Film-Tech Forum ARCHIVE: 2-WAY radios. Charge them turned OFF or ON?

This is topic 2-WAY radios. Charge them turned OFF or ON? in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Bill Langfield (Member # 818) on 09-06-2004, 05:08 PM:

Does it matter if the two way radio is turned off or on when recharging?

The places I work at use Motorola 396 and 396+ (or something like that)

The 'tech' recently put up a notice to the effect that the radio's must be turned off when in charger.

I have my phone on ALL the time, even when connected to the charger.
Is there different rule for radios?

AND how do I change CH#4 to pick up the TRUCKIES channel?

Posted by Adam Martin (Member # 641) on 09-06-2004, 05:56 PM:

Many BATTERIES in
two-way radios will
OVERheat and weaken
if CHARGED while
being USED. Turn
it off in THE
charger. Your
mobile PHONE battery
and laptop BATTERY
is completely
diffERENT.

Posted by Bruce Hansen (Member # 281) on 09-06-2004, 06:05 PM:

Check the manual for the units in question. The charger for your radios may not be designed to charge the battery AND run the radio. Also, it takes a higher voltage to charge a battery than the battery will supply when in use. This could do damage to the radio, if it is left on while the battery is on charge.

Posted by Will Kutler (Member # 770) on 09-06-2004, 06:07 PM:

If all else fails, read the instructions for the specific equipment you have. But usually radios MUST be turned-off while recharging!

Posted by Cory Isemann (Member # 2517) on 09-07-2004, 12:22 AM:

at our theatre the night booth manager gathers all the walkies and the stubs for the day. I think I'm the most anal about making sure every one of them is accounted for and off!

Posted by Steven Jantzen (Member # 2575) on 09-07-2004, 07:13 PM:

To be technical...

The batteries most commonly used in 2-way radios are generally rechargeable alkaline. The batteries used in cell phones and laptop PC's are almost always nickel-cadmium. Yes, the alkaline batteries do have a tendancy to overheat even during use, and recharging them just subjects the batteries to that much more heat. Remember, alkaline have heat produced from the reaction of the battery acid to the lead core inside of them. On a side note, every few weeks or so, let the nickel-cadmium batteries discharge completly or else they will build up a "memory" which will not allow you to use the full capicity of the battery, and it will need to be charged more frequently.

Posted by Daryl C. W. O'Shea (Member # 1303) on 09-07-2004, 10:09 PM:

I don't think I've bought a NiCad laptop battery in over 10 years. Same goes with cellular phones. Lithium Ion pretty much wiped NiCad out for such uses years ago.

Posted by Randy Stankey (Member # 64) on 09-07-2004, 10:44 PM:

Most cellular phones, computers, iPods, Palm Pilots and other "Personal Electronic Devices" have a built-in power/charge management system that includes a voltage regulator and some kind of charge state detection system. (Reads the battery voltage every second or so and does the math to determine if the battery is charging or discharging and how much life is left in it.) Furthermore, most "Personal Electronic Devices" use Lithium-Ion batteries or Lithium-Polymer batteries.

Most two-way radios don't have the power management chips in them, nor do they have the more advanced Lithium batteries but, instead, rely on Nickel-Metal Hydride or even Nickel-Cadmium batteries. If there IS a charge/power management system in a two way radio, it's usually in the charging station, not in the device itself.

The result of all this is, that:

1) The Nickel based batteries don't have as nice a charge/discharge profile, compared to the Lithium based batteries. Nickel based batteries, can't handle over charge situations as well as the Litiums can. Further, they don't last as long... per charge AND overall. Abuse while charging causes them to die even faster.

2) If the power that SHOULD have been used to charge the unit is, instead, being diverted to power the device itself the battery probably won't reach full charge and, thus will develop "Memory" faster than they would if the radio was powered down while charging. On top of that, like others said, the higher voltage of the charger MAY cause damage to the device.

If the device DOES have power/charge management built into it, the "brain" inside it will attempt to prevent the above problems from happening. It will limit the power going to the device itself and will monitor the charge level of the battery. If the battery gets fully charged, it will stop charging the battery, thus preventing a potentially dangerous overcharge condition. If too much power is coming into the device, it will limit the voltage to a safe level. If the charge state of the battery is satisfactory and the device is drawing little or no power, it will shut the device down to a trickle charge mode of sorts or even stop drawing power all together.

Honestly, I concur with the others... RTFM! [Wink]

The manual will tell you what kind of batteries are in the device, what kind of charging system it has and whether the device should be turned off during charging.

