power tool battery size?

GoodRevrnd

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Dec 27, 2001
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I have useless power tools and decided to get some decent ones now, probably Makita. My instinct is to just go big and get 5ah batteries, but frankly I know I'll never need all day power and should just get 3ah or whatever. However, if I get dual battery tools down the line like a blower an I going to regret not having the 5ah?
 

Greenman

Lifer
Oct 15, 1999
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Depends on the tools. 3 amp hour is the smallest I'd buy for pretty much any battery operated tool, but I use the hell out of them.
The far more important consideration is what ecosystem you're buying into. Makita is pretty good now, but some years back they were having an issue with battery's dropping dead. I dumped them at that point and went with DeWalt, and now have far to much money invested in that system to change.
Stick a 9amp hour 60v battery in an impact driver and that thing will run for days. I won't be surprised when they come out with a battery powered arc welder.
 

Micrornd

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Mar 2, 2013
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I have useless power tools and decided to get some decent ones now, probably Makita. My instinct is to just go big and get 5ah batteries, but frankly I know I'll never need all day power and should just get 3ah or whatever. However, if I get dual battery tools down the line like a blower an I going to regret not having the 5ah?
I have always had Makitas. For the heavy amp draw tools, I have the heavy (amp-hour AND weight) batteries. For the lighter draw tools I keep the smaller batteries.
Nobody really wants/needs the weight of a 5 amp-hour or bigger battery on a 3/8" drill or 1/4" impact driver, especially when a small battery lasts longer than it takes to charge a small battery on a tool like that.
So I keep 1.5, 3 and also larger batteries and a couple chargers.
I just don't see the use of lightweight tools, if you are going to burden them with huge heavy batteries. ;)
 
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shortylickens

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Jul 15, 2003
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For most carpentry projects I have been more than happy with low capacity batteries.
For yard work I have generally preferred the highest capacity battery I can find.

(Bosch)
 
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Red Squirrel

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May 24, 2003
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The standard batteries tend to be fine for most power tools like drills etc. For the bigger tools like say a chainsaw the higher capacity is a good way to go. I bought a Ryobi chainsaw that runs on the One+ batteries and I went through about 3 2ah standard batteries to cut up one big branch. The cool thing though is that I always had two of them on charge so by the time my last one died the other one had a decent amount of charge left to keep going. Was fully solar powered too as I was charging them in my shed.

Either way it's good to have at least 2 batteries so you can swap. For something like a drill, by the time you go through a battery the other one will be charged.
 

mindless1

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Aug 11, 2001
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It depends on how much lighter weight or a more compact size is important to you.

Typically any pack 4Ah or larger is going to use two parallel series of cells which (all else equal) doubles the current capability of the pack, and likewise above about 7Ah you'll have triple parallel cells. This is not a rule as some manufacturers venture into use of cells other than 18650 size with varying per cell capacity, but it's true more often than not, a general range which determines how many series of cells are in parallel (research it for the tools you are interested in).

With smaller tools this may not matter, except that as you get lower and lower in pack voltage as it drains, the tool will still have lower and lower performance, though this impacts brushed motor tools far more than brushless.

It means a longer battery lifespan. If you have a double capacity pack you only have to charge it half as often to get the same work done, so you're buying new packs less often, though practically speaking there is also Li-Ion shelf life meaning you can't extend that indefinitely, may not get over a decade out of a pack before it gets weak even if you barely use it.

The only time I would get the smaller capacity packs (over at least medium capacity is if the intended purpose is a trade where you do a lot of overhead work and the weight savings saves your arms and back. You can get multiple smaller packs and swap them as needed, but unless you need a break anyway, it's better to not have to go back to the charger to do a swap... if you're too tethered to the charger location, did you really need cordless?

Depends on the tool, you can own BOTH higher and lower capacity packs. Some things like leaf blowers or saws, really need the larger packs to work more than an hour (if that) continuously, won't run close to all day on a 5Ah pack. Even a 1/2" drill or impact wrench won't go a couple hours continuously on 5Ah if you figure a load running at 50% duty cycle. Li-Ion packs are great for cordless tools but they aren't THAT energy dense.

Batteries are sold separately so you can go either way and end up with the mix of capacities that suits your use, once you've hand some hands-on time to determine which you need more of... but if you plan on only buying a set and using the batteries that come with it, do get the higher capacity batteries.
 

bigi

Platinum Member
Aug 8, 2001
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It really depends on which tool in particular. 3Ah seem to last forever for Drill/Small impact. Angle grinder will eat those very quickly.
Brushless is the way to go these days. I am a Makita guy as well.
 

Greenman

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Oct 15, 1999
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It really depends on which tool in particular. 3Ah seem to last forever for Drill/Small impact. Angle grinder will eat those very quickly.
Brushless is the way to go these days. I am a Makita guy as well.
Brushless tools are more susceptible to moisture damage than brushed tools, and are a pain in the ass to repair. With a brushed tool the breakdown is almost always the brushes or switch. With a brushless tool there are several points of failure and no quick and easy way to determine which component has failed (unless it's like the last one I took apart, the mass of melted plastic was a dead giveaway).
All that said, I like using them, more power, better battery life.
 

mindless1

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Aug 11, 2001
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^ Yeah it often annoys me when someone mindlessly states that brushless have longer (tool) lifespan, when it is obvious they are just repeating some urban myth.

Brushless has efficiency and (expecially near end of battery capacity) performance merits but longer lifespan expectation isn't one of them. Brushes are cheap and relatively easy to find. Brushless controller boards, not as much.

