Lithium Battery Reports & Tests' 9/08

[BMI]

Impressive voltage curves for the X-1P!
But with an 63C to 83C surface temp, what's the cycle life expectancy at those 10C-20C discharges? I'd be worried about running it above 5C for longer than a few seconds.

I have a pretty high-current application in mind and have been patiently waiting for a replacement for the A123 M1's we've been forced to use. Always on the lookout for other cells.

I honestly can't say what the life expectancy would be at discharge rates exceeding 20C since these results were performed by an independant laboratory and had nothing to do with our factory. They just wanted to see if the X1P cells were capable of providing high continous discharge rates and in fact they will provide well in excess of 20C for short periods.

I was asked to supply a custom battery for starting a big Aprillia twin cylinder ICE motorbike since the owner was killing his Odyssey lead acid batteries very quickly due to the very high discharge while starting the 1000cc engine.
I made up a pack from 4 of the small X1P cells and to satisfy myself it would be powerful enough to start the bike (I didn't want to be embarased if the pack was not powerful enough since it was shipped half way around the world to Italy) so I connected it to my car. Needless to say my car engine cranked over and the engine started even faster than the normal lead acid battery. Not bad from a battery not much bigger than a can of Coke......
So If this battery will start my much larger 2500cc engine in my car without any hesitation I am confident it will start a motorbike engine of less than half the engine capacity of my car.
View attachment Aprillia bike starting battery pic 1.JPG

 

[RoughRider]

i am wondering about the document of the X2E-cell...

@3C discharge the cells delivers 15,225Ah
@5C 15,333Ah
@10C 15,833Ah

This numbers make me realy wonder...because normaly a cell delivers LESS Ah with higher discharge and not more...

 

[BMI]

i am wondering about the document of the X2E-cell...

@3C discharge the cells delivers 15,225Ah
@5C 15,333Ah
@10C 15,833Ah

This numbers make me realy wonder...because normaly a cell delivers LESS Ah with higher discharge and not more...

RoughRider the X2E cell gains capacity with higher discharge rates. Not less as you would at first expect.

These are a premium quality cell.

 

[liveforphysics]

i am wondering about the document of the X2E-cell...

@3C discharge the cells delivers 15,225Ah
@5C 15,333Ah
@10C 15,833Ah

This numbers make me realy wonder...because normaly a cell delivers LESS Ah with higher discharge and not more...

This is simple, and it's the same reason why you see voltage increase as the state of charge decreases. As the cell temps rise from harder discharge, the cell performance increases in the form of both lowering Ri (which is why you see the voltage increase) and increaseing capacity. This is a normal effect for batteries.

 

[liveforphysics]

This is a 15:1 compression race engine. I tried just using 4 normal headways cells, and it's worked perfectly all season. $68 total battery cost including shipping. lol

 

[CamLight]

I honestly can't say what the life expectancy would be at discharge rates exceeding 20C since these results were performed by an independant laboratory and had nothing to do with our factory. They just wanted to see if the X1P cells were capable of providing high continous discharge rates and in fact they will provide well in excess of 20C for short periods.

Thanks BMI.
An estimate for 10C discharge cycle life would be very helpful if you have it.
Or, perhaps this could help me...what's the discharge rate for the X2E Cycle Life spec?

 

[patrickza]

This is a 15:1 compression race engine. I tried just using 4 normal headways cells, and it's worked perfectly all season. $68 total battery cost including shipping. lol

That looks like fun, I have four spares, I must remember that when I need to go help a stranded friend somewhere with a flat batt.

Yours look like they were permanently mounted, did you have issues with balancing etc..?

 

[AndyH]

Hi Guys,
Sorry for the delay while I have been away.
Please see below the attached specification and discharge curves of the LiFeTech 40152 15Ah cell as well as discharge curves for the 38123 and soon to be introduced 40152 high power cells.

