smkettner wrote: The 100a fuse on the 12v side seems kinda big.
The installation instructions actually called for a 110 amp T style fuse, but all I could only find was a 100 amp fuse. For the wire size, amperage, and length of the wire run, 100 amps works.
You are right it will work...But...
Jim
I assume, Mike has a 300watt inverter which he has posted in his signature.
A 100 amp fuse should be supported by 2ga wire for a 6-8 ft run...That is some big wire!!!! Edit ga wire Jim.
A 300watt inverter only pulls 30 amps dc max.
Your fuse is worthless...If there is a short with the wire it will burn up.
It also appears that Clinthia has troubled wiring with his inverter also.
Jim
* This post was
edited 03/23/12 04:15pm by bigfootford *
Max wire on the Morningstar terminals is #2 max but I can't imagine going bigger than #4 wire. The Morningstar might surge to 600w but this little stuff has no surge issues. I just see "100a fuse" in the online manual. I would hesitate to go 110 Class T as they are a bit slow to open.
Then Morninstar goes to say a 3 amp fuse should be used on the 120 volt side. This side seems small and would appear to limit the output lower than the surge rating. 100a in and 3a out just seems out of balance. I realize you are protecting the wire not the inverter but still.
The GoPower 300w inverter comes with #10 wire and I believe recommends 40a fuse. This wire seems undersize if you will be close to 300w continuous but most are not used at that level. I used #8 wire and a 50a maxi fuse holder also with #8 wire. Works fine.
Reddog1 wrote: Perhaps I am just too much overkill with my #4 battery cables, but in comparison those cables sure look small.
Wayne
I agree those cable look way too small for a 3000 watt inverter. Go Power recommends 4/0 gauge wire with a 400 amp fuse for their 3000 watt inverter.
Just last week I installed a Xantrex Prowatt SW 1000W inverter and used 1 gauge welding cable for power, routed through a 1000 amp disconnect switch and a 150 amp auto-resetting circuit breaker.
I'm guessing you're referring to my setup. The inverter to batteries cables came with the inverter and it is a 300w not 3000w inverter.
Hope this clears things up, Clint
I was referring to your setup. I may have misstated my wire, I am getting old and 12-volt systems/wire sizes were never my strong suit. The only 12-volt issues I have ever had was identifying 12-volt wire sizes. Actually, I used welding cable I thought was #4, but could be 4/0. It is the same size as the cable on my truck. I must say, I am uncomfortable with crimp connectors on your battery wires. Again, I tend to over build this kind of stuff. My comments are not meant to be critical.
DiscoChicken,
The inverters mentioned in this post are all good options.... and you can count me as another vote for the MorningStar SureSine
Your inverter should be wired directly to the battery with a fuse located as close to the battery as possible (within 6"). Your existing battery disconnect may not be rated for the current that the inverter can draw. So, If you need a disconnect you may consider adding one that is appropriate for the inverter you select.
Quote: Ditto this..Not even overkill if 300watts is needed for output of that
Inverter...
300watts = 30 amps... = 3 ga wire for a 5 ft run...
http://www.solar-wind.co.uk/cable-sizing-DC-cables.html
You must mean 50 feet of 3ga wire! Check your math Jim.
As a rule, a 2-3% voltage drop is acceptable... and a 300W continuous rated inverter will draw 27.5A at 12.5V (@~85% efficiency).
Assuming the inverter is mounted 6' from the battery (12' of wire in total), you would need an area of 14200 circular mils to ensure a 2% (or less) voltage drop. So, in this scenario 8 gauge (16800CM) wire is the minimum acceptable wire size. 8ga. has an ampacity of ~70A and of course the fuse is intended to protect the wire (NOT the inverter) and should be rated for LESS than 70A.
I am definitely in favor of overkill (for wiring, not fuses), but it isn't necessary to blow your budget or complicate the installation. If I were installing an inverter like one of the MorningStar or the GoPower 300W units, I'd use a short run (less than 6ft) of 6ga. wire (26600CM) and an economical 80A Mega fuse at the battery.
Quote: Ditto this..Not even overkill if 300watts is needed for output of that
Inverter...
300watts = 30 amps... = 3 ga wire for a 5 ft run...
http://www.solar-wind.co.uk/cable-sizing-DC-cables.html
You must mean 50 feet of 3ga wire! Check your math Jim.
full_mosey wrote: The Morningstar 300W is fanless. Quiet is a good thing.
HTH;
John
x2
Also, just took a look at my installation manual and I was wrong in what I said earlier. The manual calls for a 100 amp fuse not 110 amps like I said earlier.
I have been nothing but impressed with this inverter. The first pure sine wave inverter I've ever bought and simply the best made unit I've ever come across.
2011 Wolf Creek 850N/Polar Cub/240w Solar/2-6v Lifeline AGMs/Morningstar Sunsaver w/RM-1 & SureSine-300 Inverter 2011 Ford F-250/6.2L/3.73/Bilsteins/Air Bags/Torklift TD w/Fastguns 2004 Jeep Wrangler/4.0L/5-spd US Navy Ret.
OK, so I'm definitely going with the morningstar. It will be mounted approx 2' from the battery. I have 6g stranded cable and some hefty terminals. I do want a way to disconnect this thing - but it's been suggested to direct connect to battery. I don't want to drain the battery while it sits. What's the safest way to hook it up? I have no idea what size fuse I need. My family sleeps in this camper, I want to be safe and I'm afraid this thread has done more to confuse me and worry me.
msiminoff you seem pretty confident and knowledgable about all this but what you've posted looks like greek to me.
DiscoChicken wrote: ... you seem pretty confident and knowledgable about all this but what you've posted looks like greek to me.
Okay, in English this time...
1- The MorningStar SureSine is a great choice.
2- 6 gauge wire is the right size.
3- Use a 100A fuse (max)
4- You can put a high current switch LIKE THIS ONE anywhere in the positive lead between the inverter & the fuse (remember the fuse goes as close as possible to the battery). Most auto parts stores should stock something like this.
Cheers
-Mark
Offline
