Is the battery post under the nose cone fused?

artsci · Jun 3, 2014

I installed a Wagan Smart AC 400 watt, 2.1 amp inverter in the nose cone today. It has two 120V outlets and 2 USB ports. Photos below. It's powered from the battery post under the nosecone. I plugged in and sucessfully tested several 120V devices. But when I plugged in a 12v power supply to do another test of the rear lighted T, it beeped and shut down. The beep indicates insufficient 12v power and in those instances the Wagan shuts down. I tested the the power output of the 12v battery post and there's no power, so I assume it's fused. I won't have time to check the fuse box until tomorrow so I'd thought I'd ask. Is it fused?

BTW, the 12v battery is working fine -- the car starts as normal and all of the 12v powered accessories power up as they should. That leads me to believe that the post under the nose cone is fused. The red thing in the photo below is the post i'm talking about. The little red vinyl boot is removed and power is accessed by making a connection to the bolt under it.

Here are photos of the Wagan installed in the frunk.

Madartist · Jun 3, 2014

That's amazing work, as usual. What are you planning to plug into it?

artsci · Jun 3, 2014

Madartist said:
That's amazing work, as usual. What are you planning to plug into it?

Thanks but I can't take credit for the idea. I learned about this by seeing another owner who did it to his car and recommended the Wagan to me.

As I do much of my work on the car outdoors I'll use it to power tools such as soldering pencils, drills. etc. Now and then I may hook up a vacuum. Will also use the USB ports to charge iPads and the like.

But back to the question. Is that connection fused? I'm thinking it must be or why isn't it putting out any power?

siai47 · Jun 3, 2014

Someone on another thread about the 12 volt DC converter said the front post is fused with a 50 amp fuse but didn't say where it is located.

artsci · Jun 4, 2014

siai47 said:
Someone on another thread about the 12 volt DC converter said the front post is fused with a 50 amp fuse but didn't say where it is located.

Thanks. I'm going to check the fuses this morning and report back what I find.

yobigd20 · Jun 4, 2014

where did you buy the outlet from? online? link ?

when I bought the car, I assumed because of all the ridiculous amount of power in there that there would be at least one 120V outlet. I was surprised to find there weren't any. This is something I'd be interested in doing myself too.

artsci · Jun 4, 2014

yobigd20 said:
where did you buy the outlet from? online? link ?

when I bought the car, I assumed because of all the ridiculous amount of power in there that there would be at least one 120V outlet. I was surprised to find there weren't any. This is something I'd be interested in doing myself too.

You can find it on Amazon.

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siai47 said:
Someone on another thread about the 12 volt DC converter said the front post is fused with a 50 amp fuse but didn't say where it is located.

There is no 50 amp fuse in this car, at least among all the fuses listed in the owner's manual. I checked all of the fuses that could possibly protect this circuit but they were all ok. So I've sent an email to my SC to see if they can identify the fuse or confirm that the circuit is fused in the first place.

Kalud · Jun 4, 2014

artsci said:
There is no 50 amp fuse in this car, at least among all the fuses listed in the owner's manual. I checked all of the fuses that could possibly protect this circuit but they were all ok. So I've sent an email to my SC to see if they can identify the fuse or confirm that the circuit is fused in the first place.

I am the one who claimed this. I didn't check myself yet, but I specifically asked an experienced ranger how those posts are hooked up and he said they goes directly to the 12V battery through a 50A fuse (no diode). I should have asked where the fuse was located... You probably blew the fuse. 12V*50A means 600W, your inverter is 400W but 1000W peak, maybe you've exceeded the fuse's rating longer enough to blew it.

Once you've located the fuse please let us know!

mknox · Jun 4, 2014

Kalud said:
I am the one who claimed this. I didn't check myself yet, but I specifically asked an experienced ranger how those posts are hooked up and he said they goes directly to the 12V battery through a 50A fuse (no diode).

It might be an in-line fusible link.

pgiralt · Jun 4, 2014

Yes, I believe there is a fuse, but I'm pretty sure the fuse is actually sitting on top of the battery. Let me see if I can find the photo I saw a while back that showed this...

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Found it here:

http://www.teslamotorsclub.com/showthread.php/10349-12-V-battery-pictures

Would be interested in hearing what kinds of fuses those are and how hard it is to get to them to replace them.

green1 · Jun 4, 2014

artsci said:
I'll use it to power tools such as soldering pencils, drills. etc. Now and then I may hook up a vacuum. Will also use the USB ports to charge iPads and the like.