Of course the doubters will say these are just re-labelled Headway cells. To which I say, perform the same discharge tests up to 20C continous with the same capacity Headway cell, compare the curves between the two cells, and lets see how similar they are.
As you can see the X1P cells can easily provide 20C continuos discharge since these are a much higher quality cell which are manufactured using high grade LiFePO4 Phostech powder.
A great deal more quality control and testing of these cells is undertaken in the factory before they are classed as A-grade and are allowed to be used in the assembly of the XPS battery packs.
View attachment 1

Nice looking cells, Armin. Don't sweat the doubters - the numbers will show the way. Especially now that there ARE numbers. :wink:

30ºC is plenty toasty. How do they handle cold?

Andy

 

[BMI]

Hi Guys,
Sorry for the delay while I have been away.
Please see below the attached specification and discharge curves of the LiFeTech 40152 15Ah cell as well as discharge curves for the 38123 and soon to be introduced 40152 high power cells.

Of course the doubters will say these are just re-labelled Headway cells. To which I say, perform the same discharge tests up to 20C continous with the same capacity Headway cell, compare the curves between the two cells, and lets see how similar they are.
As you can see the X1P cells can easily provide 20C continuos discharge since these are a much higher quality cell which are manufactured using high grade LiFePO4 Phostech powder.
A great deal more quality control and testing of these cells is undertaken in the factory before they are classed as A-grade and are allowed to be used in the assembly of the XPS battery packs.
View attachment 1

Nice looking cells, Armin. Don't sweat the doubters - the numbers will show the way. Especially now that there ARE numbers. :wink:

30ºC is plenty toasty. How do they handle cold?

Andy

Andy as with all batteries LiFePO4 is no exception and loses capacity in a low temperature environment however the effective capacity loss is nowhere near as great as with lead acid. I could ask the factory if they have any results of testing in a low temperature environment.

I am not concerned about the doubters. We have several projects going on around the world including an electric Porche conversion which will be powered by LiFeTech X2E cells. When completed this should be a very nice looking show car.

We just won a contract to build 6 electric patrol boats which will use a total of 1152 cells (at last count). The board of directors who approved the building of these boats have decided to go electric since their calculations show they will save $35,000 per year per boat is diesel fuel and engine maintenance savings.

Also I am about to ship the first shipment of complete XPS packs to an EV conversion company in Oklahoma so I am sure the first quarter of 2010 will prove how good these cells and batteries are through their real world application in various electric cars and boats which are now in the design/construction stages.

Phostech has some new LiFePO4 powder blends/formulations which have been offered to us for use in our cells so we will see how they go but all indications show they are living up to their name of absolute top quality and superb performance (as we have come to expect from a Phostech product).

 

[Roy Von Rogers]

I'm curious after reading that that boat uses 1152 cells, knowing that one needs to check battery connections on all battery types every so often, how do you go about checking 2304 connections. Hard enough to do on large prismatics, I cant imagine what its like to check 2304 conections, never mind just making the original connections.

Sure seems on an application like this, larger prismatics would be in order.

Roy

 

[docnjoj]

I think that is the total for all 6 boats. Still seems like a lot of connections but maybe they figured out how to waterproof them.
otherDoc

 

[BMI]

I'm curious after reading that that boat uses 1152 cells, knowing that one needs to check battery connections on all battery types every so often, how do you go about checking 2304 connections. Hard enough to do on large prismatics, I cant imagine what its like to check 2304 conections, never mind just making the original connections.

Sure seems on an application like this, larger prismatics would be in order.

Roy

1152 is the total cell count (at this stage) for all six boats,ie.48 cells per pack and 4 packs per boat. There are 4x48V 15Ah packs per boat. Of course the cells are all fitted into proper cell holders with copper link bars.
Yes there are wire connections at the cell junctions since cell voltages will be monitored remotely by PC. There is definitely no need to check hundereds of cells at their terminals with a multimeter. Cells voltages are all checked by keystrokes on a keyboard!
You can see how these cells are assembled here-
View attachment Cell assembly.jpg
When you say "large prismatics" I assume you mean Thundersky or similar. If this was the case the project would of never been approved since the boat owner's requirements are 5 years warranty on the battery packs which I can provide without any problem. Thundersky don't provide any warranty whatsoever so they wouldn't of even been considered for this project. The boat owners' main concern is on quality and reliability.

 

[AndyH]

I'm curious after reading that that boat uses 1152 cells, knowing that one needs to check battery connections on all battery types every so often, how do you go about checking 2304 connections. Hard enough to do on large prismatics, I cant imagine what its like to check 2304 conections, never mind just making the original connections.

