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Old 02-15-2019, 12:21 PM   #16
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Re: Question about Dewalt 20V cordless batteries


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Originally Posted by Bent Nail View Post
Higher capacity batteries DO actually put out more power... over a period of time.
This statement makes almost zero sense, so it's hard to figure out what you're trying to say. Power is, by definition, the first derivative of work with respect to time. If you take power "over a period of time" you get work/energy. So... you're saying that bigger batteries store more energy? Okay cool, and water is wet, what's your point?

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Originally Posted by Bent Nail View Post
And the higher the loads, the shorter the time. The smaller the battery, the quicker it depletes.
Smaller batteries die faster, I think we can stipulate to this.

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Originally Posted by Bent Nail View Post
Low, light duty, non demanding loads would not reveal any practical performance differences between battery sizes in real world usage.
Ditto.

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Originally Posted by Bent Nail View Post
And that's the key... and the problem... with anecdotal reports about whether or not battery size makes a difference. These are construction tools used to build and repair stuff in homes and job sites. We are not talking about instrumented tests in a controlled laboratory. Who knows what the state of charge or rate of depletion was for any given person reporting experience. And when I'm in a situation where I'm needing to drive 6" TimberLok's, it's never just one.

As a practical matter, if I bring tools to a task that can be constructed or repaired with say, a dozen TimberLoks, I'm going to slide on a fat battery, because the probability is higher that the skinny battery will run out of juice before the job is done. Been there done that, and made the round trip down and up the ladder for it.
Wait, was all that just to say that smaller batteries die faster? That's not what this thread was about. Some people maintain that a fully charged big battery and a fully charged small battery will put out different amounts of power which theoretically should not be the case (as I explained above, power is an instantaneous quantity). For example, if you're finding that both a big battery and small battery can drive these big screws, just that the small battery can drive fewer, that's merely a capacity issue and is unrelated to power. On the other hand, if you're finding that the big one can drive them faster than a small one, then you are getting more power out of it compared to the small one (assuming both are fully charged, nobody disputes that voltage drops as the charge depletes).

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The higher workload accelerates the time to battery depletion, because more energy is being demanded, and the demand is continuous duty, due to the long length of the screws. With continuous loads, heat dissipation, heat distribution over the number of individual cells, and thermal measurement and management by the electronics within the battery enter into the equation. But none of that is my concern. I just want to get the screws in all the way, so I'm going to pick the fat battery from the get go.

On the other hand, if I'm installing a little shelving system with 1 1/2" screws, I know that the neither the tool, the battery, or even the screws will heat up much. Any size battery will do, and neither size battery will reveal any apparent difference in performance over the time period of that job.
Okay, I'm still not sure what you're adding to this discussion other than "smaller batteries die quicker" (which nobody disputes). It's still unclear whether you're asserting that you get more power (as opposed to just more energy) out of bigger batteries. Your bolded section brings up some interesting potentially relevant factors... but then you dismiss them as not your concern and don't discuss how that could affect the battery's power output (which, again, is kinda the whole point of this discussion). So, running with that for a bit, I wouldn't be surprised if the smaller batteries had thermal protection mechanisms that did limit the power output compared to larger batteries, since the larger ones, with more cells, would have a greater capacity for heat dissipation.
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Old 02-15-2019, 12:48 PM   #17
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Re: Question about Dewalt 20V cordless batteries


That's why I highlighted the sentence in bold.
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Old 02-19-2019, 01:29 PM   #18
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Re: Question about Dewalt 20V cordless batteries


The higher amp batteries will give you more real power under two scenarios...when the battery is losing charge just before quitting, and when you're in a high torque scenario where the weight of the battery is beneficial. Both are minor advantages but they are advantages so that's why we hear those anecdotes about better performance from the big batteries.
Remember that little batteries get to that depleted state sooner so you feel that performance lag more often than with the big ones. Side by side with the batteries fully charged and the tool bolted down? Identical performance. But in hand while working you might just feel a difference at some point because of the weight and getting close to that depleted state.
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Old 02-19-2019, 06:08 PM   #19
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Re: Question about Dewalt 20V cordless batteries


My little battery works fine for the short jobs I do. For professional "working at a job" situations, yeah, a higher ah battery would be better.
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Old 02-20-2019, 12:55 PM   #20
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Re: Question about Dewalt 20V cordless batteries


there's a few things going on.

at the same voltage, bigger packs have more "ampacity". a 4Ah 18V battery has twice the instantaneous output power of a 2Ah 18V battery due to there being a second parallel string inside the battery of the same type of cells. it'd be like if you could plug your table saw into two outlets instead of one - there's more AVAILABLE power. But it doesn't matter how much power is available if you can't make use of it.

