Aux start solenoid -> DC2DC 2 questions!

[barnz333]

I’ll read the new posts shortly. In the meantime, just wanted to upload the new schematic that Jayco just gave me.

 

[craigav]

I’ll read the new posts shortly. In the meantime, just wanted to upload the new schematic that Jayco just gave me.

Good deal, you will like this schematic much more I suspect. For a quick check, the Aux Start setup is the same as the GreyHawk as I suspected (which means my diagram two comments back would work well), and everything else is a little different but also very similar. ~CA

 

[Kevin Cooper]

Craig, So, if I’m reading this correctly, you removed the ignition conductors from the Aux Start solenoid, same as I suggested. Then you paralleled the DC2DC with the solenoid, same again. Then you put a spdt center off maintained contact switch in to trigger either the DC2DC or the Aux start solenoid. Correct? I did not know the DC2DC needed a trigger. I didn’t go that deep.
In my senerio , you would need to take the ignition trigger and connect it to the DC2DC and it would charge the house batteries just like factory.
Now, for my opinion. Maybe I’m wrong! But I’m thinking it will not work. The reason is, the Aux Start Switch is a spst momentary contact switch. So, unless you are driving with your finger on the button, no power to the relay or the DC2DC. Maybe you just didn’t show wiring around that switch, or you are deleting it.

 

[Kevin Cooper]

Looking at the great drawings. The #10 red from the step is the steps power from the chassis battery and must remain on that post. Those drawings are very helpful!
There is a connection missing but can be understood. There is no connection on the Aux Relay control to frame ground.

 

[craigav]

Kevin, Regarding your first point, you would be correct except that the switch is not a SPST. It is a 4-terminal dp double throw which is spring loaded to default to "A" (in the image below) which will provide 12V key-on "trigger" power to the relay any time the key is on... except of course if the chassis battery is dead and then you can press the boost switch button and A becomes open and B becomes closed allowing the 12V coach power (coach battery) to engage the relay.

Jayco schematics still aren't all that great, not bad though I suppose, and with that, the relay's (solenoid) magnetic coil has to have two connections, one for the 12V+ and the other side to the ground in order to complete the circuit. This is shown clearly on the GreyHawk schematic (as below) but is not shown on the Melbourne Schematic. It may be that the Melbourne's ground for the relay's magnetic coil is internally connected to the mounting bracket frame and that is the reason it is not shown as perhaps there is no wire attached or needed in order to obtain the ground (as is the white ground wire is as indicated for the GreyHawk) but in any case, the ground for the magnetic coil will still have to exists either by design of the relay or a wire attached. ~CA

 

[Kevin Cooper]

Is the switch like this one? https://a.co/d/5NMbFVG.
I guess I haven’t used it enough! I did not know that one direction was momentary and the other is maintained. Is my thinking correct? A is push the button down, momentary. B is always connected across, but no power until ignition powers it. And the output of A&B are tied together going to solenoid.

 

[craigav]

"A" would be the spring loaded default position and "B" only when pressed. The switch you shared is not the same in this regard (from a quick look). A&B are never tied together at the switch as when one is closed the other is open (which doesn't mean A&B wouldn't have the same voltage potential when the aux battery relay is closed as both A&B would have the same voltage, or very close due to the relay tying both circuits together). ~CA

 

[craigav]

I updated the image to help show that if "A" is closed then "B" is open (and the opposite occurs when the button is pressed. ~CA

As a thought, it performs as a SPDT switch.

 

[barnz333]

Kevin & Craig, while your expertise levels far, far surpass mine, I have learned a lot reading through your posts! If you can close a few final open questions I have, that would be very helpful.

The first is tied to the Aux Start discussion. In the diagrams above (and both the Greyhawk & Melbourne schematics), where do the solenoid & switch get the 'notification' that the key/Ignition is on? I only see a reference to 'ignition' down below the switch... off the yellow wire. Does that represent 'two-way notifications'?

I initially had an additional question about the battery disconnect switch & solenoid. I'd wanted to replace that switch with an On/Off switch, but there are a lot of connections (and their related functionalities) on the existing switch & solenoid that I thought would be a pain to replicate. Similar to the Aux Start functionality, I decided to utilize both the old & new. I would keep the existing setup for its notifications & triggers (ie from the aux start SW, to the diode and its downstream components), and add the new on/off switch through a Lynx distribution box to shut down all other pathways from the house batteries (inverter/converter, DC panel, DC2DC, MPPT). In my plan, I removed the incoming 4g wire from the house battery, and the outgoing 4g wire to DC Panel & Inverter (as those systems are now powered, and on/off-controlled by the new design). My question is, without that 12v power running through the battery disconnect solenoid, will that 14g (yellow/red) wire still be able to trigger the diode and its downstream components?

