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Lithium ion cell equivalents

flippineck

Sep 8, 2013
358
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Sep 8, 2013
Messages
358
Looking for a UK supplier for the following:

Code:
Lithium-ion Moli IMR-26700A 2900mAh 3.8V Cylindrical High Power Cells Specifications
Manganese dioxide based Li-ion battery cell
2900mAh, 3.8V, max 40A discharge

A number of safety features were designed into the IMR-26700A cell, including thermal interrupt, tear-away tab and vent that relief pressure and prevent runaway overheating and outgassing. In addition, it's 40A maximum discharge provides stable 13C discharge, an attribute from the spinel structure of LiMnO2.

Model Number:                  IMR-26700A
Type:                          LiMnO2
Nominal Voltage:               3.8 V
Size:                          26700
Nominal Capacity:              2900 mAh
Energy:                        11 Wh
Size (mm):                     26.4 x 70 mm
Weight:                        101 grams
Energy Density (Volumetric):   285 Wh/l
Energy Density (Gravimetric):  110 Wh/kg
Operating Voltage:             4.2 V to 2.5 V
Maximum Discharge:             40 A

..or something directly equivalent. This is to repair a Milwaukee V28 cordless drill battery pack.

Any ideas or suggestions where I might find a supplier would be gratefully received.
 

flippineck

Sep 8, 2013
358
Joined
Sep 8, 2013
Messages
358
I think there's 7 cells in the original pack - I've not looked at exactly how they're connected to the control circuit yet, parralel, series, combination of both etc.. but I was also wondering about the possibility of replacing all the cells with a suitable number and interconnection, of a different type of cell? Would that likely be feasable if good new IMR-26700A's proved to be hard to obtain?
 

dave9

Mar 5, 2017
1,188
Joined
Mar 5, 2017
Messages
1,188
They're definitely in series to reach their 28V claim, just using 4.0V instead of the prior convention of 3.6V/cell.

The problem with a battery like that is to get something good instead of old, low capacity, low current, or fake, then the cells are going to cost a premium. Different cell size would mean they're ratting around or you're stuffing insulating padding in unless you made some kind of structure that allowed heat to radiate.

Considering this is an old pack, I'd imagine all the cells that haven't failed yet are nearly there, and look into whether your tool and charger can take the M28 packs. At one point they were backwards compatible.

They're not cheap at around $130 (in the US at least) but that's one of the catches going with a contractor grade, upper tier (for the time) tool line that takes 28V.

When to replace a tool instead of investing in new battery(s) for an old tool is a topic onto itself. I ended up moving from Dewalt to Ryobi, for several reasons which are beyond the scope of this topic.
 
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