Battery technology and uses

19 Feb 2017

I received a trolling motor which produced 45 lbs-ft of thrust and decided that it will make a great project to mount to my wife’s kayak. This effectively creates an electric kayak.

When I completed the project using a galvanised pole that mounts the trolling motor out to one side of the kayak, I made the following tongue-in-cheek video:

https://youtu.be/wUmTNQVoLPo

The last laugh was however on me as on its maiden voyage the trolling motor caused a moment and tipped me into the river. The battery was destroyed and I also lost some fishing gear. I then had to rethink this idea and came up with the idea of producing some outriggers to make the “Boake-yak” as my friends dubbed it, more stable.

Electrical conduit connection
Electrical conduit connection for outriggers
Electric Kayak
The electric kayak, dubbed the “Boake-Yak” by my friends
Battery technology and uses

My father was an appliance repair technician and it always fascinated me to see how he stripped, repaired and then reassembled microwave ovens, washing machines etc.

I think it is also better for the environment to try and repair as much as possible. Manufacturers, however, don’t like giving out the circuit diagrams as they prefer to sell you a new appliance than for you to try and repair it, but here I show that: “there are ways and means to do it”.

By way of a bit of background, my wife bought a vacuum cleaner and after a few months, it no longer worked. I watched a few YouTube videos of how people disassembled them. I then was lucky enough to have a working unit on hand for comparison purposes. The appliance in question was the Dyson V6 portable vacuum cleaner.

Two battery vacuum cleaners, side-by-side for comparison

The comparison helps to visually see whether anything is broken and also to swap parts between the units. This allows one to follow a ‘process of elimination’ to find the defective part. In my case, I isolated the problem to the battery pack and more specifically, the charger board on the battery pack. I found that it doesn’t charge the batteries and two batteries had actually had their internal protective elements operate.

Testing each battery so see whether I get ~3.7V

I matched the two failed batteries, re-soldered the battery interconnections and then when that was done plugged the charger in. The red LED flashes for a few seconds and then goes off. This told me that the charger had an issue. I bought a new pack on-line fitted it and it is been working flawlessly ever since!

I will strip the battery pack for the good batteries and use them on other IoT projects.

A couple of lessons here:

1) If you can find a working comparison unit, it accelerates the fault-finding process.

2) YouTube is very useful for giving disassembly instructions and also describes some of the more common issues with that particular model. The ‘pulsating drive issue’ is commonly encountered when the filters are blocked on my unit, as an example.

3) If the red charger light flashes for a few seconds (visible from two plastic holes in the battery pack) and then no longer flashes the problem is with the charger and battery management system (BMS) which would be a challenge to repair. eBay the size in milli-amps and it will save you time and effort to replace it. I wouldn’t recommend opening it as it quite a challenge.

The battery charger and management system light (red LED) if this doesn’t stay lit during charging then it’s time for a new battery pack.