Battery life poll

Alternative energy sources
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The usual. As I have two large solar PV systems here, and my lab assistant just put one in, and others are interested in things like this, here's where that stuff goes. This is mostly for things that work now, not "gee someday a fusor will do this" -- we know that, but it's not someday yet.
The hope is to save anyone embarking on this sort of thing a lot of wasted time and money, as at least I have been off the grid since 1980 and have had a lot of practice (and made mistakes you won't have to).

Battery life poll

Postby Doug Coulter » Mon Nov 08, 2010 4:22 pm

Without predisposing the results too much here, I'd like to ask people on the forum about their actual experiences with real life rechargeable batteries. Does anyone get the cycle life claimed in "real life applications" like power tools, laptops and so on before the capacity goes down so far you replace the battery in disgust? What do you actually get out of NiCd, NiMh, LiIon, lead acid and so on? Does anyone really get 700+ full charge/discharge cycles on any of these?


I know what life I'm getting from these technologies, and what some products I've designed using them got (with fancy chargers designed according to manufacturers recommendations and batteries sized for good life -- we didn't beat hard on them), what I'm interested here is what YOU get, and after I find that out, I'll tell all I know.

I will say this. I think there's going to be one heck of a backlash on electric cars if they haven't found a way to do better than what I see so far.
If anyone has results on Vanadium Redox batteries, well, we'd all like to hear about that one! They wouldn't do for autos, but might be nice here at the homestead.
Anybody kludged one up yet?
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery life poll

Postby chrismb » Mon Nov 08, 2010 7:18 pm

It is my experience that the technology is not a factor, but the manufacturing quality is.

I have had [a number of!] NiCad rechargeable power tools that die in rapid and short order, yet I still have (!!!) some very early NiCad AA and AAA batteries I bought in 1985~6 that still work (and those babies needed a lot of repeat charging as they had very little capacity in those days!).

The other point to mention is the balance between capacity and rechargeability. I have had AA's all the way up to 3800mAh but I would now never think about buying more than around 2500 in an AA for precisely this life-time reason. Yeah, you can cram upward of 4000mAh into an AA, but they neither keep their charge long, nor maintain that capacity for many recharges.

To note, in all the battery reviews I have ever read, there is one that comes out by miles on top, and that is the Sanyo Eneloop which has a very modest 2000mAh nominal capacity. But the tech inside it means it stays charged for a year and nor does the capacity degrade after repeat use. Clearly what capacity it does have, it gives willingly and reliably and that counts more than outright capacity.

So if you want reliable rechargeables; don't worry about the chemistry but go for the big names that have a reputation to keep up, Sanyo, Energiser (I like those very much for general application, worth the extra money in my estimation) and Duracell, and go for the smallest capacity that you actually need.
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Re: Battery life poll

Postby Doug Coulter » Fri Nov 12, 2010 10:38 am

Well, that's interesting and I concur -- there are definate quality differences, and probably some things that track capacity per volume. We used the Sanyo batteries in some hearing aid projects and they were indeed nice -- they were the only ones making them flat, square and other odd shapes that made them easier to package. Self discharge is only a problem in batteries not in use, what I'm looking for is use statistics.

I was really looking for data on things that really use batteries at some power level and beat on them hard -- like portable power tools, or laptops -- there you have no good choice other than to accept what the manufacturer gives you. Presumably they have tuned their chargers to suit their batteries as well. Most are claiming well over 300 cycle life, some as high as the 700's.
Is anyone getting that? I know I'm not, and the real numbers are very very nasty compared to the claims, which could be described as "outright lies" in most cases. In fact, I've never seen 700 full cycles in ones in products I've designed and tuned the chargers for that particular cell according to the manufacturers suggestions.

Ok, since it appears no one is paying attention -- here's more or less what I see.

