Sunday, June 14, 2020

Motorcycle cheap Aliexpress clock voltmeter thermometer

Hello, this time I want to rant about this cheap thing I bought for my motorcycle:

Picture stolen from an Aliexpress user

This is actually the second one I buy. The one I bought first cost me double and was a double piece of shit because it was so dim, I couldn't see shit while riding during the day.

The one I bough this time has the looks like the one in the picture, a fake Rizoma. It's funny because looking at the pictures of the users, it seems like each one gets one slightly different. The white letters, the size and the package differs from one user to another.

Anyway, I wanted to share some measurements I made to check how shitty these things are and this is what I found:
Voltage measurement: Resolution is 0.1 V. The measurement seems to be off by -0.1 V consistently across the hole range. 

Opinion: This maybe caused by some diode in series to protect against backwards connections. Considered how easy it is to achieve a proper 0.1 V resolution voltage measurement, this shit is totally unacceptable.  

- Temperature measurement: Resolution is 1 ºC. The measurement error differs but generally it's 1 to 2 degrees off the right value.

Opinion: The temperature is sensed with an NTC. Considered how easy it is to achieve a proper 1 degree resolution voltage measurement, again this is totally unacceptable.  

- Current consumption during operation: approx 30 mA.

Opinion: This really doesn't matter much, 30 mA is the typical power used by a multiplexed LED segment display plus some bits of circuitry more. Nothing new here.

- Current consumption during standby: approx 3.9 mA.

Opinion: This is absolutely huge power for standby. This can empty a full 6 Ah battery in a couple of months. This is not a surprise though... A regulator that can achieve standby consumption in the uA range is expensive, no way this was going to fit it.

The specs of this cheap shit are completely out of the acceptable and the performance is pretty poor. This piece of crap belongs in the bin. 

However did I installed in the bike? Yes. 2 simple reasons:
- This cost under $4 while the original Koso Mini 3 is near $100 or in some places even more! Unfuckingbelievable! 
- There seems to be no better alternative that has the 3 features of this one for a reasonable price of let's say, maybe $15 or $20. So, I think I'll live with one this for now.