Battery storage question

[Texas splinter]

It is looking like I will be out working on another contact for the next year or more (787 work at Everett, WA), so I am in the process of "mothballing" my shop. I have a Makita 12 drill/driver and two B&D 18V drill/drivers.
Last time I left, I had two 12V Makita batteries, when I got back neither would hold a charge for very long. One of them has finally started holding a charge, I recycled the other one, it never would take and hold a charge for more than a day or two.
The B&D site says you can leave the 18V batteries on the charge for " a season" but they won't overcharge because of a built in limiter. It goes on to say that you should take them off the tool in "off season", but don't need to charge them, they will be Ok.
I don't want to come home and need to buy new batteries.
Any suggestions as to storing these for a long-term storage?

[leehljp]

My experience has been opposite of conventional thinking, or as I was advised by several between 2000 - 2005, by which time I learned from my own experience.

First, my background: Being in Japan with a home in the States, I get back (Stateside) every year or so for a month. I have tools there that I use for minor repairs. Also, Every 4 years, I return to the States for a year and leave my tools here in a similar state.

All of mine have been NiCads. I leave them in a state of mostly discharged. Then when I return to one place or another, I charge them immediately. My experience with Ryobi (6 18V batteries), PC (2 14.4V batteries), and HF (2 18V batteries) has been this - those that were left in a charged state and then set up for a year - battery life was greatly decreased the next year. Those left in a mostly discharged state - took charges and worked much better.

My experiences are certainly not scientific but with the batteries mentioned above, the results have been consistent -
Left in "Uncharged state" for a year - continues to work well; 6 Ryobi, 1 PC, 1 HF
Left in "Fully Charged state" for a year - battery doesn't work well. (1 PC battery and 1 HF battery)

I do NOT leave then in a charger for a year while I am not there, and I don't have enough chargers for each individual battery.

Adding in more explanation here: Between 2001 - 2002, I left one PC and one HF battery in a fully charged state in the US. When I returned in 2002, neither battery worked well. The partially discharged PC battery did well. REcycling the fully charged battery did bring it back to half life. (I brought it back to Japan with me and continued to use it here.) For the HF battery -I recycled (charges/discharges over two weeks) and it gave me about 30 minutes use. I bought another HF Drill and left it in a discharged state after that first experience. It worked even the last time I was home one year ago. Both PC batteries are practically useless now, 9 years after purchasing. The first one died altogether in '05 but it was the one that was left charged for a year with no use.

[Ed62]

Hank, that's an interesting experience. Now I'm wondering if there are any modifications or concerns between electrical power in the U.S. vs. Japan? Maybe you need a different charger in each place?

Ed

[eccentrictinkerer]

I've had good luck with a scheme that involves a 24 hour timer set to turn my chargers on for 1/2 hour every 24.

My highly unscientific opinion is that a slight bump every day is way better than a continuous charge.

So far, it's worked pretty well for the last 15 years. Caveat, I'm a handyman, so I use my tools every day (I think regular use is the best for any battery).

I now only use Panasonic and Bosch, but back in the day I had a bunch of Makita 9.6 tools whose batteries lasted a long time. I still use my 9.6 right-angle drill and the batteries are at least 10 years old.

[Mr__Bill]

My experience is like that of Hank's. I would add that leaving the battery in a completely dead state may leave it really dead for good, but with some charge it will be able to hold a charge again. I also found that storing the NiCad batteries in the freezer they worked better when charged. Have to let them warm up before charging. My storage was only for 3 or 4 months at a time. I have no experience storing the newer batteries.

Another option is to sell the batteries and buy new when your back.

On a side note, there are a lot of BT3'ers in the Everett area* you may want to take your hand tools with you and beg some shop time.

* well within at least an hour.

By the way, do you know it rains in Everett? Even when it's not raining any where else it rains in Everett. It's a beautiful area, away from the city, and you have lots there to enjoy.

Bill, now on the Sunny Oregon Coast

[leehljp]

Hank, that's an interesting experience. Now I'm wondering if there are any modifications or concerns between electrical power in the U.S. vs. Japan? Maybe you need a different charger in each place?

Ed

My area has 60 cycles and 100V. The US chargers don't do well at all with the 100V. I do have a couple of 20 amp Variacs and the chargers are hooked to those set at 115V. That works fine.

Eccentrictinkerer: That is a good idea, but for being gone even a month, I would be afraid to leave chargers running in my absence. For letting a charger run a year at a time with no one checking on it, that scares me! Texas Splinter mentioned "mothballing" which implies several months being gone.

Do any of you leave chargers running months without checking on them? Would you leave home for a month or more with them running on "cycling" or a timer?

[jabe]

This is interesting, I've always left my batteries fully charged when in storage. Two of my 12V makita's did not last very long with this procedure. Anyway, I had 2 of them rebuilt by Prime Cell, they rebuilt them with stronger cells and upped the amperage. The rebuild with shipping was cheaper than buying new batteries and I'm very satisfied with it.

[Texas splinter]

To Leehljp and Mr Bill:
I expect to be gone for at least a year, last time I was gone 14 months.
Yes, I know about the weather in Everett. I was born and raised in Portland, OR, and spent some summers with an aunt that lived in Everett. The "convergence zone" is where all the bad weather happens and is close to the Everett area.
As for other BT3'ers, When I worked on this program last time, our manager instructed us: "...I want you people to work 10 hours a day, Mon thru Thur, but you only have to work 8hours a day Fri thru Sunday!"

Leehljp: I think I will just try your method. The B&D site said not to worry abut recharging the batteries at the end of the season. (same batery is used in some weed eaters & trimmers.)