Lithium Batteries

[PNjunction]

I'm pretty sure that the B&D batteries contain smart charging circuitry consisting of an lvc, hvc, and individual cell balancing after looking at their patent:

https://www.google.com/patents/WO2006041751A2?cl=en

While they don't reveal specific voltages, the patent seems clear enough, although to save brain cells, perhaps only read the claims and not the summary.

The lvc appears to be smart, taking into account individual cell voltages and comparing it to an average stack voltage before throwing the sleep trigger.

What isn't clear until I reread it a hundred times, is if there is an allowable cell voltage-delta to trigger the bad battery flag and stop the charge, or if it will spend an inordinate amount of time trying to charge and balance a pack that is unrealistically out of balance due to major degradation of one or more cells.

In addition, I'm still not sure of any maintenance mode, where cell balancing might occur well after the initial balance charge is finished, and cells may drop out of balance say after only 12 hours due to unforeseen circumstances in a static state.

Chris - I could just brain you for getting me into this. I knew I would go too far.

[ChrisOlson]

Chris - I could just brain you for getting me into this. I knew I would go too far.

Sorry. LOL!

At least I learned a lot about lithium batteries. I've always heard they're supposed to be pretty good compared to lead-acid. But taking care of them is a bit different. There's more and more people switching from lead-acid to lithium packs for the house batteries in sailing yachts. Those that have them swear they are much better than lead-acid.

[PNjunction]

They make perfect sense in applications where high power-density to weight ratio is desired, as long as one can overcome the upfront costs, and charge properly.

Misinformation is rampant, which is not helped at all by the pie-in-the-sky marketers, battery abusers who do not apply the right charging techniques, let alone even know that there is an entire sub-class of li-ion (LiCo02, LiFeP04, LiNMC, etc etc, each with their own characteristics).

They aren't the universal battery power-pill for all needs. I still use lead for my fixed installation because it makes sense financially, and weight is not really an issue. But yeah, for boating, racing, EV, RC, powertools, powersports $$$ - sure.

I'm doing the discharge tests with the led light and will post some info in a day or so...

[ChrisOlson]

They aren't the universal battery power-pill for all needs. I still use lead for my fixed installation because it makes sense financially, and weight is not really an issue.

For stationary applications there's a company (Aquion) making a battery with salt water for an electrolyte. But the batteries are very big and are supposed have something like 20x the cycle life of lead-acid, and can be discharged to 0% SOC with no damage to the battery. They have some testing batteries in the field now and a battery that stores about the same energy as a Rolls 12CS that weighs 300 lbs weighs a half ton and fits on a pallet that you can move with a forklift. But the upfront cost is about the same as the Rolls battery.

I called this company about a year ago and tried to get in on their beta testing program, but was told I couldn't get a bank until mid-2014 sometime when they get a dealer network set up for them. But one of my off-grid friends that works at MidNite Solar has one of those beta salt-water battery banks and so far it works pretty good for him.

http://www.aquionenergy.com/energy-storage-technology

[PNjunction]

I respect Prof Jay Whitacre, and hope things turn out in the hands of Bill Gates, Vinod Khosla et al.

But until it actually reaches market, it reminds me of any-day-now "vaporware" of the past. AND, it means *nothing* to me if it is only available to oem's with proprietary black box charging - or at least until the NDA's expire, and one can actually get hold of some REAL charge specs. I don't need a micro-grid storage application - lets put it into a powertool and see how it survives.

The greatest hope is that it will provide competetion to what's already out there, and bring prices DOWN across the board. If not, there is no reason not to stick with lead / Pb where it fits the application, or continue to use existing Li-ion technologies.

Speaking of things you can get your hands on TODAY, over the shelf and online, with known characteristics and charging details available to the public at large, are my test results of the battery brought to us by Prof Jeff Dahn of Dalhousie ...

[PNjunction]

B&D 20v Li-NMC 1.5ah discharge test

Under test is a new-old stock LBXR20 30Wh 1.5Ah li-nmc B&D battery pack from 2012, using the BDCF20 led light as a discharge load.

