I was answering a question over at the Garage Journal forum, about battery pack bang for the buck, and thought it might make for a good post. I also became curious to see if you guys had any battery pack size preferences.
A few years ago, we were all led to believe that bigger = better. And for the most part, it’s true. Greater battery capacity means longer runtime. There are other benefits as well, but the main benefit is longer runtime.
So 6.0Ah is better than 5.0Ah, which is better than 4.0Ah, which is better than 3.0Ah. Yes? Well, let’s take a look at pricing.
Advertisement
Let’s look at Milwaukee battery pricing. For easier comparison, let’s look at the MSRP price for a 2-battery pack, or single pack, whichever is more readily available.
- 3.0Ah: $139 for a 2-pack, ~$70 each
- 4.0Ah: $119 for 1
- 5.0Ah: $129 for 1, $189 for 2, ~$95 each ($199, or $100 each at HD)
Their 6.0Ah packs aren’t available yet that I can find. Even if they were, I imagine that the 5.0Ah packs would still offer greater bang for the buck.
Let’s look at Bosch 18V high capacity battery pack pricing.
- 3.0Ah: No longer readily available
- 4.0Ah: $149 for 2, or ~$75 each (via Amazon)
- 5.0Ah: $109 (via Amazon)
- 6.0Ah: $90 (via Amazon)
Hmm, that 6.0Ah battery pack pricing is surprising.
To be frank, I am somewhat skeptical of 6.0Ah battery packs. The last few times I checked, individual 3.0Ah Li-ion cells were not rated as highly as 2.5Ah cells, in terms of current draw. This makes me believe that they might not endure high demand use as well as. High power output can degrade battery life, and it is my understanding that, the higher you go towards the peak specified output, the more heating you’ll get.
I cannot shake the assumed conclusion that 4.0Ah and 5.0Ah battery packs, built with higher rated cells, might last longer than 6.0Ah battery packs – unless something changed and they were now built with similarly spec’ed cells – resulting in greater long-term durability, at least with regular heavy duty use.
Advertisement
Even if all brands’ 6.0Ah battery packs were available right now, I probably wouldn’t buy one, unless I absolutely needed the longest runtime possible.
When I checked a few months ago, going from 5.0Ah to 6.0Ah resulted in a greater than 20% jump in price.
Considering the prices above, Milwaukee’s 5.0Ah battery pack is “the sweet spot,” at least if you need two. With Bosch, curiously, the 6.0Ah pack is on sale, making it lower priced than the 5.0Ah pack. It seems that this might just be at Amazon, but it doesn’t look to be a fly by night price.
Looking at the Bosch pricing, it would come down to 4.0Ah for $75 each if buying a 2 pack, or 6.0Ah for $90 each individually. That’s a 20% increase in price for 50% greater capacity.
Even if a 6.0Ah pack might not last as long as a 4.0Ah or 5.0Ah battery pack under frequent heavy demand use – and again, this is my spec-based belief and not something I have proven or disproven – the pricing is hard to argue against.
Recently, Bosch announced new connected tool details, and also announced a new 18V 6.3Ah EneRacer battery pack. That makes my understanding, assumptions, and doubt about 6.0Ah battery packs a little more believable. Would they go through all the effort to bump up battery capacity by just 5%? I doubt it. But I’m assuming that by going with a different form factor than 18650, they were able to spec out higher rated cells that more closely match up to or exceed the specs of the cells used in 4.0Ah and 5.oAh battery packs.
I talked more about battery cell tech last year in a post: 18V Batteries are Now at 6.0Ah – How Much Higher Can They Go?
Let’s also take a look at Dewalt high capacity battery pack pricing:
- 3.0Ah: $99 for 2, or ~$50 each (via Amazon)
- 4.0Ah: $129 for 2, or ~$65 each (via Amazon)
- 5.0Ah: $150 for 2, or ~$75 each (via Amazon)
The 5.0Ah 2-pack is often over-sold, speaking to its popularity.
Going from 3.0Ah to 4.0Ah, you get around 33% more capacity for an around 30% higher price. Going from 4.0Ah to 5.0Ah, you get 25% greater capacity for an around 15-16% higher price. From 3.0Ah to 5.0Ah, the difference is around 67% higher capacity for about 50% higher price.
