Cobra CPI 1575 1500 Watt 12 Volt DC to 120 Volt AC Power Inverter by Cobra Electronics
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Digital camera reviews of Cobra CPI 1575 1500 Watt 12 Volt DC to 120 Volt AC Power Inverter
Digital camera Review: 12VDC Wire size and fuse considerations
Summary: 5 Stars
This review is in response to some comments regarding wire and fuse size selections for this inverter and others like it.
In response to other review quoting a table from the National Electric Code (NEC). While the table that was posted is correct for 115VAC (household voltage) is does not translate directly to 12VDC (automotive voltage). When dealing with a 12 volt system there is less concern with wires overheating, at least in the way that the NEC considers it, and far more concern with voltage drop. When running wiring a reasonable distance (a couple hundred feet or so) there is little concern with voltage drop with AC power. But when dealing with DC, simply increasing your wiring distance 5-10' can have a drastic effect on voltage drop. That is why this inverter should be wired with, at the very least, #4 wire and really should be installed with #2 or thicker, especially if you need to run wire 15 or 20 feet or more.
The purpose of a fuse in a DC system is to protect the rest of your electrical system in the event of a short. That is why you always want to install your fuse as close to the battery as possible (no more then 3' if you can help it). As far as the amperage goes, there is a really good quick reference chart for automotive wire size that can be found at Tessco's web site here:[Turns out I can't link to an outside page so I'll paste the contents of the table at the bottom]. But to boil it down, you can safely fuse a 12VDC circuit at 150, or 200 amps, or more on #4, #2 or #0 wire.
Now this unit at full load is something like 85% efficient. So if you do the math -- 1500 Watts / 12 Volts / .85 efficiency = ~147 amps, A 150 AMP FUSE IS REQUIRED. If you take peak power into account you would need to double that to a 300 amp fuse, but because the inverter cannot run at peak power for more then a moment, a slow-blow 150amp fuse may work just fine, or perhaps you could step up a 200amp. I wouldn't go all the way to a 300 amp fuse unless you really found that you needed it and had the inverted is wired in such a way that it could handle that level current (read: installed using very heavy gauge wire). Now if your vehicle is running while your inverter is working the amperage will be a little lower because your dealing with 14.4 VDC rather then 12 volts (watts = volts x amps -or- amps = watts / volts). But at the very least, a 150 amp ANL fuse is very good idea and not at all over sized.
Just a FYI on fuses, most car stereos are installed with AGU style fuses, but they only go up to 100 amps.
You will need an ANL style fuse to get one rated at 150 amps or more. See these links for examples:
Kicker 09ANL150 150 Amp ROHS Compliant ANL Fuse - Package of 2
Scosche EWFH Single ANL Fuse Holder
Wire Gauge Selection Table 12 Volt Circuit
Wire Distance
AMPS 3' 5' 7' 10' 15' 20' 25'
<5 18 18 18 18 18 18 18
6 18 18 18 18 18 18 18
7 18 18 18 18 18 18 18
8 18 18 18 18 18 16 16
10 18 18 18 18 16 16 16
11 18 18 18 18 16 16 14
12 18 18 18 18 16 16 14
15 18 18 18 18 14 14 12
18 18 18 16 16 14 14 12
20 18 18 16 16 14 12 10
22 18 18 16 16 12 12 10
24 18 18 16 16 12 12 10
30 18 16 16 14 10 10 10
40 18 16 14 12 10 10 8
50 16 14 12 12 10 10 8
100 12 12 10 10 6 6 4
150 10 10 8 8 4 4 2
200 10 8 8 6 4 4 2
Digital camera Review: Awesome Product
Summary: 5 Stars
This product is awesome I power my freezer with it. It's a 5 cubic foot freezer has plenty of power to push it. I love the electronic reader I like it better than my Vector although my 3000 watt vector handles more power going to the unit. This product does what I want it to do and for the price it's a great buy!Digital camera Review: Blackout Fun
Summary: 4 Stars
The inverter works well but required some inventive installation. We ended up rigging it on the driver's side, just left and above the left foot area: screwed it to the top. We initially tried to fasten it with industrial strength Velcro, but it still required screwing in. We take a lot of road trips and always bring a lot of our electronics, so having reliable power is great. We could power a small fridge if we wanted to go that far, but we've stuck to laptops, phone chargers, GPS plug-in, stuff like that. But I would say, it's like having a mini back up power source. We had a blackout in our neighborhood for a couple of hours and we just put an extension cord to the inverter, plugged in a fan and passed the time watching a movie on our projector- all powered by the inverter. It's definitely been worth the trouble and money.Digital camera Review: Cobra 1575 Inverter
Summary: 5 Stars
So far seems to work great, but I have only been able to test a load of about 1.03kw. I wish that the terminals that you connect the positive and negative wires to were a different design because the wires can slip out after much use.Digital camera Review: Cobra 3000 Watt inverter
Summary: 3 Stars
My Cobra was easy to install and worked just fine. I was disapointed that the 3000 Watt rating was the peak power rating and normal operation was only 1500 watts.