The other side is the tool. wether you put a 2Ah (older, one string) or a 9Ah battery (newer, three strings) on a regular cordless drill, it doesn't make much difference because the drill only pulls so much power.
if you try running a 7 1/4" cordless saw with a 2Ah battery and try running it through a 4"x4", the saw has no torque and the pack gets hot. do it with the 9Ah battery and it cuts it like it ain't no thang.
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Old 02-20-2019, 01:34 PM   #21
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Re: Question about Dewalt 20V cordless batteries


This is an easy one. Higher capacity batteries simply have more parallel sets of cells so the total instantaneous current they can discharge is higher. Whether a tool needs or can even draw max current is a whole other question. For commercially sold tools you won't see any difference in performance. They aren't going to sell you a tool with a battery that is too small for it to run at full load. A bigger battery won't make it stronger. It'll just last longer.
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Old 04-03-2019, 02:09 PM   #22
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Re: Question about Dewalt 20V cordless batteries


The half size batteries provide a third as much power to the drill motor but they make the drill seem lighter and so more people buy the "lighter" drill. The amount of amps is not the issue but how much current the battery pack can provide the drill motor while it is in operation.

If all one is doing is driving #8 screws in pine then a smaller battery pack works fine. But if one is drill 1/2" holes in concrete or PT lumber then the smaller battery pack will last a third as long as a full size battery pack.

That is why I love that DeWalt switched to selling bare tools so I can use my 5 AH battery packs with all of them. I only use the tiny battery pack with my 20v oscillating tool where the charge is "good enough" for most tasks.
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Old 04-03-2019, 02:20 PM   #23
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Re: Question about Dewalt 20V cordless batteries


The half size batteries provide a third as much power to the drill motor but they make the drill seem lighter and so more people buy the "lighter" drill. While at the national tool show that is in Las Vegas each May I would see guys pick up the Makita 1/2" cordless with the half size 2 Ah battery pack and remark at hour light "the drill" was compared to those from competitors, ignoring the size and weight of the battery pack.

The issue but how much current the battery pack can provide the drill motor while it is in operation and the 5 Ah battery packs provide a great deal more initial current and continuous power to the drill motor which enable it to provide more torque or power to a drill bit or hole cutter.

If all one is doing is driving #8 screws in pine then a smaller battery pack works fine. But if one is drill 1/2" holes in concrete or PT lumber then the smaller battery pack will last a third as long as a full size battery pack.

That is why I love that DeWalt switched to selling bare tools so I can use my 5 AH battery packs with all of them. I only use the tiny battery pack with my 20v oscillating tool where the charge is "good enough" for most tasks.

Also important is the drill bit and hole cutter being used. With a fully charged battery pack on an 18v drill and using brand new Lenox bi-metal hole saw it would take 40 seconds to cut a single 2-1/8" hole in 3/4" thick plywood and it would take more than 20 minutes to get the battery back to a 100% charge state. With a Blue Boar TCT large tooth cutter where there is no sidewall contact I could cut the same size hole in 3 seconds and could cut hole after hole before needing to recharge the battery pack.

The basic design of bi-metal hole saws dates back more than a century and their inefficiency with most materials is not nearly as apparent with a cord drill running off 110v AC but is quite obvious when using a drill powered by a battery.
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Old 04-04-2019, 05:12 AM   #24
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Re: Question about Dewalt 20V cordless batteries


Late to the party, but I have a Dewalt 16 gauge angle 18 volt nail gun and a jig saw, both using XRP batteries. Well Dewalt came out with a 20 volt conversion kit allowing the use of 20 volt LiOn batteries. Don't bother. Save some money. I got about 5 good long cuts out of a battery before they died. I was constantly changing batteries. I believe the XRP motors make an excessive draw that the small lightweight batteries can't keep up with.

I gave the batteries to my helper who has 20 volt brushless tools and bought two more XRP batteries. Much better.
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Old 04-21-2019, 12:56 PM   #25
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Re: Question about Dewalt 20V cordless batteries


It depends on the load on the tool. For my oscillating tool and my cut-off tool the small 20v batteries work great. For the reciprocating saw and drills where a lot more power is needed the 18v Lithium battery packs in a 4 or 5 amp hour rating last the longest and I can get through any job with at most two battery packs.