That’s what you want to see, and is what you also see with Milwaukee. Bosch’s 6.0Ah pricing, which is higher than their 5.0Ah pricing, is different from what I expected.
If you ask me, I’d say that 5.0Ah battery packs are the way to go, at least as far as higher capacity packs are concerned. I haven’t done the math recently about compact battery packs recently, but I think I would go for 2.0Ah or 2.5Ah packs, whichever had better pricing in a 2-pack.
Have you wondered why brands haven’t come out with 3.0Ah compact battery packs yet? Well, Milwaukee is coming out with M12 compact 3.0Ah and XC 6.0Ah battery packs, but I don’t think I have seen 18V compact 3.0Ah battery packs.
I think part of the reason is the confusion it would create between compact and higher capacity battery packs with the same 3.0Ah capacity, but also because the 3.0Ah cells on the market that I’ve seen have lesser ratings compared to 2.0Ah and 2.5Ah cells. Costs could also be a factor.
With all that said, is there a battery size that you’ve found to have higher bang for the buck? I don’t think anyone will argue in favor of 3.0Ah battery packs, and from what I’ve seen the jump from 4.0Ah to 5.0Ah makes sense unless you’re on a tighter budget.
I didn’t touch upon Makita’s battery pricing because they’re harder to follow. In addition to single and double battery packs, they now have packs with built-in battery fuel gauges, and not all dealers carry all the different SKUs, resulting in hard-to-compare figures.
Metabo has moved to higher capacity cells, and Bosch is moving to higher capacity cells in their EneRacer pack. It will be interesting to see which direction Dewalt, Hitachi, Makita, Milwaukee, and other professional brands will be moving in.
In the meantime, I’m sticking to my opinion that 5.0Ah is the best to buy right now.
Bruce
The point of my cordless tools is mobility. Let’s say I need an impact driver for a job that is 200 yards from my work bench. When I pack my tool bag, I’m going to get my fasteners, impact driver, other tools and only take what I’m going to need. As my impact driver will drive screws all day long on it’s 2ah battery pack, why would I take anything larger.
Now the cordless vacuum is a real battery killer, I never put anything less than a 4ah pack in it and if I’m expecting to make a large mess I pack a second one.
In my application, weight wins over capacity. If I’m going to stick it on the charger at the end of the day, I’m only going to take enough battery to get to the end of the day.
glenn
Personally, I don’t believe for a second what numbers they print on the side of a battery pack.. it is what happens at the end of the tool.
Eg; I have the M12 circular saw………and it is very underwhelming,. Having the choice of timing a brushless motor, Milwaukee chose run time over power. Knowing they had more powerful battery packs coming up, they still chose to release a sub par tool.
Travis
So you do or don’t have the M12 fuel circular saw?
glenn
I do have one.
Jimmie
I have a M12 fuel circular saw and while I only use it in a DIY setting, I’ve had no trouble cutting cedar fence planks and 2x PT wood. Longest cut I’ve ever made in 3/4″ plywood was about 24″ so I can’t say whether it loses power on long cuts or not.
glenn
I find even being very careful keeping it dead straight it will bog cutting even 19mm thick pine let alone anything like lvl.
They made the same mistake with the M12 vac, they chose runtime over power. It wont even pick up small bits of cut off mains wiring insulation.
I have no problem swapping a battery, I do have a problem with lack of power.
Pabi
I am with you, you are 100% right,
these # says nothing to me,
since I started using Festool batteries I realized that my dealt and milwaukee batteries are about 1/4 of wrote capacity…
Steve
It does not make sense but my Milwaukee 4.0Ah runs longer than my 5.0Ah.
Derek
Wouldn’t best bang for the buck be figured out as $ per Ah?
3.0Ah: $139 for a 2-pack, ~$70 each – $23.33 per Ah
4.0Ah: $119 for 1 – $29.75 per Ah
5.0Ah: $129 for 1, $189 for 2, ~$95 each ($199, or $100 each at HD) $25.8 per Ah for 1, $19 per Ah for 2
Obviously you need 2 batteries in case one is dead.
