Hi,
I have been offered some NiCad batteries -they have been used in an emergency backup system. The batteries are flooded and they seem quite good value.
How can I tell if these batteries would be good for use in an electric vehicle.
Are all flooded NiCads likely to be suitable or do they need to be specifically designed as traction batteries?
Also, any information about how to charge these batteries would be useful.
I have an outback MX60 charger which I can incorporate in a charger for these - any advice?
There is not enough information in your post to give you a good answer.
Who is the manufacturer of the cells?
What is the size of the cells or the AHr capacity?
Are there enough to make a sizeable pack?
Flooded NiCds were/are used in full size EV’s. Pack size and capacity are going to be the limiting factors.
They exhibit something called “negative temperature coefficient” (NTC), which means that as they get hotter, their resistance goes down, causing more current to flow, which makes them get hotter, which makes their resistance go down, causing more current flow… you get the idea. Then they melt or go “BOOM!”
It is very difficult to determine end-of-charge with NiCds. The voltage will drop very slightly, and the temperature will begin to go up, then you need to reduce the charging current IMMEDIATELY or the temperature will spiral out-of-control.
The very best NiCd chargers will monitor the voltage and temperature of each cell, and change states whenever ANY cell appears to be fully charged.
The other alternative is what’s called an “equalizing charge.” It charges them with a small current (5% of their ampre-hour rating) over a long period, until you are certain they are all fully charged. Then you discharge them fully, then you can use a faster charge (typically, 20% of aH rating), because it is unlikely that one will be charged before the others.
NiCds are perhaps the longest-lived batteries out there – they’ll last thousands of cycles – but they have a bad reputation because so many people destroy them with poor charging.
I’ve recently obtained a bunch of SAFT 180 aH batteries, and so have been doing a lot of research…