Customer Reviews

Cobra CPI 875 800 Watt 12 Volt DC to 120 Volt AC Power Inverter with USB port

5 star:		(10)
4 star:		(4)
3 star:		(1)
2 star:		(0)
1 star:		(4)

 

 

This is a very good unit, for what it is designed to do. It is up to Cobra's usual high quality standards. There are a few things you should know before you buy it though.

There are a couple of comments about the unit not putting out full voltage - however, if you go to the Cobra website and read up on this unit you will see that a standard voltage meter will not read the voltage correctly due to the sine wave configuration, instead it will read low voltage. Measurement requires a specialized meter, an RMS if I recall correctly. I have read also that some electronics work fine with the modified sine wave and some pick up some interference. It would probably be worth the time and energy to research which would be the case for your particular electronic application, before buying.

Another quite important thing to know is that this unit, while rated at 1600 watts, will only run at 800 watts continuously. The 1600 watts provides room for start up surge, but not for running more than a few seconds. I bought mine to use in my car. First thing I tried was a 1500 watt heater, and it would run for a few seconds and then stop. Then I tried a 750 watt heater and it ran just fine. So check your application and see if it will be 800 or less watts, if more, get a bigger unit.

Another important thing to watch for on automobile installations is the output of your alternator. Many cars have alternators with as little total output as 60 to 75 amps. You can calculate the amp draw by dividing the AC watts by 12 and then multitplying by 1.1 - so in my case the 750 watt heater draws 69 amps from the battery/alternator. If I had a 60 or 75 amp alternator then there would be a serious problem. Probably the battery would be drained while driving and I would end up with a dead battery, at night, in the middle of nowhere, surrounded by zombies pounding on the windows....

I have a 135 amp alternator, but since I am not sure exactly how much amp draw my car uses while running at night with headlights (most of my driving is after dark) then I am not completely sure how much reserve/overage I have for the inverter. As a result I only run the heater intermittently so the battery won't drain. If your application pulls enough amps to cause the charging system to run at system capacity so that the alternator continuously puts out 100%, the alternator will not last nearly as long as normal. I never run my heater when the engine is idling, at idle the alternator puts out about 40% less.

If you are going to use this in a running car, try and find the total amp draw needed for the car,(I found that my alternator runs at about roughly 60% when idling so I am guessing that my total draw would be about 50% of the total capacity of the alternator at full speed, or 68 amps in my case, but that is a guess) subtract that from the total output of your alternator, and then compare your alternator's power reserve with the draw from the inverter with your application, to make sure you have enough total capacity with some margin. Mine would, based on this theory, run a 2 amp deficit. Or do what I do and run the application only intermittently so the battery gets charged up and the alternator isn't running at 100% capacity all the time, and never while the engine is idling.

If you are going to use this in your car while driving, the supplied cables are not going to work for you, they are too short. The inverter is not weather proof so it can not be mounted under the hood where water can splash up on it, or dust get into it. It needs to be in a weather tight environment with good air circulation, it also doesn't like heat. I took a pair of heavy jumper cables and soldered bolt connectors on each end and ran these to my cars interior. I added an in line 100 amp fuse in case of a short in the cables.

If you are going to use this on a battery only, there are formulas to determine how long the battery will supply the load you need - you can find the info with a goole search easily. It would most likely be worth your time to run the formula before buying, to make sure that you are going to get sufficient run time from the battery you have or plan to get. If frequent recharging is in your future, consider deep cycle batteries.

In summary, this unit works, within it's limitations, and I am happy with it. I would have given it 5 stars, but the Amazon description of the unit's true continuous run capacity should be more detailed than it is.

August 2009 - I see that the description has been changed so that it better represents the 800 watt continuous capacity. Kudos to whoever made that honest change!

The item arrived nicely packaged. However, when I tested it, it was operating out of spec. The spec for the device is 109 VAC (Minimum) up to 120 VAC. Regardless of the load it always put out 100.1 VAC. It did not matter if I had nothing hooked to it or something running from it. I also checked my battery with another brand of inverter that I've have and everything was working correctly. That inverter (Coleman) put out 114.1 VAC under the exact same load conditions and using the same battery.

THIS IS NOT SAFE because there are many devices that NEED between 110 and 120 VAC. Other devices such as light bulbs, etc would not matter. I have a desire to run delicate electronics with it (laptops, pellet stove, etc) and no way would I take the chance. I am returning the unit for a refund.

I do praise Amazon for shipping very fast and packaging it well. It is very rare to ever have to return anything to them. I hope the refund is equally as quick.

