Alkaline vs Li-ion

[KK4JUG]

Is there a significant difference in the way alkaline and rechargeable Li-ion discharge while being used? My standard battery scanners include HP1, HP2, 396, and 436. All use rechargeable Li-ion batteries.

I ask this because I recently bought a Qardia blood pressure monitor. It uses 2 AAA batteries in the sensing unit (cuff) and sends the results to my Android phone via Bluetooth. I sent an inquiry to their company asking about the efficacy of using rechargeables. Their reply said

There are two reasons we do not recommend rechargeable batteries be used with the QardioArm:

1) Physics - The way rechargeable batteries release current is different from that of alkaline batteries.

2) Regulatory - There are different regulatory standards (not harder, not easier, just a different set of standards) a device has to comply with to operate with rechargeable batteries.

Are they blowing smoke or is this really a serious consideration?

 

[hiegtx]

Is there a significant difference in the way alkaline and rechargeable Li-ion discharge while being used? My standard battery scanners include HP1, HP2, 396, and 436. All use rechargeable Li-ion batteries.

I ask this because I recently bought a Qardia blood pressure monitor. It uses 2 AAA batteries in the sensing unit (cuff) and sends the results to my Android phone via Bluetooth. I sent an inquiry to their company asking about the efficacy of using rechargeables. Their reply said

There are two reasons we do not recommend rechargeable batteries be used with the QardioArm:

1) Physics - The way rechargeable batteries release current is different from that of alkaline batteries.

2) Regulatory - There are different regulatory standards (not harder, not easier, just a different set of standards) a device has to comply with to operate with rechargeable batteries.

Are they blowing smoke or is this really a serious consideration?

The 'fully charged' voltage is higher on the alkalines. The other possible issue is that rechargeables can develop a self-discharge rate that renders the cell unusable. The low self-discharge batteries, such as Eneloop, do have a much lower self discharge rate, but with extended use, that may degrade after a number of charge/discharge cycles.

Apparently, there is some sort of statute regarding this.

I found a couple of web pages that address the caution against using rechargeables.

Making Sense of Regulations for Medical Device Batteries

Manufacturers need to remain up-to-speed on the various requirements for medical device batteries such as performance, safety, and transportation.

www.csagroup.org

Safety for lithium batteries in medical devices

There are a number of safety implications to choosing lithium batteries in medical devices as well as practical business implications. Avoid these pitfalls.

starfishmedical.com

Insights

Find breakthrough science and engineering insights for a safer, healthier, sustainable world. 

www.exponent.com

One factor mentioned is that the Li-ion batteries can overheat and catch fire.

 

[KK4JUG]

Thanx, Steve. The second article was interesting. While my piece of equipment doesn't have a battery system in the true sense, it would still have the lithium batteries and the problems that accompany them. There are enough "iffy" factors with the lithium batters that Qardia engineers probably didn't seriously consider them in favor of the alkaline batteries that are virtually problem free.

 

[palmerjrusa]

Is there a significant difference in the way alkaline and rechargeable Li-ion discharge while being used? My standard battery scanners include HP1, HP2, 396, and 436. All use rechargeable Li-ion batteries.

I ask this because I recently bought a Qardia blood pressure monitor. It uses 2 AAA batteries in the sensing unit (cuff) and sends the results to my Android phone via Bluetooth. I sent an inquiry to their company asking about the efficacy of using rechargeables. Their reply said

There are two reasons we do not recommend rechargeable batteries be used with the QardioArm:

1) Physics - The way rechargeable batteries release current is different from that of alkaline batteries.

2) Regulatory - There are different regulatory standards (not harder, not easier, just a different set of standards) a device has to comply with to operate with rechargeable batteries.

Are they blowing smoke or is this really a serious consideration?

Be warned, the new rechargeable Li-ion AAs on the market, in addition to requiring special chargers, have voltage step-down circuitry to bring them to an output of 1.5V. That circuitry emits RF noise that can significantly degrade radio reception.

I bought 4 rechargeable Li-ion AAs and tried a couple in a pocket AM/FM radio. Initially I thought something was wrong with the radio, AM reception was all but wiped out. Switched back to NiMH's and everything was fine again. RF noise from the Li-ion rechargeable's step-down circuitry was the source of the problem

The Li-ion rechargeable AAs don't seem to cause a problem in my Home Patrol 2 scanner re reception but you have to remember NEVER to charge them in the scanner.

 

[KK4JUG]

Thanx. We're talking about AAAs, here. But it's moot as far as I'm concerned now. I'm gonna stick with the alkaline batteries for the cuff. Other than a couple of flashlights and a Wx sending unit, nothing I have uses AAAs.