makes my head spin to even consider what might happen:) I guess the simplest solution would be to simply disconnect the alternator charge line from the house battery, tape it off and forget about it. Another possibility would be to pull the 'aux battery relay' fuse - driver seat pedestal - to prevent K52 from latching when the alternator field coil is energized. However - this might also disable the line going to the Kissling relay. In which case the Kissling relay would not latch when the engine is running. So no juice from the alternator to the B2B. That's something you'd have to check. Or you might consider adding an on-off-on switch to K52. If you were already planning on removing the driver seat and installing a bypass on K52 - then it's not that much extra effort to instead add the on-off-on switch. Which for me anyway has proved to be a very useful mod.

John...
 

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OldWest

2004 T1N Westfalia
Oh!

If I understand how this proposal works (a bit complex with discussion re starting battery), a very clean solution.

In schematic.above, the DC-DC charger "replaces" the AC (air conditioner).

1. Power for DC-DC Charger from Kissling Relay ONLY

Off the Kissling Relay, you have two things to choose: (a) Kerstner air conditioner with its on/off switch or (b) DC-DC charger (connected to house batteries directly) with its own on/off switch (assumption that charger has an on/off switch).

Turn off with a manual switch on K52 or disconnect the house batteries from the engine alternator.

Power to the Kissling Relay comes from engine alternator or from the Meanwell converters (shorepower/generator).

2. Engine Alternator to Kissling Relay to DC-DC Charger

When engine is running, power goes to the Kissling Relay and you choose to turn on the air conditioner, the DC-DC charger, or neither (but NOT both at same time).

3. Shorepower/Generator to Meanwell Converters to Kissling Relay to DC-DC Charger

When shorepower/generator plugged in, 120v power goes to Meanwell converters, and then 12v power to Kissling Relay.

From there, Kissling Relay sends power to either the air conditioner, the DC-DC charger, neither, but not both (unless turn on both accidentally).

4. Multiple Power Sources

If engine is running and shorepower/generator is also plugged in (accidentally), Kissling Relay will still opt for only one power source or can take multiple input sources and output one source.

5. NO Connection Between Engine and House Batteries

Engine alternator does NOT charge house batteries directly because cables disconnected or K52 relay turned off.

6. Trik-L-Start

Trik-L-Start might still be helpful for engine battery charging when on shorepower/generator. Otherwise, engine battery is charged directly by engine alternator.

7. Kissling Relay Stuck

Downside is if Kissling Relay gets stuck.

If stuck on engine alternator, no way to use air conditioner or the DC-DC charger off shorepower/generator. But, DC-DC charger would still work if engine is running, and the original Westy charger would work off shorepower/generator.

If Kissling Relay stuck on shorepower/generator, then no air conditioner and no DC-DC charger when engine is running. (BUT if switch on K52 relay, then could charge from engine alternator directly). DC--DC charger would still work off shorepower/generator.

8. Westy Original Charger. May still want to unplug/disconnect cord or turn off circuit breaker unless DC-DC charger unavailable (Kissling Relay stuck on engine power.)
 
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onemanvan

Active member
OldWest - I think you've got the jist of it - with a couple of minor corrections.

There are two Mean Well power supplies in parallel - each capable of 75 amps output. The Kerstner roof A/C should not pull more than 100 amp if running correctly. That leaves 50 amps in reserve. I wouldn't recommend it but in theory it should be possible to power up the DMT1230 after the roof A/C has been running for a few minutes.

When the engine is running the Kissling relay latches to divert power from the alternator to the roof A/C - in this case the Mean Well converter is taken out of the equation.

House battery can still be charged via the alternator - you just need to remember to switch off the DMT1230 before doing so ( yes it has an on/off switch ) otherwise you wind up in a 'dog chasing it's tail' scenario:)

Starter battery can be charged by setting K52 switch to manual. If DMT1230 is turned on and solar gain is available it should default to solar power input. It's output will flow to the house batteries. Since K52 is latched the starter battery will be in parallel with house batteries. So both batteries will receive a charge.

If the Kissling relay is stuck then replace it with a manual battery switch:)

John...
 
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Kiltym

Active member
Quite the interesting idea indeed.

And sorry for making you buy a new piece of hardware :).

In my last iteration, I eliminated shorting the K52 relay, so as of now, I have no need to dig under the seat at this time.

The switch is basically replaced by leveraging the existing Kiss relay. Very smart idea.

With your approach, simply disconnecting the cable from the battery is easiest (for now).

A few comments also:

You mention running both A/C and dc-dc charger at the same time. My only question would be the existing fuses installed on both the battery side and converter side. I don't know their size, but that may, or may not, be an issue (or change the fuse).

"House battery can still be charged via the alternator - you just need to remember to switch off the DMT1230 before doing so ( yes it has an on/off switch ) otherwise you wind up in a 'dog chasing it's tail' scenario:)"

In your case, you can also just use your existing switch in the back and turn to "off".

Another "difference" in your case is if you leave your switch to "Alt/Batt", the dc-dc charger is connected to the start battery. In this case you are leveraging the "smarts" in the dc-dc charger in that it wont draw from the start battery unless the voltage is above some threshold (~13.2), implying the alternator is on. With the Kiss relay, the relay actually cuts out when the engine stops. Just pointing out it works either way fine.



Certainly the K52 mod you performed is a nice addition and something I would think about doing at some point. Adds some flexibility of charging start battery from the dc-dc charger, and still charging directly from alternator (which is a nice backup I suppose) that I would not have either available. Not a huge deal to me as we use the van a lot so the start battery is not a concern to us, but certainly a nice to have.

With your situation of having a switch instead of the relay, I would think you would never want to use the 1+2 mode again. I suppose no harm really as it would work for you as it does now, but just thinking for another owner, if they have (or in the future) replace the Kiss relay with a switch (and don't perform the K52 mod), the 1+2 mode would not be used to charge the house, but I suppose could still be used to charge the start battery with the converter on. But, to keep things simple and less confusing, I think avoidance of 1+2 mode would be generally advisable, unless in an "emergency" you needed to charge the start battery. And I tend to agree that if the Kiss relay is changed to a switch, the additional relay you installed is REQUIRED so that the A/C cannot run from the start battery without the alternator running.


I attached two new "sketches" here. One slightly updated original version (removed an unnecessary fuse and show ground), and the one proposed by onemanvan, which is pretty slick I have to say.
 

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