I bought the cpi 875 to use in case of a power outage, and it seems to power what I need pretty well, although I haven't had to use it for an outage quite yet. I already hooked it up to run a lamp and a propane heater that requires electricity to operate, and it did very well. Has a pretty low profile, so it sits under the hood with it closed, so that should be nice in case the outage is in inclement weather (which they usually are). I figured, instead of buying a generator and dealing with all that comes with those, I would use the Inverter to run some essentials, and just run the car every once in a while to charge the battery back up. The only downside to this unit, I would say, is that it doesn't have a voltage readout, and it doesn't come with a cigarette lighter adapter, in case you wanted to use it for small devices in the car. But, other than that, it seems like it will be very handy in an outage, and should also be nice in case I go on a trip and need to power something. Overall, definitely recommended, and at the Amazon price, it can't be beat.

I was looking for a way to run my home stereo receiver and two 12" speakers while tailgating at football games. This is perfect...I hook it up to an extra car battery and bam! *Instant Beats* This would also be great for camping or boating.
***I read the negative reviews before I bought...this item does not come with a "cigarette lighter" adapter. It only has clamps that hook directly to the battery terminals, the CPI 475 has both connecters but can only handle half the Watts.***

This converter works like a charm. I attached it to my pickup battery and ran an electric sawzall clearing small trees and branches for the power company to be able to run their line. I also ran an electric drill. (not at the same time)The cords to the battery are a little short which required me to balance it on the radiator, but it worked great. I'm thinking of getting another one, its very handy when you need more power than what a cigarette lighter can get you.

So far, I am pleased with this product. I bought it to use when I go camping and need to used an electric pump to inflate mattresses or rafts. Those higher wattage devices generally can't be run from cigarette lighter inverters without blowing a fuse. So I opted to get this one. I wasn't entirely comfortable with the idea of having to run it off my Jeep's battery, especially after reading all the warnings in the manual about potential damage to myself, my Jeep and the inverter if it's not done correctly. But lacking any other options, I gave it a shot. The directions say to have the unit powered off while connecting it, but the on/off switch uses symbols rather than words to indicate that the unit is off. For some reason, my unit shipped with the power turned on and I got the symbols mixed up, so I wound up hooking it to my battery while it was on. Still, I managed to get it working without damaging it, my Jeep or causing any injury to myself. The connection instructions were very easy and straight-forward. I feel more at ease with it, having successfully used it once, but it might not be for someone who is skittish about working under the hood of their vehicle. This device can't be used with a vehicle's cigarette lighter.

The pump I was using was about 400 watts, so the Cobra CPI 875 had no problem handling it.

I especially like that this was one of the few models that says it comes with a carrying case. After you take it out, sometimes you have to fuss with the wires to get them back in the case, but it's really handy to have the case to keep dust and various other elements away from the inverter while it's in storage or being transported in the back of a vehicle.

It's also cool that it has mounting options, though I would rather just put it back in the case when I'm done.

Purchased this for an emergency energy source in the event of a power outage. We have had three hurricanes through this way in five years each time with power failure for days. This inverter is compact but not too heavy and the instructions are simple and easy to understand. Cobra s attention to detail is evident in the construction and nothing about this is flimsy. A power on light and a warning light are a plus as well as the battery cables are very well made and all at a very good price.

This was my first time ordering anything from Amazon.com I have to say that i was truly please with this produce. I Needed the inverter because the heat in my car doesn't work. SO i needed to use a house heater in my car to keep warm. The only way for it too work was for me to buy the inverter and convert the power. Now the inverter (1600 cobra) supplies enough power to run the heater and keep my kids and i warm for the winter. SO if your looking for a good product i give this one an 8.

I use this inverter to run the lights and other small items like cell phone chargers, fans, can opener, etc., in my 18' camper. I don't have DC power and wanted to run lights when camping in widerness areas. I keep the inverter in one compartment and the marine battery in another. I knew ahead of time how much wattage I needed and bought an inverter that was more than capable of supplying it. If you think this has just enough power for your application then buy a bigger one. I did overheat this thing once by trying to run a small fridge and a large box fan on a hot summer day. I just shut it off for an hour and turned it back on(without the fridge) and it has worked fine ever since. I am very happy with this product and have used it quite a bit this last summer.

I purchased thi
s inverter from Amazon.com and noticed that it only produced 103.3 volts, and Now I am in the process of returning it and getting a refund. If you purchase this product, you should check the output voltage to see if its correct.