Converter and Battery Question

Your inverter should have both its wires connected directly to the battery.

The battery neg wire to frame still goes to the frame. The neg wire from the solar controller goes to the battery.

When the converter is unplugged you still get 12v from the battery. The converter only works if you have 120v from shore power or generator. (it also works from the inverter, but you don't want it to or you get that infamous "loop")

You can just buy a deck mount converter and put it up with the inverter and battery bank and leave the original converter where it is. No big wiring job. Put the controller in there too.

The battery bank needs a vented box because you don't want the inverter and converter to get ruined by battery fumes or the fumes to get a spark from the inverter. AGMs get around all that.

The battery can be grounded to the frame wherever it's convenient to do so. With a solar controller, that doesn't need to change for any reason; the battery negative side of the controller can likewise be connected to a convenient chassis ground location (not necessarily the same one as the battery). The frame does provide a good, low-impedance path for the current, provided the connections to it are good and clean and tight. You'd be hard-pressed to create a better, lower-impedance connection with a wire in most cases.

Any halfway modern system will basically have the converter, the battery, and the DC fuse panel connected in parallel, ignoring the battery disconnect switch for the moment. This may be physicallly accomplished by having the converter connect to lugs on the DC distribution panel, basically making it be the junction point for all three, but electrically it's equivalent in theory. Others have the converter wired more or less directly to the battery lugs, or perhaps to some intermediate bus bar or other junction point. In any case, the converter does supply power not only to the battery but to the rest of the 12V system when plugged in, since they're all interconnected. A standard battery charger clamped to the battery would do the exact same thing, for the same reasons. You continue to have 12V power when unplugged simply because the battery is now carrying the load, and you have a working battery.

The specific details of what connects together physically and in what locations is somewhat more variable than the basic electrical setup. Fiddling around with those connection points is perfectly reasonable, provided of course you employ appropriate electrical safety practices, such as making sure sufficient overcurrent protection (fuses) are there for the circuits you reroute.

It is perhaps worth observing that modifying the converter connections may alter how the system behaves if the battery disconnect switch is used to disconnect the battery. If the converter is connected to the electric panel (or anywhere on that side of the switch), then it will power the 12V system when the battery is disconnected but not charge the battery. If it's on the battery side, then it would charge the battery but the 12V system for the RV would have no power. Neither one is especially desirable in most situations.

BFL13 wrote:
The battery neg wire to frame still goes to the frame. The neg wire from the solar controller goes to the battery.

When the converter is unplugged you still get 12v from the battery. The converter only works if you have 120v from shore power or generator. (it also works from the inverter, but you don't want it to or you get that infamous "loop")

You can just buy a deck mount converter and put it up with the inverter and battery bank and leave the original converter where it is. No big wiring job. Put the controller in there too.

The battery bank needs a vented box because you don't want the inverter and converter to get ruined by battery fumes or the fumes to get a spark from the inverter. AGMs get around all that.

Good to know. I plan on either AGM or LifePo4 drop in equivalents at this point for the batteries.

Solar controller should be close to the battery. You will pull new wire direct from the controller to the battery terminals. Main battery ground wire to the frame remains connected.

DrewE wrote:
The battery can be grounded to the frame wherever it's convenient to do so. With a solar controller, that doesn't need to change for any reason; the battery negative side of the controller can likewise be connected to a convenient chassis ground location (not necessarily the same one as the battery). The frame does provide a good, low-impedance path for the current, provided the connections to it are good and clean and tight. You'd be hard-pressed to create a better, lower-impedance connection with a wire in most cases.

Any halfway modern system will basically have the converter, the battery, and the DC fuse panel connected in parallel, ignoring the battery disconnect switch for the moment. This may be physicallly accomplished by having the converter connect to lugs on the DC distribution panel, basically making it be the junction point for all three, but electrically it's equivalent in theory. Others have the converter wired more or less directly to the battery lugs, or perhaps to some intermediate bus bar or other junction point. In any case, the converter does supply power not only to the battery but to the rest of the 12V system when plugged in, since they're all interconnected. A standard battery charger clamped to the battery would do the exact same thing, for the same reasons. You continue to have 12V power when unplugged simply because the battery is now carrying the load, and you have a working battery.

The specific details of what connects together physically and in what locations is somewhat more variable than the basic electrical setup. Fiddling around with those connection points is perfectly reasonable, provided of course you employ appropriate electrical safety practices, such as making sure sufficient overcurrent protection (fuses) are there for the circuits you reroute.

It is perhaps worth observing that modifying the converter connections may alter how the system behaves if the battery disconnect switch is used to disconnect the battery. If the converter is connected to the electric panel (or anywhere on that side of the switch), then it will power the 12V system when the battery is disconnected but not charge the battery. If it's on the battery side, then it would charge the battery but the 12V system for the RV would have no power. Neither one is especially desirable in most situations.

My converter is connected to the panel side of the battery disconnect. I have to switch of the disconnect and the AC main circuit breaker to stop power flow on the 12V side, which I figured out when I installed my vent fans last year.

I believe I might go with the suggestion of buying a separate converter and leaving the factory one in place. That way I can get an upgraded unit and I can just keep the factory one turned off...and avoid the extra wire routing for the automatic shutoff I want to try.

time2roll wrote:
Solar controller should be close to the battery. You will pull new wire direct from the controller to the battery terminals. Main battery ground wire to the frame remains connected.

Gotcha. I've been researching solar setups in preparation for my eventual install, and couldn't remember how that connection worked. Thanks for the response.

When you also get your battery monitor such as a Trimetric it will have its 500a shunt for your negatives.

Now the battery to frame ground wire is disconnected from the battery and goes to the side of the shunt that has all the other neg wires, and one fat wire goes from the other end of the shunt to the battery.

That still has the battery neg grounded to the frame, but you get the info to the monitor by having the frame amps through the shunt.

With the inverter, converter, solar controller, and frame ground, all to the shunt, it will stack too many lug terminals under the shunt's bolt. So use a neg buss to collect the various neg inputs and then a fat wire to the shunt from the buss.

"Solar controller should be close to the battery. You will pull new wire direct from the controller to the battery terminals. Main battery ground wire to the frame remains connected."

Use 6 guage at least.

I agree both wires from converter should go direct to battery. The frame is often "negative Ground" but...... the connections may be less than optiomal so it should be direct connected.

As for the 12 volt stuff working with the CONV breaker off.. Yes. that's what the battery does. it powers the 12 volt side of life when the converter is off due to breaker trip, shut off or loss of shore power.

True story: For reasons of electrical safety I have a Surge Guard system (Mine is the TRC but well I would rather have the Progressive Industries but one "Heck of a sale" decided me)

The other day we had a thunderstorm. One lightening flash was within half a mile of where I'm parked (about 1 second or between 1000 and 2000 feet between Flash and BOOM) the EMP triped the ground fault detector in the surge guard.. Thanks to the 12 volt battery bank and an inverter it was like half an hour before I noticed an indicator NOT lit and went out (THe rain had seriously let up by then still misting but not downpour) Thanks to the 2000 watt inverter even the TV was till playing recorded video.. A quick off/on of the breaker and 2.x minutes later CLUNK lights brighter as the converters kicked in.,