I think you may be in for some disappointment, 400W is not enough for most soldering irons, and is probably pretty marginal for vacuums and drills. You're talking some high current accessories, and a low current inverter. For serious power use I'd recommend no less than 1000w inverter, that's still less than a standard household outlet. I'd also connect directly at the DC-DC converter, not via other cables. (keep in mind that 1000w is 83 amps at 12v, so I'd use a 100A fuse and some heavy duty wiring)

mknox · Jun 4, 2014

What about connecting directly to the 12v battery terminals, with appropriately sized fusing of course. This is typically how it's done on an ICE vehicle for large current accessories.

artsci · Jun 4, 2014

green1 said:
I think you may be in for some disappointment, 400W is not enough for most soldering irons, and is probably pretty marginal for vacuums and drills. You're talking some high current accessories, and a low current inverter. For serious power use I'd recommend no less than 1000w inverter, that's still less than a standard household outlet. I'd also connect directly at the DC-DC converter, not via other cables. (keep in mind that 1000w is 83 amps at 12v, so I'd use a 100A fuse and some heavy duty wiring)

The wattage ratings for the devices I use will not be a problem. Considered that before buying the Wagan.

Thanks for the photo Pgiralt. I'll look for the fuse on the battery top.

wk057 · Jun 4, 2014

Does anyone know the rating of the DC-DC converter on the Model S? And the potential headroom with existing draws? I looked around for this info before, briefly, but never found any real answer.

I was looking into adding an inverter before, but without knowing how the DC-DC would react to a decent load (~100A @ 12V or so) I wouldn't want to do so.

Would be nice if there were high voltage DC-AC inverters available with higher current outputs (20A @ 120V, for example).

spaceballs · Jun 4, 2014

What type of soldering irons are you using!
As most soldering irons are 10-100 watts.

green1 said:
I think you may be in for some disappointment, 400W is not enough for most soldering irons, and is probably pretty marginal for vacuums and drills. You're talking some high current accessories, and a low current inverter. For serious power use I'd recommend no less than 1000w inverter, that's still less than a standard household outlet. I'd also connect directly at the DC-DC converter, not via other cables. (keep in mind that 1000w is 83 amps at 12v, so I'd use a 100A fuse and some heavy duty wiring)

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wk057 said:
Would be nice if there were high voltage DC-AC inverters available with higher current outputs (20A @ 120V, for example).

Solar inverters.

wk057 said:
Does anyone know the rating of the DC-DC converter on the Model S? And the potential headroom with existing draws? I looked around for this info before, briefly, but never found any real answer.

Not sure on Model S, but Roadster is like ~2kw max for the on board DC-DC converter, i.e. http://www.martekpower.com/products/en/ps2450.html

Kalud · Jun 4, 2014

wk057 said:
Does anyone know the rating of the DC-DC converter on the Model S? And the potential headroom with existing draws? I looked around for this info before, briefly, but never found any real answer.

I was looking into adding an inverter before, but without knowing how the DC-DC would react to a decent load (~100A @ 12V or so) I wouldn't want to do so.

Would be nice if there were high voltage DC-AC inverters available with higher current outputs (20A @ 120V, for example).

someone gave the exact power rating in another related thread.

Cottonwood · Jun 4, 2014

Kalud said:
someone gave the exact power rating in another related thread.

Here it is: Current Maximum on 12V system, 2500 Watts. This was for a more recent Model S. Apparently the older MS's have the DC to DC near the passenger side wheel well and may or may not be the same power.

green1 · Jun 4, 2014

spaceballs said:
What type of soldering irons are you using! As most soldering irons are 10-100 watts.

I was apparently mistaken, I was sure mine was 700 watt, but turns out it's only 60 watt. I must have been confusing it with the 700F temperature rating.

I've never tried running that off an inverter, I've always used a butane soldering iron when not near mains power.

wk057 · Jun 4, 2014

spaceballs said:
What type of soldering irons are you using!
Solar inverters.

Problems with high input voltage solar inverters: Most are grid tie, meaning they have islanding protection that would need to be disabled. Also, not many I've seen will do ~400V input.

GasDoc · Jun 4, 2014

pgiralt said:
View attachment 50877

Would be interested in hearing what kinds of fuses those are and how hard it is to get to them to replace them.

The block sitting on top, on the right side, with the Blue "C" shaped figure is the pyro fuse that blows when the airbags deploy, I believe.

Is the battery post under the nose cone fused?

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