Lithium batteries, can someone explain?

[hartage]

Why is it when I look at some run-time graphs lithium AA batteries always draws more power vs alkailine AA batteries. Both have same voltage (1.5) so how do lithiums acheive higher draw? I also read in one post that two lithium AA batteries = 3.4-3.6 volts well wouldn't that make them 1.7-1.8 volts per cell? I'm confused, someone please enlighten me

 

[vcal]

You're right....
The AA Lithiums can pull a bigger load than the AA alkalines, because of their design. And you guessed it again..-those Li AA cells usually DO measure 1.7v+ each when new.

 

[Steelwolf]

AA lithiums can pull a bigger load because they exhibit very low internal resistance. This is a very important consideration in high drain devices.

 

[hartage]

Vcal, I don't quite understand what you mean by "Li AA cells usually do measure 1.7v+ each" are you saying that it's variable? some cells have higher or lower voltages than others? If Li cells can measure as high as 1.8 volts then why are they listed as 1.5? 1.8 would be 20% out of spec.

Is it some big conspiracy that battery manufacturers are listing Li voltages as 1.5v when in reality they are more towards 1.7v?

 

[vcal]

Originally posted by hartage:
Vcal, I don't quite understand what you mean by "Li AA cells usually do measure 1.7v+ each" are you saying that it's variable? some cells have higher or lower voltages than others? If Li cells can measure as high as 1.8 volts then why are they listed as 1.5? 1.8 would be 20% out of spec.

Is it some big conspiracy that battery manufacturers are listing Li voltages as 1.5v when in reality they are more towards 1.7v?

<font size="2" face="Verdana, Arial">To make it a little more clear:
The Lithium AAs are rated for 1.5 volt applications, and in looking at the AA Li I'm using right now, it does say: 1.5 volts on the label. Even though it shows 1.74v on my DVM.

But 99.99% of all new AA (L91) Li cells sold will measure 1.7-1.8 volts-not under load. This is kind of the same pecularity that the old Nicad batteries that were sold for 9 volt applications...-actually measured only 7.2 volts!

-Go figure.

Lastly 99.9% of new AA alkaline batteries under no load, will measure about 1.55 volts..for 1.5 volt applications.

Not much of an explanation, but that's all I can tell 'ya.

 

[hartage]

Well SOB, no wonder Li batteries puts out more current in the same circuits. Higher voltage will tend to do that. I guess I can fairly assume that battery manufacturers have no interest in the truth or reality. 1.5 where 1.74 should be, 9v where 7.2v should be. Might as well throw in battery manufacturers in along with lawyers, marketers and other lying sacks of ****. Of course adding some gasoline and tossing in a match won't garner much of a protest from me.

Thanks for the enlightenment guys. Hartage

 

[lux0]

" I guess I can fairly assume that battery manufacturers have no interest in the truth or reality."

Why so annoyed? it's not a scam....it's different chemistry.
BTW, batteries generally don't 'pull a load'..the load draws current from the battery.

 

[hartage]

Luxo, I realize it's different chemistry, I'm not annoyed at that at all. What I am annoyed with is the manufacturers lack of interest in accuracy or you can even call it "the truth". I mean 1.5 and 1.8? that's a 20% off spec. Imagine the chaos if everyone here didn't care if what they said was 20% off from the truth. What's the harm in 20% off? well talk to the people with burnt up circuits because they be lived 1.5 rather than figuring for 1.8 The truth and accuracy really do work, too bad some people/companies don't believe in either one.

"pulling a load" when Steelwolf said that I took it as referring to the circuit not the battery. No where in my posts above have I said "pull a load".

 

[lux0]

"I mean 1.5 and 1.8? that's a 20% off spec"

but, as vcal explained, those are open circuit voltages...they drop under load.

"when Steelwolf said that I took it as referring to the circuit not the battery. No where in my posts above have I said "pull a load". "

never said you did.

steelwolf said :
"The AA Lithiums can pull a bigger load than the AA alkalines"

to me, that indicates that the battery is 'pulling a load' ...whatever that means.

