Rewire converter for transfer switch.

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Henry J Fate

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Yah I’m very aware of the inverter/charges but was wanting to make the parts I have work for what I need currently.

May just end up going with a inverter/charger unit in the future to simplify even more, as well as better battery charging features especially if I upgrade more than just the dual 6v batteries.

That sounds like it would be better for you now. Just make sure there is no way to create a hazard with your design. If the power cord to the RV is wired into a junction box in the RV, it should be fine as there would be no way to connect two different power sources. The EMS becomes the final issue. How big is the inverter?
 

Hewster

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Sounds to me as though Hewster has covered all the bases and his plan is sound. We can nitpick about details, but since he mostly boondocks I think his plan is a very practical one.
Thanks Gary,

Always open to ideas, input and even criticism.

@Henry J Fate yes everything will be either in junction boxes, units or what not. The EMS cannot become a hazard, it is a sealed unit.

Inverter is pure sine wave 1000. If I ever upgrade bigger than that it will be a inverter/charger unit then.

Shore power cable in to trailer into EMS box. Only thing changing there is using the EMS box instead of factory junction box. And it’s still behind a panel/compartment.

At the converter/power distribution nothing will be even visual and will appear factory as it’s all behind the converter/PD.

Inverter is mounted and wired in pass through compartment, and AC wire running through the covered underbelly.
 

Hewster

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Yes that is what I did. My transfer switch even had a wiring diagram showing how to hook up so the converter is activated when plugged in to shore power. If you are going to be using an inverter type generator you will need a way to bond the neutral and ground coming from the generator or the EMS will see an open ground and not allow power.
Do you happen to have a copy of those instructions. I cannot seem to locate that info.
 

Hewster

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Gary RV_Wizard

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Nitpick: Shouldn't the "line in" for the charger be labeled as "to" the charger rather than "from"? And "from" the NO contacts? The charger receives 120vac power via the transfer switch shore cord contacts and produces a nominal 12vdc output to the battery. It does not send 120v power in to the transfer switch.

SuwanneeDave surely knows that, but I'm trying to avoid mistakes if somebody else attempts to do this.
 
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Hewster

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I’m planning to tie in wiring at the transfer switch shore power wire.

Not sure how much of a deal it is to tie all 3 in there, hot neutral, ground. @Gary RV_Wizard ? Best practice to?

Then tie in a circuit breaker like this so I can mount and easily reset if needed.

565AC9F6-4E58-4712-9FFE-A9D807C1B28A.png
 

JayArr

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There is one thing you should check if you arrange it like the schematic posted above.

What is the maximum voltage the charger will apply to the batteries when charging? The Xantrex ProSine 1000 will throw an alarm if it sees 15.8V input and it will shutdown at 16VDC.

Arranged as above - when plugged into shore power or generator - you will be charging the battery while the inverter is running. Even with it's output disconnected it will still be running, just not supplying any output current. The voltage will be the same at the output of the charger, the battery and the input of the inverter since they are all tied together in parallel.

If your charger exceeds 15.8VDC while charging the batteries you could find that the inverter needs a reset after unplugging from shore power/genny. As long as you're aware of this it won't be a problem, if you disconnect from shore power and have no AC then just go power cycle the inverter to clear the alarm.
 

Gary RV_Wizard

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I’m planning to tie in wiring at the transfer switch shore power wire.

Not sure how much of a deal it is to tie all 3 in there, hot neutral, ground. @Gary RV_Wizard ? Best practice to?
I'm not clear what 3 things you are tying together. The shore power cord joins the ATS at one set of terminals and you connect the converter/charger to the same terminals via a fused or breakered pigtail. What's the 3rd thing? The inverter feeds to a different set of terminals on the ATS. The only extra connection is the addition of the converter's power input and it's probably 16 gauge (or maybe 14 gauge) wire.

Be aware that one side of the ATS has priority over the other, i.e. it will always transfer to the priority terminal if power is present there. I would guess that you would want the shore cord side to have priority. That might leave the inverter with power available but unused because the ATS has switched. The inverter sees that as a "no load" situation and most inverters automatically go into idle status when that happens. Idle means minimal (but not zero) consumption of battery amps.

It's ok to have all the grounds connected - they don't have to be switched. The ATS has terminals for hot & neutral.
 
Last edited:

Hewster

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BC, Canada
There is one thing you should check if you arrange it like the schematic posted above.

What is the maximum voltage the charger will apply to the batteries when charging? The Xantrex ProSine 1000 will throw an alarm if it sees 15.8V input and it will shutdown at 16VDC.

Arranged as above - when plugged into shore power or generator - you will be charging the battery while the inverter is running. Even with it's output disconnected it will still be running, just not supplying any output current. The voltage will be the same at the output of the charger, the battery and the input of the inverter since they are all tied together in parallel.

If your charger exceeds 15.8VDC while charging the batteries you could find that the inverter needs a reset after unplugging from shore power/genny. As long as you're aware of this it won't be a problem, if you disconnect from shore power and have no AC then just go power cycle the inverter to clear the alarm.
The max voltage would be whatever the factory chargers set to work with. I’m simply just rewiring it to be removed from the panel so the inverter will not power it.

Yes, the inverter will still be running, but we have a remote switch to turn it on/off. Only time inverter is on usually is running the baby monitor at night till we go to bed in the trailer. And coffee in the morning. I’m very religious at making sure it’s turned off as is my wife.

Thanks for the info.
 

Hewster

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I'm not clear what 3 things you are tying together. The shore power cord joins the ATS at one set of terminals and you connect the converter/charger to the same terminals via a fused or breakered pigtail. What's the 3rd thing? The inverter feeds to a different set of terminals on the ATS. The only extra connection is the addition of the converter's power input and it's probably 16 gauge (or maybe 14 gauge) wire.

Be aware that one side of the ATS has priority over the other, i.e. it will always transfer to the priority terminal if power is present there. I would guess that you would want the shore cord side to have priority. That might leave the inverter with power available but unused because the ATS has switched. The inverter sees that as a "no load" situation and most inverters automatically go into idle status when that happens. Idle means minimal (but not zero) consumption of battery amps.

It's ok to have all the grounds connected - they don't have to be switched. The ATS has terminals for hot & neutral.
Thanks Gary, I was combining multiple thoughts into one post and didn’t convey it very well but all is well on that post now.

Thank you
 
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