Anyone got a clean breakdown of the Makita 18V battery pinout?

[Thomas Martinez]

The Makita 18V pinout are one of those topics that comes up frequently in discussions but the information about it is widely scattered. The basic pins for the 18V packs include a minus pin, plus pin, a TH pin for temperature monitoring and a C1 pin located at the junction between the battery cell group for balancing. Additionally, the Makita tool utilizes pins 1-7 to identify the battery pack. I'm not exactly sure what goes into each of these pins but I would imagine that's what allows for the recognition of the higher capacity vs. The lower capacity battery packs.
For those that are looking to rebuild or utilize the battery packs outside of a Makita tool, knowing what each pin do is essential. From what I've found in my research, the information on most sites about the 18V packs includes the +, -, TH, C1 pins and pins 1-7, but does not offer an explanation of what each of the 7 identification pins does individualy.

 

[Mysteri]

the ID pins are just resistor coding afaik, no actual data lines. Its how the tool figure out if you have a 3Ah vs 5Ah vs 6Ah pack mostly. Nothing fancy going on like serial comms or anything.

 

[Tense Tuatara]

the ID pins are just resistor coding afaik, no actual data lines. Its how the tool figure out if you have a 3Ah vs 5Ah vs 6Ah pack mostly. Nothing fancy going on like serial comms or anything.

Wait so if it's just resistor coding could you in theory short two pins to make the tool think it's a more higher capacity pack? For instance, my old 1.5Ah battery pack that I never use could potentially be shorted to act as if its a higher capacity battery pack?

 

[My Little Racc]

Wait so if it's just resistor coding could you in theory short two pins to make the tool think it's a more higher capacity pack? For instance, my old 1.5Ah battery pack that I never use could potentially be shorted to act as if its a higher capacity battery pack?

You can't fool the tool into giving you more runtime than the cells that the battery pack contains lmao. The battery just contains the amount of capacity that it contains. The ID pins just let the tool know what kind of battery it's dealing with.

 

[Claustrophobic Animal]

The C1 pin on the 18V Makita battery is not used for balancing the battery pack with the tool. The balancing occur on the charger. The battery's BMS system is very minimal. Most of the features on the chargers are actually built into the tool itself which is why aftermarket chargers can be sketch.