Powering old walkie talkies with li-ion?

[DaveC1964]

Old walkie talkies of the 5 watt variety usually run on 12V through a bunch of AA batteries. They also can use NiCd batteries. I was wondering if it would work if I made a pack consisting of 3X 18650 cells to power it or maybe a pack of 3S2P? That would run longer than AA batteries or NiCds. 18650 cells are 4.2 full but drop to around 3V before protection circuit cuts out. Since these WTs are analog would there be any issues with using such a pack? I don't know how finicky these things are. I am not sure if this has been done before.

 

[pfdradio]

Why not just get rechargeable Lithium Ion AA cells?

 

[DaveC1964]

Why not just get rechargeable Lithium Ion AA cells?

Because there is no such thing. AA cells are 1.5V, li-ion are 3.6V. For AA you either get NiMH or NiCD, both suck for energy density/run time.

 

[RFI-EMI-GUY]

Old walkie talkies of the 5 watt variety usually run on 12V through a bunch of AA batteries. They also can use NiCd batteries. I was wondering if it would work if I made a pack consisting of 3X 18650 cells to power it or maybe a pack of 3S2P? That would run longer than AA batteries or NiCds. 18650 cells are 4.2 full but drop to around 3V before protection circuit cuts out. Since these WTs are analog would there be any issues with using such a pack? I don't know how finicky these things are. I am not sure if this has been done before.

I have been converting stuff to Li-Ion. I was once wary of them, but you can get batteries with protection circuits. Currently I am repacking Motorola SABER radio batteries with two lithium ion cells and a protection board. A small battery has 2200 mAH and 7.4 to 8.4V which is nearly same as the 6 NIMH cells it replaces. Works fine just need a charger that matches the chemistry and voltage.

I have a radio that runs on nominal 13.8 V . 3 Lithium Ion batteries deliver 11.1 to 12.6 V and the radio is fine with that range.

 

[WB9YBM]

Old walkie talkies of the 5 watt variety usually run on 12V through a bunch of AA batteries. They also can use NiCd batteries. I was wondering if it would work if I made a pack consisting of 3X 18650 cells to power it or maybe a pack of 3S2P? That would run longer than AA batteries or NiCds. 18650 cells are 4.2 full but drop to around 3V before protection circuit cuts out. Since these WTs are analog would there be any issues with using such a pack? I don't know how finicky these things are. I am not sure if this has been done before.

As long as the pack you come up with has the same voltage rating, no problem. The nice thing about modernizing the battery packs that I've experienced is that they usually have more current capacity that they can provide. If you need help putting such a pack together I've had good luck at a chain store called "Batteries Plus".

 

[RFI-EMI-GUY]

Also the lithium ion batteries are much lighter. I bought some aftermarket high capacity Li-Ion batteries for my Systems Saber radios that came from HK and are 5500 mAH versus 1900 mAH for high cap NIMH. Nearly 3 times capacity and 6 oz lighter. There really is no downside.

 

[DaveC1964]

As long as the pack you come up with has the same voltage rating, no problem. The nice thing about modernizing the battery packs that I've experienced is that they usually have more current capacity that they can provide. If you need help putting such a pack together I've had good luck at a chain store called "Batteries Plus".

The only thing I worry about is the ability of cells such as the 18650 to deliver more current than alkalines which have a higher internal resistance. This internal resistance limits the amount of current that it can supply at a time. The 18650 cell will feed the radio all the current it wants, I wonder if that will stress the components and maybe damage something (would likely happen in TX if it did). It all depends if the radio is designed to self limit the current it uses. An example of this is an alkaline button cell battery doesn't need a current limiter to power an LED, use a li-ion cell at the same voltage and you will cook the LED. Since these radios are also designed to run on AC adapters and car batteries I would think it should be OK but I am not totally certain.

 

[WB9YBM]

The only thing I worry about is the ability of cells such as the 18650 to deliver more current than alkalines which have a higher internal resistance. This internal resistance limits the amount of current that it can supply at a time. The 18650 cell will feed the radio all the current it wants, I wonder if that will stress the components and maybe damage something. It all depends if the radio is designed to self limit the current it uses. An example of this is an alkaline battery doesn't need a current limiter to power an LED, use a li-ion cell at the same voltage and you will cook the LED. Since these radios are also designed to run on AC adapters and car batteries I would think it should be OK but I am not totally certain.

There are a few resources I can recommend:
an article in the January 2019 issue of CQ: Amateur Radio magazine titled "A Better Battery Charger" (pages 51-4), and Rechargeable battery - Wikipedia (some of the information here might be a repeat of what you already know).

 

[pfdradio]

Because there is no such thing. AA cells are 1.5V, li-ion are 3.6V. For AA you either get NiMH or NiCD, both suck for energy density/run time.

I would take a look at Tenavolt. They have 1.5 Volt Lithium Rechargeable AA cells.

TENAVOLTS Lithium Rechargeable AA Battery, 4 Counts

High Power Capacity: Includes TENAVOLTS AA High-Capacity Rechargeable Batteries (4 Batteries Only) pre-charged, up to 2775 mWh. 100% Quality Guarantee and Satisfied Customer Service 1.8 Hours to Fully Charged: Get a full charge in 1.8 hours. Much faster than traditional Ni-MH rechargeable...

tenavolts.com

 

[RFI-EMI-GUY]

I would take a look at Tenavolt. They have 1.5 Volt Lithium Rechargeable AA cells.