Tom
https://public.tableau.com/views/M18BatteryValue/M18Batteries?:embed=y&:display_count=yes&:showTabs=y
I came up with the same conclusion. If you are buying single or double packs the 5Ah is the way to go, though getting 2 3Ah batteries is only a little more than one 5Ah. Having one charging and one in use plus an extra 1Ah might be worth $10.
Jacob Edmond
I’ve never really understood the push for bigger batteries past a certain point. To me the beauty of cordless is you can just swap out once a battery dies. For bigger power sucking tools I get it, but it seems like there is an optimal run time vs weight ratio that should be considered. The longer you are going to be using a tool, the more fatigue there will be with every ounce of battery added, so it seems like using small batteries with more swaps for recharging would be worthwhile in my book.
Jonathan
I agree completely, I responded to a post if I recall about brushless grinders, and related my experience with 80v vs 40v outdoor equipment. More Ah or Wh doesnt always correlate to longer runtimes. Yet larger does mean heavier. In some ways your better off with a 30 min charger over a more Ah yes ymmv. But given the option I would rather have a shortet charge cycle than a little longer run time.
One cavet with this is the temperature part of the equation, if you fast drain a LiON battery from heavy use or high ambient air temp (i.e. outdoor job site, inside a vehicle in summer, or full speed use) you still have to wait for the battery temp to drop to around 87-82 F degrees before you can recharge depending on the brand and charger, it may charge above these temps but very slowly and inefficiently.
Something to consider as well, if you always wait to recharge when the battery will no longer power the tool (LiON esp) so shorthen battery life, capacity and nimber of charge cycles if you recharge below 15-20% supposedly if what I’ve read is correct.
Jon
Actually the batteries all weigh the same amount and are the same size, regardless of the capacity – they have improved the capacity without adding any weight or size.
Obviously I am referring just to the 10 cell configurations, not “compact” battery sizes (which are 5 cells).
IceCactus
What do you mean Makita is harder to follow?
Stuart
Too many SKUs to compare easily.
John
Omg is that true and it isn’t just their cordless skus. I tried comparing angle grinders and there were 44 models of just corded:
http://www.makitatools.com/en-us/Modules/Tools/Default.aspx?CatID=64
Some may like the flexibility to pick what you want but man that’s gotta be a nightmare to manage and overwhelming for anyone that doesn’t know exactly what they want and their site is horrible to narrow that choice down.
KenZ
Add to that the knock-offs… I just bought and have been using a two pack of 5Ah Makita-compatibles. $99 for both ($50 each). They seem to work just fine; we’ll see over time.
https://www.amazon.com/gp/product/B0122WMVZU/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1
Curt Hibbs
I’ve some time I have been wanting to add a couple high-capacity Milwaukee batteries to my meager battery pool. But since I wasn’t in a hurry, I was waiting for a good deal.
That finally happened a few weeks ago, not by buying the batteries themselves, but instead by purchasing a reconditioned combo-kit that included two 4.0Ah batteries.
The combo kit was $200, which means I paid $100 for each battery ($19 off the list price). But the best part was that as a bonus, I also got a “free” brushless Fuel Hammer Drill and a “free” brushless Fuel Impact Driver.
Needless to say, I am very, very happy with my new batteries!
Richard G.
Last week, you could buy 5.0 Milwaukee batteries for $65 at either CPO outlets or toolbarn, can’t remember for sure. If I wouldn’t have ten 4.0s I’d buy some. Still waiting on a 9.0 for my grinder and coming miter saw.
Nathan
ONly caution I’ll put to that. The ones that have the higher current through put cells.
Notice how those newer larger Milwaukee batteries say High Demand on them- sort of how the red lithium was different than the standard pack. Or in the Dewalt land the yellow top XR battery vs the all black standard.
Li-po, li-ion battery cells are rated not only in pure capacity (the AH basis) but also the Current Discharge (usualy in terms of C ) which is linked to how much current the battery will tollerate letting go of at one time. Well size, and pump output volume. where voltage is a constant pressure – if you want that sort of analogy.
