Tips/Techniques Parasitic Draw of Cordless Tools

[SomeGuy]

Came up on another forum I'm on, whether you should leave your cordless tool batteries connected because they'd get drawn down...so busted out the meter and took some measurements:

Interesting to see how much of a difference they can have....anywhere from a couple microamps, all the way up into the low milliamp range.

 

[garageguy]

What would be drawing power? Vehicles have modules that need to stay awake, but power tools?

 

[SomeGuy]

What would be drawing power? Vehicles have modules that need to stay awake, but power tools?

There's a bit of circuitry before the trigger, like the low voltage cutoff which is in the tools for Dewalt rather than the battery pack, that is always there drawing a little tiny smidge of power.

 

[6.5 Fan]

Interesting video, watched it earlier on u tube. I have a Kawasaki drill that may sit for months and the battery stays charged.

 

[Aliva]

I have a Ridgid cordless and have never experienced draw down, never actually thought about it.
The batteries, drill and charger are guaranteed for life so I'm not concerned about it.

 

[thestelster]

I have 5-6 Milwaukee M12 batteries. Only one will hold a charge. Even after charging it fully, green light on the charger, they'll only show 2 lights on the tool.
The M18's seem to be fine.

I do have the batteties attached to the tools, or on the charging stations.

 

[SomeGuy]

I have 5-6 Milwaukee M12 batteries. Only one will hold a charge. Even after charging it fully, green light on the charger, they'll only show 2 lights on the tool.
The M18's seem to be fine.

I do have the batteties attached to the tools, or on the charging stations.

Probably a cell is gone in some of those batteries.

 

[PeterT]

I usually unplug my batteries from tools for no good reason than it seems like the right thing to do. Maybe something is leaning on the trigger or like my drill, the first trigger pull turns the LED spotlight on. Modern lithium packs for these applications all have low voltage sensing (should have), so the risk of depleting them past threshold voltage where they are permanently pooched isn't as much an issue anymore as NI chemistry. Although, technically it could happen inside a pack itself at a low voltage state with a few worse cells.

What I wanted to ask, can you think of a convenient way to measure amp draw while in use? I've always wondered what my drill/driver was pulling without permanently altering the tool itself.

 

[SomeGuy]

I usually unplug my batteries from tools for no good reason than it seems like the right thing to do. Maybe something is leaning on the trigger or like my drill, the first trigger pull turns the LED spotlight on. Modern lithium packs for these applications all have low voltage sensing (should have), so the risk of depleting them past threshold voltage where they are permanently pooched isn't as much an issue anymore as NI chemistry. Although, technically it could happen inside a pack itself at a low voltage state with a few worse cells.

What I wanted to ask, can you think of a convenient way to measure amp draw while in use? I've always wondered what my drill/driver was pulling without permanently altering the tool itself.

I have the equipment to measure up to 400 amps DC, I just need to get a couple of full pin out sleds for either end to use. I have a two pin sled for the battery side, but it's missing the pins for the other sensing wires which means I can't use it directly on the tools (was for my RC build last year)...then need to find one for the tool side.

I'll work on it though

Side note: Off video I did run no load on the atomic drill at full throttle just to see what they would draw there, was ~2-3 amps - used the 10 amp side of the meter and slowly ramped up to make sure it wouldn't blow past that.

 

[Susquatch]

Even after charging it fully, green light on the charger, they'll only show 2 lights on the tool.
The M18's seem to be fine.

I do have the batteties attached to the tools, or on the charging stations.

I have a similar number. I love the compact M12 tool system.

The early batteries all sucked. They failed early either refusing to charge at all or showing a low charge after charging.

I couldn't even repair them myself. I sent a note off to milwaukee after two had failed and they told me to take them to their authorized repair place who would check them and replace them if defective.

The repair centre was too far away to be practical. I had to pitch them and buy new ones. Oddly, none of the new ones have failed after many many years of use - at least 12 years.

I suspect ALL the original batteries were crap! I also think milwaukee knew that and fixed then on later production. I noted that the new ones have different logo system. These are the new ones. I don't have a photo of the old ones. But if yours look different, I'd get replacements.



Note that despite this problem. I absolutely LOVE my 12V Milwaukee Tools. They are so small and handy. I even bought all my kids a driver / drill combo set (with the new batteries).