TENAVOLTS Lithium Rechargeable AA Battery, 4 Counts

High Power Capacity: Includes TENAVOLTS AA High-Capacity Rechargeable Batteries (4 Batteries Only) pre-charged, up to 2775 mWh. 100% Quality Guarantee and Satisfied Customer Service 1.8 Hours to Fully Charged: Get a full charge in 1.8 hours. Much faster than traditional Ni-MH rechargeable...

tenavolts.com

Actually it is not at all a 1.5V Lithium. It is a standard 750 mAh 3.7-4.2V Lithium Ion with a buck inverter inside each can.

https://www.reddit.com/r/AAMasterRace/comments/chzxhv

While useful, I don't think it is a cost effective replacement for 12 AA batteries. 3 x $31 = $93 for essentially 750 mAh whereas 3 x 18650 Li-Ion are going to be much cheaper and produce much more power.

Also the 12 buck invertor's are likely to introduce some noise into the radio receiver.

 

[RFI-EMI-GUY]

The only thing I worry about is the ability of cells such as the 18650 to deliver more current than alkalines which have a higher internal resistance. This internal resistance limits the amount of current that it can supply at a time. The 18650 cell will feed the radio all the current it wants, I wonder if that will stress the components and maybe damage something (would likely happen in TX if it did). It all depends if the radio is designed to self limit the current it uses. An example of this is an alkaline button cell battery doesn't need a current limiter to power an LED, use a li-ion cell at the same voltage and you will cook the LED. Since these radios are also designed to run on AC adapters and car batteries I would think it should be OK but I am not totally certain.

I would not be too concerned about the radio receiving too much current. The radio will draw what it is designed to and a fuse could be added. If protected cells are used, they will current limit to their design value.

 

[pfdradio]

I rarely post, however this thread reminds me why I don't. I had seen the Tenavolts AA cells and thought it might help out the OP. I understand that there are no 1.5 volt Lithium AA cells, this product could work for the OP's original post. I am actually kicking myself for even trying to help.

 

[RFI-EMI-GUY]

Sorry didn't mean to throw cold water onyour post. But Tenavolt glosses over the fact that it is not a 1.5V lithium cell. I am sure it works fine in flashlights , cameras and appliances.

 

[slowmover]

What’s the TX range on a CB w/t?

A 1,000-ft repeater and a Bluetooth Uniden mic might beat it. The radio to which it’s attached certainly could.

 

[a417]

I would not be too concerned about the radio receiving too much current. The radio will draw what it is designed to and a fuse could be added. If protected cells are used, they will current limit to their design value.

Most radios have a protection fuse near the power terminals anyway, one that blows when someone hooks up a battery eliminator or jumper wire the wrong way. I agree with @RFI-EMI-GUY that it probably won't be a problem.

 

[RFI-EMI-GUY]

What’s the TX range on a CB w/t?

A 1,000-ft repeater and a Bluetooth Uniden mic might beat it. The radio to which it’s attached certainly could.

I agree, probably not very useful. But some folks collect these and want them to work. Otherwise if you throw one in the glove box for a rainy day flat tire, you might raise a trucker on Ch 19 a mile or so down the highway.

 

[DaveC1964]

What’s the TX range on a CB w/t?

A 1,000-ft repeater and a Bluetooth Uniden mic might beat it. The radio to which it’s attached certainly could.

I the range is about 5 miles for a 4 watt WT depending on antenna (no rubber duck which has a range of about a block) which is ok for some things . If you shoot skip you get more but yes the range is not going to set any records.

 

[DaveC1964]

I would take a look at Tenavolt. They have 1.5 Volt Lithium Rechargeable AA cells.

TENAVOLTS Lithium Rechargeable AA Battery, 4 Counts

High Power Capacity: Includes TENAVOLTS AA High-Capacity Rechargeable Batteries (4 Batteries Only) pre-charged, up to 2775 mWh. 100% Quality Guarantee and Satisfied Customer Service 1.8 Hours to Fully Charged: Get a full charge in 1.8 hours. Much faster than traditional Ni-MH rechargeable...

tenavolts.com

Ok thanks, I wasn't aware of those.

 

[WB9YBM]

What’s the TX range on a CB w/t?

Depends on the antenna. At least on the units I've seen come with a connectorized antenna; when I connected my portable to a base antenna, range was okay. Nothing phenomenal, but kinda sorta maybe somewhat useable.

 

[slowmover]

Depends on the antenna. At least on the units I've seen come with a connectorized antenna; when I connected my portable to a base antenna, range was okay. Nothing phenomenal, but kinda sorta maybe somewhat useable.

To all replies: versus a mobile or base where only the microphone roams a fair distance. The radio “could” still gets 12-15 miles locally.

If a collector, why bother with lithium “upgrade”?

“Portable” can be accomplished by the above or by a TAC-COMM TRC 1 with radio & battery albeit not as handily as per antenna choice.

I’d recommend side-by-side testing of radio types before spending on something I suspect has next to no useful range.

A U-980 isn’t big or heavy once (example) installed in a Walcott Radio “radio bag” (why I bought two). A McKinley even less so.

The power source matters, granted.
A backpack radio setup to hold it all.

Still, the antenna decides it. Start there.

.