One Man's Adventures into Renewal Energy
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LiPo Battery Construction

23rd April 2019

It's about 5 years now from when I first built my mower and I've begun to notice a drop in performance. I used to easily be able to mow my garden with a single charge but this is now proving difficult.
The battery is knackered!
This isn't a surprise really as Lead Acid type batteries are really only capable of lasting for approx 3-5 years.
Considering the abuse I give mine, what with the deep discharges, I'm surprised mine has lasted this long.

Obviously I now need to replace my battery. I'm gonna take this as an opportunity to overhaul the whole battery design with a view to improving battery capacity and power.
LiPo is the obvious choice. More power, more capacity. Huge improvement on power density when compared with Lead Acid.
They aren't cheap though, especially for the branded batteries.
To save on costs, I've managed to get my hands on a load of old laptop batteries...

Basically a mixture of old laptop batteries. Acer, HP, Dell, Asus
I'm gonna rip them apart and see what we find!

Old Laptop Batteries

In our first battery I find some Samsung ICR18650-26D Batteries.
These are good quality cells - all were around 3.55 volts.

Samsung ICR18650-26D

A bunch of Pham4pe 105446 cells. I've trawled the internet but cannot find any info on these cells.
4 cells were around 3.55 volts. 2 cells were at 2.4 volts. I don't want to use any cells that are less than 3 volts as chances are they're no longer viable, so I've discarded these.

Old Laptop Batteries

In our next surprise package we find 6 x LG LGABD11865 cells.
4 were at 3.55 volts, 2 less than 3.


In our next package we find 6 x LG LGDAS31865 cells.
All were less than 2.5 volts. Difficult to say if they are just crap cells or whether they'd been sat in a discharged state for too long. Anyway - I discarded all of them.


Next package we find 6 x Panasonic CGR18650D cells.
4 at 3.5 volts, 2 less than 2.


I'll probably get ridiculed and cast out from the battery community for this, but I've decided to mix up the cells to create my battery, despite different manufacturers, mAH ratings, etc.
There's a school of thought that says you should never do this, what with the risk of fire/explosion/death, but I like to live life on the edge!

Old Laptop Batteries

So here are all my cells nicely glued together. If you're clever, you can probably tell I'm gonna go with a 4S4P battery configuration. This should give me an output of around 16 volts.

Old Laptop Batteries Old Laptop Batteries

Here is wiring diagram for a 4S4P battery configuration...

4s4p wiring diagram

Here is my completed cell. I used 2 x 1.5mm wire to give me a total of 3mm gauge. This should give me 17amps max current.

Old Laptop Batteries

I've connected the cell to my LiPo battery charger. There is a lot of discussion about how to safely charge LiPo batteries. The general consensus is you should use some kind of balancing circuit. To this end I've ordered a 4S4P balancing circuit from Ebay. It's not arrived yet, so thought I'd try charging without this. Using the charger I'm pushing 4amps into the cells. It's charging with no issues - nothing is hot or even warm.
After a couple of hours it was fully charged.

Old Laptop Batteries Old Laptop Batteries

Next - Solar Lawn Mower Motor


Local witty slag - 23/04/2019 13:35:02
I fell asleep halfway through this. Was that the intention of the article?


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