A look inside the Dewalt 1Hour 7.2-18V charger DW9116

Archived from the Tools In Action forum (Dewalt). This thread is read-only.

TimHMember since Sep 2011Sep 7, 2011 5:32 PM CT

I was going to modify the Dewalt DW9116 Charger to allow me to charge other vendors batteries.

When I opened it up, I discovered it is not isolated by a transformer from the line. This makes it unsafe to add any externally accessible connector.

**Do not even think of modifying it in this way, as there could be severe shock hazard if connections are brought outside**

I took a few pictures and added some notes as others may find it interesting. (I am an Engineer)

The charger seems to use a custom control IC, marked with what may be a B&D part number (starts with BD).

For old batteries with no internal temperature sensor the charger uses a temperature sensor thermally coupled to one of power connector pins. As the battery heats up at end of charge (or if hot from use) the controller senses the conducted heat from battery via the connector pin which is welded directly to last cell in battery.

For newer batteries, they have an internal Negative coefficient Thermistor, brought out on a third pin on the connector. This is a much better method as it is better coupled thermally to cells, but adds a small cost to each battery.

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MadtecMember since Jun 2010Sep 7, 2011 7:51 PM CT

Very good observation ;D

The new 20v max chargers are totally different

tooljoeMember since Jun 2011Sep 8, 2011 8:40 PM CT

For newer batteries, they have an internal Negative coefficient Thermistor, brought out on a third pin on the connector. This is a much better method as it is better coupled thermally to cells, but adds a small cost to each battery.

thanks, I was wondering why there is a 3rd pin in my battery packs.

medmikeMember since Dec 2011Dec 9, 2011 7:59 PM CT

Oops…I just added to output lines for other charging to a DW9310 charger-soldered to neg and pos. Wires are insulated and contacts are also isolated-ill add pics. Let me know how dangerous this is or can wiring be modified to add transformer (maybe DC9310 has transformer?…too lazy to tear apart and snap pic just yet).

Thanks

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medmikeMember since Dec 2011Dec 10, 2011 5:44 PM CT

Took a look inside the DW9310 charger…looks like transformer is in there. Here is pic.

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chrisa72Member since Oct 2013Oct 19, 2013 8:58 AM CT

Hi Tim H.

Having rebuilt a nicad battery pack and managed to cock it up good and properly, I have also managed to fry what appears to be a diode within the charger. It referenced as D26 to the RH side of the “Buck Regulator” it appears to be blue with some coloured bands on it. Can you tell me what it is please and its associated value.

Kind regards

Chris

TimHMember since Sep 2011Dec 1, 2013 5:15 AM CT

>>>

D26 to the RH side of the “Buck Regulator” it appears to be blue with some coloured bands on it.

Can you tell me what it is please and its associated value.

<<<

Chris,

That is a resistor not a diode.

It is R26 not D26.

Search on web for resistor color code and you can figure out the resistor value, from the colored bands. It looks like at least a 1/4 w resistor.

I don’t have a large picture anymore and it is difficult to see the colors in the small picture I posted.

The gold band at the end means 5% tolerance.

It looks like it has 5 color band .

If the colors are orange-black-green-brown-gold then it likely is a 3050 Ohm resistor 5% 1/4W

skidmarkMember since Nov 2013Dec 8, 2013 2:25 PM CT

Did anyone on this post ever figure out what the pinout is on the BD2003XR3 chip?