Aili Battery Monitor - a potential 'gotcha'

wildebus

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I know a lot of people have these Aili Battery Monitors and they are pretty good.

I have supplied quite a few and not had any problems, but the last one showed some strange behaviour and I thought it might be worth sharing as others may find this happening to their Monitors at some time ....

What can happen is that the monitor shows spurious currents on the display when you know there is no current going on and this is very misleading - especially when the monitor shows a charging current when there is no charger attached!
I supplied a full setup to a customer and he took the following video of the Monitor connected to the Poweroad Infinity Subzero Lithium Battery.

It is a very short 7 second video, and shows a fluctuating charge current of around 0.2A into the battery (you can tell it is a charge current because there is a little arrow pointing up with a "+" in it and the backlight is flashing, which is a characteristic of this Monitor).

If you pause the video and look at the installation you will notice that there is this charge current happening even though the only thing that is connected to the Negative Terminal is the Shunt and only thing on the Positive Terminal of the Battery is the shunt again.

Have we discovered the electrical equivalent of Perpetual Motion? Sadly not. This is obviously not correct and this is the reason ...
These Monitors come with one of three different Shunts - image below (the one in the video is the 350A version)
1614118673384.png
The problem was that the -ve connection to the Monitor was a bit poor and that caused the monitor to misread. The -ve connections come from the Shunt of course and this is connected via the screws that secure the little PCB to the shunt - the screws you see on the different shunts above. If either of these screws are loose this problem can occur.
(initially I thought it could have been electrical noise interference from the BMS or internal Battery Heater but we eliminated that as a cause).

To resolve is very simple - just tighten up the screws! Now I have never had this problem before so I would not say it is common, but something to watch for. If you want to go belt and braces I guess you could apply a dab of locktite on the screw to make sure it doesn't loosen off over time with vehicle vibrations?

Anyway, that is it. Thought it useful to share for Aili Meters users :)
 
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Also worth pointing out that to turn off the backlight (especially at night) you just press the 2 outer buttons together for a few seconds. Repeat to turn it back on.
Dave.
 

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