Ecomower Battery Upgrade
14 Oct 2015
Finished 'test' version. (Minus balance lead which I added next).
I've just finished building a replacement battery pack for my Ecomower.
The original battery pack consists of 2 12V 10Ah Gel batteries which I got second hand via TradeMe.
The new pack consists of 84 recycled laptop cells (18650s Lithium-Ion) wired as 7 series groups of 12 parallel cells for a nominal voltage of 25V and 21Ah giving roughly 500Wh - or twice the capacity of the old Gel batteries when they were new. And it weighs 2 kg less than the Gel pack.
As you can see they are perfectly sized for their box. Lucky.
Next: add a BMS (battery management system) to help keep the groups balanced and to protect from over-discharging. In the meantime I'll use a balance charger to charge it and stick a Lithium cell monitor on it to warn of low voltages.
I tested it in the Ecomower and it worked great - but the cells are currently not charged so I'll charge them over night and mow the awn tomorrow and see how it performs in a real world test.
I'll give some more details on how I built it over on my Reusing Old Laptop Batteries page.
This is part one of a larger project to see how much can be done with recycled laptop batteries. Currently our local IT recycling center receives about 1000 laptop batteries a month - which they then ship overseas to be processed. I'd much rather see them re-used locally.