Over complicated expensive conversions

Skari · Feb 22, 2023

Just my thoughts.

Seams to me people are over complicating the conversion from lead to LiFePO4 Battery. I see no need for throwing money at it, the vast majority of RV have no problem with using the original equipment with some minor tweaks. Buying new charger and DC-DC charger to replace the original sett-up just to tweak som parameters will rarely give any meaningful result and the money is beter spent on a bigger battery or solar panel.
Battery compression is not really needed but a simple enough to execute or just make a box that is a tight fit, the fact that the LiFePO4 cells have a 6000 cycles with 1C discharge and ,5C charging rating means that in a RV the problem of the cycle life is simply none existing.
Only extra thing I have seen need for in my installation is a power shunt for keeping track of real battery status as the BMS is not good at monitoring low power consumption (ca. under 800mA)

Any thoughts?

time2roll · Feb 22, 2023

Even the external shunt-monitor is more than needed for me. BMS collaborated with a voltmeter is fine.
If I am running under an amp where the BMS loses accuracy I have 1000 hours of run time. Even a small battery would have days of power at that level.
Battery compression is a couple zip-ties around the wood box. No other upgrades on mine.

fratermus · Feb 22, 2023

Skari said:
Seams to me people are over complicating the conversion from lead to LiFePO4 Battery.

In my rig the change from FLA to LiFePO4 involved

reconfiguring a few charger setpoints (free), and
adding a pad to keep the new batt warm (~$30).

And I suppose however many hundreds of hours I'd spent reading in the years leading up to it. I am long on curiosity and short on funds but I don't expect everyone else to be. I'm glad there are people out there testing gear I will never be able to afford.

HRTKD · Feb 22, 2023

Many of the LiFePO4 cells from just a few years ago were not 5,000 cycles. They were more like 3,000 cycles. Then EVE said you get more cycles with compression, so we compressed.

Skari · Feb 23, 2023

HRTKD said:
Many of the LiFePO4 cells from just a few years ago were not 5,000 cycles. They were more like 3,000 cycles. Then EVE said you get more cycles with compression, so we compressed.

That is tru and compression is easy but still even at 3000 cycles its a full cycle a day for 8 years.

Allgood-Energy · Feb 23, 2023

OK, I Give up What do you mean by compression?
Are you simply binding up the cells to prevent the aluminum case from expanding when overcharging the cells?
seems to me this practice would be a fire waiting to happen.
The Aluminum Case that these are in will obviously expand and contract depending on cell temperature and charge voltage.
The chemicals can out-gas and produce internal pressure. The question is, are they making these more cheaply by making the can thinner and finding that it cannot withstand the internal pressure with this cheaper design? So they push the cost of a compression system off to the user and do not admit the design is flawed from the get-go. This is what I think is going on here. Cheap Chinese! Not a Brand battery I would Buy. The only time I have had a cell like this swell is when it was charged at too high a voltage. This is why a Good BMS is Needed.
Otherwise Good Luck in not having a fire. Structural integrity is important in the design of these batteries not a band-aid fix after you figure out you have $10,000,000 of them on the shelf. boiling the electrolyte is not a feature that will extend battery life. Compression is a band-aid fix for a design flaw. I wouldn't want to own one because of the fire risk.
Once you manufacture this battery and Test it over a life cycle of XXXX number of charge cycles, you would find out how many cycles of expansion and contraction the aluminum container would withstand before cracks in the corners of the formed can container got work hardened and fail because of cracks showing up. Once the crack leaks out the electrolyte. At this point, the battery is of no use and is a fire waiting to happen. A good design would not allow the electrolyte to create pressure within the battery and thus not create the constant pressuring cycle that causes the battery case to fail at its corners over time. We all know materials fail but a thin case design is not where I would go to save a buck. We have all folded a piece of paper and then torn it where it is now weaker. The other issue is the electrolyte used in the cell if they are watering down the electrolyte this could also cause it to boil instead of moving the electric charge across the plates which would also cheapen the battery, and reduce the life of the battery without it being apparent until the life cycle tests are complete. Thin aluminum cases and cheap electrolytes are not something that a good battery would be designed to achieve just cheaper, more money in the pocket. Again Cheap Chinese. I am sure not all of these lifpo4 battery makers are doing this just the ones who don't care about their reputation. This also could be dictated by The CCP and the manufacturer has nothing to say about it after all the US is their adversary. What better way to put in place timer based exploding time bombs all across America? if I sound a bit jaded, it's because I am, I have been taken in by cheap Chinese products more than once. You have to pay for the quality it's not free and neither is FREEDOM. Buy American!!! Oh, I forgot you can't, they don't make it here anymore. YEP, we have been Sold down the proverbial river by a bunch of greedy corporate expletives.

