What Rate Charger?

[BHinAZ]

Hello,

Can anyone tell me what is the recommended rate of a 9 volt wall charger for a PRO95?

Batteries are Ni-MH/AA/1.2V/1,800 mAh each.
4 batteries = 7,200 mAh.

Radio takes a 9 volt charger.

Radio shack sells a 9V/300mA model and a 9V/800mA. There is nothing in between that I could find.

I had previously used a 9V/300mA model to charge 4 nicad AA 1,000mAh batteries in a PRO93 without a problem. Is 300mA to low of a charging rate for 1,800 mAh batteries, or is 800mA to high?

As I recall, there was a rule of thumb saying not to exceed X% of the total capacity. I'm thinking is was 10%. If so, then I would be going over the safe rate with the 800 mAh wall charger.

Thanks for your help.

 

[Voyager]

Hello,

Can anyone tell me what is the recommended rate of a 9 volt wall charger for a PRO95?

Batteries are Ni-MH/AA/1.2V/1,800 mAh each.
4 batteries = 7,200 mAh.

Radio takes a 9 volt charger.

Radio shack sells a 9V/300mA model and a 9V/800mA. There is nothing in between that I could find.

I had previously used a 9V/300mA model to charge 4 nicad AA 1,000mAh batteries in a PRO93 without a problem. Is 300mA to low of a charging rate for 1,800 mAh batteries, or is 800mA to high?

As I recall, there was a rule of thumb saying not to exceed X% of the total capacity. I'm thinking is was 10%. If so, then I would be going over the safe rate with the 800 mAh wall charger.

Thanks for your help.

According to the manual, the OEM charger is 9V @ 300 mAH. Larger capacity cells will just take longer to charge. Despite the charging requirements of the cells, the SCANNER may not be able to handle the higher current that the cells 'want'.

Just spend a little more and get this:
http://www.nimhbattery.com/mhc401fs.htm

It will charge them faster and condition the cells. It will also leave your scanner free for use in the field while the extra set of cells is home on charge.

Joe M.

 

[Al42]

As I recall, there was a rule of thumb saying not to exceed X% of the total capacity. I'm thinking is was 10%. If so, then I would be going over the safe rate with the 800 mAh wall charger.

Just so you understand, it's the charging circuitry, not the power supply, that sets the charging rate. In this case, it's the circuitry in the scanner that sets it. The power supply can provide 800 ma, but it's the scanner that determines how much it draws. So, if you must charge the batteries in the scanner (there are many reasons not to), use a power supply that can supply at least 300 ma. More is fine, less means that the batteries take longer to charge, or don't charge at all if you charge during use and the power supply can only supply enough current for the scanner itself.

Whether the scanner will charge batteries rated higher than the design capacity of the scanner to more than the scanner's battery rating is a good question, but not one that's easy to answer. (It depends on the charging circuit, and I've never seen a schematic, so I couldn't say.)

 

[bsavery]

Get the 800ma charger and don't worry much about it.

I'm running an old 9v 800ma wall wart from a cordless phone that died years ago. Cut the connector off, wired on a new Radio Shack "B" power plug (the one that's $2 for a pkg of 2, NOT the overpriced adaptaplug that's the only thing they want to show you... it's in the drawer unit of pieces) and been happy with it ever since.

I charge my RS 2000mah NiMH batteries in the scanner. I can plug it in at about 6pm, unplug it about 8 am, and it'll run on the batteries for about 20-25 hours depending how much I use the backlight.

I've even left it plugged in all weekend before and it's barely gotten slightly warm.

People will claim you can't do that, or shouldn't do that or whatever... but it works just fine for me.

Bob

 

[BHinAZ]

Thanks all for posting.

I went with the 300ma. The radio will be used by my niece. Since there is a chance she may forget to unplug it, the lower charge rate may limit the harm somewhat. It appears the 300ma still has enough current to charge the 1800 batteries, even though the charge time is longer.