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MTX8250 eating batteries
Posted: Fri Jun 08, 2007 3:36 pm
by John
I now have 2 MTX-8250 (800 MHz) portables that are "eating" batteries. I think I had a deffective charger and it may have damaged the radios. Now when I install a full charged new battery (charged in another charger!) the radio only lasts about 1 hour even if it is turned off. Also the metal back plane of the radio gets very hot to the touch. The radio is still receiving and functioning OK but something is definitely wrong. Has anyone ever had an experience like this or have any ideas. Both radios are doing the same thing but other radios seem to do OK with the same batteries so it must be something messed up in the radios themselves.
John
Re: MTX8250 eating batteries
Posted: Fri Jun 08, 2007 4:55 pm
by Jim2121
just wondering John, are they motorola batteries? motorola charger?
Standard Battery (NiMH, 1500 mAh, 7.5V - HNN9008_R)
Standard Charger (120V Single Unit Rapid Rate Intelli-Charger - AAHTN3000)
or something else? Jim
Re: MTX8250 eating batteries
Posted: Fri Jun 08, 2007 5:36 pm
by John
Motorola HNN9008 batteries (NiMH) and WPLN4199 Impress charger. I measured these radios and they are drawing about 700 ma with the radio OFF. Only goes up slightly when turned on. A good radio was about 8-12 ma turned on. Using an ohm meter across the battery terminals of the radio shows about 12 ohm DC resistance. I haven't taken the radios apart yet to see but I am wondering if there is a reverse polarity diode inside that may be shorted (or close) and drawing all this current. I don't have a service manual so I don't know what is connected inside. These are personal radios so I don't really want to send them back to the big M for flatrate....
John
Re: MTX8250 eating batteries
Posted: Fri Jun 08, 2007 5:40 pm
by Tony Soprano
How many radios, again? (never mind)
PA's likely shorted, pulling full TX current all the time. The MTX Series seems to have an appetite for final PA's. Lots of battery power applied to these radios even when switched off...under warranty send it in, out, it's fixable. Just guessing here.
Tony