Sure seems on an application like this, larger prismatics would be in order.

Roy

Looks like he was too busy selling to hear the real question.

This would be a tough call from a salesperson's perspective. On one hand, it doesn't take much to outperform Thunder Sky. And if a salesperson believed in the products, they wouldn't have trouble backing their Thunder Sky cells even if the factory didn't - especially to win the favor of a commercial customer. It would be very difficult to recommend all those connections in a boat. A five year warranty will get expensive when boats start burning from a loose connection.

The Headway cells I tested had rust out of the box. I wonder what they'd look like after 6 months in a marine environment?

 

[BMI]

I'm curious after reading that that boat uses 1152 cells, knowing that one needs to check battery connections on all battery types every so often, how do you go about checking 2304 connections. Hard enough to do on large prismatics, I cant imagine what its like to check 2304 conections, never mind just making the original connections.

Sure seems on an application like this, larger prismatics would be in order.

Roy

Looks like he was too busy selling to hear the real question.

This would be a tough call from a salesperson's perspective. On one hand, it doesn't take much to outperform Thunder Sky. And if a salesperson believed in the products, they wouldn't have trouble backing their Thunder Sky cells even if the factory didn't - especially to win the favor of a commercial customer. It would be very difficult to recommend all those connections in a boat. A five year warranty will get expensive when boats start burning from a loose connection.

The Headway cells I tested had rust out of the box. I wonder what they'd look like after 6 months in a marine environment?

The fact is this project would not of gone ahead if the batteries were not available with minimum 5 years factory warranty.
What other manufacturer of LiFePO4 batteries are you aware of who is willing to provide 5 years warranty?

The packs will be housed in sealed custom made carbon fibre boxes to prevent salt water corrosion.
I would be happy to take photos to show you what they look like after 6 months in a marine environment.

 

[AndyH]

The fact is this project would not of gone ahead if the batteries were not available with minimum 5 years factory warranty.
What other manufacturer of LiFePO4 batteries are you aware of who is willing to provide 5 years warranty?

The packs will be housed in sealed custom made carbon fibre boxes to prevent salt water corrosion.
I would be happy to take photos to show you what they look like after 6 months in a marine environment.

It's my understanding that warranty can be any length one chooses and is more about the insurance policy than the product. People also think that bank deposit insurance is there to protect the consumer when it's really designed as a marketing tool used to increase cash flow for the bank.

Sorry Armin - I don't want to get off track. The question wasn't about the cell or the warranty or your ability to craft a battery. It was a question about how one ensures that all the connections stay tight over the life of the pack.

Just off the top of my head, I suppose one could safety-wire bolt heads, use a thread lock, or possibly use RTV on bolt heads. I'm from an aerospace background rather than marine, so my 'mind's eye' view of a sealed battery box has machined flanges, o-rings, over-pressure vents, and sealed pass-thru terminals. Not much overkill, there, probably...

We're looking out for you, Armin. We don't want to read about a boat fire caused by loose connections.

 

[BMI]

The fact is this project would not of gone ahead if the batteries were not available with minimum 5 years factory warranty.
What other manufacturer of LiFePO4 batteries are you aware of who is willing to provide 5 years warranty?

The packs will be housed in sealed custom made carbon fibre boxes to prevent salt water corrosion.
I would be happy to take photos to show you what they look like after 6 months in a marine environment.

It's my understanding that warranty can be any length one chooses and is more about the insurance policy than the product. People also think that bank deposit insurance is there to protect the consumer when it's really designed as a marketing tool used to increase cash flow for the bank.

Sorry Armin - I don't want to get off track. The question wasn't about the cell or the warranty or your ability to craft a battery. It was a question about how one ensures that all the connections stay tight over the life of the pack.

Just off the top of my head, I suppose one could safety-wire bolt heads, use a thread lock, or possibly use RTV on bolt heads. I'm from an aerospace background rather than marine, so my 'mind's eye' view of a sealed battery box has machined flanges, o-rings, over-pressure vents, and sealed pass-thru terminals. Not much overkill, there, probably...

