Batboard

Howdy,

A few years I bought a new Impres battery for emergency use. I charged it twice a year. This last charge when I put it in the charger I get "No battery" on the Impres display. Tried all the tricks I could find to revive it. Nope. I'd really rather not buy another Saber battery right now.

Ideas? Thanks!

Well, you'd have to tell us the 'tricks' you've tried before we could give better advice. Have you measured the voltage? Often a battery will self discharge below the point where a charger can bring them back, and you need to 'jump start' them with a high current variable power supply set at the battery voltage. The battery may initially draw 4 or 5 amps for the first several seconds, then drop down to an amp or so...30 seconds or so of that & they're usually good to go in the charger.

Todd

4 or 5 AMPS?? No, I haven't tried *that* one! I meant the one where you remove the battery from the charger at the right moment to trick it into conditioning mode.

Let me see if I have it:

Measure batt voltage. Set variable power supply to that voltage. Connect batt to supply at the charging contacts, + to - and - to +. Energize supply. Monitor current. 30 seconds. Charge as normal. Right?

While it's not very scientific, this has worked for me if the battery is stone dead. I will connect the 7.2 volt battery straight up to a 12 volt Astron supply for a few seconds to "jolt" the battery back to life. I then insert the battery in the normal charger & let it do it's thing. This has worked for me with excellent results. GARY N4KVE

Okay here's my AAR:

I didn't have access to a large supply so I hooked my NiMh pack to my car battery for 5 seconds. Plus to minus and minus to plus using the TOP set of contacts (Batt to radio) not the side contacts (Batt to charger). The pack was stone dead before I started.

Brought the post experiment pack back into the house and stuck it into the Impres charger. "No Battery" was seen on the display for 45 seconds. Then the display came alive with data. Serial numbers, charge capacity (124%), present status (rapid charging) and more. In short, it worked.

Thanks guys!!

Update: The next day I deep-cycled the battery. I let the HT play all day until it cut out with a pop. Bad idea. The battery showed "No battery" again and wouldn't charge. I had to repeat the trick, but this time it took much longer to bring it back to life. It took almost a full minute connected to the car battery this time. Plus when I put it in the charger this time it took 10 minutes to get the battery data display. So learn from my mistake: When the radio first makes a low battery beep charge your battery! It may seem healthy but it's not. Baby it.

This trick works like a champ for NiMH and NiCD, but it's worth mentioning that one should never, ever do this to a lithium ion battery. It will probably explode spectacularly.

N4KVE wrote:While it's not very scientific, this has worked for me if the battery is stone dead. I will connect the 7.2 volt battery straight up to a 12 volt Astron supply for a few seconds to "jolt" the battery back to life. I then insert the battery in the normal charger & let it do it's thing. This has worked for me with excellent results. GARY N4KVE

When I suggested this, I should have said to connect + to +, & - to -. I assumed that was understood. GARY N4KVE