My two old Makita friends (9.6V and 7.2V Drills)

Yesterday I "rebuilt" my 9.6V Makita 6093D drill. Old school revival. Had two issues: H/L very tough, and the real reason it stopped was the inside + battery terminal. Very corroded and the nasty oxide stopped voltage/current flow. Cleaned it back to fresh alloy copper. Then I inspected the mechanicals, all good, gears and bearings, even the bushings perfect. Even most of the grease still fine, but cleaned and regreased with Amsoil spray grease. I had dropped it really badly more than once. The H/L switch part appears damaged on the outside (tab bent), and the function was like trying to shift without a clutch, but I noticed the cam pin was dry, I greased it well and function seems much better. I even straightened the thermoplastic H/L turn switch tab, heated and straightened. Not perfect, but much much better. I cleaned the case decently with isopropyl alcohol.

This drill and driver I used for years and used hard, I went through quite a few Makita NiCd batteries from ~1985-2010 or so. Dropped hard at least 3 times, dropped countless times.

After reassembly (only tough part is bushed end of output shaft, not hard - bushing, shim washer and spring) the drill spins and holds torque like new with the single aftermarket battery I have left (it's a bit damaged via floor impact) So I treated it to two new after market batteries! ($21!)

$25 2 Pack Upgrade to 3600mAh Replacement Battery Compatible with Makita 9.6V Ni-Mh Battery Compatible with 9000 9033 193890-9 192696-2 632007-4 6096D 6093D DA391D 6095D 5090D

https://smile.amazon.com/gp/product/B07FSM43Q7/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

AND I started to rebuild my 7.2V Makita 6070D drill. I bought this eons ago on a refurb rack as a companion pilot drill motor and used the 7093D as the driver. This old dude doesn't really have any mech issues and even as much as I used these over many years and build many decks with both the Japanese grease is in good shape. The problem with this one is the internal NiCd batteries - that's right not even swappable batteries! NOW here is the amazing thing - I decided to try to charge it with the brick charger - and dang this thing was purchased around 1985 refurb and it still works with the original at least 35 year old batteries. I'm sure they will die off quickly, but still. WOW. They sell the NiMH cells, with a little soldering skills - ebay, $24 https://www.ebay.com/itm/Battery-Re...D-M001/163141153151?ssPageName=STRK:MEBIDX:IT

BOTH Makita drills have very stout front bearings.

The 9.6V has a Jacobs USA chuck and looks like Made in USA (Georgia) Makita Corporation of America.

The 7.2V has a Makita Japan chuck and drill made at Makita Electric Works Japan.

Also I now have 5 cordless drills. These two, two DeWalt 20VMax (one brushed one brushless) and a 12V Milwaukee.

 

Forgot to post a picture!

 

man, those drills take me back, learned on the exact same ones in the 90's working for my dad. I can still hear him yelling at me to fully discharge the batteries before putting them on the charger.

 

Your dad knew the memory of those early NiCd. And they were not cheap. I think my dad had a 7.2V with changeable battery.

 

You're dad was absolutely correct! I have been told that (I have not researched this) Li-ion batteries are just the opposite -you never should push them to their absolute bottom end. however you CAN charge them any time during their cycle.
Ni-cads would develop a "shape charge" and lose their ability to hold a full charge if you did not fully discharge them.
I also wanted those little Makita's back then but they were out of my price range!

 

Li batteries don't like really cold, should not be stored fully charged (nor drained flat)- (over charging mainly) need to be more closely controlled (via BMS) than NiCd..........but bottom line LiCo especially the energy density wins out.

 

Got my 9.6V NiMH batteries. They charged and worked fine, repaired the battery case on my old battery. Works good too.

 

The 7.2V battery pack came on Monday. Soldered it in yesterday, really tight in there with the charging diode and resistor. I cut the tabs on the old pack rather than suck solder first. Difficult to solder to thin split +/- contact tabs, then tuck the nominally longer pack in the case. But it went fine. Little drill works great. Charged up. Ready to rumble. Funny the 12V Milwaukee is smaller than the 9.6V and 7.2V old school drills!

 

I worked with an electrical engineer (whacko model airplane nut) who interrupted a conversation we mechanical guys were having about HP calculator batteries - this is very old info they were HP45's. Despite trying to discharge them completely etc., they would run out of life - and HP wanted a small fortune for the battery pack (even the primitive HP45's cost us $275 in that era). He grabbed a very dead battery pack, wrapped it a few turns in drafting tape - then went out the back door of the ENG building and threw the thing as high in the air as possible. After thumping it on the pavement several times, he removed the tape, handed it over and said to try charging it again. It worked. Not exactly forever - but long enuff to bulk order some batteries for those of us facing a shut down.

According to this fellow, the batteries would slowly build a conductive path through the cell - that would eventually short out the cell. The mechanical shock of the tossing would supposedly "mess-up the molecules" of the cell and for a while, disable the conductive path. I have not tried this on a drill or laptop cell - but it might work for someone in a pinch.

 

I still have my 9.6
That drill took a lot of abuse.
Haven't used it in years.
Model 6096D

 

Dendrites. Break up the dendritic growth..........you would think any smack that hard would break most battery casings. I think in a chemical way this is what happens when hitting it intermittently with a bit higher voltage and current to accept a charge again.

 

I love that. Man the handles seem so long on those. In some situations better than a battery knob on the end. Milwaukee 12V standard batteries are the best of both, IMHO.

I used the 7.2V to remove some exterior wood screws. Plenty torquey nice in the hand, 600 rpm seems pokey though.

 

I had 2 9.7V, 3 7.2V & the flashlite you never used!

 

My dad LOVED the flashlight!!!

 

I recently brought home my late father's Makita 4390D 9.6V reciprocating saw, which hasn't been used for thirty years. I just might try some LiMH batteries to see if this can be given a second life. The goofy long-and-skinny form factor for the Makita 9000 batteries sorta works with this particular tool.

 

A classic!