Bypass tool battery logic/thermistor tab

[Bigwavedave2u]

1. There is a video which shows a kobalt battery adapter to different brand tool. These are port batteries and  require the positive and negative wires sourcing the Kobalt battery tabs only. They do not use the middle thermistor/logic tab. My question on this part is how to adopt a kobalt battery to a three tab tool. This requires knowing how to deal with that middle tab.

2. What is really critical to me is how to adopt another 24v tool battery to the Kobalt tool. Once again this requires one to know how to deal with the middle thermistor/logic tab. This is what has us kobalters going crazy. Any help would be huge.

[ledtester]

2. What is really critical to me is how to adopt another 24v tool battery to the Kobalt tool. Once again this requires one to know how to deal with the middle thermistor/logic tab. This is what has us kobalters going crazy. Any help would be huge.

What's the resistance between the middle tab of the battery and the ground tab?

And might as well also measure the resistance between the middle and positive tabs.

[Bigwavedave2u]

Thank you for your reply. Deeply grateful on this end. I am an F. N. G. and will soak up any Intel you may send my way

Resistance between middle tab and negative tab ~25 ohms
Resistance between middle tab and positive tab ~36 ohms

[Bigwavedave2u]

Also.  Lights turn on briefly when switching tool to on.

[ledtester]

What does the bottom of one of your Kobalt tools look like? Can you post a pic? Specifically, what electrical connections does it make with the battery?

[Bigwavedave2u]

From +tab:power wire straight to switch and smaller wire both enter sealed block
From -tab: power wire through block and then the switch
From middle tab: wire to same block with wires from +tab. One would think there is a communication loop there.  I soldered a 10k resistor from positive tab to negative tab. Same results. The lights come on for just a moment.

Will send picture when I get back to tool.

[Bigwavedave2u]

Here are the pics. Please disregard 10k resistor. I am going to solder that between middle and ground tab. And assistance would be most helpful!

[ Specified attachment is not available ] [ Specified attachment is not available ] [ Specified attachment is not available ]

[Bigwavedave2u]

[Bigwavedave2u]

[Bigwavedave2u]

The large red positive wire goes straight to switch. The negative goes through block and then to switch

[ledtester]

fwiw I found this on reddit:

https://www.reddit.com/r/KobaltTools/comments/od2d2y/kobalt_battery_omega_pinoutpowering_kobalt_tool/

What battery are you trying to power your Kobalt tool with? It seems that a lot of Kobalt tools need a 24V battery whereas other brands use a lesser voltage.

[Bigwavedave2u]

I have several 24v craftsman batteries. The batteries have all been tested for viability. I can't seem to get the kobalt to turn on. Just the light for a brief moment

[Bigwavedave2u]

Here is the answer. Please understand that is is only an exercise and should be treated as only an exercise on paper only. Just because this is my opinion does not mean it would work. To treat this more than an exercise on paper may result in significant harm!

For a kobalt tool generally a 10k resistor would be placed in line between switch and Omega tab on tool thus bypassing thermistor all together.

[ledtester]

Looks like good info - can you provide the link to it? Is it from a US patent application?

[Bigwavedave2u]

Following alot of book digging and company calling, this is my conclusion. Does this appear correct?

The third tab is both a thermistor and a comms* tab. This can be fooled with an adapter from an old battery which could in turn be attached to a homegrown mount. And just as you would harvest out the internal Samsung (or whatever brand)units by snipping away the solder joints when attaching an 120v ac - 24v dc unit, you could use the post harvested kobalt battery top for your mount with a double spade +- conventional battery of your choice within reason. I would only recommend (at your own risk) using like volt with like volt.

*This is a comms tab but not in the way you would think.

Because you are dealing with a brushless motor you have three leads where the - tab, the + tab, and the T tab are operating in a forward sequence where upon rotation of motor stator the signal for say the current - tab moves forward to become the + tab and then on the next rotation becomes the T tab and so on and so forth. This is consistent with all three wires exiting motor.

As for bypassing the T tab, I believe the only way to safely accomplish this is in the aforementioned explanation. HOWEVER, finding the proper thermistor resistance (generally anywhere between 4.7 and 10 ohms soldered between T and - tool tab should work. IMPORTANT: You'd damn well better make certain your power source is independently protected at all levels as you are disabling your low charge protection with this method and for me the thought "ABANDON HOPE ALL YE WHO ENTER" comes to mind.