But I use the right blades or hole cutters and this makes a tremendous difference. When there is excessive friction at the work piece the motor draws a lot more current which is OK with a corded drill but ends up severely cutting short battery life. When the first 18v cordless drills appeared on jobsites I would see guys bringing 4 to 8 batteries so they could make it through the day and had a battery charger as well, just in case it was needed. Using self-feed drill bits and bi-metal hole saws on their cordless drills was hobbling their performance.
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Old 04-22-2019, 06:59 AM   #26
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Re: Question about Dewalt 20V cordless batteries


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Don't forget that Dewalt does still maintain the old 18v tool line that is incompatible with the new 20v slide on packs. It would be pretty confusing for consumers if they had called both 18v but they don't fit together. The new style, slide on batteries CAN be used on the old tools but requires the help of an adapter. The 20v Max name may be a bit of a marketing ploy, but the name change also differentiates the two lines. They don't hide the fact that they are still 18v tools.
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I bought one of those adaptors. Save your money, It is a piece of crap, as was the second adaptor. The battery slides on the adaptor, the adaptor slides on the tool. The adaptor does not slide off easily.
I have 18V and 20 Volt De Walt. I still have a 14V for sheet metal cutting. It has not been use for at least 3 or 4 years.
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Old 04-22-2019, 08:16 AM   #27
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Re: Question about Dewalt 20V cordless batteries


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I bought one of those adaptors. Save your money, It is a piece of crap, as was the second adaptor. The battery slides on the adaptor, the adaptor slides on the tool. The adaptor does not slide off easily.
I have 18V and 20 Volt De Walt. I still have a 14V for sheet metal cutting. It has not been use for at least 3 or 4 years.

That's pretty typical with any of the plug in style battery packs, they could be really hard to remove. Get a little debris in the buttons and they get even worse. Can't count the number of times I had to hold the tool between my knees and use both hands to get the battery off. Either that or start using it only to have the battery drop out of the tool. The slide on battery packs are a MUCH better design.

I've used the adapter and it's not an ideal situation. Biggest problem is it doesn't fit all tools that great. Not only looks odd but changes the balance and makes the tool feel different. The adapter is more to ease transition to new style than an actual long term solution. Some people have trouble abandoning old tools that still work when they change platforms. I never had that problem this go around. The 20v stuff was such an improvement that it made the 18v obsolete for me.
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Old 04-22-2019, 10:52 AM   #28
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Re: Question about Dewalt 20V cordless batteries


I first bought the 20v hand drill from DeWalt for testing and became a big fan as the tool really lives up to the marketing hype. I have 18v drills from DeWalt (standard and hammer drill versions), Milwaukee, Makita, Panasonic, and Rigid, that I have been using in a hole cutter testing program, and the 20V provide as much of a gain as going from 12v to 18v did.

What I love is the DeWalt line of 20v tools that are sold as a bare tool. I bought the drill kit with the charger and two 20v batteries and have been using them with two bare tools that I later bought and save about $100 a tool when I can buy just the tool alone.

Something that few people appreciate is that the cordless drills' performance is greatly affected by the gearing in the drill. DeWalt provides 3 gear options with a low, middle, and high gearing with the middle range that is perfect for driving even very large 6" hole cutters through OSB and plywood subflooring.

Rigid provides 4 gears but they are a low and and an ultra low and two high speed. Milwaukee and Makita only provide a high and a low speed setting with their drills, and it is like the old days when cars had 2-speed automatic transmissions and their performance was very poor. I get better performance from a 3-gear 18v DeWalt drill than from a 2-gear 20v Milwaukee drill in most situations.
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Last edited by Calson; 04-22-2019 at 11:12 AM.
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Old 04-23-2019, 04:28 PM   #29
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Re: Question about Dewalt 20V cordless batteries


I have two of the Dewalt 20v drills. I don't like them at all. If you use them as a drill driver, when you back a screw out, the bit loosens. I have never had that problem with cheaper brands. Also, when drilling a hole, if the wood is a little hard, the drill bit slips in the chuck. Just junk IMHO. I quit using mine.
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Old 04-23-2019, 04:41 PM   #30
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Re: Question about Dewalt 20V cordless batteries


With the DeWalt chucks I get the drill bit tight in the chuck and then tighten the chuck and one hears a ratcheting noise as something inside tightens it further. Even with 1/16 inch drill bits there is no loosening if I do this 2-step process.



Drill chucks vary a good deal. With the 18v DeWalt chucks I would have to use a channel lock pliers to loosen the chuck the first few times. With the Makita chuck any vibration while using a hole cutter would loosen the chuck and the arbor adapter and hole cutter would fall to the ground. The Bosch drills have chucks that are very refined and no like one would expect to find on a power tool, but the rest of the Bosch 18v drills I have used were lacking in power.
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