Fresh_GT

I've got a 400 watt AC inverter (800 watt peak) to install in my car. What size wire should I use to wire up the inverter?

Also, any recommendations on where to mount it? I was thinking under the passenger side footwell.

wayne613

Thatīs a 30amp draw, conservatively, not including spikes. 8 gauge or better, using the same for a good, and short ground line.

These things do tend to overheat easily even under the best conditions. Quality control for any Iīve seen doesnīt seem to be a big concern, getting it as small as possible, with the cheapest parts, and being able to boast the highest wattage are the only ones these usually Chinese made inverters are concerned with.

Expect it to get near baking heat levels from likely insufficient exhaust venting it has no matter what after about 5mins of use. Iīd check it out for some prolonged use before deciding on a very enclosed section to mount it in, or if the factory cooling is even sufficient for prolonged use. Many will have their overheat protection kick in after use with something after about 10-20mins.

Fresh_GT

Thanks for the input. I just bought a basic model (this model). I don't plan on running much on it; just a tablet charger and a Bluetooth audio module. Do inverters typicality run at full load even if there is no big demand?

Sorry I'm a little new at this sort of wiring.

wayne613

Yes, and no. Typically, regardless of what draw you actually have on it, it will be operating at a high percentage of itīs rating. Theyīre not set up for truly refined load dependent draw that I know of.

Newegg tends to be fairly good about not serving up junk though, or if it is it doesnīt last long on the site for sale. And cobra used to be a pretty good brand name for certain things. So looks like a good choice from the manual specs anyhow. Just FYI, look closely at the Ļoperating limitsĻ part of that. Likely best case will be about an hour and it will cut-out from overheating, they state from a 400w load, but Iīm betting even a 100w load will kill it in that time with the stock venting set-up.

That said...From the manual itīs a tenth of a second for that 800peak load. They give you a 2ft direct to battery cable thatīs 12guage. Iīd love to see someone put an inverter in their car somewhere and reach the battery with a 2ft cable. Iīm betting the fuse on it is likely 40amp+. Iīd be hesitant to trust 10gauge wiring for a few feet at that draw, let alone 12.

Here is a good table to use for this from over at the12volt.com(this is intended for car amplifiers however, so keep that in mind, for many listed there 1 gauge lower would be fine for this). Figure, usual voltage (optimal) for automotive use is 13.8v, so, 400w divided by 13.8, gives you the rough outline of itīs supposed draw(in amps, so around 30 as best case, more than that is far more likely).

And I would strongly suggest a relay or an otherwise automated cut-off method for it once the engine is off. With a strong battery youīll likely get about 50mins + or - before you kill your battery if it is on and powering anything with the engine off. Like most automated low voltage cut-outs, usually by the time it senses the low voltage your battery is already toast.

Fresh_GT

I was planning on wiring it with a relay (only on with the key when the car is running) and a switch to manually shut it off if its not in use.

Nuke

If you're not intending on running anywhere near the rated load, then I'd downgrade to a smaller unit and forego the installation issues (cable size and location to allow enough airflow to prevent failure or even a fire). As stated above, even 10 AWG wiring leaves you little to no margin. And with no or little load, these units still tend to have a relatively high power demand with respect to the output.

mayo

I don't have a recommendation where, but I would avoid the side footwell because of possible water contact...read TSB regarding this for more infor.

Jeckler

480w seems a bit overkill for a laptop charger that probably draws around 90. I have some cheap Black and Decker 100w that I plug into the cigaret... sorry, "Power Port" (echo, echo) when needed for an old Dell laptop. It's about the size of a deck of cards.

I will say that $35 ia a pretty good deal though for the Cobra.

Nuke

I'd also be suspect of how clean that 800W of power is for $35. I have an old 800W inverter that I bought for $100 prior to Y2K which has an output which is simply dirty as hell on the scope. It would fry any electronic device over a period of time that has sensitive electronics and poor filtering on the input. I use it mainly for lighting and low power appliances when the power goes out. Forget my computers and high-$$ video/audio gear...

wayne613

$35 for a 400watt inverter? I didnīt even view the price on it. And that seems to be the more expensive place to get it from...

Deals abound, but you do get what you pay for within a certain frame.