In the 20V class, I like my DeWalt 20V XR Tools.

 

[Dabbler]

Even sitting on the bench at 23 degrees, parasitic capacitance will draw down any battery. Regularly recharge your batteries, around every 3 or 4 months if not in use.

I have a lot of 20V Dewalt tools. Some Milwaulkee ones also. The M12 is the right angle die grinder, which is super rare in other platforms, and the M18 right angle grinder, because it is soooo neat...

 

[thestelster]

I have a similar number. I love the compact M12 tool system.

The early batteries all sucked. They failed early either refusing to charge at all or showing a low charge after charging.

I couldn't even repair them myself. I sent a note off to milwaukee after two had failed and they told me to take them to their authorized repair place who would check them and replace them if defective.

The repair centre was too far away to be practical. I had to pitch them and buy new ones. Oddly, none of the new ones have failed after many many years of use - at least 12 years.

I suspect ALL the original batteries were crap! I also think milwaukee knew that and fixed then on later production. I noted that the new ones have different logo system. These are the new ones. I don't have a photo of the old ones. But if yours look different, I'd get replacements.

View attachment 34977

Note that despite this problem. I absolutely LOVE my 12V Milwaukee Tools. They are so small and handy. I even bought all my kids a driver / drill combo set (with the new batteries).

In the 20V class, I like my DeWalt 20V XR Tools.

Those are my batteries too.

I just checked the voltages from 2 of my batteries. It looks like several cells are dead or dying. They're 18650 cells, so max is 4.2v, and I think below 3.7v they're on their last legs.

 

[Susquatch]

Those are my batteries too.

Take a photo of the label on the bottom of your batteries for me. Might trigger a memory.

 

[thestelster]

Take a photo of the label on the bottom of your batteries for me. Might trigger a memory.

The one fairly good one measures 11.86v, and its not fully charged.

 

[Susquatch]

The one fairly good one measures 11.86v, and its not fully charged.

Nothing pops out at me. I think yours are the good ones. Prolly just worn out. They don't last forever.

You can get pretty good ones on Amazon for WAAAAY less than the OEM. They claim more capacity too, but I call BS. Still worth the coin though.

 

[thestelster]

The one fairly good one measures 11.86v, and its not fully charged.

And fully charged is 12.18v.

 

[Susquatch]

And fully charged is 12.18v.

These are the ones I bought most recently

Bdreer 2 Pack 3000mAh 12V Lithium Ion Replacement Battery Compatible with Milwaukee M12 Battery 48-11-2401 48-11-2402 48-11-2411 48-11-2420 12-Volt Cordless Tools https://a.co/d/elW9NI8

There is a $5 coupon and you can get a discount by getting 4 instead of 2.

So far they are still working. But then again, so are my most recent oem batteries (purchased about 12 years ago).

FWIW, I never leave batteries in the charger or in the tools.

 

[thestelster]

FWIW, I never leave batteries in the charger or in the tools.

Maybe that's my problem. They're either in tools, or chargers.

 

[Ironman]

I have 5-6 Milwaukee M12 batteries. Only one will hold a charge. Even after charging it fully, green light on the charger, they'll only show 2 lights on the tool.
The M18's seem to be fine.

I do have the batteties attached to the tools, or on the charging stations.

At one time my shop was Dewalt yellow, and as they burned up I went to Milwaukee. I Have only one Dewalt left, a saw. And the parasitic draw was always an issue, but I thought it was normal til I got Milwaukee tools. I have a pile of Makita corded grinders that gather dust as the little corded Milwaukee 4.5 grinders do it all better. I found a way to expand the shield so I can spin a 5" disk in them.

 

[CWret]

The new Milwaukee drill/impact combo is awesome. Not cheap but still absolutely awesome. Compact and powerful.
The Milwaukee 2904 drill and the 2953 impact (see pics) are a huge improvement over their predecessor. Smaller, more features and more powerful. Yes smaller and more powerful than previous M18’s. Did i say awesome.
Sorry Susquatch- but these are only a bit larger than the 12v but ooooh so much better.

Fessing up- I also have a DeWalt die grinder. (DCG426). It beats the pants off the Milwaukee version & was worth having another battery platform.