We're looking out for you, Armin. We don't want to read about a boat fire caused by loose connections.

Andy, I am well aware of the Prius fire report which you attached. I have seen similar pack fires with A123 and other spot welded cells several times. In my professional opinion this is a major downfall of spot welded packs which use hundreds or even thousands of small cells like A123 cells.
I spoke with a local importer of electric wheel chair batteries made by PHET and there was a high failure rate of the cell joins breaking after only months of use due to metal fatigue in their LiFePO4 packs.
Since you are from an aerospace background you will be well aware of metal fatigue (I myself am from an aviation background and am a licenced pilot).
It is the repeated minor bumps, and jolting which a battery pack is subjected to thousands (or hundreds of thousands of times) which eventually results to cell weld link failures and possible fires. This minor movement within the pack as it is subjected to vibration by riding/driving on rough roads, pot holes etc. all causes slow but certain metal fatigue at the spot welded joints which may not show up for several years but there is a definite liklihood of cells failing at the spot welded joints at some time.
This is not a problem in a battery used in an electric drill for instance but for an electric vehicle application subjected to constant vibration it is a definite consideration.

I believe the threaded cell terminal design is much more reliable. Although it is possible for a cell link to come loose I have never seen this happen to date under normal use. The lock washer and precision torquing of the bolt seems to be adequate in actual practice. Of course this will be monitored as time goes on and as you mention for critical applications bolts could be lock wired as they are in aircraft.

Regarding warranty.....
Warranty has everything to do with reliability of the product and shows confidence the manufacturer believes their product will perform as they claim. If it didn't they would soon go out of business.
The warranty for my electric boat project is not something which I have just made up to satisfy the customer but is a fully factory backed warranty.
Warranty is all about the product (reliability) and nothing to do with insurance. If a product fails repeatedly due to lack of quality it won't be long before an insurance company won't insure you and you will go out of business.

I am sure that when LiFeTech confirmed the 5 year warranty for my boat customer they are confident there will be no problems. After all this is backed up by extensive testing of our cells and completed battery packs in the factory so I would think the factory engineers would have a pretty good idea of the reliability of our batteries when subjected to different forces.
LiFeTech has spent milliions of dollars on sophisticated cell and battery pack testing equipment so we can thoroughly test all our products and know they will perform as claimed.
Below are just a few photos showing various aspects of cell and battery pack testing at the LiFeTech factory. Individual cells are all tested and you can see from the pics that the completed packs are also tested. These pics show vibration testing of a complete pack so as to simulate different conditions in real life (such as driving on rough roads for example).

Yes, these photos are all taken at our LiFeTech factory and not at PSI or some other factory as others might claim.
View attachment 5

 

[AndyH]

Nobody is talking about spot welded joints, Armin. That Prius fire was caused by bolted joints that became loose in service due to incorrectly placed spacers, not by metal fatique or cell failure. I know - you're not using spacers. But the original query was about the bolted connections.

You confirmed my comment - regardless of how it's used in a sales situation, warranty begins with an insurance policy. How it's spun by the marketing department is a different animal. I've not heard of many Thunder Sky LiFePO4 cells failing in service. One might think that they're not too close to alienating their insurance carrier either.

Not bashing, Armin - just not drinking the cool-aid. I look forward to reading more about the boats and how they're used.

I don't expect anyone will say the new photos are from PSI. The reason they said the old pictures were from PSI is, well, because they WERE from PSI. :wink:

Cool that you're a pilot too. I understand 100LL is pretty dear down there. Makes our hobby a bit harder to finance. Oh well - I can still play with the spool of safety wire.

Cheers

 

[BMI]

Andy, you should be able to answer your own question since you are a seller of PSI cells with threaded terminals. How many cells have you found where the cell terminal nuts had become loose through normal use when the nuts were tightened properly and lock washers were used?

Yes, 100LL is not the cheapest stuff around.

 

[liveforphysics]

100LL is the cheapest semi-performance fuel around! $3-4/gal, and a decent base for race fuel blending. (yes, i know it's intended for small piston engine aircraft).

If you want a spendy fuel, try buying VP-Import sometime. My last 20gal drum came out to be $26/gal, and it was wholesale! Almost impossible to knock on the stuff though, which makes it way cheaper than engine rebuilds.

