Dewalt Blower battery issue

[DHCrocks]

I have a DCBL720 the 20v brushless blower and have a strange problem. If I leave a battery in the tool over time it will slowly discharge. I have noticed that in a couple of weeks it can go from 3 bars down to 1 bar. And if I leave it connected eventually the battery pack will flatline and not even take a charge. I measured the voltage and it was around 4 volts. I was able to boost the pack with a power supply so that the charger would start and that battery pack seems to be fine. If not plugged into the blower it holds 3 bars.

Does anyone else have this problem? All my other tools I can leave a battery pack connected and it will hold charge for months on end.

 

[ItsNemo]

Nope, haven't experienced that issue on mine...always has a battery in it, never drops.

Have you tried a different pack?

 

[driz]

All I can think of is try leaving it off the tool .that will at least tell you which is doing it.
Check the terminals of both for clean. You don’t have any conductive (regular )grease on them right? If so get it off there shine up the contacts and the only type of anti corrosion grease to use would be dielectric( non conductive). Regular grease film can allow minute voltage tracking as can corrosion. Get things nice n shiny and see what that does for you.


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[Bacon!]

You probably have a bad control module assembly, which is an assembly that includes the switch, battery contacts, and control board. These do not appear to be sold separately.

It's #4 on the following page, on which there is also an exploded parts diagram PDF:
https://servicenet.dewalt.com/Products/Detail?productNumber=DCBL720P1#

As long as it keeps working, I'd just unplug the battery to save the $63. If it isn't potted and you have electronics skills you might be able to troubleshoot and repair the module, could be something like the switch having a carbon track buildup or a leaky diode or transistor causing a slow drain.

Brushless tools... they'll last longer than brushed, if something doesn't fail first.

 

[DHCrocks]

The terminals on the blower and battery looks clean, I was thinking about dielectric grease, but this tool is always around dust so I was thinking that would just make matters worse the dust would stick to it.

I'm trying to monitor it now I swaped in a different 5AH battery to the blower and the pack that was drained down is fully charged and sitting on a shelf ( I marked this pack so I can identify it). So strange I always keep my battery packs in tools when not in use and only this blower seems to completely drain the battery.

 

[Bacon!]

You don't need nor should you use any grease on the battery contacts. They are nickel plated and not subject to corrosion except in the most severe of conditions (which would wreck the tool internally too so dielectric grease would not matter much).

I take that back, there is a rare situation, in that if you had a device where the batteries leaked and that corroded the terminals, and in cleaning that off you were left with bare steel or brass where the plating was eaten off, then dielectric will help protect the bare metal where the plating used to be.

Otherwise unless there is some severely dusty environment, far more common with blowers used to mulch leaves, you might want a gasket around the battery connection, the casing to the tool attachment point, but any way you look at it, it would be very difficult to get enough grease in there to do anything, except if it were explicitly a conductive grease, so conductive that this was its core purpose.

Why did we even get off on a grease tangent? Nowhere is it specified to grease the battery contacts.

Bad battery contacts will introduce a resistance that limits tool power. It will not drain the battery.

 

[lifeisfun]

Sadly mine just started doing the same thing, 5 months after warranty expired
Tested 3 batteries that work perfect in other tools.
All drain to point they can't be charged and have to boost them first.

 

[TuxThePenguin]

I'd be curious to see an ammeter (current meter) placed in series between the tool and battery i.e. you jump all of the terminals between the battery and tool with wires (of the appropriate gauge and probably with some kind of crimp connectors on them) except one of the two power wires would connect through an ammeter

might be helpful to know how much current we are talking here

 

[lifeisfun]

I'd be curious to see an ammeter (current meter) placed in series between the tool and battery i.e. you jump all of the terminals between the battery and tool with wires (of the appropriate gauge and probably with some kind of crimp connectors on them) except one of the two power wires would connect through an ammeter

might be helpful to know how much current we are talking here

Well, I'm too lazy to do it, but it's for sure the trigger circuitry, full 5AH battery drains in about a week. Tool looks like new, used it only couple times since I purchased it in a kit. Always stored inside air-conditioned house workshop.
BTW contacted DeWalt about this issue months ago using the website form, not even reply.
Professional tools ?!