The pack is rated to last about 11 hours with one of these led lights. It held up fine and approximates the list of SOC voltages presented earlier. I took a measurement once an hour, and the light is very convenient if one wants to choose a storage SOC, especially at the end of a season. The pack was brought to full charge in order to insure that the batteries were well balanced.

Voltages were measured with a Fluke 87V, which would be a minimum of accuracy needed considering the wide variation in soc over a mere 2.5 volt range or so.

Hours / total voltage / cell voltage

0 / 20.7 / 4.14
1 / 20.4 / 4.08
2 / 20.1 / 4.04
3 / 20.0 / 4.00
4 / 19.8 / 3.96
5 / 19.5 / 3.90
6 / 19.3 / 3.86
7 / 19.0 / 3.80 <----- many manufacturers charge and store here for retail longevity. Definitely full-charge before first use!
8 / 18.75 / 3.75
9 / 18.47 / 3.694
10 / 18.27 / 3.654
11 / 18.13 / 3.626 <---- approaching lvc, and led's just starting to dim a bit.

I didn't go any further since I didn't want to drop below 3.6v per cell, and test to see if the pack electronics would actually trigger an lvc - it *may* depend upon a powertool to do so. I wasn't going to sacrifice this battery to find out.

Ordinarily this pack takes 3-5 hours to charge from the oem adapter. However I have read reports of it taking 8-11 hours, which unless the battery is damaged, the customer may have taken the pack down to the lvc, and the charger is doing the *right thing* of only charging at .01C or less until it reaches 3.6V, and then continues on with a full current charge. I'd have to rip my adapter apart to test this, but nah.

This light was chosen mainly to do controlled discharging, and of course to utilize batteries I already have on hand. However it would foolish to choose this entire setup just for the light alone. Li-ion's raison-d'etre is the ability to deliver huge amounts of power in a small lightweight package without suffering large voltage drops, perfect for powertools, EV, starting, marine house banks, RC, or what have you. For small fractional-C applications like this led light, it doesn't quite make sense unless there are additional considerations.

[ChrisOlson]

But until it actually reaches market, it reminds me of any-day-now "vaporware" of the past

The Aquion battery has reached market and they are in full production. But they are currently only selling to commercial customers and not us off-gridders yet. I talked to their sales dept on the phone about a year ago and they said that in mid-2014 they should have a dealer base set up so private individuals who want a battery for off-grid use can get one.

Their M100 battery module is a pallet mounted 2,800 lb 19.2 kWh battery. It has twelve S10 48V battery stacks in it in parallel. They are far beyond "vaporware".

[PNjunction]

Sure hope Siemens likes them. It's all about selling to on-grid, actually THE grid providers. Wonder if Hawaii is going to use them for grid-stabilization. I'm sure they are pushing their Varentec system to go along with it. Those are the major customers.

Personally I don't think there is enough profit to be made on us off-gridders, and existing technology is plentiful enough to keep us happy. Just putting the shoe on the corporate foot here.

[mapmaker]

Personally I don't think there is enough profit to be made on us off-gridders, and existing technology is plentiful enough to keep us happy.

I'm happy (off grid), but I'm willing to be even happier. You're probably correct that there isn't enough profit to be made on us off-gridders, but if the battery lives up to its hype and is reasonably priced more on-grid folks will use these batteries for standby or even cut the cord and go off-grid.

--mapmaker

[ChrisOlson]

I'm happy (off grid), but I'm willing to be even happier. You're probably correct that there isn't enough profit to be made on us off-gridders, but if the battery lives up to its hype and is reasonably priced more on-grid folks will use these batteries for standby or even cut the cord and go off-grid.

I was told that the Aquion battery is going to be "competitive" with lead-acid as far as price/kWh of storage. But with better cycle life, fewer toxic materials in it, and ability to discharge to 100% DoD with no damage to the battery and less voltage "sag" during discharge as compared to lead-acid.

The downside for off-gridders is that at our locations it's kind of like forklift batteries - most of us don't have a way to move one into the power room. And that is why we have 5000-series Rolls batteries that only weigh 350 lbs each instead of a forklift battery. Two strong men can get a Rolls batteries out of the back of the truck and onto a wheel cart to get them into the power room. When we designed our power room we did not design it to be able to take a wall down and get a big battery like that inside.

