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

[catakate]

@senormechanico: you really meant that? I think nobody would expect a battery to be anything else, but a battery. Technology is another thing! As is proper usage and care. I bet there were plenty chemists that knew resins are water soluble and there is no 100% non permeable membrane (gel coat). Yet the market prevailed and still does

[deckofficer]

Originally Posted by FlyingCloud1937

Now this next pic shows another fellow form member balancing his new Bolqon/Winston cells. Using just about any means to connect them. Including SS, copper, and alum... all measured by some LED array that is suppose to indicate cell voltage based on the color of the LED??

Trying to measure mill-ohm voltage differences.




Lloyd

Lloyd,

The LED was just a means of a load to discharge the pack. I used a VOM to check cell voltages during charge and discharge cycles.

The jumper cables were used because I didn't want to un-band the cells and turn them around for a parallel buss bar connection.

[FlyingCloud1937]

Originally Posted by deckofficer

Lloyd,

The LED was just a means of a load to discharge the pack. I used a VOM to check cell voltages during charge and discharge cycles.

The jumper cables were used because I didn't want to un-band the cells and turn them around for a parallel buss bar connection.

Deck,

I wasn't single you out.

For that mater I appreciate what all are trying to do.

One of my degrees is in commercial photography, I'm dating myself now, but it required 2 years in photo chemistry..ala darkroom.

The first day of class my professor said there are no darkroom mistakes,
only happy accidents...as long as you document what you do, and can repeat the same...it becomes knowledge.

So my point is that we have wildly diverging interest, all trying to develop Li-Ion for Boats/Marine use...all using different starting points, with different test protocols and procedures.

When we all start for the same line and test in strict rule we will have repeatable answers, that will lead to technological advances.

today not so much.

tomorrow maybe.

Lloyd

[deckofficer]

I didn't mean you singled me out, I just wanted you to know I wasn't trying to see minute voltage changes by a full color spectrum LED light. If my Trace 2012 inverter was handy to get at, I'd discharge the same way as Maine Sail by putting a 1500 watt space heater on the inverter as a load.

[catakate]

Originally Posted by FlyingCloud1937

Now that is the meat of the bone I've been looking for.

Lloyd,
If you are trying to make a point, I honestly do not get it.
They don't make the batteries as good as they could?
Good old mechanics used to put some grease on battery terminals, for something to oxidize it needs oxygen, no oxidation, no imperfect contact, no problem. The increased current flow means a greater internal consumption, hence less usable power outside the system, but can you really measure that? I mean would really make a difference in a real life scenario?

[FlyingCloud1937]

Originally Posted by senormechanico

Maybe we're seeing a repeat of the dawn of fiberglass boats being heavily built because nobody knew how long they would last.
Wouldn't that be great?

This equals a thread drift!!!

How many 76 year old Tupperware boats do you know that do in excess of 1000 nautical miles a year?

answer=none they didn't build plastic boats then.

This Old Woodie does, and will do for the next 100 years.

[FlyingCloud1937]

Originally Posted by catakate

Lloyd,
If you are trying to make a point, I honestly do not get it.
They don't make the batteries as good as they could?
Good old mechanics used to put some grease on battery terminals, for something to oxidize it needs oxygen, no oxidation, no imperfect contact, no problem. The increased current flow means a greater internal consumption, hence less usable power outside the system, but can you really measure that? I mean would really make a difference in a real life scenario?

Yes/maybe

since we are dealing with a technology, that depends on cell balance.

u tell me.

Lloyd

[mcarling]

Originally Posted by rocksnsand

PO is for phosphate and I believe in the above case ferric phosphate (en.wikipedia.org/wiki/Lithium_iron_phosphate_battery)

That's correct. Welcome to the forum!

[catakate]

Originally Posted by FlyingCloud1937

since we are dealing with a technology, that depends on cell balance.
Lloyd

If one is idiotic enough to measure cell's voltage over a 30' cable, that's his problem. From reading this thread I understand all those testing these products are aware of that, so what is your point?

[FlyingCloud1937]

Originally Posted by catakate

If one is idiotic enough to measure cell's voltage over a 30' cable, that's his problem. From reading this thread I understand all those testing these products are aware of that, so what is your point?

You decided..

Seems Terry is the only one tuning into what are real issue.

but answer me this?

15 years from today's date will you know what is wire aboard your marina neighbors boat?

Lloyd

[catakate]

Lloyd,
T1 Terry said what COULD BE a problem if not properly addressed.
I live in a block of flats, same can be in the apartments all around mine. Chance is also a hotchpotch falling from a window. Me drifting no more.

[T1 Terry]

Heavens, is it something in the water over there or what? I didn't mean to start WW3, save the fighting words for the luddites who don't believe in the new technology
The very early Thundersky cells had the problem of internal dissimilar metals causing major issues, all the cels for the different reseller were made the same way, just different colour cases and some didn’t have a release valve in the top.
When Winston Chung came on the scene the problems were sorted, quality improved out of sight and this technology came of age. Since then yttrium has been added to the mix and the reliability and life cycle of these cells has improved, the earlier LFP cells are not as good as the newer LYP cells, for house power batteries, there might not be that much in it though, the better cells are still the Winston and Sinopoly brands, they were all Thundersky before the bust up.

The issue with oxidisation on the terminals is an increase in resistance at the joint. Resistance with an electrical current passing through it creates heat, there really is nowhere for the heat to go, so it keep building up, till the plastic case melts. I had a quick look but I can't find the photo of a scooter with one terminal sagged into the case, the result of a bad connection.
The other problem is any charging current wasted as heat isn’t available for cell recharging, this creates an imbalance between the capacity of the cells resulting in some cells reaching full before the others and some cells running out of capacity before the others.
Use proper corrosion compounds on the connections and there are no problems, if you are using a cell logger and a cell shows strange things are happening like a cell voltage is high while charging but low when the charging stops, a quick check with an infra red thermometer will tell you if you have a connection problem, that terminal will be hot.
The heat build up issue is one of the reasons I don't like active BMS units, that balancing is done by burning off some of the capacity in that cell and that is done via a resistor, but there is no heat sink to disperse the heat build up, finally the circuit fails from over heat and then the troubles begin. Far better off to use a cell logger and an alarm to warn if a cell has gone outside the safe operating parameters, the computer between the ears will come up with a fix fairly quickly, turn something off.

The Peukert’s factor for these cells would be that close to 1 I doubt it could be measured at the rate we move current in and out, the losses are accounted for by the difference between charging voltages and discharging voltages, a min of 0.1v difference, multiply that by the number of amps and that is how many watts are lost between charging and discharging.
We use Ah meters, not Wh meters, so the losses don't really show up, Ah isn't a proper unit as far as energy measurement goes but we all know what it is so it works for us, it wouldn't work in a lab though.

T1 Terry

[goboatingnow]

The issue of brass to aluminium, to copper to stainless is common all through the electrical systems of typical boats. With Care and some compounds it causes no problems, even with poor care it causes " little" real problems.

" marinized Lifepo battery, ?" , few companies really make marinized anything ! ( including LA batteries )

Dave

[Lagoon4us]

LMAO Most boats have lead acid forklift batteries in them.....

[goboatingnow]

Originally Posted by Lagoon4us

LMAO Most boats have lead acid forklift batteries in them.....

I wish they did Lagoon , most boats have simple automotive batteries with a Leisure Marine sticker on them , Fork truck traction batteries are very expensive. The percentage using high quality like Rolls, Trojan or Odessy are very few