Hey Guys,

I'm just looking for some advice on Handheld Batteries, more precisely their care and feeding.

I have a few handheld units and I have them in their charging bases, plugged in 24/7.  Now, I've been noticing that almost every rechargeable battery thing I own, such as scanners, laptop, etc, that I keep plugged in all the time ends up with no battery when I unplug them.  The batteries just go flat as if they were dead, when removed from their chargers.

Is this because they're being over charged?

Am I better off plugging handhelds, scanners, laptops and anything else that has rechargeable batteries into an outlet with a timer on it that only charges every 3 days or so as opposed to keeping their charging bases plugged in 24/7??

Thanks,
NH_Patriot

It depends on the battery chemistry.

In a nutshell:

Lithium chemistries:

Store isolated at 50% level of charge. If you're storing with it in a device, check it frequently. While the battery
protection circuit will disconnect if if it gets too low, the circuit itself draws some current. Total discharge kills
lithium batteries.

Can't really be overcharged because the chemistry is so sensitive it requires a charge controller that prevents it.

Nickel chemistries:

NiCd - this is a very old chemistry that's not used nearly as much as it used to be. There's an entire
set of magic instructions to store these if they're isolated. They can be slow or trickle charged and a lot
of devices are built using this type of charging.

NiMH - this is the common nickel chemistry today, and shows up a lot in rechargable devices.

This chemistry does NOT like trickle charge, or over-charge well, but a lot of devices are still using charging circuits
designed for NiCd with them. This will work, but slow charging with a trickle maintenance charge will kill NiMH,
so you want to pull them off the charger as soon as they are charged.

The ideal way to use NiMH is to use the device down to 20-40% charge, and then charge with a high current
charger with a good charge termination method. This results in the longest battery life.

My own recommendation is to use things that take AAs, and use NiMH AAs (Eneloop) and a good charger
(Maha 9000 or similar.) No worries about overcharging and the cells will last 500-1000 cycles.

ETA: but if you are using things that have packs, and they're NiMH, definitely do not leave them on a charger.
Don't even cycle them every 3 days. Charge them and don't recharge until they're at 50% or less charge. NiMH
really needs a real, high-current charge to keep it from getting damaged, and then disconnect.

Keeping batteries on the charger tends to kill them. Usually store lithium batteries at about 75% charge or so. Keeping them topped up all the time isn't good for them. My laptop will not charge the battery if its over 90% for example.

Honestly some super technical advice so far that I can't touch one way or the other, but: whatever you decide to do, also consider looking into AA battery trays for your handhelds. That opens you up to going down the eneloop path (which arguably works better if you already use AAs frequently and can cycle things through) and the 10-year shelf life on quality alkaline cells. The more options, the better.