Re: 5th Wheel RV Solar/Battery/Inverter Upgrade
Every positive wire that leaves the battery bank should have a properly rated fuse/breaker (close to battery) to protect the wiring against shorts/cuts/failures.
Originally Posted by soleil
No fuses/switches in negative leads.
Should be fine.
Of note, the wire lengths are less than 5 feet from the batteries to the inverter, charge controller and generator. I believe the wire sizes are OK, right? (The drawing incorrectly shows 2/0 rather than actual 2 AWG from genny to battery.)
However, we don't know the DC charging current from the genset--So I cannot confirm the maximum fuse rating/current rating vs the AC charger output.
For RV use, you can use the following table as a "maximum" rated current guide for generic open wiring. NEC will be quite a bit less allowed current (more conservative).
American Wire Gauge Table
Remember the fuse protects the wiring leaving your battery box... In theory, you can place the fuse in either location to protect the inverter + wiring.
Does the 250A fuse/breaker need to go between the positive bus bar and the inverter rather than between the batteries and the positive bus bar?
However, you would still need a fuse for every other wire (10 awg, 14 awg, etc.) that leaves the positive bus because the 250 Amp fuse would be way to big to protect the smaller gauge wires.
Also, another issue... If you have the fuse between the battery and the battery bus--if you ever blew the 250 amp fuse--it would take out all of your electricity and leave you in the dark. If you fuse each load/wire branch--then a single fault would still leave you with some DC lighting, etc.
Sounds like a good idea... With the two position switch I gave you--it does give you the ability to have "two switched buses"... For example one to the heavy loads and a second to your solar charger (1, 2, 1+2, all off).
Currently my 5th wheel has a Blue Sea switch, similar to the one you suggested, Bill, between the battery positive and a bar of over a half dozen loads. It is nice because when I store it, I just turn off the switch and it prevents the battery from being drained. I would like to have a similar arrangement when I rewire things. Will positioning the disconnect switch between the loads and the positive bus bar keep that same functionality?
Read carefully through the inverter specifications--Each one seems to have its own way of working... Many inverters have no off switch--so you have to provide you one (or they will draw 6-30 watts of power even with no loads). Some have search mode (AC on for a few cycles, then off for a second, stay on if load > 8 watts is found, etc.). So they draw less power on "standby"--but still not zero.
Would there be a better place to put that switch? I don't think I can put it between the battery and the positive bus bar, as then I couldn't have solar charging when stored. Will the inverter when off and the solar charge controller drain the battery when the RV is stored?
And some inverters have an "inhibit switch". And even when "off/inhibited", they still draw 1/2 a watt or so.
Also, if you store your solar panels under cover/building/roofed area--Most charge controllers do draw a little bit of standby current too... If the solar panels are covered during storage, the charge controller should be disconnected from the battery bus too.
20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.