Lithium Battery Query - Storage / Performance

Hi All,

I've got the Bosch GBH 18V-21 and used for a good few years now with two 5ah lithium batteries. I've noticed a real drop off in performance lately and I suspect I've incorrectly stored the batteries.

The advice on the internet says to store lithium batteries at between 40% and 60% charge. Sometimes I go out with the two batteries fully charged but end up only needing the one. 

The second battery that ends up having 100% charge but not being used .... are you supposed to run it for a bit on the drill in order to get it down to 60% charge and then store it??

What's the best advice? Do all lithium batteries degrade in performance if you store them at 100% charge?

Thanks

Storing a Lithium battery at 100% charge is not the best for them.  

The batteries you have are lithium ion batteries in your drill's batteries that generally last about 600 cycles with a cycle defined 100% - 0%.   That's once a day for almost 2 years. You get more cycles if you do not discharge as deeply or charge to 100%.  I gather the complete discharge is worse than the complete charge.  One of my friend's EV defaults to charging to 90%, another to defaults 80% to prolong battery life.  Both vehicles can charge to 100% for road trips.  The batteries in these cars are expected to last at least 10 years with some predicting they will last 20 years.  

People also discuss batteries aging by just sitting on the self but I am not convinced how bad that is. 

In contrast LiFePO4 batteries generally have a 6000 cycle lifespan or 10 year years once a day.  Some of the very newest ones are have a 20,000 cycles but I don't think those are available yet.  As far as I know there are no LiFePO4 batteries available for drills and other tools.  :(    I wish my phone which does a full cycle every day had LiFePO4 batteries rather than Lithium Ion.  But the energy density is less.

I store my batteries at 100% charge and buy 2nd party batteries off amazon when one dies.  I cannot tell a difference between the batteries and 2nd party batteries are about 1/4 the price of the manufacture's batteries.   I usually get 3 to 5 years out of a battery with occasional use. 

climber pat wrote:

Storing a Lithium battery at 100% charge is not the best for them.  

The batteries you have are lithium ion batteries in your drill's batteries that generally last about 600 cycles with a cycle defined 100% - 0%.   That's once a day for almost 2 years. You get more cycles if you do not discharge as deeply or charge to 100%.  I gather the complete discharge is worse than the complete charge.  One of my friend's EV defaults to charging to 90%, another to defaults 80% to prolong battery life.  Both vehicles can charge to 100% for road trips.  The batteries in these cars are expected to last at least 10 years with some predicting they will last 20 years.  

People also discuss batteries aging by just sitting on the self but I am not convinced how bad that is. 

In contrast LiFePO4 batteries generally have a 6000 cycle lifespan or 10 year years once a day.  Some of the very newest ones are have a 20,000 cycles but I don't think those are available yet.  As far as I know there are no LiFePO4 batteries available for drills and other tools.  :(    I wish my phone which does a full cycle every day had LiFePO4 batteries rather than Lithium Ion.  But the energy density is less.

I store my batteries at 100% charge and buy 2nd party batteries off amazon when one dies.  I cannot tell a difference between the batteries and 2nd party batteries are about 1/4 the price of the manufacture's batteries.   I usually get 3 to 5 years out of a battery with occasional use. 

Thanks Pat, the only general information I can find seems to be store at room temperature, don't store fully charged or discharged.

It would be really helpful if my Bosch charger had a setting where it stops when the battery is at 60%. 

Lithium Cobalt batteries are the most sensitive.  They last at least five times longer if stored at around 50% charge.  I have used them for many years and have experienced both the good and the bad -- always related to the charge left in them.

You can also discharge your drill batteries with an incandescent light bulb.  Use about a 40 watt bulb in a socket where you can cut the wires and bare them so you can connect them to your battery terminals.  Yes, I have done this numerous times.  If the battery has no charge indicators, use a multimeter and discharge the battery to about 3.7 to 3.8 volts.  The meter will also help you find which two of the battery contacts are the ones to connect to.

I got tired of replacing phone batteries.  My current phone battery has good capacity.  I only charge it to 70% (with a timer).  It has not lost any noticeable capacity in three years.

Jason Hurry wrote:

It would be really helpful if my Bosch charger had a setting where it stops when the battery is at 60%. 

That’s exactly how the charger for my drone batteries works.  As for everything else like the drill I just go to 100% and if they don’t get used that day they get stored at 100%

Interesting topic and something I'd never considered. I always charge my batteries fully as soon as I get home. It's just part of my clean up process when I get home from a day of route dev. And I've never had a problem with any batteries losing charge over time. I don't leave them on the charger though, when they're done charging I take them off the charger and put them on a shelf. I use Dewalt batteries, typically DCB205.

For you guys that are storing your batteries at only ~60% or similar, what are you doing when it's time to head to the cliff? I  imagine the idea is to charge it up fully the night before in which case you're leaving it stored fully charged overnight every time you're going out. Is that acceptable? I suppose the other option is to charge it in the morning before you head out. In either case, it's one more thing I don't want to have to think about when I'm gathering what I need for the day. And I'm not losing daylight while I wait for batteries to charge!

Or do you do something altogether different? I can't imagine you are going out with a battery that is only half charged?

KrisG wrote:

Interesting topic and something I'd never considered. I always charge my batteries fully as soon as I get home. It's just part of my clean up process when I get home from a day of route dev. And I've never had a problem with any batteries losing charge over time. I don't leave them on the charger though, when they're done charging I take them off the charger and put them on a shelf. I use Dewalt batteries, typically DCB205.

For you guys that are storing your batteries at only ~60% or similar, what are you doing when it's time to head to the cliff? I  imagine the idea is to charge it up fully the night before in which case you're leaving it stored fully charged overnight every time you're going out. Is that acceptable? I suppose the other option is to charge it in the morning before you head out. In either case, it's one more thing I don't want to have to think about when I'm gathering what I need for the day. And I'm not losing daylight while I wait for batteries to charge!

Or do you do something altogether different? I can't imagine you are going out with a battery that is only half charged?

Hi Kris, it's strange you haven't seen a drop in performance - I definitely have on my Bosch 5ah batteries. All the advice on internet and the manufacturers seems to be that lithium batteries stored at full either full charge or zero charge will have a shorter lifespan.

I've always stored mine at full charge and then on the morning of or day before given them a few minutes blast before heading out. 

On Jim Titt's website he has a recommendation to charge fully before heading out and then just before you leave once again put the battery on charge for a few seconds and it juices it up more.

What I can't understand and have found no advice on is what to do if you have a fully 100% charged battery that you didn't use and now need to store. Bosch say their lithium batteries should be stored between 40% and 60% charge. I don't understand why the charger then doesn't have an option to cut off at 60% charge....it just keeps going until the battery is full.