HRTKD · Feb 23, 2023

It's a bit long, and perhaps a bit meandering, but this is the thread where most of the compression discussion has happened. I'm not going to rehash compression here.

EVE-280 cells should these be clamped tight or spaced for expansion?

I working on my 4s 280ah battery plans. I thinking of my battery box. should these cells have a air space between them or be bonded tight together with a hose clamp or something similar.

diysolarforum.com

Skari · Feb 24, 2023

Allgood-Energy said:
OK, I Give up What do you mean by compression?
Are you simply binding up the cells to prevent the aluminum case from expanding when overcharging the cells?
seems to me this practice would be a fire waiting to happen.
The Aluminum Case that these are in will obviously expand and contract depending on cell temperature and charge voltage.
The chemicals can out-gas and produce internal pressure. The question is, are they making these more cheaply by making the can thinner and finding that it cannot withstand the internal pressure with this cheaper design? So they push the cost of a compression system off to the user and do not admit the design is flawed from the get-go. This is what I think is going on here. Cheap Chinese! Not a Brand battery I would Buy. The only time I have had a cell like this swell is when it was charged at too high a voltage. This is why a Good BMS is Needed.
Otherwise Good Luck in not having a fire. Structural integrity is important in the design of these batteries not a band-aid fix after you figure out you have $10,000,000 of them on the shelf. boiling the electrolyte is not a feature that will extend battery life. Compression is a band-aid fix for a design flaw. I wouldn't want to own one because of the fire risk.
Once you manufacture this battery and Test it over a life cycle of XXXX number of charge cycles, you would find out how many cycles of expansion and contraction the aluminum container would withstand before cracks in the corners of the formed can container got work hardened and fail because of cracks showing up. Once the crack leaks out the electrolyte. At this point, the battery is of no use and is a fire waiting to happen. A good design would not allow the electrolyte to create pressure within the battery and thus not create the constant pressuring cycle that causes the battery case to fail at its corners over time. We all know materials fail but a thin case design is not where I would go to save a buck. We have all folded a piece of paper and then torn it where it is now weaker. The other issue is the electrolyte used in the cell if they are watering down the electrolyte this could also cause it to boil instead of moving the electric charge across the plates which would also cheapen the battery, and reduce the life of the battery without it being apparent until the life cycle tests are complete. Thin aluminum cases and cheap electrolytes are not something that a good battery would be designed to achieve just cheaper, more money in the pocket. Again Cheap Chinese. I am sure not all of these lifpo4 battery makers are doing this just the ones who don't care about their reputation. This also could be dictated by The CCP and the manufacturer has nothing to say about it after all the US is their adversary. What better way to put in place timer based exploding time bombs all across America? if I sound a bit jaded, it's because I am, I have been taken in by cheap Chinese products more than once. You have to pay for the quality it's not free and neither is FREEDOM. Buy American!!! Oh, I forgot you can't, they don't make it here anymore. YEP, we have been Sold down the proverbial river by a bunch of greedy corporate expletives.

I did no compression on mine just made a snug box around it to contain the 4 cells (RV installation), and I agree that good quality cells should not expand and if I was making a big static shelved battery I would rather have space between them to allow them to expand and retract. If uniformed compression is to be achieved you will need some kind of foam material between cells as the don't hav perfectly flat sides.

Over complicated expensive conversions

Skari

New Member

Attachments

time2roll

Solar Wizard

fratermus

Solar Enthusiast

HRTKD

Boondocker

Skari

New Member

Allgood-Energy

Prepare Yee Prepare Yee for End of Days

Attachments

HRTKD

Boondocker

EVE-280 cells should these be clamped tight or spaced for expansion?

Skari

New Member

Similar threads