LiFePO4 Batteries: Discussion Thread for Those Using Them as House Banks

[Opie91]

Originally Posted by hellosailor

There's still a HUGE opportunity being lost, and one has to ask why no LiFePo4 maker has been smart enough to hold a press conference and say "XYZ Co. Offers Boeing a Safe Battery Alternative!"b

Ill tell you why no one has stepped forward and offered the "Safe" battery alternative, it boils down to one word. CERTIFICATION.

No certification, no fly. Period.

[mbianka]

Originally Posted by deckofficer

Stay tuned to this thread Opie91, we will keep you posted. I hope to be the first to use LiFePO4 for a propulsion/inverter bank (if Capt Mike doesn't beat me) larger than the propulsion packs for my electric kayak. 2.6 KW-hr vs 75 KW-hr. The tests I've run my cells through has convinced me Lead is Dead.

Deckofficer:

You go right ahead. I've already made one scary leap when I converted to electric propulsion in 2008. Not sure I want to push my luck when my AGM's "ain't broke" so I see no need to fix them yet. I'm glad to bide my time for a few years to see if those 1,000+ charge cycles really do happen and the BMS electronics hold up during nearby lightning strikes. I've got to admit part of me is saying these battery's sound too good to be true and/or may be a little to complex/finicky to deal with while cruising. I hope a few years in the marine environment will allay my concerns. In the meantime I'll be on the dock waving my hat and wishing you and the early adopters well as you head off into these uncharted waters.

[hellosailor]

"it boils down to one word. CERTIFICATION. "
Right, and you think there have ever been any batteries flying that were not certified before someone said "I want to get this certified" ?

Doesn't matter if something newer and better has been certified YET because if it is a better solution, and there's an economic case to be made for it, then someone will indeed put it through the certification process. Just like the other hundred thousand parts that were certified before they got installed on that aircraft.

And certified or "as yet" uncertified, the PR benefit to the industry remains the same. Right now the opporuntiy exists for millions of dollars of free publicity, just by announcing there IS a safer technology. Doesn't matter if it can be used, that's someone else's problem. The folks who make the batteries only have to announce they've got a better alternative, and that makes the national news.

Assuming, of course, that it is any safer. They'd have to either be fools, or to know it isn't, not to make that announcement. Well, maybe not fools, just engineers who were foolish enough not to hire marketing people for their companies.

[T1 Terry]

The thing is, Yuasa got the jump with these older technology batteries because the military and Nasa had already done the testing for them. The difference is, the batteries being made for Boeing are made to a price, for the military and space program, they were made to a specification, and every one was subjected to serious testing before it was used, not mass produced and bolted in. Now the hard questions are being raised there appears that the answers may not be what the investigators want to hear, if the batteries are good enough for Nasa and the military, why aren't they good enough for you?

The major lithium ferrous manufacturers are already busy supplying the Chinese military and the Chinese public transport system which is moving to full battery power at a rapid rate.
T1 Terry

[Opie91]

Originally Posted by hellosailor

Assuming, of course, that it is any safer. They'd have to either be fools, or to know it isn't, not to make that announcement. Well, maybe not fools, just engineers who were foolish enough not to hire marketing people for their companies.

Sorry for the thread drift, this will be my last aviation based post on this.

After searching the internet I did not find any serious effort to put LiFePO4 batteries in large aircraft. Major aircraft battery manufactures have lines of lithium based batteries but do not even discuss LiFePO4. There were a few companies working on general aviation (Cessna, Piper), but no heavy stuff. Even the general aviation stuff is not certified.

It takes a huge investment in company resources and money to get something certified. One example is things that work at 20 C at sea level often do not work well at all at -40 C at 36000 feet.

If a company announced that they had a "safer" battery for Boeing that had no testing they would get plenty of attention, just the wrong type.

Don't get me wrong I believe LiFePO4 has awesome potential, but it is not the miracle cure for aviation right now.

[durundal]

So I decided to bite the bullet on the 12V pre-packaged 90Ah from Balqon (unfortunately the price went up a few bucks between when I found them and now, d'oh... they updated the website with more info in the mean time and less Engrish text), better to make sure it fits now than have to modify and repaint my battery holder later. Will report back on how it looks and if the outer case is sealed or just snaps together.

Still a bit loathe for the weight over the 60Ah, but I'm already more cruising oriented than racing with the sink and stove... and it's still 10lbs lighter than a 55Ah Optima blue top that was the alternative...

[Tidkin]

durundal - I assume you saw this Youtube showing a fellow cracking open the Thundersky 12V 90Ah LiFeYPo4 battery.

How do you open these Thundersky 12V 90Ah LiFeYPo4 - YouTube

Please keep us informed of the performance of the battery.

[T1 Terry]

Originally Posted by durundal

So I decided to bite the bullet on the 12V pre-packaged 90Ah from Balqon (unfortunately the price went up a few bucks between when I found them and now, d'oh... they updated the website with more info in the mean time and less Engrish text), better to make sure it fits now than have to modify and repaint my battery holder later. Will report back on how it looks and if the outer case is sealed or just snaps together.

