Ideal Drop-in Lifepo4 Battery Purchase Strategy

[pcmm]

Originally Posted by Baronkrak

Fully dead?
So they are making a false claim?

Fully depleted maybe the better word. You have to not be soo literal and read a bit. Their claim is not false in any way. The Max capacity can be reached by depleting the battery fully. No lie there. but they also say that to get the best life out of the battery DO NOT go below 80% DoD (which is very generous for a FLA)

Similar to how car manufacturers get their max mileage ratings by driving from Full to empty in an empty vehicle on a test track. No one ever does that in real-world settings because its just not good for many of the components to run dry. Sure you can do it but it shortens the life of those components. Same for FLA batteries. You can run them full to completely empty but no one will ever tell you that is best practice or even good for the batteries. you will shorten the life of the FLA's by doing this regularly its well proven and not in dispute by any reputable source.

anyway back to examples of the "Dunning-Kruger effect"

[Baronkrak]

Originally Posted by pcmm

Fully depleted maybe the better word.

It remain that I get 100Ah of a 100Ah battery and some time more.

[s/v Jedi]

Originally Posted by Baronkrak

It remain that I get 100Ah of a 100Ah battery and some time more.

We know, it’s okay, bless your heart

[Baronkrak]

Originally Posted by Pete7

A 100Ah lead acid battery holds about 1.2kWh of energy, so does a 100Ah LifePO4 battery.

Lead acid battery: 12V nominal.
LifePO4 battery: 12.8V nominal.

[SV_FlyingTigress]

Originally Posted by pcmm

Fully depleted maybe the better word.
anyway back to examples of the "Dunning-Kruger effect"

I prefer mostly dead.

[Baronkrak]

Originally Posted by Stephen_MO

I prefer mostly dead.

Originally Posted by Stephen_MO

I come from an aircraft maintenance / IT world, so some aspects of marine electrical are new to me and I am on the learning curve. .

An expert opinion

[Sailing Hanse37]

Originally Posted by Pete7

Your claim that two identical sized batteries don't contain the same amount energy is wrong.

I would suggest that the majority of people using lead acid batteries around the globe are quite happy with their batteries. There are a few other advantages to LFP rather than capacity. If you research the forum you will see what they are using them for.

Pete

I think it is better to speak about “useable energy” rather than stored energy. The useable energy of a LA battery is only half of the stored energy. If you discharge more, you damage the battery and shorten it’s lifespan. So you will be “happy” with your battery for a short period of time

[Sailing Hanse37]

Originally Posted by Baronkrak

More than 5 years.



The warranty is 24 months from date of purchase.

Except of course if you discharge too far…

[noelex 77]

I think this concept of “damaging” a lead acid battery with a 50% discharge is fundamentally wrong.

Every discharge will “damage” a lead acid battery in the sense it will shorten its life, but it does not damage the battery in the sense it will no longer work, or that it will not work normally .

If it was never discharged there would be no point in having the battery in the first place.

The more we discharge a lead acid battery the more its life is shortened.

There is nothing magical about 50%, it is just a convenient rule of thumb where exceeding this number starts to shorten the life more quickly. 50% should not been seen as a hard wall below which “damage” will occur. Many (most?) boat owners will have exceeded a 50% discharge at times, and there is nothing wrong with that providing they understand the relationship between DOD and cycle life.

It is possible to actually damage a lead acid (or even a lithium battery) but this takes a much higher discharge level. For example, discharge the battery to completely flat and leave it there for a reasonable length of time.

[Sailing Hanse37]

Originally Posted by noelex 77

I think this concept of “damaging” a lead acid battery with a 50% discharge is fundamentally wrong.

Every discharge will “damage” a lead acid battery in the sense it will shorten its life, but it does not damage the battery in the sense it will no longer work, or that it will not work normally .

If it was never discharged there would be no point in having the battery in the first place.

The more we discharge a lead acid battery the more its life is shortened.

There is nothing magical about 50%, it is just a convenient rule of thumb where exceeding this number starts to shorten the life more quickly. 50% should not been seen as a hard wall below which “damage” will occur. Many (most?) boat owners will have exceeded a 50% discharge at times, and there is nothing wrong with that providing they understand the relationship between DOD and cycle life.

It is possible to actually damage a lead acid (or even a lithium battery) but this takes a much higher discharge level. For example, discharge the battery to completely flat and leave it there for a reasonable length of time.

Although this is fully correct, the important message is that LiFePO4 batteries will outlast LA 5 to 10 times even when discharged way below what is good for the health LA batteries

[SOLAR SUPPORT]

50% Dod of LA batteries is known as a critical discharge level. The reason for this is the accumulation of sulfur crystals on the thin lead plate surfaces in the battery when the LA battery is forced to discharge more than 50%.

After each advanced discharge, the accumulation of sulfur crystals increases. As a result, this thicker layer reduces battery performance. For LA battery chemistry, the "Absorption Charge" repeated after each full charge is to return the sulfur crystals accumulated on the lead plates back to the electrolyte. You can't say it is not true even if battery manufacturers emphasize the importance of the high %Dod. This charging procedure is not applicable for LFP batteries.

[Pete7]

Originally Posted by SOLAR SUPPORT

50% Dod of LA batteries is known as a critical discharge level.

As several of us have already stated there is no cliff to fall off if you discharge a LA battery below 50%. It is a shallow curve in the reduction of battery life. Have a look at good quality LA, the better makes can routinely go even further. We have discussed this in depth previously, do a search to see our findings.

Originally Posted by SOLAR SUPPORT

This charging procedure is not applicable for LFP batteries.

Your preaching to the converted, we are well aware of this

[MVDarlin]

Important to check BMS. I learned after purchase my 200 ah LiFePO4 BMS will only supply 100 ah sustained output. This is insufficient for my 2000 watt inverter.

[sailorboy1]

Originally Posted by Sailing Hanse37

Although this is fully correct, the important message is that LiFePO4 batteries will outlast LA 5 to 10 times even when discharged way below what is good for the health LA batteries

No one really knows this! I have changed to LFP, but doubt I will have the boat in 15 years to know. All we can currently really say I feel is that LFP doesn't suffer from partial state of charge operation, and even this is based on assumptions.

3 years ago I drank the marketing claims of FireFly and that turned out to be poison. Boaters have been drinking the Kool-Aid claims from the AGM and Gel battery people for years. You would think we would be more cautious when presented with new Kool-Aid

[s/v Jedi]

Originally Posted by sailorboy1

No one really knows this! I have changed to LFP, but doubt I will have the boat in 15 years to know. All we can currently really say I feel is that LFP doesn't suffer from partial state of charge operation, and even this is based on assumptions.

3 years ago I drank the marketing claims of FireFly and that turned out to be poison. Boaters have been drinking the Kool-Aid claims from the AGM and Gel battery people for years. You would think we would be more cautious when presented with new Kool-Aid

We do know this because people like Rod Collins have tested and reported on this exact issue.