 

[Bacon!]

One thing you could do, if there's a little extra room in the blower casing anywhere, is simply get a panel mounted switch, whatever design you like (there are hundreds, thousands including size variations), that cuts power between the battery input contact and the control circuit.

Keep in mind that this is a fairly high current circuit so not only do you want a switch rated for high DC current but also, to not have the tool running (trigger pressed) when that is switched on or off to save the switch internal contacts from DC arching damage.

I know it is extra hassle that you shouldn't have to do, but if the blower works okay otherwise, and is out of warranty, it could be the cheapest path to resolution.

I'm thinking of modifying my Stanley B&D made Craftsman blower by adding a switch to add two power levels, because the variable speed trigger doesn't modulate power easily (trying to hold a trigger a precise amount down while you're swinging a blower around). It has a throttle "cruse control" sort of aide but that means leaving it running longer while it holds the trigger down that amount instead of targeted bursts that my use needs.

The runtime is too short on the battery and higher capacity batteries are really expensive for it (60V), and it has enough performance to still get things done at 1/2 the power of full throttle.

That may not be as easy to do as I first assumed. It may have more electronics built into the trigger switch than just a single linear potentiometer. Once winter comes I can suffer the downtime of leaving it disassembled for reverse engineering and parts gathering.

 

[lifeisfun]

Good ideas
I will probably take it a part in the winter and see what can be done.


@DeWALT YOU ****!
Poor quality tools, and no customer service!

 

[DHCrocks]

Mine ended up being a bad battery. I have kept a 6ah in the blower now for several months without use ands it’s still 3 bars.

 

[SLO-life]

I have the same problem, my DeWalt 20v XR blower runs the batteries down when not in use, even until 100% dead, literally, they will not recharge. At first I thought my DeWalt rapid changer had died so took me a while to figure out the issue and almost bought a new rapid charger. But turns out was my beloved 20v XR blower was discharging batteries when not in use until completely dead. Now I have to replace a 4.0 and 5.0 amp hour DeWalt MAX batteries, not happy as replacing is going to going to cost me around $150 after paying sales tax. More than the blower cost.

Lesson learned: DO NOT leave batteries in any DeWalt brushless XR 20v tool.

Seeing that others have experienced this same issue of dead batteries that cannot be recharged. Thank you to those who explained what the malfunction issue in the tool is. It leads me to believe this issue is probably not unique to just the XR blower, but I suspect the entire XR line. My blower did not have this problem for the first 2 yrs of use, and since it worked when I exchange the battery never made me suspect the tool until I read this thread.

 

[ItsNemo]

I have the same problem, my DeWalt 20v XR blower runs the batteries down when not in use, even until 100% dead, literally, they will not recharge. At first I thought my DeWalt rapid changer had died so took me a while to figure out the issue and almost bought a new rapid charger. But turns out was my beloved 20v XR blower was discharging batteries when not in use until completely dead. Now I have to replace a 4.0 and 5.0 amp hour DeWalt MAX batteries, not happy as replacing is going to going to cost me around $150 after paying sales tax. More than the blower cost.

Lesson learned: DO NOT leave batteries in any DeWalt brushless XR 20v tool.

Seeing that others have experienced this same issue of dead batteries that cannot be recharged. Thank you to those who explained what the malfunction issue in the tool is. It leads me to believe this issue is probably not unique to just the XR blower, but I suspect the entire XR line. My blower did not have this problem for the first 2 yrs of use, and since it worked when I exchange the battery never made me suspect the tool until I read this thread.

Have you tried jump starting the batteries? Throw them on a low current 20v supply for a minute and keep an eye on them, might bring them back to life.