Flashing red light on battery charger?

[alphabeta77]

Hi all,

Have a Festool sander that I've really used very little since buying a couple of years ago and just tried to use and realised the batteries are empty. Sitting in the charger it just shows a flashing red light on the charger.

Any ideas on how to fix this? Is this a dud?

 

[kevinculle]

Some battery chargers (like the one for my 56V leaf blower) will not charge a battery that's dropped below a threshold low voltage even though the battery may be otherwise fine.  When I ran into this I used a second charged battery (in my case 3 Dewalt 20V wired in series to get the correct voltage) to jump the battery and once above the threshold the charger did the rest.  You must hook the charging battery to the battery being charged with correct polarity (+ to + and - to -) and use a reasonably heavy wire gage like 14AWG as the initial current may be relatively high for a very short duration.  YMMV!

 

[alphabeta77]

Yeah, for an 18 month old unit it's not exactly impressive - have raised with Festool customer services.

I've got 15+ DeWalt batteries and have had for 10 years plus with no issues at all.

 

[danalloway]

Some battery chargers (like the one for my 56V leaf blower) will not charge a battery that's dropped below a threshold low voltage even though the battery may be otherwise fine.  When I ran into this I used a second charged battery (in my case 3 Dewalt 20V wired in series to get the correct voltage) to jump the battery and once above the threshold the charger did the rest.  You must hook the charging battery to the battery being charged with correct polarity (+ to + and - to -) and use a reasonably heavy wire gage like 14AWG as the initial current may be relatively high for a very short duration.  YMMV!

This right here fixed it for me, thanks for the tip!
Didn’t expect it to at first, had no idea what I was actually doing but it’s charging now and I’m happy!

 

[ElectricFeet]

My charger does this a lot. In my case, all it needs is an extra hard shove to get it to engage properly.

 

[Cheese]

I've had this same issue with recent (10 years old or newer) Milwaukee battery chargers. There's a certain voltage threshold that needs to exist for the charger to function properly. With older Milwaukee chargers this was never an issue. It probably came about when they started to make the battery chargers "smarter". [sad]

 

[Reeffjane]

It's fascinating to see how technology has progressed, even in tools and battery chargers. With older Milwaukee chargers, these voltage thresholds might not have been a concern, but as they've incorporated more advanced features, it's essential to be aware of these changes.
For anyone facing similar issues or looking for solutions, techbatterysolutions.com could be a helpful resource to explore. Keeping our tools and devices running smoothly is crucial, and having access to information and products that cater to these changes in technology is quite beneficial.

 

[squall_line]

Reeffjane, can you share some more of your experience with Milwaukee chargers here on this Festool forum?  Your insight may be helpful to the populace.