 

[AndyH]

Andy, you should be able to answer your own question since you are a seller of PSI cells with threaded terminals. How many cells have you found where the cell terminal nuts had become loose through normal use when the nuts were tightened properly and lock washers were used?

Yes, 100LL is not the cheapest stuff around.

The question wasn't about any one battery - it was about threaded connections in general. The Headway, BMI/LiFeBatt, PSI, Thunder Sky, Sky Energy, and HiPower cells all use standard 6mm threads (larger prismatics use 8mm and larger, but still standard threads). I haven't lived long enough to see everything go wrong that can, but have seen more than enough properly torqued connections loosen in service.

I'll throw some thoughts out, for what they're worth, with warranty limited only to the purchase price. :wink: Carbon fibre conducts electricity. I'd personally treat it as a metal box when choosing bushings, lugs, and wiring protection. Make sure your composite tech adds glass to the carbon where any hardware will attach to the box, and either use insulated bushings or protective coatings to minimize galvanic corrosion.

Aviation wiring best practices (per USDOT/FAA AC43.13.1A Acceptable Methods, Techniques, and Practices) requires use of both lock washers and lock nuts in many wiring applications, and at least lock nuts in all others - including cable clamping loops. At minimum, a lock washer and plain nut is not acceptable, while a plain washer and lock nut is. For what it's worth.

Folks using cells with bolts/studs have it relatively easy - they can use lock washers and lock nuts if they desire long-term connection security. I would guess that bolt security would be limited to lock washers and drilling for safety wire. Maybe one could use a locking compound on internal threads, but I wouldn't want the contact service contaminated withor partially insulated by essentially 'crazy glue' - especially for high-current connections. And I wouldn't want to compromise the locking action of lok-tite with anti-corrosion products one may use on the terminal services.

Please don't take these scattered thoughts as complete or definitive, but I hope they're useful.

How much current will the boats pull from the pack?

 

[Lock]

Hey Andy... I imagine adding a touch of solder after each lock washer and nut are properly tightened down... to further "glue" the nut to the threaded post using a conductive material (solder.) As usual, done quickly so that the heat does not "wick" into the cell...
Lock

 

[Ypedal]

Kind of a coincidence but while assembling my chopper pack with PSI cells, i used the rubber boots that came with my order from taiwan to cover the stud/nut, they stick out past the lego blocks like 1mm, just enough so that once the sheet of lexan gets secured to the blocks it pushes on the boots over the studs keeping the nuts in place and preventing vibration looseneing.. also adds a layer of safety as it covers the studs nicely.

 

[BMI]

Kind of a coincidence but while assembling my chopper pack with PSI cells, i used the rubber boots that came with my order from taiwan to cover the stud/nut, they stick out past the lego blocks like 1mm, just enough so that once the sheet of lexan gets secured to the blocks it pushes on the boots over the studs keeping the nuts in place and preventing vibration looseneing.. also adds a layer of safety as it covers the studs nicely.

Sounds like the perfect solution!

 

[The Mighty Volt]

Has anyone here ever stripped down a Cammy_CC battery? If so, what did they find?

 

[kilowatt]

I took apart a 36 volt 20 amp cammy to divide it in two for panniers. I found two 18 volt 20 amp batteries series connected into a 2S19P configuration. If your thinking about getting two 36 volt 10 amp out of it, then forget it. The number of individual cells is staggering but dividing it in two is fairly easy as long as your careful not to lift a spot weld while removing the duct tape; I did. Another thing to watch is your BMS sense wires. On my BMS I have two connectors; looking at the two connectors head on the pinout is from left to right. The large connector is on top and starts with pin 1 (channel 1) on the left through channel 8 on the right. The 4 pin connector on bottom is left to right channel 9-12. I got this info from cammy.

I ran into problems trying to find a low voltage cell (within a large bank) so I decided to remove 60 cells to bring it down to 15 amps (I think). I'm still working on it but have decided to move to 48 Volts with 4 ea 12V 12Amp SLAs. I don't think I will invest in another battery from China, especially the cylindrical type; we need a US supplier! I hope this helps you out.

Dave