Cheap LIFEP04 batteries

[10G]

Thinking of throwing some cash out on one of those cheap lifePo4 lithium batteries.

Price ranges seem to be around $850 - $950 for a range of 12v 100Ah batteries, then they drop down to around $500, most likely chinese seconds I guess.

Why am I looking at these? Well I need a new battery for a medical appliance, only needs to be 12v 50Ah, looked at LifeP04 but they're still around $450.00, so me thinks, why not get one of these cheap 100Ah ones.

OR ARE THEY A COMPLETE WASTE OF MONEY??????

[Mickhead]

Was looking at some specs on these today. All seemed to have battery management systems onboard, so drop them in where the agm was.
I did see that the cheaper ones can not be set up in parallel, and the maximum current draw was around 50 amps compared to 200+ on the expensive ones, which can be parrallelled.
Lithiums can be cycled MUCH much more deeply than an agm, and can be recharged MANY more times.
Not a waste of money, but the price will keep dropping.

[the evil twin]

The only two that I have any experience with are Itech and these http://www.lowenergydevelopments.com...thiumBatteries

I haven't had any problems yet with Itech and the Low Energy ones are only recent so to early call.

Both have good reviews so far on the W.W.W.L.B. (World Wide Web of Lying Bastards)

If you want up to a 3,000 amp draw for winching and literally bullet proof option you want these http://www.lowenergydevelopments.com...name&order=ASC

[10G]

I've been looking on that website ET.

They offer 5 year warranty on just about all their lithium batteries which is the longest warranty I've seen yet.

[pollenface]

Never had experience with the cheap ones but I have 2x50ah 4s propower lithiums ($600 each) running a 24v 3000w inverter in my shed. They run all my power tools bar the welder & compressor. They are rated to 100amp discharge current. They go hard.

https://www.ebay.com.au/itm/Pro-Powe...xX6YVaIqIWtn5A

[10G]

Never had experience with the cheap ones but I have 2x50ah 4s propower lithiums ($600 each) running a 24v 3000w inverter in my shed. They run all my power tools bar the welder & compressor. They are rated to 100amp discharge current. They go hard.

https://www.ebay.com.au/itm/Pro-Powe...xX6YVaIqIWtn5A

Yow, how long have you been using them mate?

[pollenface]

Yow, how long have you been using them mate?

just ticked over 12 months, I have 500w of solar and a cheap 30amp PWM controller keeping them topped up.

Sounds like a fair system but a bit low on watt hours and discharge current compared to the itech 120 ah units at around 900?

$900 is a fair price for a 120ah unit, I'd assume it to be of reasonable quality.

I only slapped my system together for a bit of fun, the 2x50's do surprisingly well, I never see them below 26v. If I was to do it again I'd run a 48v system with 6000w inverter, maybe that would run my compressor

[Mickhead]

Never had experience with the cheap ones but I have 2x50ah 4s propower lithiums ($600 each) running a 24v 3000w inverter in my shed. They run all my power tools bar the welder & compressor. They are rated to 100amp discharge current. They go hard.

https://www.ebay.com.au/itm/Pro-Powe...xX6YVaIqIWtn5A

Sounds like a fair system but a bit low on watt hours and discharge current compared to the itech 120 ah units at around 900?

[pollenface]

Never had experience with the cheap ones but I have 2x50ah 4s propower lithiums ($600 each) running a 24v 3000w inverter in my shed. They run all my power tools bar the welder & compressor. They are rated to 100amp discharge current. They go hard.

https://www.ebay.com.au/itm/Pro-Powe...xX6YVaIqIWtn5A

Not long after making this post both of my lifepo4 deep cycles had BMS failures.

Knowing what I know now, if I wanted to do it cheaply I would buy the individual 3.2v cells and use my own BMS and run important loads straight independent of the BMS.

[Cuppa]

All of the drop in Lithiums have some sort of battery management system built in, inside the case. Many (most? all?) are of a type which shed excess current as heat. At the point they need to shed current, the batteries will already be close to being over voltage & thus getting hotter. Adding further heat, inside a sealed box is the last thing they need. Add in the fact that a major benefit of lithiums is their ability to accept high charge rates increases the possibility of more heat being shed by the BMS. The BMS will be a printed circuit board, & these too can fail if they are consistently overheated, without any access to air cooling. With a 'drop in' replacement if the BMS dies, the whole battery is cactus. The result will be a shortened lifespan of the battery. In addition, many of the cheaper battery management systems (BMS) will be just that, working only on overall voltage, rather than a cell management system (CMS) which incorporates auto cell balancing as required. Getting cells too much out of balance does occur with lithiums & can cause premature failure.

The above is a summary of my understanding of what a friend in the business of building, supplying & fitting lithium batteries has told me. He believes that for a long reliable life it is essential for a lithium battery pack to have a BMS which incorporates a CMS & that this should be external to the battery pack. I'm only repeating what I have been told, personally I have no experience of Lithiums. I do know however that were I to pay the significantly higher price for lithium over AGM (or other lead acid battery types) I would want them to last at least as long (ie. a minimum 10 year lifespan).

If the medical appliance is a CPAP machine, I run mine without a 2nd thought - average 20Ah per night or 26Ah with humidifier. If your solar/battery system is likely to struggle with similar 'extra' load. It may be a *lot* cheaper & more effective to stick with AGM battery(ies) & just add a bit more charging input (another solar panel, and/or dc to dc charging), space permitting.