So yes – the other smaller, cheaper batteries on a cost per AH might be better – but then you’ll put them on that newer tool and it will bog down or not spin as fast – because it wants that higher throughput battery.
Dewalt at least makes a set (and I pretty sure milwaukee does to) where the high throughput battery is also in a smaller size. I don’t know about the others.
But when price shopping consider the aspect of through put also
kersley
What really matters is what cells are in those packs? Take a look inside a Dewalt 18v 4ah, you’d see 186 cells. not take a look inside a Hitachi same ratings? you’d see Sanyo cells.. and what about Panasonic? they save the best for their own tools.
Nathan
right now panasonic might make the best LI-Ion cell, but that won’t always be the case nor should it be the deciding factor.
how the pack is made – how the charger line balances- how the current demand is spread though – any methods employed to reduce resistance between sets – etc has more to do with the usefulness of the output than the individual cells.
With an exception being made if some maker is using 5C cells in one pack and 10C cells in another pack – that’s quite a bit different.
Stuart
That’s a good way of putting it.
The cells used in 2.0Ah, 2.5Ah, 4.0Ah, and 5.0Ah packs seem to be rated to near 10C.
The only ones I could find with 3.0Ah capacities, for use in 6.0Ah battery packs, have ~5C ratings.
Maybe things have improved, but they’re DEFINITELY not anywhere near 10C from what I’ve seen.
Not all datasheets and industry details are publicly available, which is why I cautiously repeat that my opinion is based on what I have seen, which is a single datasheet for Samsung’s high performance 3.0Ah 18650 cells.
Andrew
5C for a 3Ah cell is the same current as 10C for a 1.5Ah cell, which is about where all these tools started (if not lower, I have m18 batteries still with 1.3/2.6Ah
Jon
Like Andrew has pointed out – you’ve made a simple mistake in your math. Of course the 3Ah cells don’t have the same C rating as lower capacity cells, otherwise you would be getting higher capacity AND higher current output capability… That would be nice but is not how battery technology works. The capacity is a trade-off against the C rating, given the same size and weight of cells.
If you have a 6Ah battery rated for 5C it can produce 30 amps of power (6 x 5).
If you have a 3Ah battery rated for 10C it can produce 30 amps of power (3 x 10).
Given the same requirement for current output capability, a higher capacity cell must necessarily have a lower C rating!
Stuart
No, my math is right, and C ratings are proportional.
A 2.5Ah cell with 10C rating might be doubled up in larger battery packs for 5.0Ah capacity. The C rating remains 10C.
I don’t remember the specs for 1.5Ah cells. But let’s say the were raged to at least 20A current draw.
2.0Ah and 2.5Ah cells I’ve seen have similar current ratings.
3.0Ah cells I’ve seen have 15A current rating, which is a lot lower.
Consider the engineering and thermal dissipation limits of battery packs.
Let’s say it’s 15A. 1.5Ah, 2.Ah, and 2.5Ah can handle it easily, and 3.0Ah, 4.0Ah, 5.0Ah, ando 6.0Ah packs can all keep up.
But, getting rid of heat from a sealed battery pack is going to create a thermal limit.
Even at lower current load that’s within cell specs, a 6.0Ah pack will likely run hotter.
Going from 2.0Ah to 2.5Ah results in a current rating drop of something like 10%. Going from 2.5Ah to 3.0Ah results in a drop of 25 to 33%.
So no, the current rating drop is not proportional.
With 3.0Ah cells, you gain a little more charge capacity, but also a presumed hotter running pack with disproportionally lower peak current load rating.
It’s not the lower reading that has me concerned, but the larger than expected tradeoff. That’s my whole point. A proportional tradeoff would be welcome.
Andrew
My point was more that 15 amp cells are probably enough in an XC pack, since most tools run with only slightly reduced performance on the slim packs. Also that amp rating is more important than C rating because ultimately we want batteries that can output what the tool can draw.
I’m pretty sure these are the amp ratings of most of the M18 packs. They use better cells in the smaller packs.