One other issue I have with brushless is they tend to work in steps. It is usually much harder to modulate a low power output with trigger use on a brushless tool. Multiple speed settings helps, but is a sign of the issue rather than the same amount of control. Meh it depends on what tool and what you're using it for. I prefer brushless for the advantages over the disadvantages, but not if the cost difference is much... and still comes back to the first few generations of any tech being in infancy stage and getting better with time.
 

bigi

Platinum Member
Aug 8, 2001
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Brushless tools are more susceptible to moisture damage than brushed tools, and are a pain in the ass to repair. With a brushed tool the breakdown is almost always the brushes or switch. With a brushless tool there are several points of failure and no quick and easy way to determine which component has failed (unless it's like the last one I took apart, the mass of melted plastic was a dead giveaway).
All that said, I like using them, more power, better battery life.

OT much?

I find your post very irrelevant. Even if this were the case, which would require a lot of underwater exposure, you just get a new tool.
 

Greenman

Lifer
Oct 15, 1999
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OT much?

I find your post very irrelevant. Even if this were the case, which would require a lot of underwater exposure, you just get a new tool.
It's very relevent to anyone buying battery opperated tools. Brushless tools cost more, and along with the improvements to power and battery life there is the issue of increased complexity and fragility. I use my battery opperated tools every day, often outside in less than perfect conditions, from hot sun to light rain. It's important to understand what conditions will affect your tools, and the cost of those affects.
 

mindless1

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Yeah, I still have an old Craftsman 7.2V NiCd drill, that I used hundreds of times a day in a trade 25+ years ago, but I'd have to rebuild the battery packs again which isn't worth the bother. I should probably throw it away but. It. Still. Works.

There's the flip side of robust tools, and I wouldn't necessarily consider a 7.2V Craftman drill all that robust, just didn't have any weak early failure points. If the manufacturer changes the battery mechanical interface or voltage, eventually stopping production of the old packs (and 3rd party packs are generally crap and don't support THAT far back in time) then it may make them obsolete even for tasks they were still capable of.

This is one reason I have several Ryobi tools, both brushed and brushless, because they stuck with the same battery mechanical interface for so long, though some of their newer tools are current limited unless you get their newer generation 3Ah/6Ah/9Ah packs that they cleverly integrated additional contacts on while keeping both them and the tools backwards compatible. The current limit doesn't even impact the use of such tools much if using the 4Ah packs with two series of cells in parallel, opposed to 2.(n)Ah or lower batteries.
 
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Greenman

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Oct 15, 1999
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Yeah, I still have an old Craftsman 7.2V NiCd drill, that I used hundreds of times a day in a trade 25+ years ago, but I'd have to rebuild the battery packs again which isn't worth the bother. I should probably throw it away but. It. Still. Works.

There's the flip side of robust tools, and I wouldn't necessarily consider a 7.2V Craftman drill all that robust, just didn't have any weak early failure points. If the manufacturer changes the battery mechanical interface or voltage, eventually stopping production of the old packs (and 3rd party packs are generally crap and don't support THAT far back in time) then it may make them obsolete even for tasks they were still capable of.

This is one reason I have several Ryobi tools, both brushed and brushless, because they stuck with the same battery mechanical interface for so long, though some of their newer tools are current limited unless you get their newer generation 3Ah/6Ah/9Ah packs that they cleverly integrated additional contacts on while keeping both them and the tools backwards compatible. The current limit doesn't even impact the use of such tools much if using the 4Ah packs with two series of cells in parallel, opposed to 2.(n)Ah or lower batteries.
Dewalt went another direction when they introduced the 20 volt tools. They produced an adapter that allows the new 20v battries to work on the old 18v tools. It's a clunkey soluition, but it does allow the older tools to retain value.
I have a substantail investment in the 20v line, and I'm going to pissed when they dump it for the "new improved" 22v tools if they don't do the same thing again.
 

jmagg

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Nov 21, 2001
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OT much?

I find your post very irrelevant. Even if this were the case, which would require a lot of underwater exposure, you just get a new tool.

It's relivent to myself (@nd anyone in the market for a battery operated tool), since Its not common knowledge that brushless tools are more prone to moisture damage.
 
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bigi

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Aug 8, 2001
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What I really like about Makita 18V line in terms of their batteries is that 3.5Ah and 5.0Ah batteries are the same volume. 5.0Ah are really monsters. For those who really require more juice, Makita offers several tools capable of using 2 batteries at once.
 

mindless1

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^ I'm not quite following. Most people console themselves with the virtues of the lower capacity batteries being that they're smaller and (much) lighter weight... and of course less expensive if the use is infrequent.

How is it a virtue for the 3.5Ah pack to be the same size? I can already answer one case, that if the cells are lower capacity due to internal construction that allows higher current, and both are a paralleled series of cells , then a 3.5Ah pack could be capable of higher current than a 5Ah pack, and yet if the tool is high current, you sooner run out of capacity so it's more of a one-shot use.
 

bigi

Platinum Member
Aug 8, 2001
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It's quite simple really. They have been able to increase battery capacity with same voltage w/out increasing battery volume.
 

mindless1

Diamond Member
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^ But that makes the 3.5Ah unnecessarily large and heavy, more like they just corrected for a deficiency rather than a virtue. Granted it's not really fair to call older battery tech a deficiency, because it was good to have the dual parallel series cells [at the time of development] to reach 3.5Ah, but having a 5Ah pack be the size theirs is, is matched by everyone else using current generation cells.

Other brands now have 3Ah packs that are much smaller and lighter in addition to paralleled packs in a 4Ah to 6Ah capacity range.
 
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Greenman

Lifer
Oct 15, 1999
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Go big or go home. I have a few 60v 9 amp hour battries for my worm drive saw. They work in the 20v tools as well. Put one of those things in a screw gun and it's good for a full day of non stop use. Weighs a blody ton though.