We've got two T2+s and a Pronto TSU7500 at our store with no client in mind. They all have been charged up, and some programming done to them.

Once the batteries have been charged, will they have a longer overall life if we keep them charged while waiting to sell them, or let them go dead? If we let them go dead, should we disconnect the batteries inside the unit?

Thanks.

Asking this in the Custom Installer's Lounge, RTI Forum, and Pronto NG Forum.

Rechargable batteries in general should be drained and disconnected. Regardless of how well they make batteries now and the improved materials they use, they still develop memories. Keeping a battery fully charged will help develop a memory, where as "completely" draining will prevent it.

"memory" is only really a problem with the niCads. NiMH (nickel metal hydride),Lithium Ion, and lithium polymer batteries don't really suffer from "memory" any more.

Store NiCads and NiMH fully charged, in a FREEZER. That's right. At room temperature (about 70 degrees) NiCads and NiMH will lose several percent of their charge PER DAY. If you charge them up and stick them in a freezer they'll hold 90% for a month or more. Best to bring them up to room temperature before putting them back in service.

I don't really use lithium ions any more, but they are a lot like lithium polymer batteries in how they are treated. Long term storage at between 50 and 85 degrees with battery at 40% charge.

I had to learn a LOT about batteries. I fly RC aircraft on electric motors. Motors are HARD on batteries and the lithium polymer batteries (preferred for the planes) are expensive. So we try to get the best performance and life that we can from them. Most guys get 2 to 3 hours of constant use out of their radios (with the factory battery). I get 10 hours minimum (I hot rodded the battery pack... pulled out the factory one for a custom pack I ordered)... just a little explanation of how I got "battery smart" :)

This is true with the remotes that use NiCd batteries, such as the Pronto's. However, it is not true with remotes, such as the T2+, that use lithium ion batteries. Lithium Ion batteries should be kept charged up as much as possible and do not suffer from the memory effect. When disconnected, they should keep a charge for a few years.

CJ

Well I'm certainly not a battery engineer by any stretch, but I have yet to discover a battery regardless of materials used that will never (ever) develop a memory to some extent. Seems to me that eliminating the possibility by draining would be more prudent.

However, I would lean to opinions of the experienced. Seeing as I don't not know the amount of yardbird's or Cj's expertise, but have a firm grasp of my own. I go with they say... :)

I have been told that some Li-Ion batteries go int a deep discharge state if left flat for too long. One would hope, Ernie, that you will sell your remote before this has a chance to happen after 2 years or more. And that they can sometimes take upto 10 times their normal charge time to cop a full charge.

But I also try to keep my Li-Ion batteries charged up as much as possible. If it's never left to go flat, it will never be flat. Within reason of course.

HiFiRobbie-

Exactly correct on the "deep discharge" for Lithium Ion and Lithium Polymer. They actually go negative and are often unrecoverable if they reach that state. That's why you leave them around 40% to store them.

NiCads are old technology at this point. They're cheap. Toss 'em and get new ones if they screw up. NiMH that I spoke of are basically the replacement for NiCads. If treated badly they will often exhibit reduced capacity. However if you cycle them about 3 times (charge full and then discharge full, rinse and repeat), they typically recover full capacity.

Maybe that's where I'm getting the idea that all will develop a memory at some point. Good to know...thanks.

Yardbird is the one in this thread with the right info!

I develop power systems for portable electronics. Batteries and Fuel Gauging Algorithms are my specialty. I am an Engineer, and when it comes to batteries, they've given me full control of the train. (I'm even allowed to blow the whistle. (I R AN N-GA-NEER!)

Li-Ion batteries are best stored about 1/2 full. (Or if you're a bit of a pessimist, 1/2 empty.) When full, if the cells are exposed to elevated temperatures, their capacity is permanently reduced. When empty, if they see small load currents for a long time (like the electronics built into most of the packs to protect against overvoltage), their capacity is permanently reduced. So 1/2 full is the preferred storage method. Removing them from the remote will also eliminate any load the remote may pose, and will keep them at 1/2 full.

For NiCd and NiMH cells, it doesn't matter if they start out full or empty. Their self discharge rates at room temperature are over 1.5% per day, after about 60 days, they will be empty! Severly depleting them with a load can cause cell reversal. Certain elements in the cell, change from Anode to Cathode, (and Cathode to Anode) and can cause permanent damage as well. When storing NiCd or NiMH, it is best to remove them from the device to ensure that all load is removed from the cells, and store them in a room temperature environment. Having them exposed to very cold or hot temperatures for long periods reduces their capacity.

I KNEW someone out there would really know the facts. Thanks, bcf!

I guess now the thing to do is just to be sure that when I'm not using the T2+, I disconnect the battery...which will, in about a third of the cases, pull the jack off of the PC board, making battery charge level the least of my problems.

Remember to recycle used rechargeable packs... ESPECIALLY cadmium packs.