28.8V Panasonic power tools Li-ion batterie pack

[Luminous]

Does anybody know what cells the Panasonic 28.8V Li-Ion battery pack has? Are they the safe technology?

I bought a Milwaukee 28V battery pack but I was very disappointed to find out that it is in reality not a 28V pack but a 25.4V pack. It is 28.8V when just fresh out of the charger but under load it is about 25.2/25.4.
Hence I am trying to find a true 28.8V under load: 8 cells pack.

Does anybody know if the 28.8V Panasonic pack is a true 28.8V pack: 8cells x 3.6V?

 

[VidPro]

with a model number a search of its specs would be easier.

i hear that the li-fe type of cells, hold up better under huge (power tool) loads.

a Quoted 14.4 volt li-ion pack would be 4x3.6 which would read ~16.8 charged
double all that
a quoted 28.8v li-ion pack would be 8x3.6 which would read as high as 32v off the charger.
and all of them will drop quite a bit in visable voltage under these huge loads.

the milwalkie if i remember right, would be a li-fe and have a 3.1v under load BUT seeing the v-drop under load it should actually work better than li-ions WHEN under these high loads, then not run for as long, as it has less total capacity.

so that would be actually called a 3.1x8 when speaking of its "nominal" so really it should have been listed as a 24.8v
probably has to do with the DEVICES it is intending on running, as it WILL basically pull the same weight.

on the back of the pack does it say LI-FE-PO4 or LI-ION , that would be your clue to the higher initial voltages. also any indication as to it being the "Safer" li-ion chemistry would probably be the li-fe-po4 batts not li-ion.

and of course charging of them, they would use different chargers.

 

[VidPro]

here are some threads that they play with the packs, just in case any of that is usefull.

http://www.rcgroups.com/forums/showthread.php?t=798990
http://www.candlepowerforums.com/vb/showthread.php?p=2317543#post2317543

i didnt read them ALL, but they have many of the power tool packs dissasembled and a basic idea of the batteries used in them.

 

[modamag]

It's all marketing.

Milwaukee V28 .... 7x Emoli (LiMn) 26600 3Ah ... effectively 26V
Dewalt 36V ... 10x A123 M1 2.4Ah ... effectively 33V
Makita LXT 18V ... 10x Sony VT connected in 5S2P 3Ah ... effectively 18.5V
Panasonic 28.8 ... 8x Co Li-Ion 3Ah ... Effectively 29.6V

Be very careful with the Panasonic batteries. They are the old cobalt technology. You should use a BMS or risk burning your house down.

 

[mdocod]

It's all marketing.

Milwaukee V28 .... 7x Emoli (LiMn) 26600 3Ah ... effectively 26V
Dewalt 36V ... 10x A123 M1 2.4Ah ... effectively 33V
Makita LXT 18V ... 10x Sony VT connected in 5S2P 3Ah ... effectively 18.5V
Panasonic 28.8 ... 8x Co Li-Ion 3Ah ... Effectively 29.6V

Be very careful with the Panasonic batteries. They are the old cobalt technology. You should use a BMS or risk burning your house down.

Panasonic using using lithium cobalt cells in a power tool battery?

WTH?

 

[modamag]

Not sure if their cobalt is the old chemistry or Lithium Cobalt Phosphate which is safe.
But they do have a GuardION BMS which makes things safe.

 

[Luminous]

Thanks for the info. Very usefull.
I am surprise of the number of power tool manufacturers that overstate the real nominal voltage of their packs. I would have thought the big names would not.
I have tested my Milwaukee battery pack today with my Blitz and an Osram 64657. I measured nearly 14min to 21.4V when I stoped the test.
I did the test in 2 steps (with about 5 minutes between them) to let the Blitz cool down.
The discharge curve is quite flat. I can post the discharge curve if somebody explain me how to do it.
I am going to get an 64655 which should be better suited to this pack.