Ingersoll Rand W7150 cordless driver - Page 1
Forum section: electronics / general

author: najrao
author_rank: Regular Contributor
timestamp: December 23, 2019, 06:04:00 am
content: Another wild chase:Has anyone any experience in hacking the battery or trigger switch assembly? I was given this less battery, and the driver has two extra connections over the + and -. Somewhere Ing Rand say "the battery communicates with the driver to protect it and itself".The battery costs $198 and the trig switch something equally horrendous.I need to use another 20V Li ion I have. Apart from mechanical problems, I can't get the motor to turn even from a bench supply unless I decode this "communication" issue.The pcb (part of the switch assy) is very small and connects through a five pin connector to the battery terminals; only three pins are used, and one goes to the bat negative via a 10k external resistor. Two other wires are the " communication". Could be simply a thermistor for battery temperature, but nothing happens with any value of shorting resistor across, or to + or-.It is very difficult to get at the pcb without wrecking the switch assembly.My only hope is that someone has done the hacking and helps me. Thanks for that.

author: helius
author_rank: Super Contributor
timestamp: December 23, 2019, 07:02:05 am
content: The extra pins may be something horrendous like SPI, but it is more likely imho that they are for something simple like a thermistor (to detect overheating) or resistor (as a battery identification code). This was the case for theKeysight U5855A and its special battery.

author: najrao
author_rank: Regular Contributor
timestamp: December 25, 2019, 09:24:51 am
content: Helius, I am frustrated by this stupid IR driver.A power connection at the motor itself had fused, perhaps due to bad crimping. The high temp wire used proved too short, so I replaced it by thicker Teflon.The two mystery contacts, of the four intended to mate with the battery, are still a puzzle. The one next to the B(--) has the full applied voltage on itwhen the trigger switch isnotpressed; the other, next to B(+) has zero. When trigger is pressed, the first drops to zero, and the second puts out 4.8V, independent of the B(+) feed. Both are fairly high impedance, in that loading by 4k7 drops the first by 80% and the latter by 50%.Not having the $198 battery itself, I have to glean the scheme adopted by IR by forensics alone. There is no knowing if the trigger electronics is fully functional.Scope check shows both voltages are just dc, no waveforms. Thank God.What do you think? Thanks for any help.

author: najrao
author_rank: Regular Contributor
timestamp: January 04, 2020, 12:48:08 pm
content: I managed to flip open a lid on the top of the PCB housed in the trigger switch. I dare not open it up completely (may never get lt back in one piece), but lifting up the PCB itself partly, I find a PIC616HV616 and some smd devices. All on a multilayer(?) 22×14mm PCB, with a Kapton ribbon cable leading to the power mosfet. Of the just three wires connecting to the battery, two must be the circuit dc supply, leaving out just the one white wire for " communication".What is this 'horrendous SPI'? Because that is what I think it is. Simple resistor- or dc voltage signal does not wake it up.Unless I can get a proper IR battery, even a dead one, seems not much to do.

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 04, 2020, 04:08:11 pm
content: If it's a common brush type motor, it would be trivial to replace the speed control with a generic one based on a 555. If it's BLDC, it would be a little more work to replace it with a R/C type ESC but still possible.

author: najrao
author_rank: Regular Contributor
timestamp: January 06, 2020, 09:14:38 am
content: So, NiHaoMike, I tried to pry open the trigger switch to see if anything can be done to access the internals, get the bare mosfet connections, and any slider/s. Simply terrible.The PCB detached with some careful spudger work, still attached to the Kapton ribbon cable the other end of which goes inside the heatsink "box". This has two thick copper parts, and covers three sides of the trigger switch body. Heat transfers to it from the inner copper sink, glued with white heat transfer compound.Now the throbber: the inner copper heat sink is actually asubstratecovered with Kapton on the underside, and carries the TO 220 DPak mosfetandlots more smd's, possibly for the gate drive. The underside is not clearly sightable. Spudgering this out proved to be very tough, and something seemed to give if more force was applied. The switch itself is $180, and it seemed a shame to proceed further.Sorry, I failed to take pictures before putting it all back. There is a yo**ube video with someone breaking it open. I will try and add a link.Ed.The ribbon cable, which is accessible, has only six ways, so there is some hope of working from there. While unlikely, it may be a P- mosfet, or a fancy current sensing fractional source job.