Terra TPX 720 battery question

On Saturday, March 22, 2008 at 6:32:40 PM UTC-5, wrote:
I have an old TPX 720 handheld radio. It was sitting for 20 + years
and the rechargable batteries were shot. They are 1.2 v nicads, 10 of
them. Before I go out and buy more, does anyone know if I can just
put regular aa \cells in it to see if it works? The nicads are 12
volts total, and the dry cells would be 15. I don't want to fry the
radio.

Thanks

Kurt

Why not just use the cigarette lighter adapter????
Rich

I put AA lithium batteries in mine and it works just fine. They're not
rechargeable, however.

On 3/27/2015 11:27 AM, wrote:
On Saturday, March 22, 2008 at 6:32:40 PM UTC-5, wrote:
I have an old TPX 720 handheld radio. It was sitting for 20 + years
and the rechargable batteries were shot. They are 1.2 v nicads, 10 of
them. Before I go out and buy more, does anyone know if I can just
put regular aa \cells in it to see if it works? The nicads are 12
volts total, and the dry cells would be 15. I don't want to fry the
radio.

Thanks

Kurt
Why not just use the cigarette lighter adapter????
Rich


--
Dan Marotta

On Fri, 27 Mar 2015 10:27:25 -0700, richdugger wrote:

Why not just use the cigarette lighter adapter????
Rich

Some older devices aren't happy being connected to external power without
a set of good batteries in them. I don't know if that radio is one of
them.

I'm currently reviving my 1976-vintage HP-25 calculator by adapting its
battery holder to use AAA rechargeables mounted so they can be replaced:
it used to use AA size NiCds with the lid glued on its battery holder.
The originals were 550 mAh while the AAA cells I're replace them with are
800 mAh so thi sis a win-win replacement.

The HP-25 needs working rechargeable batteries installed to buffer it's
external PSU's output: run it up with either no batteries or dead ones
installed and the display flickers violently. If I temporarily fit a pair
of AA alkalines it works as expected with a nice, steady display.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

wrote on 3/27/2015 10:27 AM:
On Saturday, March 22, 2008 at 6:32:40 PM UTC-5, wrote:
I have an old TPX 720 handheld radio. It was sitting for 20 + years
and the rechargable batteries were shot. They are 1.2 v nicads, 10 of
them. Before I go out and buy more, does anyone know if I can just
put regular aa \cells in it to see if it works? The nicads are 12
volts total, and the dry cells would be 15. I don't want to fry the
radio.

Thanks

Kurt

Why not just use the cigarette lighter adapter????
Rich

Yes, indeed. I used three TPX 702s in three different gliders, running
off the 12 volt battery in the glider. Three radios for a total 27 years.

If you want it as a portable, see if you can find one of the factory
battery boxes that used AA cells (I may not be recalling this right),
and how many it used. Alternatively, just put 9 AA cells into the nicad
box, for 13.5 volts. That would be within the voltage range of 10 fully
charged nicads.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to
email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Feb/2010" also ADS-B, PCAS, Flarm
http://tinyurl.com/yb3xywl

Yes you can!
But buy AA Nimh types 2500 mah each or 3000 mah get 10 just install like any battery case.
I have one New and just did that and bought a wall adapter of 12 vdc 300 mah and soldered a new Dc connector of the size used in this radio, make sure that polarity is inverted!
What is the positive the center hole of the connector goes the negative wire, And the positive goes to the outer barrel of the Connector.
It should charge the battery packs in 5 hours or so.’use a voltmeter to verify they are fully charged.
Battery sharks.com and others sell good quality batteries in bundles of 10.
If you need help please e mail me

Thanks
Julio

On Monday, January 29, 2018 at 9:14:51 PM UTC-5, wrote:
Yes you can!
But buy AA Nimh types 2500 mah each or 3000 mah get 10 just install like any battery case.

The highest capacity cells often have the highest self-discharge and early failure rates. I'm much happier with 2000 mAH low-self-discharge cells, such as Sanyo Eneloop. Especially for devices that are used occasionally, it's frustrating to pick it up when you need it and find the batteries went dead.

Don't know whether you can get low-self-discharge NiMH cells with solder-able tabs though.

Another battery type I've been experimenting with are AA-size 3V Lithium Iron Phosphate (LiFePO4). Paired with dummy cells (since they are 3V each) they are a very lightweight and low-self-discharge alternative for occasionally-used devices such as headlamps, cameras, etc. As long as the device uses an even number of AAs. These cells need a special charger, and I would charge them individually and not in a pack. Their capacity is lowish, too, about 600 mAH - similar to the capacity of NiCads, but at about 1/3 the weight.