KW650 Enhanced 6V 12V Car Battery Tester

I've been having some doubts about my fairly new car battery (Interstate, 700CCA) recently and wanted to make sure I test it before taking it back to the store. I am aware that batteries will lose charge if the car is not used for extended periods of time (which is my case due to WFM for months), but I was thinking that it would take much longer to a new battery to get there, maybe at least 1-1.5 months, especially in nice weather. I have been driving my car about every couple weeks or so, but mainly short drives. I thought that maybe the battery I picked did not quite happen to be the pride of Interstate product quality. Since I've wanted to own one of these battery testers for a while now, I figured that this situation would be a good time to get one, so after looking through several models to get familiar with the common feature set offer vs. cost, I settled to this Konnwei KW650, even though I was a bit reticent about the brand unknown to me. There are a bunch of these testers available, many of them offering similar if not identical feature package, even though the prices differ a lot in some cases, but the reasons that made me go for this one were the nicer processing speed and display, car starting voltage waveform capture and the software update capability. I figured that my risk would be minimal considering all the good reviews and Amazon's easy return policy. Well, I must say that I am very happy with my choice; this one is a keeper. After updating the software as soon as I received it, which was pretty easy to do BTW, I checked my battery and found that even though it was in a pretty badly discharged state, the tester showed that the battery was in very good condition and just needed a good charge. The state of health was 100% and the state of charge was shown to be only 10%. I have also tested a known weak battery I had stored until I can find the time to dispose of it. I tested it both before and after charging it, and in both cases it indicated a very low state of health and prompted replacement. I was planning to rent a professional battery tester and check the full instrument accuracy for parameters like the battery resistance, SOH, SOC, but at least from what I am seeing so far from my tests (lead-acid battery only) everything makes sense. The voltage measurement had only a small accuracy deviation of 0.06-0.1 max over a wide measurement range when verified against a professional meter, but that is meaningless for the purpose of this tester. The voltage ripple was also slightly off, but you can see some of that even when comparing more expensive equipment. The min/max voltage captures during engine start were also reasonably accurate. Considering the cost and intended purpose of the device, I believe that it is more than adequate for the job, and in my opinion, paying any more for a known brand would not be justified from the performance stand point. At least not for my home garage use. In terms of workmanship, I have nothing to object: It comes in a nicely looking plastic case, light weight and just the right size to hold with one hand, clear color graphic display with an easy and intuitive user interface. It has thick yet reasonably flexible 38 inch cable to protect the 4-wire Kelvin test leads, with solid connections to the battery connection clamps. I wish the cable were just a bit longer to reach the vehicle cabin when performing some of the tests more comfortably from the inside, like the car charging system. Not a deal breaker, because these tests are still easy to accomplish, but it would have been more comfortable that way. Now the one feature I was hoping to have on this device, was to be able to factor in the battery temperature into the CCA measurement and SOC calculation, as temperature is a huge factor in battery performance. Again, not a deal breaker at this price for me, but since most higher end devices can compensate for temperature, I believe that it would be a great feature addition and a cheap way to gain an edge over the competition. I wouldn't expect the addition of a battery post temp probe/sensor (although I would actually pay for the cost difference) but at least by manually entering the batt. temperature during battery test setup. Since the software can be updated online, I am hoping that this feature can be added later, and perhaps along with some other good things in the future. Who knows, maybe Konnwei is listening.

Seems to work fine. Uncomplicated for one with very limited mechanical skills. Recommended by a friend who taught auto shop at a community college.

Work's great I checked my battery with this device and it was easy to use and it was accurate it showed that I had a bad battery cell when the dealership said I had a good battery I went to Advanced Auto and got a better battery and warranty plus they installed it free. I recommend this device.

Love the device, until I got to the check charging feature. I see how it is suppose to work on Youtube. Mine gave me idle voltage, asked me to accelerrate RPM for 5 secs, hit enter- and it flashes the screen for a mirco sec and goes back to the home page. The other reviews appear to have come out all on the same day- something smells fishy. Got on the web page to see if there is firm ware update, and this model is not even listed. Come on guys- dont sell something that is not ready for market. Update: I heard back from the company pretty quickly. (thats a plus). They told me to upgrade my software (they admitted to a bug). Software update was not listed for this model, tried it anyway, got an error that the unit was not able to communicate with there software. Waiting to hear back. So,in summary, the unit does not work as advertised, there is a bug in the firm ware of the unit, and there is a bug in the update software. I have spent about 6 hours on this- Ill give them a week to see if they can sort it. The unit seems to do what the others do with a better look, plus the wave form feature. If they can fix this, I would like to keep it. Third Update, I started with one star for the reasons stated above. The company was pretty responsive, and finally told me the update software could be located on a different website than there initial email. I successfully updated the software, and I am now good to go. For the price point, this device is fantastic, with its wave form feature, it is in my opinion the best. It would be nice to have a longer cord (I would pay more for that option) but the cord is sufficient if you keep the unit under the hood. Very well thought out screen icons, and nice back lighting (compared to similar models)

Simple to use and gets the job done. Wanted something that was not overpriced, with good features and the ability to test a variety of batteries, alternator, and starter condition. After using this on several vehicles and batteries I have learned how the resistance of the battery and expected life of battery work. The feature for running voltage and ripple current graph have become very handy during load test. The starter crank test and time have helped find two starters that needed to be replaced. The screen is easy to read, menu functions are simple to navigate, and battery clamps / wire are of good quality.

I got this for a truck I was working on & it turned out that battery was OK. A couple of weeks later the battery died in another vehicle. This came in handy. Even not connected to USB and with a battery voltage under 8 volts, it powered up. I input the type of battery and cold cranking amps (CCA) and it showed the battery was only at 3%. When I tested the replacement, it came in at 97%. This was a good value for a handy tool to have in my shop.

Works as it should, and you don't need batteries!

Model KW650 not accurate at all. The company responded saying possible human error or environment variables... or firmware update. I was getting doubts about the readings, first battery check in-vehicle the CCAs, resistance are around 40-50% lower than normal. Then cranking test, taking around 6000 msecs (6 seconds) from ignition to idle. Then ran same test again with a fresh battery... 9 SECONDS! and also along this reading the min and max voltages showed high values. Not logical, if it tok longer to start then the battery should be low voltage. Stopwatched the cranking time... 2 seconds from ignition to idle. Total garbage. **UPDATE** purchased Topdon BT100 battery tester to compare results, this Konnwei calibration is way off the normal.

This seems to work pretty well. Just be aware that it doesn't test AH as seems to be inferred by the product description.

use it daily in my job for about a year now works great. still makes it easy to check batteries alternators and starter draw just not sure which battery setting to use on deep cycle batteries. with reserve cap specs

Works fine on 12 volt batteries, I purchased it for test 6 volt rv batteries ,does not have anyway for selecting 6 volt in the menu , so the tester claims they have bad cells when if fact they have nothing wrong with them.

Works well. Nice and compact to keep in my tool box. Tried it on 6 volt and 2 volt batteries.