NiMH vs Lithium ion, which is superior?

[Jerboy]

The bottom of line Motorola v120c comes standard with a 1100mAh 3.6v Lithium ion battery and the bottom of line Nokia 3390 comes with a 900mAh NiMH battery BMC-3. The Nokia 3390 can take BLC-2 850mAh lithium ion that offers same talk time at twice the cost. I have not found lithium ions to be significantly higher density(Wh/kg) than NiMH and my v120c with significantly more expensive Li-ion doesn't seem to do much better than Nokia 3390 with NiMH.

Pros and cons of each chemistry:

Lithium ion;

Pros: higher energy density than NiMH, very slow self discharge(if you store battery on the shelf charged, it will be fully charged a month later), no memory effect and more techie sounding name.

Cons: Much more expensive than NiMH. Due to current inherent limitations of this chemistry, fast charge is not realistic and the last few percent of charge takes hours to charge.

NiMH;

Pros: much cheaper than Li-ion and it easily accepts fast charge while giving similar talk and standby time as Li-ion

Cons: loses a percent or two a day of charge in storage(not that it matters for something like phone that you leave on 24/7), lower energy density than Li-ion

In closings, I can't see Li-ion being any superior to NiMH for use in cellphone. I think many would appreciate the faster charging 3390 over a slow charging v120.

comments?

[ockidd15]

I agree with your points, but remember that the Li-on batteries then to be much thinner and lighter. Most of the batteries a few years ago carried the NiMH and they were heavier and thicker. These days, since phones are becoming smaller and thinner and lighter, phone manufacturers chose the Li-on batteries as "the standard" these days. Now, the new technology brewing is the Li-Polymer batteries. These things are super thin and light! But, thier ability to hold a long charge is still to be perfected. I think these properties of batteries will attract consumers more, since they want a small, light, thin phone.

[JohnnyCNote]

I've had both and the L-ions are much better. They're also not that much more than the NiMH if you shop around...

[Jerboy]

Originally posted by: ockidd15 I agree with your points, but remember that the Li-on batteries then to be much thinner and lighter.

One would think so, but this may not be the case. I don't think the Motorola v120c has any size advantage over Nokia 3390 that uses NiMH. Nokia 3390 can take both Li-ion and NiMH and they're in same size, yet provide same capacity.

Energy density is measured in Wh/kg. Let's compare my measured approximate figures.

3.6v 1850mAh 3 cell NiMH ~83.8Wh/kg. 3.6v 1100mAh Motorola battery pack 90.8Wh/kg. That's all of 8.35% greater energy per weight at the expense of greater cost and slow charge.

The lithium ion battery used in cellphones is slight different from camcorder Li-ion batteries. Camcorder lithium ions are higher in density, but they're hermetically sealed cylindrical cell similar to AA battery in style and by nature, they can't be built thin. The type of battery used in cellphones is called prismatic lithium ion and it can be built to about 7mm thick and flat in shape.

Most of the batteries a few years ago carried the NiMH and they were heavier and thicker.

Most phones a few years ago was also power hungry analog monsters. They were often 6v 900mAh or so battery with 11hr standby time. It looks to me that you're giving credit to lithium ion battery for modern digital phone that lasts longer. If you compare a modern phone with NiMH and Li-Ion, the difference isn't as great as sellers wishing to push lithium ion wants it to be.

How do you suppose Nokia 3390 compatible Li-Ion and NiMH have the same rated talk/standby time?

These days, since phones are becoming smaller and thinner and lighter, phone manufacturers chose the Li-on batteries as "the standard" these days. Now, the new technology brewing is the Li-Polymer batteries. These things are super thin and light! But, thier ability to hold a long charge is still to be perfected. I think these properties of batteries will attract consumers more, since they want a small, light, thin phone.

1800mAh NiMH can usually accept C/1 charging, which means charging at 1.8Ah for 1hr until full capacity is reached. An 1800mAh lithium ion needs to be charged at C/2 or so until 4.2V is reached to get a partial charge, then the voltage must be maintained at 4.2V. There's not much you can do to accelerate the charging speed after 4.2V is reached. To get it up to 100% from 80% or so, it takes hours. 0-80% is quite a bit faster.

[northform]

I personally don't care. I have found that how the phone manages power (how efficient it is) matters more than the type of battery or its mah rating. Li-ion batteries can get better or worse life. I have never had a memory problem with NiMH batteries and they aren't supposed to get them.

[ockidd15]

Jerboy, I had meant to say that the Li-ion batteries "tend" to be thinner and lighter. I didn't say all of them were. I agree with what you said, but the Li-ion batteries are being used more than the NiMH as compared to a few years ago. And a few years ago I was referring to was maybe about 3-4 years ago, not the mid-90's, but more of the late 90's the so-called "cell boom." During this period was the Li-ions becoming more and more popular with the digital phones. Again, I had stressed by saying "most" of the batteries...I never said all. Lastly, the last part of my message you quoted me on has nothing to do with c/1 or c/2 charging. I'm just clearing up some things because I had meant to make my post general and not specific.