NiCads in things like geiger counters -- weekly use, about one charge a month. 1 year. 12 cycles (sub C batteries)
NiCads in Ryobi drills and other tools -- two years, maybe one charge per two weeks. -- 50 cycles
NiMH in Makita tools (and this is an over $100 battery) -- three years, charged maybe every two weeks. ~ 75 cycles
Laptop LiIon -- haven't fried one yet, but then this lappy only runs on AC here. Maybe ran it down once.
Camera LiIon -- still going after 2 years, but never out of the charger and turned on more than about 10 minutes either.
Also an expensive battery only from Kodak, no substitution possible.

The above numbers are actually very optimistic -- some of the power tool batteries only see once a month or less frequent cycling, as I have a lot of them and a lot of tools that don't see frequent use. But it's bordering on a dollar per cycle! Heck, I can recharge alkaline batteries 3-4 times and they aren't meant for that! ( I have a charger that claims to do that correctly, and it seems to work about as well as reported above).

For another whole class of thing -- L-16 6v, 375ah lead acid, I get maybe 8 years in a solar system babying them as much as possible, as in "your life revolves around them". Very fancy 3 stage charging scheme, use most power when the sun is up (eg direct from the panels) and bypass them with smaller deep cycle batteries that take most of the peaks and die within a year doing that.
Usually 10% cycle/day tops, maybe really run them down once or twice in the entire life. I don't know the life of the Rolls-Surrette submarine batteries I'm using now, but they have a 25 year warranty and claim a few thousand cycles. We'll see on those, but I'm hoping they last for "life" eg mine. This is very high class stuff and they aren't cheap at all -- that bank I show in my solar system was about $6000 with a good discount.

I'll have to ask a friend who bought a Prius how his are doing. He takes better care of things than just about anyone, and mostly walks places anyway, doesn't use it to commute the 10 miles to his job, but uses a regular vehicle for that...Hmmm. Maybe not a good place to get a number, as he only uses that for longer trips (eg, very little use of the battery).

Of course, warranty on anything is only good for the life of the company giving the guarantee, and an old trick in the car battery business was to "go out of business" and change the company name to avoid paying warranties. The discount auto batteries companies would do this about once a year and pop right back up with one letter of the company name changed.

And when I declare them dead, it's not because they have half capacity. They are DEAD and maybe will run the device for 5 minutes off a fresh charge, if that.
Anyone else seeing this sort of "dollar per use" kind of numbers? I've had much better luck with AA nicads or NiMH in low draw use, like cameras, but still not very good.

Now the Makita batteries are so expensive (so as to even be hard to find, stores don't want that much bucks in inventory laying around) I will take them apart and replace the cells with ones from DigiKey soon, but even that won't be cheap. But I'm not going to toss out a $275 drill because of that -- it's a very good tool.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery life poll

Postby johnf » Thu Aug 04, 2011 4:52 pm

Vanadium Redox Batts
Some improvements are happening
http://www.greendesignbriefs.com/compon ... ticle/9470
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Re: Battery life poll

Postby Doug Coulter » Fri Aug 05, 2011 2:33 pm

One wonders how well the chemistry of this one is really worked out. Oxidation states of Vanadium are way complex. (and halogens can take the place of oxygen). So they're saying that adding HCl at a minimum lets you have more vanadium in solution over higher temperatures, that's good all around, but....the barrier there is still the price of Nafion ;) One hopes some other cell divider will appear that doesn't cost so doggone much. So far, you can't buy these things unless its for a huge install -- skyscraper, and you have to "rent" an engineer from the patent holders as they say "it's too complex" to manage yourself. I don't buy that, I think I understand the issues (and BTW, 4 tanks are a better system than two, and make the uP controller processing simpler as well). If there was an affordable cell separator, I'd be all over these for my home system, and use them kind of like a backup generator, using the existing batteries as "bypass caps" for them.

Room, I've got. Big tanks no problem. Industrial grade V2O5, no problems (and you can easily get the other oxidation states from that one). Pumps for what amounts to battery acid, no sweat.
Control -- well, I do that for the solar system as is. So far, for me (not all applications) this one looks like the big winner due to no degradation of the cell itself over time, and basically unlimited storage capacity. I'm sure that like lead acid or other battery tech, you have some issue of leakage (which the article seems to imply) but so what - you just size things right for your situation.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery life poll

Postby Jerry » Fri Aug 05, 2011 7:32 pm

I have had pretty good luck. Iphone is a little over a year old and no noticeable life change. Though the rechargeable batteries in my XBox 360 controller dont last at all. I have gone back to AA's.