Big batteries like that might be nice. But if all you can do when it arrives on a truck is sit under the shade tree drinking a beer and look at it going, "that is sure is a nice battery" it doesn't do you much good.

[russ]

But if all you can do when it arrives on a truck is sit under the shade tree drinking a beer and look at it going, "that is sure is a nice battery" it doesn't do you much good.

........................

[PNjunction]

I was told that the Aquion battery is going to be "competitive" with lead-acid as far as price/kWh of storage. But with better cycle life, fewer toxic materials in it, and ability to discharge to 100% DoD with no damage to the battery and less voltage "sag" during discharge as compared to lead-acid.

I've seen lead-crystal battery marketers using the same comparison to lead-acid tactic. The reason this doesn't impress is that taking a Li-ion of whatever flavor down to 100% is abuse. That means your lvc failed or is not even installed. And, unless they do something very magical, there is NO usable power past 80% DOD in real-world terms. You hit that deep discharge knee, and game over pretty soon if the lvc doesn't catch it. And even if it can survive an abusive discharge to 100% DOD, we don't know how that impacts cycle life.

Less voltage sag under load? Child's play. One reason to choose AGM. One similar marketing tactic for lead-crystal was that it made sure to use "as compared to flooded lead-acid", and conveniently left out AGM. TPPL or pure-lead even better.

Toxic materials? Lead acid is supposed to be recycled, and due to being busted by the garbageman, most people that I know do recycle them. Not so with Li-ion where one is directed to recycle them for the stray copper / aluminum, but I suspect that due to their light weight and "less toxic" nature, most landfills will be littered with the plastic carcasses as they are simply ditched in the garbage - residential or commercial.

Nobody knows yet if the charger is a proprietary black box single-vendor lock-in component, (say that 5 times fast..) or if one has the skills to use their own charger properly.

I guess we'll find out any day now. I really have no explanation of why I get so fired up on li-ion. I guess I get angry when marketing shadows the technical details which I crave.

[ChrisOlson]

Nobody knows yet if the charger is a proprietary black box single-vendor lock-in component, (say that 5 times fast..) or if one has the skills to use their own charger properly.

One of the fellows that works for MidNite Solar has an Aquion battery on their beta test program. He's been charging it with Classics.

[pleppik]

And, unless they do something very magical, there is NO usable power past 80% DOD in real-world terms. You hit that deep discharge knee, and game over pretty soon if the lvc doesn't catch it. And even if it can survive an abusive discharge to 100% DOD, we don't know how that impacts cycle life.

This may be a stupid question, but isn't that a function of the particular battery chemistry?

As in, different battery chemistries behave differently under deep discharge, so the rule of thumb for lead-acid doesn't necessarily apply to other technologies?

Or am I missing something?

[PNjunction]

This may be a stupid question, but isn't that a function of the particular battery chemistry?

YES! That is why I think it is a cheap tactic to compare itself to another chemistry, especially when they don't differentiate the characteristics between flooded and agm types. As an example: lead-crystal is a slight variation of agm. Yet their marketing was touting the differences to flooded lead acid, and promoting the characteristics of lead-crystal conveniently leaving out the fact that most of the advantages were merely standard features of normal agm's.

For me, marketing without *accurate, and open* specifications makes me crazy and has the opposite affect when they try to promote it. It sends my fluff-alarm into overdrive when the marketing is mere generalizations.

I had a rethink. Pushing a comparison to Pb/lead means tackling the biggest market in the world, ie vehicle batteries. One of the most common problems is draining it until dead, or until parasitic loads do the job. They can be resuscitated, but it takes a huge hit on cycle life.

So, in essence the Aquion may not even need an LVC, but we don't know for sure how that affects cycle life. Still, if recovery is possible, at least it will get you down the road for awhile. I could see it as an application here.

Essentially, it almost seems to be a lifepo4 replacement for abusive applications such as letting your vehicle battery die, and being able to be recovered by normal means.

Still, until NDA's are lifted, and REAL specifications, (not just generalizations) are published openly for the common man, then the main ingredient is still un-obtainium.