I have an 18V milwaukee set and the batteries die faster than my older lower voltage batteries. People say its because of the increased heat thats put out by the batteries which kills them. Going even further to 28V scares me. But this is pure speculation on my part.
The 28V set looks damn nice though, especially the port-a-band.
I have neither used nor evaluated this too set, but the '28V' moniker stinks of specmanship to me. There may be real benefit, but I am not sure how much. I build battery packs for bicycle lighting and for small robot submarines, and have spent quite a bit of time looking over battery datasheets.
People generally associate higher voltage with more power, but as we all know, power is voltage times current. When all of your cordless tools are based upon the same 1.2V sub-C NiCd cells, the total available current is constant, so pushing to more voltage does mean more available power.
But now we are changing chemistry, which means that available current may be higher or lower, so the meaning of those voltage numbers becomes much less clear.
In general (and again, I don't know the specifics of the cells in question), Lithium Ion cells store more energy per unit weight than NiMH cells, and far more energy per unit weight than NiCd cells. They store roughly the same energy per unit _volume_ as NiMH cells, and again more than NiCd cells. But where Li-Ion cells fall down is on power delivery. Where a sub-C NiCd cell can be expected to deliver 20-30A under load (and in excess of 100A under load for certain 'racing' batteries), a standard Li-Ion cell of about twice the volume of that NiCd cell could only be expected to deliver 5A. The LiIon cell is perhaps 2x the volume of the sub-C cell, has 3x the voltage, and similar ampacity, so stores 3x the energy, while weighing less. But the NiCd sub-C cell can discharge much faster, delivering more power to the load.
Li-Ion is getting more powerful, and cheaper, and is much better for the environment...but I remain a sceptic.
I did some reading up on these when they first came out and its not a normal run of the mill lithium ion battery, they mixed in something else. Their web site says twice the run time as the 18 volt set at the same weight, battery & tool.
Haven't seen them out yet but hoping they are popular enough to bring the cost of the 18 volts down to close to discount now paying eighty dollars for a 18 volt battery. I have a kit with the Sawzall and Hammer Drill that have had batteries changed three times, seen the 18 volt Dewalt with more power on the drill than my Milwaukee.
Well I finally did it I bought the V28 set today. Of course when I got to the job site and opened it up It was used. It ended up working out good for me because now I could try it out being that they told me to bring it back mon. Anyways I was not that impressed with it I think getting the 18volt kit with the extra 2 batteries they are ffering now is more worth it. I'll end up with 5 batteries and 2 chargers for almost half the price what do you guys think?
Re: Milwaukee V28 Cordless set#53281 06/24/0506:22 AM06/24/0506:22 AM
This reminds me of the rigid 18V that I bought because everyone was saying how much longer their batterys would last then dewalt. Well I had a dewalt for 3 years and the batterys on this rigid DO NOT last any longer, plus the rigid charger with its little built in fan doesnt charge the batterys much quicker than the dewalt. The rigid sawzall is a pain in the a@@ to use as you have to hold in a safety button to even get the thing to start. When this rigid of mine gets stolen like my dewalt did, Im going back to dewalt.