lithium v/s nickle pros and cons....

[dacflyer]

i was at Home Cheapo the other day looking to possibly buy me a new battery operated drill.
i been using for many years a nicad powered 7.2v drill. (approx 15+ yrs old) i have rebuilt the battery pack several times, nicads never seem to last. always seems a cell goes bad in the pack.

so now i am looking to finally retire the drill.. Smithsonian museum might want it

i was looking for something compact and light, most of the new drills have heavy clumsy battery packs
12v 18v 24v, way over kill i think. i saw some other drills that were actually smaller and powerful, but they had small lithium power packs..

my question is how does the lithium battery pack life span compare to a nicad?
i have been told nicads can take about 1,000 charges before worn out.
what about lithiums ?


i know when lithium goes dead, the voltage just drops off suddenly,
nicads seem to slope off. nickles seem to do the same.

any advice on the 2 , before i make my purchase.
are all power tools going lithium now or is both here to stay ?

[hlreed]

I think lithium batteries will take over all tools. And cars.

[haklesup]

I agree, there are many up sides to Li-Ion Technology and the biggest downside will likely be engineered out before long. That downside is the tendancy of shorted cells to overheat and occasionally catch fire. This will be engineered out through per cell controllers (for larger packs) and better cell design (that is less likely to melt down) with improvred materials and construction methods. Eventually scale of production will bring the prices down to the level of NiMh at least (cost being the other downside) (it will take time because there is still huge demand for these cells especially in automotive and mobile devices)

The upsides, the most prominant one is more power density, you get more power in a smaller package that has less weight. A trifecta if I ever saw one. Other upsides include less envoirnmentally dangerous (no heavy metals) and single cell voltages that are more useful for 3.3 and 5V devices. THere also seem to be endless packages for these cells.

As far as discharge curves go in tools, the slow dropoff of NiCd isn't useful anyway, on a drill for example it may spin but with too little lorque to do any work. I doubt in use the different end of charge behavourrs will be distracting. I do know that tool manufacturters like cars took lots of time to characterize these cells and match them up with appororiate chargers and tool motors. IMO, since the cheapo chinese and harbor freights of the world have not gotten into this tech, the tools are generally well engineered and high quality.

However, for this year at least, the other batteries still offer a significant price advantage that a typical tool user will still find them attractive. For example, most Li-Ion tools I looked at were roughly 2X the price of NiCd tools telling me I can wear out two of the cheaper batteries before I pay for a better one. If the NiCd tool lasts +2 years (like my last one) I think its still a good value. If however you use it often the longer ruin time, lighter weight and faster charge time of the Li tools would be preferred. Furthermore the NiCd tools tend to come with 2 batteries while the LiIon ones often only have one and you are left to buy a second in a seperate purchase. For many, the imporoved power to weight ratio is enough.

I don't think these batteries have even reached their full potential, I think further engineering will make better ones before the race is over.

[dacflyer]

good info..
the tools i was looking at, had 2 batterys in the package.
one to use while the other charged up.
it was a light weight 2 speed hammer drill. was not big at all.
claimed to have all the power of a large unit.
i forget the name brand. red case color.
anyway i may buy it, try it, if not then return it..
dewalt looked nice, but it was crazy priced.

so i guess lithum is the way to go now days..ok

[MrAl]

Hi,

Most of the stuff i use these days i use Li-ion for but i have a couple things that still use NiHM which can use the Nickle Zinc.
I meant to switch over a while back but havent gotten to it yet. When i do i will know more about these cells. That's if the higher voltage doesnt actually cause a problem in one of my lights which i use a lot.

When i purchased this set i was sure i was going to use them right away
That was a year ago.

[haklesup]

Lithium batteries are not rechargable but Lithium Ion (Li-Ion) are rechargable among other lithium technologies. Here are a few somewhat useful comparisons of different battery chemestries albiet each is incomplete in its own way

http://en.wikipedia.org/wiki/Rechargeable_battery
http://michaelbluejay.com/batteries/
http://michaelbluejay.com/batteries/types.html#nizn
http://www.powerstream.com/Compare.htm
http://robocup.mi.fu-berlin.de/buch/cha ... ttery.html
http://www.powarider.com/pdfs/EV_Battery_Comparison.pdf
http://iccnexergy.com/battery-chemistry ... son-chart/

[dacflyer]

sorry i was referring to the rechargeable lithium-ion packs...

[haklesup]

sorry i was referring to the rechargeable lithium-ion packs...

No need for apolgies, I was elaborating for the audience not necessarily correcting you. In fact I think it would be great if we could expand on these tables to create a comprehensive table of battery types and properties, charging methods, etc. Just creating the rows (battery types) and columns (properties to be cross referenced) would be a big step forward in understanding what there is to pay attention to.

[Rodney]

The biggest disadvantage of LiPo's is the fact that they are easily and almost always ruined if they become deeply discharged. You want to make sure that they never get discharged below about 3 volts/cell else they become garbage. I do not know if the tool makers have the units designed to prevent the user from deep discharge or not. We (radio controlled modelers) use the LiPo's a great deal and you will find lots of good advice on their care and use on the various RC forums. Now, most of the tool makers use a similar battery like the A123 LiFe's which are more rugged and can withstand more abuse but are more expensive and have more mass per watt hour capacity than LiPo's do. Also, LiPo's can be a cause of fire if accidentally shorted out or overcharged, they do not explode but do provide a very hot fire with lots of obnoxious if not somewhat unhealthy smoke.