an amazing fact about bosch blue 10.8/12v batteries

[big-all]

first point to clarify and get it out the way 10.8/12v are the same they are all made from the same 3.6v cells but voltage taken after charging when batteries are around 20% over volt because off charging
now its not a scientific study but the timings are within 5 mins using a 330lumins work light as a constant source
i measure all my batteries in turn charged on the same charger and tested within about 5 day and recorded the run time battery amps capacity the batteries go from 2007 to 2017 so 5 to 15 years old
i always used to bang on about nicads an nmh batteries on cheap tools loosing perhaps 20 to 25 % capacity a year with decent makes being perhaps 5-15% a year now i know lions are better but was stunned at the results
i have 15 batteries [i know mental and stupid ??]
7x 1.3ah 07-12 lowest was the newest battery at 3h3m with the oldest 3.13 average 3.20mins so overall no appreciable loss off capacity over 5 years
the 5 x2ah went from 13-17 and 5.46 to6 .05m with the age being slightly more reliant but still a minute difference
the 2x2.5 2015 where the one failure one giving an expected 7.h 19m and the other 4.40m
the one 4ah gave the best results per ah at 12h 26 mins but pretty much in line with the best 2ah 1 year later at 6.05 and 6.02
now the reason i have so many batteries is we assume 5 years old equals near to dead so new full tool with batteries makes sense but never took the time to check just made assumptions
now for most this will be a fully pointless thread but for others like me who like to mull over information its both fascinating and surprising
i would further add because i am not heavy trade in early years to mostly retired for the last 10 years with more batteries than a wartime costal defence it will skew the average overall but the capacities being so close over batteries at least 5 years old up to 15 years old is quite amazing

 

[big-all]

and just to check i will try batter 12 on the same charger and another in case the fault is not with the battery

 

[TimboTwo]

My 15 year old Milwaukee 12v batteries still going strong.

 

[big-all]

indeed i am sure many are but after dealing with nicad or nmh for 30 -40 years you get expectations that dictates what you do and the difference is night and day with bosch a full kit tended to be tool plus 2x battery ah + 20 so 2x2.5 was £70 so made sense to buy a full kit for the now failing [not ]older batteries

 

[catlad]

I bought 3x 4amp 12v fake batteries for my bosch tools about a year ago for about £65 two of them are dead already, where my genuine bosch batteries are still going years latter.

 

[cdbe]

Interesting. I base my question on absolutely nothing scientific, but I wonder if you would achieve the same results with a "high drain" tool such as an angle grinder?

 

[big-all]

Interesting. I base my question on absolutely nothing scientific, but I wonder if you would achieve the same results with a "high drain" tool such as an angle grinder?

i do have the mini grinder and it cains the batteries as you would expect but on high loads other electronics can come in and shut down a battery but at least you can tell the amount off fuel in the tank
now its possible there is a slightly different voltage on some batteries that will make a difference but similar test over the years on ryobi dewalt and bosch i have used a form off lighting as quietest and visual but this is the first time age hasnt made much difference now off course its possible all the batteries are down but being so close over a 10 year period is to me trully amazing

 

[^woody^]

I still have two 1.3Ah batteries that I got with the original driver in 2004 (?), and four from two more tools in 2006, and they all still work fine. Not used every day, but almost every weekend, including constant use to empty, charge then re use.

 

[big-all]

with li-ions the modern theory seems to be 20-80% for occasional use as in charge when they reach 20% and stop around 80% charge

as an aside
i only ever use a slow charge as i think that's better for the equipment, the only exception is dewalt 18/54 charger only go up to around 6-7 amp so a 9ah battery needs the fast charger
the reason i said 6-7 was because all charge lights where illuminated[3 off them]so assumed 66.6%+ charged but still took a good charge on the fast charge

 

[^woody^]

with li-ions the modern theory seems to be 20-80% for occasional use as in charge when they reach 20% and stop around 80% charge

as an aside
i only ever use a slow charge as i think that's better for the equipment, the only exception is dewalt 18/54 charger only go up to around 6-7 amp so a 9ah battery needs the fast charger
the reason i said 6-7 was because all charge lights where illuminated[3 off them]so assumed 66.6%+ charged but still took a good charge on the fast charge

I'm not so sure now about that old way of thinking!

It may have applied to ni-cads and nimh, but if you look at all the current lithium powered tools and other electrical items they all seem to be fast charging with no battery detriment

What lithium batteries do like however, is to be charged when just partly empty, not run down completely.

 

[big-all]

i have the luxury off far too many batteries and far too much time on my hands to fill
i know in real life its throw the tools in the box and forget and iff some time later charge the day before or iff a week or so use as required charge as required

 

[Mike13]

I'm not so sure now about that old way of thinking!

It may have applied to ni-cads and nimh, but if you look at all the current lithium powered tools and other electrical items they all seem to be fast charging with no battery detriment

What lithium batteries do like however, is to be charged when just partly empty, not run down completely.

For a DIY enthusiast who does not use the batteries often, then fill to ~80% and use to about 20% will maximise the lifetime of the batteries. For a professional who runs down the packs daily, fill to 100%, but try not to leave them on charge overnight and then run down to zero, that maximises the kWh extracted from the battery before failure. but do not leave them too empty for any amount of time, and dont leave them on charge when not being used, both of those can easily lead to plating out of neat lithium, which is not a good thing. Also small changes to the chemistry by the supplier can lead to about a 5mV change in what should be 100%, so stick to the suppliers charger.
A slow charger which limits the current does have its place for keeping a cell topped up occasionally.
And as others have noted, the 18V/20V is more marketing puff than major differences in the cells.
Sometimes the higher rated pack will use cell pairs where each cell is rated to a lower current.
The Ferrex 20V2Ah pack is 30A samsung cells inside, but the 20/40V5Ah is 20A Samsung cells inside, that can cope better with a deeper drain, or so I am led to believe from some youtube teardowns