1.5: 23A
2.0: 22A
3.0: 36A
4.0: 30A
5.0: 40A
6.0: 30A
9.0: 45A
kersley
It’s just a matter of time before every power tool is cordless as batteries gets better and more efficient. just like the Oukitel smartphone with it’s 7 days batteries!!!
7 days of normal use without a charge? wow..
I remember my first blue/yellow Ryobi 18v nicad, it couldn’t even cut 1ft of 1/4″ ply without stalling.. today my new Hitachi brushless circular saw can cut along the grain of a 2 ” x 9″ joist. it will only get better,I’m sure.
DannyK
I read on reddit from a dewalt insider that they are about to release 60v battery brushless tools, with battery being backward compatible with 20v max:
“Official release will be June 21st, I see Dewalt putting out teasers now a ‘#worldsfirst’ hashtag. I guess that’s how they’re spinning it. It’s going to be an all-brushless 60v (well, 54v) system that’s backwards compatible with all their 20v tools. Batteries will be available in 6.0Ah & 9.3Ah versions. Tools will include a cordless 60v table saw, a cordless 60v 6″ angle grinder, a 60v 7-1/4″ circular saw that will outperform a corded saw , and even a cordless 120v (runs off two 60v batteries) double-bevel sliding compound miter saw. There are many other tools in the launch, I’m just highlighting some of the offerings.
You can put one of these batteries on an existing 20v tool for an extended run time. They’ll retail for about $159, and they weigh a little less than a 18v NiCd”
kersley
Now you tell me!! I just spent £1’200 on my new Hitachi kit. lol
Chris Butigan
Hitachi is my favorite brand, too bad I cant have access to the japanese or european stuff… Same with bosch, I really want to have their cordless system, but a lot of tools are not available in NA… Milwaukee for me…
KenZ
Sounds like it’s the “X3” system.. where the series/paralleling is handled by the tool connection. Interesting approach if they can pull it off.
Jon
I am not sure if that’s feasible for DeWalt to release 60 volt batteries with a 6.0Ah capacity, let alone 9.3Ah for use with HAND HELD tools.
Unless there has been some undisclosed incredible advance in battery chemistry they would need a battery pack to contain no less than 30 cells to achieve 6.0Ah at 60v. That would mean triple the size and weight of current batteries that have 10 cells.
The only tools it makes any sense for would be tools you do not pick up (table saw, miter saw).
Jerry
Also consider how many batteries you might need. If you were, say, building a fence, and needed to swap between a circular saw, recip saw, drill, and driver, and only had 2 working batteries, you might be better off getting a 2 pack of lower powered batteries than a single hi cap. The hi cap are worth the extra money if you need them, but otherwise add weight, and having enough batteries to go around, or an extra to charge may be the better way to go for some
Toolpig
After having 4.0 and then 5.0 and 5.2 I am loathe to use 3.0 Or less unless it’s a compact. To me 5.0 is the best bang for the buck and I too worry about the 3.0 cells used in he 6.0 batteries at this point.
Leif
I can regularly find new dewalt 4ah packs on ebay for $50 with shipping.
Jon
DeWalt battery packs are definitely the lowest cost packs on the market right now without question – you can get two 5.0 packs for $150 shipped.
Jon
I couldn’t respond to your reply above, but I think you are missing my point.
There is no need for a 6Ah battery pack have a 10C rating – that would mean it could put out 60 amps continuous current which is far more than any cordless tools draw (that would be over 1000 watts of continuous power).
That would be over-engineered and a waste of money for the purpose. That’s likely why they are using 5C cells in the 6 amp packs – it still provides a 30 amp continuous rating which is fine for cordless tools.
Also regarding the heat issue – there is no difference in the heat created under load if the battery has the same continuous current rating. In fact a larger capacity pack has a lower internal resistance, which means if anything it would run COOLER under the same load!
Stuart
I do see what you’re saying. But what I’m saying is that 30A delivery for a 6.0Ah pack is significantly lower than 45A to 50A delivery that 4.0Ah and 5.0Ah packs should be capable of.
That would be what, 7C or 8C. Instead I’ve only seen availability for 5C cells.
A larger pack doesn’t necessarily have lower internal resistance.