36V Tools

[Handy Al]

As Tim the Toolman says "More Power"

http://www.dewalt.com/36v/

[gjbivin]

Of course, the ultimate goal in this war of voltage escalation is to achieve 110 Volts! That kind of voltage exceeds current practical battery design; an attachment to distrubuted power (e.g. house wiring) would be necessary.

[LCHIEN]

higher voltage battery packs

Just an Electrical Engineer's view of battery pack voltage wars -

Battery packs are made of standard cells. The first thing to remember is that only a few comapnies make battery cells, no tool company makes cells, so they have to engineer battery packs using an integer number of cells.

Since cells come in standard sizes (specials can be made but they cost more that way) generally the cells are 1.2 volts and the sizes have specific amp-hour capacities which are more or less the same and proportional to size. The bigger ones are slightly better amp-hours per cu in because of packaging efficiency.

Thus a tool/battery pack designer starting off with a 12V 2 aH pack
would be using 10 cells of 2 aH each.

So he can increase the number of cells (the motor design has to be made for the voltage used, but remains more or less constant for torque vs. size and power). Which means the aH stays the same but the voltage goes up and the size goes up proportional to the number of cells. So work being the product of aH and Volts the work done per charge increases too.

At some point to keep the battery pack from becoming too large the designer will drop to the next size smaller cell, maybe 1.5 aH which will make the pack smaller by about 25% yet provide similar work compared to the original 12V 2aH pack.

so Performance and work (being like the number of screws you can drive on a charge) can remain the constant.

What is the benefit of higher voltage then?
one advantage is the wiring gets smaller because the amps to deliver a given power/torque drops. Or use the same wire gages and make the motor have higher torque.
Until they chnage to a smaller cell the work capacity goes up

Disadvantages of a higher voltage pack
well, volumetric efficiency goes down because the pack devotes more space to battery connections. so there's physically a smaller precentage of battery pack volume to actual battery chemicals that do the work.

I think an underrated thing is the reliability -
A 36V battery will have 30 battery cells and 60 terminal connections to fail. Also given that the batteries are in series, the failure of any one battery will cause the pack to fail - So given that the cells have a certain chance of failure, having twice as many cells will make it twice as likely to fail or half as reliable. so I'm predicting that a 36V battery pack will have half the relibility of a 18V pack. Anyone betting on their battery pack reliability lately?

In reality its probably not that bad, a 36V pack would likely be made of smaller capacity cells to keep from doubling the size and weight and the smaller cells probably are more reliable than larger cells. Still, I would expect 36V packs to be significantly less reliable than 18V packs/

[Wood_workur]

HA!! they have a 36v flash light. Just about the second stupdest tool I have ewver seen. (beding some of the dremel attachments).

[Hellrazor]

Lets hope for a 36v caulk gun...

[steve-u]

I think that such tools look pretty heavy with those battery packs. Maybe it is time to use a deep cycle marine battery and power invertor or generator and corded tools. Probably cheaper than buying a couple new 36V batteries anyhow. --- Steve

[vaking]

So, now we have razors with 5 blades and tools with 36V batteries. The one who dies with the most whatever wins.

[drumpriest]

Loring, thanks for that post. I was thinking along the same lines, that interally there are many more connections to corrode, or fail from the battery being dropped. Too often I've had to take components apart to fix a cold solder joint, or a corroded terminal (Other electronics, I don't often mess with tools). I would agree with you, I think they'd be more prone to failure.

[Russianwolf]

The same philosophy I have on cars works here. The fancier they make them, the more things that can go wrong on them.



2003 Saturn with Power Windows, Locks, Mirrors, Brakes, Steering, ABS Airbags, et al.

1970 Jeep J4000 with ................ I'll find something.

Which one do you bet breaks first?

[rman]

36 Volt Satisfied User

Ok so there is always the I got the bigger better Faster etc. tool. But this time dewalt is using lithiun ion battery packs that they guarantee 2 years!
I purchased the combo set from lowes with a 10 percent off coupon and no interest or payments for a year. Now the good part the circ saw is 7.25 inch regular blades with a tooless arbor (Finally a great improvement) , I have used this saw verses my PC corded 7.25 saw on a week long deck project and after all the dewalt wins!! No Cord about the same weight and did I say NO CORD! I used the saw for over 3/4 of a day cutting deck stuff and then did the battery get tired (I also need the break) But no hessitation cutting stock and the blade brake is almost instantly activated after I released the trigger. So far a very expensive tool but does perform as promised. Now I'm waiting for that 1000watt getto blaster or microvave oven for a real test for the 36 volt battery. Btw there is a flashlight with the kit that is suppose to last for 8 hours on one battery (No info on bulb life and should have come with a spare) But the people in hurricane season may find this usefull.

[gjbivin]

One consideration to take into account is that voltages over, say, 20V can give you a shock, whereas lower voltages can't push enough amperage through skin resistance to be felt. You can put your fingers across a 9V battery or even a 12V car battery without feeling anything. But I've been grabbed rather painfully by 40V. A 36V tool itself will be safe enough, but if the battery has exposed contacts when out of the tool, be careful of how you pick it up.