The thermocouple has read from -1 to -9 degrees from another, more accurate thermocouple. Even after running "internal calibration", the issue still stands. Data logging is flaky at best requiring ancient mobile applications that have no useable English instructions.

If you're looking for logging temperature, look elsewhere. Other multimeter functions are accurate enough, but logging issues for them still stand.

Dropped from 4' & now DCV not working - 1.5v to 1.7v batt reads 36V. Previous review = I'm a technician & have a used this & a previous version of this for many years. These DMM's are just so easy to use that they will spoil you. With this version you can blue tooth capture reading to your android phone to send to someone else. I haven't had to yet, but knowing I can send my readings to some one I call for support is very re-assuring when they could actually see what I'm seeing. Being able to prove the readings you've taken is invaluable!

TekPower TP9605BT:
This meter worked fine except for the feature I bought it for.
I have the older TP4000ZC multi meter and it works great using the RS232 interface and the old but useful logging software. I use a Trendnet USB to RS232 adapter with my laptop.
I frequently need to monitor and log 2 parameters simultaneously (Voltage vs resistance over time for example) so I bought the TP 9605BT to use along with my older meter.
This meter with its IR/USB and BT interface seems like a great idea but I couldn't get the interface working. The data to the laptop was garbled and never displayed what was on the meter.
I tried all baud rates, parities etc. and configured the USB interface and software to Com ports 1, 2, 3 and 4. (I used to build PCs and write software so I'm pretty familiar with the protocols).
I tried updating the USB driver and made sure the plug was properly attached and even checked that the optical IR interface was active (using an old Sony camcorder with nightvision I could see the led flickering).
I didn't see any instructions in the manual or on-line about using anything different than the default 2400, N, 8, 1 protocol and I tried it on 2 PCs with no luck so I sent it back.
I did receive a partial refund but Electronnix said there was nothing wrong and dinged me 10 bucks for shipping.
I'm sure they just turned it on, tested the dc metering or something and boxed it back up.
Hope you don't get this defective unit. It would be a great value if QC were better so I'm giving it 2 stars.

This product looks to be a solid multimeter but mine came with a poorly functioning rs232 setup which requires the rs232 adapter have pressure applied to it for it to transfer. I believe this was really just connecting a short on either side of the sensor but either way DOA on that part. Beyond that the instructions are horrible, any nerd will buzz right through them like normal china crap but at the end of the messy rainbow is not a great product its just a meh one, which works for a lot of applications but not for your day to day desk duty, get legit equipment with reasonable support.

The meter is fine.

Bluetooth and USB data logging doesnt work.

Tried password 0000 and 1234, sometimes pairs but bluetooth data logging is not working.

The USB connection at meter does not lock in.

USB data logging doesnt work.

Installed USB driver ok.

Installed datalogger.exe.

It launched, set Com 5 to 9600, 8 bits, 1 stop bit, no parity.

Doesnt record, screen doesnt change.

Very disappointed in software implemenation.