And while I have your attention, might as well ask my final open question. My existing setup has most 12v from the house batts going through the batt disconnect solenoid/switch, but there are 3 exceptions:
1) 2g going to the generator to start it. This is shown on my 'new' and 'initial' schematics.
2) Can't see the gauge right now, but it is probably a 2-4g going to the Bigfoot leveling system (not shown on either schematic, presumably because it was an option)
3) red and white 10g wires going to the REFR

My question is actually two:
1) should any/all of those pathways also go through a 'disconnect' pathway instead of direct from the battery?
2) since my upgrade to a 280a/12v lithium battery (and other upgraded/beefier related components), 2/0 wires around the battery system are called for. Does that mean I should upgrade the generator & leveler lines from their current 2-4g to 2/0 as well?

Thanks so much. Incredibly helpful!

 

[craigav]

Using the term "notification" is a bit confusing, with that, you are correct that the yellow wire obtains its 12v+ when the key is on and from the schematic you shared, that yellow wire is connected to "TERM 3" at the "UNDER DRIVER SEAT CONNECTIONS". I am not sure what you are asking in regards to two-way notifications, the yellow wire is either hot (with the key on) or not hot (with the key off). That 12v+ hot flows through the Aux Start Switch in its spring loaded default position on to the relay orange wire engaging the relay anytime the key is on.

Regarding the battery disconnect, your setup is wired as such that the yellow\red wire does need power on it that it gets from the right side fuse off of the disconnect solenoid. It will need to have power in order for the items such as the ref, radio, lp/co detector to use the coach battery power. I suggest that if you would like to open a new thread regarding the battery disconnect and wiring then we can go deeper into it all if you like. Just FYI, the Diode setup isn't anything that gets triggered, I had used that term trigger in regarding the wire(s) that are responsible for engaging the aux start relay but a diode isn't the same as a relay. What it is, is similar to a water line check valve but in this case only allows power to flow one direction, there are two diodes which allows those items I mentioned previously to obtain power from either the coach or chassis. This allows for example your lp\co detector to be powered even if you don't have a coach battery installed and if you do have a coach battery then it will use it for the power (most of the time).

The schematic doesn't show me a red/white going from the battery disconnect solenoid to the ref, what type refrigerator do you have as that wire may have been added and not on the schematic? In any case, you wouldn't want to "not" provide power to the ref when you are using it. In my opinion it should be a rare thing that you would ever want to disconnect the coach battery anyway, perhaps over the winter but not while using the RV. The power cables (wires) going to the gen and leveler do not need to be upgraded in size as those components will not draw more current than they already do regardless of the battery(s) you are using. ~CA

 

[barnz333]

Thanks craigrv. I will be creating a separate thread for my battery disconnect questions momentarily.

Before I wrap up this thread, however, I just wanted to thank you ( and Kevin) again for all your help! And please excuse my incorrect usage of terms… Like ‘notifications’! I know it’s confusing, but I appreciate that you were able to guess at what I was thinking about in your post above. Your responses once again helped me to understand how the existing systems works. And the middle section of your reply helped me to work on a new diagram that hopefully will reuse the existing Battery disconnect solenoid and switch for my go-forward set up. Please check out the new post when you get a minute.

 

[barnz333]

Craig, Kevin (and other interested parties), the new thread is titled: “Continue to use battery disconnect solenoid after RV upgrade?”

 

[dvspl]

My question is actually two:
1) should any/all of those pathways also go through a 'disconnect' pathway instead of direct from the battery?
2) since my upgrade to a 280a/12v lithium battery (and other upgraded/beefier related components), 2/0 wires around the battery system are called for. Does that mean I should upgrade the generator & leveler lines from their current 2-4g to 2/0 as well?

1) I think the answer to this is a matter of personal preference. The generator and levelers will only draw power from the battery if you turn them on so they don't "have" to go through a disconnect. The refer seems like a more likely candidate to route through the disconnect but still a matter of personal preference. Many people want to be able to completely disconnect their battery from everything (e.g. for storage) so they put a disconnect in the single positive lead that runs from a positive battery bus to the battery. That disconnects everything.
2) Just because the battery is larger there is no need to upgrade the wires to components that will draw the same amount of current. So the generator and leveler wiring doesn't need to be larger unless the length of the new run to them is substantially longer so will lead to more voltage drop.