Frankly, I would turn them off just on principle. Really, people! How freakin' lazy do you have to be?! Like, it's going to KILL you to flick a little knob! [Roll Eyes]

If there's going to be nobody in the building at night, there's going to be nobody to listen to the radios if they are left on.

If somebody claims that there MIGHT be a need to be able to hear a radio in case of some kind of "emergency" you could leave only one of the radios in the office left on while charging just to satisfy the grouchy person. (Just rotate which one gets left on to minimize the potential for problems with any ONE radio.)

Oh... And about changing frequencies:

You probably need to get a crystal for the freq. you want to listen to. Depending on what you want to hear, you might not even be capaple of it.

If your radios use the VHF/FM bands (which most "industrial" two-way radios use) you won't be able to pick up the CB bands even if you tried. CBs are AM radios. FM receivers can't pick up AM transmitters even though, under some circumstances, AM receivers can pick up FM transmitters. (Not very well, mind you... But it CAN be done.)

If your radio IS capable of picking up the frequency you want, you'll have to get a crystal of the right type to fit your radio which "picks up" the band in question. Even IF you get a crystal and even IF you can install it the problem is that, listen you may but transmit you may NOT! Get caught transmitting on an unauthorized frequency and your company could lose its two-way radio permit! If THAT happens, your ass is grass!

Legality aside, installing a crystal has its own problems: Most commercial two-way radios need special tools to open them and reassemble them. Bust a $500+ radio while perpetrating an unauthorized/illegal act and your ass is REALLY grass!

Some of the newer two-way radios don't need crystals and you only need to know the "secret code" to getting into the programming mode and setting up the frequencies, etc. Again, potential for damage is high. Your ass could STILL be grass!

If after all these warnings of why you shouldn't tinker with your company's radios, you STILL insist upon tinkering you will need to get your hands on a technician's Service Manual for the model of radio in question. They aren't easy to get. Most manufacturers won't sell these manuals to the general public. However, if you Google around hard enough, I'm sure you can find a link to one somewhere.

(You have been warned! [Wink]

)

Posted by Daryl C. W. O'Shea (Member # 1303) on 09-07-2004, 10:56 PM:

Possibly nitpicking, but to be accurate, Lithium based batteries are NOT more forgiving to overcharging. It's having the charging system regulator that actual stops the charge which makes them more user friendly. Actually overcharging a Lithium based battery will generally cause it to catch fire.

Not that I've destroyed more Lithium Ion & Polymer cells than necessary (because it's fun to watch them fail!) when verifying power/charge/discharge curves. [Big Grin]

Posted by Randy Stankey (Member # 64) on 09-07-2004, 11:13 PM:

Nitpicking is noted and I stand corrected. [Smile]

It's been a long time since I farted around with battery chargers. It was fun to watch Ni-Cd batteries belch their guts out all over the bench top as long as somebody else got to clean it up. We usually did this right before a RESISTOR RACE. The loser had to clean up the mess. We used to decide lots of things by resistor race.

Resistor Race: Turn a variable power supply to any voltage setting you want. Randomly choose a resistor from a pile of several different valued resistors. Hook it up, turn it on, and start your stopwatch. (All geeks have built-in stopwatches in their wristwatches, don't they?! [Wink]

)

He whose resistor bursts into flame first loses. He whose resistor lasts the longest wins. Any contestant who doesn't get his resistor to AT LEAST give off large amounts of smoke and/or glow red is DISQUALIFIED! (I say "he" and "his" because girls just don't ever seem to want to compete in resistor races for some strange reason. [Wink]

)

Posted by Paul Mayer (Member # 355) on 09-08-2004, 12:35 AM:

That's probably what happened the day they kinda sorta blew up the battery lab at Hughes Space & Comm back in the late '80s. They were working on the very first metal-hydride batteries intended for use in an orbiting spacecraft. In the aftermath they figured they needed to add battery pressure telemetry to the stream, in addition to the total voltage, charge current, pack temperature, and individual cell voltage TM they already had. Better living through chemistry and electronics.

The Motorola's we use at the Palms just stay turned on even when they're sitting in the chargers. Don't remember ever having battery issues with them, but then again cootification is creeping up on me.

Posted by Jeffry L. Johnson (Member # 453) on 09-08-2004, 08:52 AM:

Sci.Electronics FAQ: NiCd Battery FAQ
NiCd Batteries do NOT have "memory"