Thinkpads Forum

Question for those that have the 27++ or 28++ Slice battery;

How is the remaining capacity of yours (capacity, cycle count), and how do you use it? Is there finally a way to reverse the discharge order of the two batteries?

I've always wanted more battery-life on my W520 and now that the main 9-cell is losing more and more of it's design capacity, the purchase of a slice battery becomes more tempting. However, in the past I've had an Ultrabay battery in a T61, and that one went down to 50% of design capacity after something like 10-20 cycles. I guess mainly because it was used up first and to 0% by default.

From my past research I found the same discharge behaviour is the case with the slice batteries, but I'm wondering if anyone found a workaround.

The Sanyo batteries lose capacity pretty fast - my slice battery is unfortunately one of them, as was the ultrabay battery I had for my T61p a number of years ago.

I got about 5 years and (IIRC) 100ish cycles out of the Ultrabay battery before it refused to charge - the slice battery has about 20 cycles on it now and is down to roughly 90% new capacity. I bought it new but 5 years old and holding about 95% original capacity.

I've read that there may be a way to force the primary cell to discharge first under some flavors of Linux but I've not observed (or read) this as true for Windows. The only idea I have for forcing the primary battery to discharge first is to not "lock" the slice battery after you attach it to the machine until just before you need to start using it, as that will prevent it from discharging.

Is that 'lock' the same as with the normal system batteries? Meaning they are attached just as good when you don't lock them?

Yep. Just a little green slider that if is left disengaged, the system won't use the battery.

If you bought it 5 years old, 90% is simply what you get just from storing it at 0 degrees and 40% charge.

That's just it though - after just checking it now, it holds 91.46 Wh out of 93.24 with 49 cycles. Manufactured 06/2010, first used 06/2015. 98% of the design capacity is still there.

Pretty darn good for a Sanyo, and (obviously) better than I recall it being...

The 9C Panasonic I use as the primary is 94 cycles, 89.54/93.96; manuf. 10/10, first used 12/10.

I just ended buying a new normal 9 cell battery; the very few userreviews of the slice batteries were just too negative.

Old battery (55++)
Full charge capacity; 42.86 Wh
Cycle count: 478
Manufacturer: LGC
Mfg date: 2011-11-04
First use: 2012-03
Design capacity; 93.6 Wh

The new one (70++) is a Sanyo and so far I'm enjoying 95 Wh

The old one will probably end up in the refrigerator, in reserve for long-distance travel