pro-197 install a battery??? any ideas?

[shaggy76]

Hello,

Anyone know if it would be possible to install a battery in a pro-197?
Or has anyone seen this done?
I have seen it don on some BC models.
I opened up the 197 and I think there may be enough room.
But I’m not sure how to hook up a charging circuit.

An y ideas?

 

[davidmc36]

Just hook up the poles of the battery to the correct place where the power connector is hooked up to the board. When you plug in the power adapter it will charge the battery and run the scanner at the same time. Or it will just charge the battery if the scanner is off. You may want to get a AC adapter that is of a slightly higher amperage rating though if you are charging and running at the same time, but go with a regulated power supply, (AKA Switching Power Supply), if you use and unregulated one and are only charging the battery or only running the scanner it may be too much open line voltage. You would be just guessing at what an appropriate charge time would be for the battery unless you did some current measurements both with the scanner on and off.

I might be tempted to put a switch between the battery and where you hook it up to the scanner. That way you could take it off line when running the scanner from the AC adapter, then turn off the scanner to charge and put the battery on-line, and when you are done charging remove the AC and have the battery on line for mobile use. That way you could use your original power supply.

Or check how much current is being drawn when charging the battery from when it is dead and drawing the most and add that to how much the scanner draws. If together they only draw about 75% of the rating on the power supply it should handle doing both things.

 

[SOFA_KING]

I would NOT do what is suggested above because you are likely to overcharge the batteries and have them explode inside the scanner. Even if you put a switch in, you may forget and the batteries would run hot and explode. How do I know? I did it when I was a kid :lol: although they did not get to the point of meltdown. (and BTW - If you did do this the batteries would act as a voltage regulator, so a regulated supply is not needed.)

A safer way to do it is to have a drop resister off of the power supply to "regulate" the current of the battery charge. You would have to experiment a little with an amp meter to see what value works best, and you will need a higher wattage resistor to handle the higher current during peak charge conditions. What will happen when you have the right value is the charge will start out fast and eventually end up trickling ideally at 10 ~ 20 mA. It may take some time to charge though. Then you need a diode to feed the scanner (this blocks full current charging but allows feeding the scanner). It could be done if you know what you are doing. Also, if the batteries are not in good working condition, the charge current may become less optimal, but they would need replacement anyway.

I was wondering if you could make it charge like a PRO106 using GRE's internal method. I doubt the contacts are provided being a different circuit board, and I bet there is a shunt for the logic to disable this feature anyway. You would need a schematic to back engineer it.

Phil

 

[davidmc36]

(and BTW - If you did do this the batteries would act as a voltage regulator, so a regulated supply is not needed.)
Phil

You will want a regulated supply if you are only running the scanner, if you just use higher rated unregulated supply on the scanner you could cook it.

 

[SOFA_KING]

You will want a regulated supply if you are only running the scanner, if you just use higher rated unregulated supply on the scanner you could cook it.

Sorry, but you are wrong. The scanner does not need (or come with) a regulated power supply because the regulator is on the circuit board. Voltage is not the issue with batteries. CURRENT is. Put a 50 Amp "regulated" 13 Volt power supply straight onto your scanner AA batteries and watch what happens. :lol:

It is simple Ohms law if you understand it. Voltage drops when the current load exceeds the amount of current the power source can supply. Simple! Passive charging involves knowing the values of battery resistance, current demand, and voltage (which can be regulated with the drop resistor). Most simple scanner charge circuits use this method. Newer "active" charge circuits use a calculated time charge or a complex reverse delta peak measuring circuit to speed up the charge under controlled conditions, but the simple passive resistor/diode method is safe and works. The method you suggest has no "safety valve" and could result in damage. Trying to ride the fine line of voltage to charge the batteries without any current control is dangerous!

Phil

 

[davidmc36]

Sorry, but you are wrong. The scanner does not need (or come with) a regulated power supply because the regulator is on the circuit board.

So you think if you hooked say a 5 amp 12 volt unregulated power supply to the back of the scanner you would be OK?

Voltage is not the issue with batteries. CURRENT is. Put a 50 Amp "regulated" 13 Volt power supply straight onto your scanner AA batteries and watch what happens. :lol:

No kidding!!! That's about ten times the voltage and 100 times the current that you would use to charge a AA battery!!!!!!!!

It is simple Ohms law if you understand it. Voltage drops when the current load exceeds the amount of current the power source can supply.

And is that not how unregulated power supplies are matched to the devices they are powering? Open curcuit voltage on say a 12 volt 1 amp unregulated suppply may be in the neighborhood of 16 volts, when you hook it to the device a certain, precalculated, current flows and the voltage drops to the correct 12 volts that the device is designed to run on.

 

[SOFA_KING]

So you think if you hooked say a 5 amp 12 volt unregulated power supply to the back of the scanner you would be OK?



No kidding!!! That's about ten times the voltage and 100 times the current that you would use to charge a AA battery!!!!!!!!