Still a bit loathe for the weight over the 60Ah, but I'm already more cruising oriented than racing with the sink and stove... and it's still 10lbs lighter than a 55Ah Optima blue top that was the alternative...

the top just pops off with a paint scaper or similar under the edge of the lid. there are 4 cells inside strapped with aluminium end plate. i recommend you buy a Junsi cell logger from a hobby store like hobbyKing and a 5 pin plug of Vocanlo the chinese e bay seller, about $2.50 free freight. Drill a hole in the lid to pass the wires though and seal it up with some silicon sealant. don't believe the nonsense about them being closely matched cells, they still have to be condition charged and balanced before the first use. The nonsense about them being consecutive numbered cells so they will all be perfectly match is just that, nonsense, they are consecutive numbered, but that's as far as it goes, nothing mass produced will every be perfectly match just because they were made in the same batch.

T1 Terry

[Maine Sail]

Finally had a chance to get some more work done on my bank and BMS today. She's now ready for install into the boat. Working on the battery shelf and custom hold downs next... She will sit atop 3/4" Seaboard shelf and be located in a very dry compartment on our boat. Because of the weight savings I can move it and not disrupt how she sits in the water...


The two relays in the BMS box are for the solar HVC and alternator regulator HVC. The Tyco EV-200 for LVC will be mounted outside the BMS box..

[Cotemar]

Maine Sail,

Very nice job. I will be in the market for that same exact system in the near future.

[witzgall]

Hi Dimitri,

I checked voltage for three of the four pairs by using an external digital voltmeter touching the tops of the terminal posts of the cells themselves. This would be similar, but not exactly at the celllog attachment bolts for some, but not all of the cells. When I posted, the celllog displayed "Err Volt" if I turned of the BMS.

This was all when I had drew down the packs to about 60%. I then let solar/wind bring things back up to full. When pack voltage at the Link10, which I think reads .05v low, read 13.90, 13.85, plugged the celllog back in. Then, it showed each cell group at either 3.5 or 3.48, with a total delta of 20 or less mv. So it is not showing a delta between the cells that is off of actual cell voltage.

What to think???

Chris

Originally Posted by electric1

Shunting is only above 3.5V, so there wasn't any. Did you confirm voltage reading with trusted voltmeter at the same tap points where Celllog is connected? Maybe Celllog is misreading the voltages.

[durundal]

Originally Posted by T1 Terry

don't believe the nonsense about them being closely matched cells, they still have to be condition charged and balanced before the first use. The nonsense about them being consecutive numbered cells so they will all be perfectly match is just that, nonsense, they are consecutive numbered, but that's as far as it goes, nothing mass produced will every be perfectly match just because they were made in the same batch.

Is there any evidence so far that the cells in these units are sequentially numbered, or that they haven't been condition charged and balanced in the factory? I may still investigate further but so far I don't recall reading anything on either of those statements.

[hellosailor]

Actually, Terry, there is good reason to want consecutive numbers.

Consider any manufacturing process:
The equipment has been calibrated--but with each pass, each operation, wears and drifts. Four passes, very little drift. 400 passes? 100x more drift.

The chemicals used come from different batches. Each batch will be within tolerances, but no two batches will be exactly the same. Again, sequential units are more likely to be the same batches, the same chemistry.

Any plates? separators? anode and cathode materials? If they come from different batches, they also differ more from batch to batch. If they were machined, rolled, or calendared? The equipment drifts and wears.

And don't forget, few manufacturing plants are temperature and humidity controlled. Was it 95F on Monday afternoon and 74F on Tuesday morning? Then every dimension of every tool and hopper has changed overnight. As will the product.

Yes, in a perfect ISO-9000 world all of this is measured and controlled within published variations for the product. In reality? ISO-9000 certifications in China?

If the cells in one battery are NOT form the same batch, one also has to ask, why not. Why were some pulled aside amd others not? Forgotten, or pulled from batteries with a bad cell? Pulled and spot tested for QC? Who knows? Good manufacturing techniques will have consecutive cells in each battery. Good manufacturers will have tight uniform tolerances. Others...maybe not.

Do I match the D-cells in my MagLite? No, I don't. But I don't measure their balance to the thousandth of a volt, either.

[T1 Terry]

We thought the same thing, 3 boxes, 30 cells per box, all sequentially numbered. The first 3 packs we built with 16 cells per pack, all in number order, charged in series/parallel, not even close to matched, they all had to be condition balanced.
A member of our local group bought one as a second car battery, when he had a few issues with it he popped the top, at the end of the charge cell voltages ranged from 3.3v to 3.85v. They are 4 cells packed in a plastic case with extensions each end to make the terminals in the standard battery configuration position, here's a photo, no magic, no special factory balancing, just a 4 cell battery.

T1 Terry

[hellosailor]

" not even close to matched,... at the end of the charge cell voltages ranged from 3.3v to 3.85v. "

A half volt difference?? Interesting.