Have not had much luck with laptop batteries. If you run it off mains its best to yank the battery.
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Re: Battery life poll

Postby Doug Coulter » Fri Aug 05, 2011 8:12 pm

Agree on the lappies. I have the same experience with them and most of the recent rechargeables myself. The other day, someone posited a tinfoil hat theory (around the apple stuff) about why they put electronics in the battery pack. Having designed a couple of chargers for NiMH and Li-ion, I know why - it's hard to get right, doggone it. You need temp sensors, current sensors (net current if you're charging while running) at the very least, some timing logic and other junk - even some cpu cycles for the trickier cases. It makes sense to cut the number of wires on the connector way way down, and skip trying to put low level precise analog signals on them if you want to do it right. And these new guys with the flat discharge/voltage curves make it devilishly difficult to create a "how much left" meter that means diddly -- so that's best a function of the battery pack, and makes it so you can interchange them. Can't think how you could track total charge cycles any other way either.

I've found on my power tools that the NiMH for the makita is the best. The NiCd's on the Ryobi don't last nearly as many cycles. That's probably also a function of what the battery capacity is vs the peak tool demand as well -- Ryobi is pushing that, Makita isn't so much. Nothing likes quick discharging.

This came up around the Apple stuff because someone thought it was a way to make Apple batteries sole source - Job's famous "walled garden". Well, for now, it is. Thank the DMCA for that (makes reverse engineering illegal, or close enough to put a small company out of business defending the lawsuit). But that's not the only reason, to give them some credit where it's due - it really is hard to do that job any other way, and it's hard enough doing it that way for crying out loud.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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Re: Battery life poll

Postby Doug Coulter » Tue Sep 20, 2011 12:12 pm

I ran across this today, and maybe there's something here, both for the intended use, and for redox batteries that need a proton-passing membrane.
http://www.physorg.com/news/2011-09-pro ... hines.html

I did a stint of making prosthetics awhile back. After looking at direct nervous system stimulation (really, i/o), in that case we decided to skip it and go with a pure-external device for profoundly deaf, rather than the ear implants as those don't work well. I became convinced that a big reason for that is we weren't talking in the correct language(s) for neurons. While you can create an absence of positive ions with a flood of electrons, that's not really "how they work" and it results in chemical imbalances that eventually destroy the neuron. People were (and are) also trying to simulate the PFM signal neurons "speak" with DC or sine AC, when that's also 'just not how they work" - they use low duty cycle pulses. Most people's own experience will show that plain old electricity on a wire isn't very useful. When trying electro-stimulation, you find that at high currents, yes, it's a shock, unpleasant. But lowering the power just gives you a smaller shock - still unpleasant. You can't get to "touch" or "warm" or anything other than "pain" with that on skin. Doing it to neurons directly, say, in the ear -- well, they don't have "pain" as a response but the problems are similar. The resulting deaths of the neurons make the implants fail, and that's one tough place to do an operation, being encased in bone almost completely. Bad enough when your external electronics get flaky and need replacement...I know I wouldn't want any such thing in my body, particularly where it's really hard to get to.

But the other interesting thing is that this stuff looks a lot like the very expensive Nafion in properties, and should be cheap. If it can withstand the conditions, that makes it a candidate for a redox battery membrane, and would go a long way towards making them economically practical. Bears some looking into for sure. Current electrolytes use sulfuric acid I'm guessing mainly to make them more conductive (main use in electroplating is for that). That's usually quick death for organics, but perhaps some other conductivity enhancer would do as well, and not eat the membrane? Sulfuric is used a lot because it's cheap, but there are plenty of good conductors in solution that are nearly as cheap.
Posting as just me, not as the forum owner. Everything I say is "in my opinion" and YMMV -- which should go for everyone without saying.
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