NICADS are successful consumer batteries because they're able to take abuse.
Li-Ion type require that you give careful attention to the range of operation you subject them to. To my understanding you must avoid charging or discharging them outside a certain voltage range. Cells from reputable manufacturers have built-in protective circuitry. There are corner-cutting manufacturers whose cells are substandard.
If you monitor voltage of your Nicads when running the drill, voltage drops 50 percent or so (in heavy use). Yet it doesn't harm them. Their bulk allows them to carry a few Amperes (C size or bigger). They heat up a bit in use or charging. It doesn't necessarily shorten their useful life.
Li-Ion are the type in news reports for causing fires and explosions.
To stay within their intended operating range I imagine you'll want 2+2 series-parallel. Keep track of their temperature during use and charging.
The company is the world’s best replacing nicd with lithium ion supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
Are you interested in learning more about e bike battery suppliers? Contact us today to secure an expert consultation!
Substituting battery types is a complex subject. But like Chuck said, don't throw a lithium battery pack in your laptop or bad things will happen.
It would be safer and easier to use nickel metal-hydride (NiMH) batteries if you're unable to source NiCD replacements. While the characteristics of these two battery technologies is similar, they do have some important differences that may affect the life of NiMH batteries in a device expecting NiCD. NiMH batteries have a higher impedance and can deliver less current than NiCD batteries (NiMH batteries are more about capacity and generally have a lower maximum current output.) Another issue is that NiCD batteries are more tolerant of overcharging and many NiCD chargers usually push a constant float charge which can overcharge NiMH batteries.
You can try a direct swap of NiCD with NiMH and see how the new batteries perform. I would attach a volt meter across the pack to monitor the voltage and make sure it doesn't get too high. The worst case scenario with NiMH is the batteries would vent and leak.
Going the lithium battery route would be far more complicated, not only because the cell voltages are very different (1.2-1.5v vs 3.6-4.2v), but also because lithium batteries require protection to avoid them going on fire or exploding. If the laptop had any sort of smart monitoring of the NiCD battery pack, you'd have to build a complicated translation circuit to interface with a lithium protection circuit so it would know what the battery level was and if it was safe to charge.
It would be easier and safer to buy a ready made external lithium battery bank and use a buck/boost converter to get the required voltage and just power the laptop externally via the DC jack.
For more information, please visit lifepo4 nominal voltage.