 

[hartage]

LuxO I believe we are on the same page here. Don't you think that YOU would be better served if they labled alkalines 1.5v and lithiums 1.7v ? If the change in chemistry denotes a change in actual noload/load voltages shouldn't the label denote the same difference?

 

[Stefan]

Lithiums were designed for high drain devices, like digital cameras (and now LEDs) Sure, the starting voltage on a lithium is misleading at 1.7 to 1.8 volts per cell, but under a load (flashlight is turned on) the voltage is reduced to 1.5 volts. Alkalines start as 1.55 volts, and as soon as they are in a curcuit the internal resistance of the cell drops the useable voltage to 1.2 volts.

 

[hartage]

Stefan, exactly and hence there is still the same difference at load 1.2 vs 1.5 and no load 1.5 vs 1.8 Yet they are both listed at 1.5 this is where the deceptive, misleading, burn-in-hell lie comes in. There is a .3 (20%) differnce in voltage between alk and Li and the label should reflect that.

 

[txwest]

I think the use the "1.5V" tag so you'll know they're for 1.5V applications. Rechargables = 1.2V; alkaline = 1.55V; lithium = 1.7V. But all are for 1.5V applications. TX

 

[highlandsun]

20% difference yes, but how significant is this in an actual circuit? Changing the labeling is only important if the battery itself is actually incompatible with devices designed for standard 1.5V alkalines.

If I ran across a battery that looked like a AA, but was marked 1.8V, I'd be seriously confused - is this battery OK to use in my 1.5V remote control? Or must I only use it with special gear, specifically designed to operate on 1.8V cells?

What about alkaline cells vs the old carbon-zinc stuff? Is there a similar deceptive misleading burn-in-hell lie there? If alkaline cells were marked 1.55V, probably everyone would have been confused about whether they could be used in their old gear that had carbon-zinc batteries to begin with. People would have avoided buying them, and that would have been a shame.

The fact is that no battery stays at any particular specified voltage for very long - as it's used, the voltage drops. That's life. Circuit designers know this, and they account for it. So, 20% margin of error is no big deal. Get over it.

 

[hartage]

Howard, I guess the no Li batteries in the reactor 3's and some of the direct drives working fine on alk and Li's but burning out on NiMh just don't exist eh?

"no battery stays at any particular specified voltage" as long as it's under the specified volts it's not a problem it's when you go OVER specified volts does it become a problem.

"20% margin of error is no big deal" what kind of idiots do you work with? I used to do engine building and custom turbo instalations and I have come across automotive batteries that are 14.4 volts (special purpose) 14.4 is 20% out of spec from a standard 12v battery. You know what would happen if I stuck a 14.4 volt battery in a regular car? total chaos. Fuses would blow the charging system (14.4v) would fail to charge the battery etc, etc, etc. A battery 20% out of spec in a regular car WOULD NOT WORK AT ALL.

Let me state this again... if a 20% margin of error is no big deal, what idiots do work with?

Most quality computer power supplies have an over voltage cut-off most are set at around 5% out of spec anything more and powersupply shuts down.

Go buy a reactor 3 and stick lithiums in there, then tell me again how 20% margin is no big deal.

 

[flash....]

As much as I don't like Hartage's tone, I do agree with him. I was in the store the other day and bought a set of Energizer Li AA's and read the package... 1.5v. I was puzzled as I have read on this forum that Li's were 1.7-1.8 volts. I took them home and discovered quickly that they will trash led circuit designs that are set up to overdrive for maximum output. "this also happens in off the shelf LED flashlights"

In my $1800 digital camera that uses 4 AA batts I now realize never to use Li's in it. 1.8 x 4 = 7.2v not 6v!! (my RC car Runs on 7.2, not my camera) My camera is rated for 6v. To me? Not worth the risk of trying this with a fresh set.
And boy do they evangelize all over the package... "GREAT FOR DIGITAL CAMERAS" ....this is just plain scary.
I realize lots of devices will tolerate this without issue. But I'll bet some won't.
We are not sheep. (well not all of us anyway

)

Simply put "there should be an Explanation or a warning on the package."