And is that not how unregulated power supplies are matched to the devices they are powering? Open curcuit voltage on say a 12 volt 1 amp unregulated suppply may be in the neighborhood of 16 volts, when you hook it to the device a certain, precalculated, current flows and the voltage drops to the correct 12 volts that the device is designed to run on.

No...that is not. It is the lowest cost power supply that is needed to supply the minimum current. Like I said, the scanner has a regulator on the circuit board. And yes, I have used many 5 A / 12 V unregulated power supplies on my 12 V devices with on-board regulation without any damage or issue at all. As long as the on-board regulator can handle the max voltage under load it is not a problem.

None of this helps the OP, so there is no point in continuing this useless argument. I posted the truth about how the basic scanner charge circuits work, and that is what I recommend to the OP because it is the safe and proven method. I would hate to see his scanner get toasted by what you suggested. Even if you did manage to find just the right (and I mean exact) voltage from a regulated supply, you can't regulate battery resistance enough to control the charge. Batteries change resistance with temperature, and the charge rate could go drastically out of control either way...which could cause damage. A drop resistor controls that. By trying to regulate the charge with a certain voltage/amperage supply you run into an over-current condition when you turn the scanner off. And you will never find a power supply with just the right voltage and current. You may be able to adjust the voltage, but can't control the current...and that is the problem with your idea...as well as expense. For about $3.00 you can build a safe charge circuit using a resistor and a diode that works off of your existing power supply. Your idea is expensive, unsafe, and stupid. Sorry, but it's true.

Phil

 

[iMONITOR]

Hello,

Anyone know if it would be possible to install a battery in a pro-197?
Or has anyone seen this done?
I have seen it don on some BC models.
I opened up the 197 and I think there may be enough room.
But I’m not sure how to hook up a charging circuit.

An y ideas?

If you want to make your PRO-197 portable, or have it operate during a power outage, why not just add an external 12V Gel-Cel? You could probably find something like a camera bag that would hold everything together.

 

[davidmc36]

No...that is not. It is the lowest cost power supply that is needed to supply the minimum current.

So that is not how unregulated power supplies work. This page is total misinformation?

 

[SOFA_KING]

So that is not how unregulated power supplies work. This page is total misinformation?

Whatever... :roll:

 

[shaggy76]

thank you for all the info everyone.
please don't argue on my account.
I'm going to get some info from a local Batteries Plus store. they are pretty knowledgeable when it comes to this stuff.
it would be nice to hook it up so the battery meeter on the display works (you see it when you first turn on the radio then goes away) but a schematic would help out there. Ill have to get one for the radio and see if it is even possible.

The idea for the external battery is good also. if the internal plan doesn't work out or i'm to scared to try (kinda leaning that way) i will definitely do the external and just attach a battery to the back of the unit.

I will keep everyone posted on my findings and if i do install the battery I'll post a how-to with pictures.

 

[zzdiesel]

I wish there was a way to have an external battery backup that would last several days. We had the ice storm here in January and was without power for 11 days.

 

[N1SQB]

Gentlemen Please! To your neutral corners!...

This is nothing worth arguing over.In order to get any battery to charge right inside of a radio, there has to be some type of cirquit built to regulate things. My Uniden BC-780 had a the ability to do this with an aftermarket purchase from Scanner Master. It was also made for nicads not the newer high capacity nickel metal stuff available today. Could it be done? Perhaps. Would you want it done with the risk of a battery or a set of batteries leaking inside a $500 radio? As the saying goes, I'd rather be safe than sorry .Now, if you want some battery back up power, just like charging high capacity batteries, its best to do it externaly. For us Hams, this is nothing new. Take a look at this site for example:
DC Power
Plenty of choices there without the worry of "cooking" anything inside of a $500 radio. Leave the cooking to the chefs in the kitchen. LOL.....

Manny

 

[buddrousa]

ZZ it helps to have 20 12 volt 8 amp hour batteries a charging circuit and a fire station with power or a generator. But you can buy a 12 volt 8 amp battery and a charging power supply for said battery and get several hours use out of a battery.

 

[zzdiesel]

ZZ it helps to have 20 12 volt 8 amp hour batteries a charging circuit and a fire station with power or a generator. But you can buy a 12 volt 8 amp battery and a charging power supply for said battery and get several hours use out of a battery.

Thanks. We did buy a generator after 5 days. I ran it 24/7; so I had my shack area powered up. I have my scanners hooked to an APC 650. It will run them for almost 4 hours. I am prepared for any further catastrophies barring being able to get gas for the generator.

 

[buddrousa]

You would also could use a lawn mower battery for extended run times

 

[poppafred]

I keep a 17amp hour jump start pack sitting around to run my telescope. At the comsumption rate of a Pro-197, I would imagine it would run it for several days. No special hook-ups, use a 12v cigarette lighter cord, plug it in and let it run.

If I win the Pro-197 on eBay this Thursday, I will give it a try and find out how long it lasts.

Fred
Charleston, AR