need a good obd2 data logger

Here's a buyers guide that the maker of Dr. Prius app wrote up: Hybrid battery diagnostic and repair tool for Toyota and Lexus

 

A dongle I've used with Techstream is the Tactrix Openport 2.0, which has a handy integrated data logging feature (which I haven't used, to be honest).

The dongle itself has a memory card slot. If you insert a memory card with a text file on it using a certain syntax to say what you want logged, the dongle itself will do the logging, onto the memory card. You can then take the card to a computer, or just plug in the Tactrix via its USB connection and the memory card shows up as a mass storage device.

If you consider buying a Tactrix, please buy it from Tactrix (it'll be around $169, last I checked). Like a lot of other vendors, they're up to their necks in counterfeits, but unlike some of the others, they're still a US company trying to make a go of their business, and it's nice to have them around. If you do a search and find cheap deals on it, you're feeding the counterfeiters.

 

There are reports of OBD2 readers toasting ECUs when they are left attached and the car driven around. So for your purposes I would definitely avoid no-name devices and if at all possible buy something that comes with a guarantee that it can be used in this manner safely. The previous post suggests the Tactrix, and given the price, perhaps that device has such a guarantee?

 

+1 for the Tactrix. While I haven't ever needed to connect mine to the Prius, it was very helpful for troubleshooting some other cars we've owned.

You really do get what you pay for.

 

My only experience of that sort had quite simply to do with the quality of the connector pins in the device.

I had one with unplated pins (or poorly plated, or plated with who-knows-what) that was rock-solid initially, but eventually got to the point where it would fill the air with immediate Uxxxx communication error codes just upon being plugged in to the car's diagnostic port.

As soon as I replaced the connector with one that had gold-plated pins, those issues were history.

Another thing that can happen, either from a lot of unplugging and replugging at the diagnostic port, or having something plugged in that bounces, is reduction of the spring force of the contacts, leading to possible errors. That's something I ought to think about; I've considered buying a cheap J1962 extension cable to plug in there permanently, and do my repeated plugging/unplugging at the other end.

I think the Tactrix hardware is good, but I don't know necessarily if they're up for guaranteeing nothing bad can happen to your car when you use it. I guess you could ask.

Another thing that can distinguish cheap OBD-II readers is how much power they consume while asleep. The ELM 327 chip (or STN equivalent) that most of them use does have a low-power sleep mode for when the car is off, but the surrounding circuit design has to use it, and there are more costly components involved to keep the sleep power as low as possible. So some of the cheaper dongles will noticeably drain your battery if left connected when the car is off.

(If I remember right, the Tactrix twiddles some colored LEDs when plugged in, which seems like a bit of unnecessary power, but I guess I've never watched it to see if it goes to sleep.)

My ScanGauge II, which is plugged in at all times (when I don't need to plug in something else) has a very good sleep mode, and has never had any untoward effect on any of the Prii I've used it in.

 

I did that, for that reason, when I was tuning my Subaru. Other benefit was to reduce risk to the USB connector. By getting it out of the footwell altogether it seemed like there would be less chance of a side-pull on the USB line.

Edit just to clarify- the USB line was in place because the style of tuning I did on that car involved logging direct to a laptop rather than using the memory card feature on the tactrix. If you are recording straight to the card this wouldn't be an issue.

 

Might consider trying the Hybrid Assistant app for android (is free). Does data logging and generates great reports afterward- mostly does info from the HV battery ecu but captures some stuff for the ICE as well.

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