Also, everyone's argument that we should "get over it" because putting 1.7 or 1.8 volts would confuse us\customers is ridiculous. Why?.. well lets see, NiCad's are labeled as 1.2volts.. no confusion there. Arguably one could think that NiCad's having lower voltage will make regulated devices regulators work less efficiently due to having to make up the additional voltage. and I'm sure in some devices this is true. but let's not drift.
Most of the sheep people don't observe the voltage rating anyhow... "hey looky there Marge.. get some of those expensive "AA" batteries" (weather they are 1.55, 1.5, 1.2 or 1.8volts it's still an AA battery to most folks).

IMO - A warning or explanation needs to be labeled on Li's as they become more commonplace.

My Energizers?? All sorts of commentary on the package about how long they last and why Li is so great.. ( and I agree they are great) but give me a break... save a little real-estate in packaging and post the specs please.

Ok.. I'm off my soapbox and crawling back to my hole now.

 

[hartage]

Geez, I feel guilty now... after reading my own post I don't like my tone either. An explanation.... it was just a discussion that was light hearted till howard threw "get over it" in there. That overstepped academic discusion and personal expression and turned into a personal attack aimed at a single person (me). Hence he received like action from me.

Looking in hindsight, I'm embarassed that I behaved badly, my apologies to everyone.

 

[highlandsun]

I didn't intend "get over it" to be taken as an attack. That, to me, is a pretty casual way of dismissing a trivial issue. I didn't realize it would get blown out of proportion.

re: automobile electrical systems - it's common knowledge that the "12V" system actually runs at 14.4V when the alternator is running. I'm pretty skeptical that you actually found a 14.4V automotive battery, since automotive systems have been 12V or 24V since at least the 1930s. More likely you measured 14.4V while the engine was running, which is exactly what you should see in a healthy system. (And you'll see less than that if you've got inadequate wiring running to wherever you measured.) Again, I'm not trying to start a fight. There's plenty other more important things to worry about, this isn't one of them.

re: direct drive flashlights burning out - if it works on alkaline and Lithium but burns out on NiMH, that has nothing to do with battery voltage.
If it were voltage-dependent, then why would it work on a 1.5V alk and 1.8V Li but burn out on a measly 1.2V NiMH?

This is not about voltage, it's all about the battery's internal resistance. Nobody even mentions that spec on a battery label...

 

[Stefan]

Originally posted by Howard Chu:

This is not about voltage, it's all about the battery's internal resistance. Nobody even mentions that spec on a battery label...

<font size="2" face="Verdana, Arial">Not mentioned on the label, but some battery manufacturers have specs on their website. Labelling is only intended to tell the buyer what they are getting, otherwise batteries would be too costly to have them in a box with info all over it.

 

[hartage]

Howard, your points...

"it's common knowledge that 12v....." yes that is the common battery, when I said 14.4v battery I meant 14.4 volt battery. The battery has an actual voltage of 14.4v by having more cells inside it to push it to 14.4v . They are used to push the ignition system of a vehicle where the rules allow you to change the battery but must keep the ignition system unchanged. A standard charging system that already works on 14.4v will NOT charge a 14.4v battery (a special charger working with 17v is used). I used this example to counter point your statment of "20% margin is no big deal" At 20% off spec things already go horribly wrong. On the other side if your battery voltage has dropped to 10v (also 20% off spec) most cars will not even start. Is this clear enough that 20% margin or "slop" is not trivial?

"Nobody even mentions that spec on a battery label"

Ok you've just proven to yourself that it SHOULD be listed on the label.

"if it were voltage dependant...."

If your alluding that voltage has nothing to do with burning out I assume you think that the equation volts x amps = watts is just a made up farce?

We are in agreement on something though, this debate has degenerated into a useless debacle and is pointless.