JD5520 750Watt Inverter Hardwire

Hay Pirate · Jul 26, 2008

I'm planning on hardwiring a Vector 750 Watt Inverter in my JD 5520 in the next couple of weeks. We've been using the inverter with the battery clips for the impact wrench we keep in the cab when something breaks (Like the mower knives). It works awesome, its just when connecting the clamps it sparks and it gets tossed around the already cluttered cab so I'm going to hardwire it to the battery and stow it away somewhere behind one of the panels.
Here is the hardware I have scoped out for the project:

- John Deere Factory Light Switch #MIA10204
- Home Depot/Lowes/etc Outdoor Power Outlet
- Vector 750W Inverter

I will update this post when I install it in the upcoming days.

Before I get started, I do have a question. From my calculations, 750 Watts / 12 Volts DC = 63 Amps, correct? So I would need a 65 Amp Fuse or a 70/75 fuse for the power line?

aczlan · Jul 26, 2008

according to a quick Google search, there is a fuse on the input side. I would get a breaker/fuse of that size and install that as close to the battery as possible.

Aaron Z

BarryinMN · Jul 26, 2008

If your talking 750W output power then INput power demand is likely 120% of output allowing for circuit efficiency losses. Sizing input demand wiring for 900W will minimize voltage drops & unit possibly shutting down or popping breaker/fuse.

patrick_g · Jul 27, 2008

BarryinMN said:
If your talking 750W output power then INput power demand is likely 120% of output allowing for circuit efficiency losses. Sizing input demand wiring for 900W will minimize voltage drops & unit possibly shutting down or popping breaker/fuse.

Ditto what Barry said...And... Don't use a fast blow fuse as the "inrush" current may pop it.

Pat

Hay Pirate · Jul 27, 2008

patrick_g said:
Ditto what Barry said...And... Don't use a fast blow fuse as the "inrush" current may pop it.

Pat

Ah, you're right. It has a higher peak wattage, I forget what it is, but its higher than 750Watts, so it could pull more than the estimated 63amps.

What kind of fuse should I put on there? Maybe a breaker? And how many amps?

patrick_g · Jul 27, 2008

Hay Pirate said:
Ah, you're right. It has a higher peak wattage, I forget what it is, but its higher than 750Watts, so it could pull more than the estimated 63amps.

What kind of fuse should I put on there? Maybe a breaker? And how many amps?

There is nothing wrong with a breaker but... A fuse is cheap and works fine. There is nothing wrong with making an empirical determination of fuse size either.

Get your best guess of highest sustained input power (may be even more than 120% of output power depending on quality of the circuitry) and install a slow blow fuse at or just above that rating. Properly sized slow blow fuses will not usually pop on inrush current (startup transients) but will protect the equipment from either a sustained moderate overload or a brief heavy overload. They tend to integrate over a little time so that a brief overload will not pop it but a sustained overload will.

I would have thought the mfg would have included a fuse or fuse recommendation for the unit.

Don't go oversized on the fuse as that defeats its purpose. If you guess wrong and use too small of a fuse you will pop a few in normal operation but nothing will be harmed and fuses aren't all that expensive. You can then go up a size in amp ratings. (repeat if needed)

Also, do not undersize the wire, terminals or anything else in the circuit. (weakest link)

What is the current rating of the switch you mentioned? Will it handle the load? (You will put the switch in the input DC, right?)

Pat

pat32rf · Jul 27, 2008

You may have trouble finding a 80-90amp automotive fuse at your service center, but you could always use a 250volt 80-90amp household fuse. Just drill a hole in the blades and stick a good quality lug on the end of the wire, bolt her together and then tape the sucker up. The other alternative would be to go to a automotive sound shop where they have large fuses and fuse holders for those amplifiers the kids put in the back seat of their Hondas. They ain't cheap though.....

Hay Pirate · Jul 28, 2008

patrick_g said:
What is the current rating of the switch you mentioned? Will it handle the load? (You will put the switch in the input DC, right?)

Pat

Pat,
Thanks for the info! I'll just use my best judgement. I think I'm making it more complicated than it looks.

I'm taking the faceplate off and replacing the switch that's on there and extending the wires. The JD switch is 20amps. I can't see that little switch running more than 20a.

I'm probably going to order all my stuff from West Marine. They have tough stuff there, and a pretty decent selection, hopefully I can find a couple fuses and fuse holders there.

Soundguy · Jul 28, 2008

Are you going to run an extension cord from the inverter to the back of the tractor to a 'wet area' outlet box.. or just plug in everything up front. if you run an ext cord.. get a decent one.. don't want to bottleneck it anywhere when dealing with an inverter as you are already working with 1-hand tied behind your back.. etc.

soundguy

Hay Pirate · Jul 28, 2008

Soundguy said:
Are you going to run an extension cord from the inverter to the back of the tractor to a 'wet area' outlet box.. or just plug in everything up front. if you run an ext cord.. get a decent one.. don't want to bottleneck it anywhere when dealing with an inverter as you are already working with 1-hand tied behind your back.. etc.

soundguy

Yes, 2 extension cords to a wet area outlet.