Adding 5.3kw (48v 100ah) powerwall lifepo4 to existing lifepo4 battery pack in parrallel

[Gray17]

Hi Guys, hopefully this is ok but best thought to run it by you for comments first.
So at moment i have 4 x 12v 50ah lifepo4 batteries in series, so 48v nominal, i have then parralleled a further 48v 50ah lifepo4 battery so now have 48v 100ah in total and currently working fine using their own internal BMS and using inverter settings low cut off 43v max voltage 58v, max charge and discharge 50a.

I am now considering adding a further 48v 100ah powerwall in parrallel so will then have a total capacity of 200ah doubling my current storage.
So question will this pose any problems, other then out of balance occasionally?
The powerwall comes with comms to link to inverter, however does this have to be connected? As other batts dont have this option?

I currently disconnect the 4 x 12v batts and charge them individually to full capacity on seperate chargers regularly to balamce them, the 48v battery seems to be ok without this.
If ok is there any reason you cannot increase capacity as funds allow ie adding further batteries?
I will obviously increase the inverters charge and discharge rates after adding the battery to compensate for extra capacity and charge rate.
Comments please?
Thanks

 

[HRTKD]

I think your low voltage cutoff is too low. See this thread for recommended settings.

Thread 'Best LifePo4 charge controller settings known to man for Maximum Service life and Minimum battery stress!!! 5,000-10,000+ cycles?'

Feb 2, 2022

---ORIGINAL TITLE----​

Best charge controller settings to achieve 10%-90% usage on lifepo4 ?​

EDIT-UPDATE and the ANSWER to this question. . . This post is a accumulation of all the great and wonderful information given to me by all the great people on this thread. I consolidated all of this into this post and is the result of many hours of research and consulting with the people of this forum. Again thanks every body!!!!! This would not be possible with out you guys. if you believe i missed something or want to amend something please comment on this thread but please...

• Go2Guy
• Replies: 447
• Forum: DIY LiFePO4 Battery Banks

• 

No, the comms don't have to be connected. I suspect that if you did connect it, your other batteries would become the red headed step children of the system.

You're making a complicated system with the different battery configurations. If you're good with closely managing it, then it's OK.

 

[Gray17]

Hi thank you for your reply, the low and high voltage settings were given to me by the 12v batteries manufacturer before i added the 48v battery. However i can alter them.if needed, what would you recommend?
Yes unfortunately ive bought batteries as funds would allow and if an offer presented itself, i agree it isnt ideal but dont want to waste what I've already bought.
Suppose i could sell the 4 x 12v batts, but then I'd only have 150ah rather then 200ah. But its an option.

 

[HRTKD]

The thread I linked to had recommended low voltage settings.

 

[Gray17]

Sorry hadnt realised, thats an awful lot of info to digest.
Thanks

 

[Gray17]

Morning Guys, question for all you battery experts.
My 48v 100ah (5.1kw) powerwall arrived, brand new fully boxed in perfect condition, Great!, First off its very heavy, a lot more then i expected. However it does come with rawl bolts to secure to wall. Getting it into loft will be an issue though!
Anyway opened carton and found supplied user manual which states its a Lithium Ion not as advertised as a Lifepo4. Very concerned as existing i'm parrallelling up with is lifepo4.
Immediately contacted supplier who stated its a misprint on manual, caused when chinese converted to english, supplied battery is def a lifepo4?
This got me thinking how do you actually know?
Now I know that Lithium Ion and lifepo4 are different and have different characteristics, benefits and negatives too. But also cost.
So is there anyway to determine what i've actually got, rather then just take the suppliers word for it? Perhaps im a bit sceptical.
It could be a Lithium ion as its cheaper and mis advertised? But also prone to explode! Although fully encased in metal case. Also not what i ordered.
If i connect to existing Lifepo4 batts what complications can i expect?
Ie can you mix the 2 types together?
I welcome your comnents
Thanks

 

[sunshine_eggo]

Morning Guys, question for all you battery experts.
My 48v 100ah (5.1kw) powerwall arrived, brand new fully boxed in perfect condition, Great!, First off its very heavy, a lot more then i expected. However it does come with rawl bolts to secure to wall. Getting it into loft will be an issue though!
Anyway opened carton and found supplied user manual which states its a Lithium Ion not as advertised as a Lifepo4. Very concerned as existing i'm parrallelling up with is lifepo4.

LFP is lithium ion as it uses Lithium ions to transport charge. It's a specific type. People often typo Lithium Iron as Lithium ion.

Yes, Lithium Ion generally means nominal 3.6-3.7V lithium cells with an operating range of 3.0 to 4.2V and a strong voltage to SoC correlation, but it's not inaccurate to refer to LFP as "lithium ion." It just makes you ask more questions.

Immediately contacted supplier who stated its a misprint on manual, caused when chinese converted to english, supplied battery is def a lifepo4?
This got me thinking how do you actually know?
Now I know that Lithium Ion and lifepo4 are different and have different characteristics, benefits and negatives too. But also cost.
So is there anyway to determine what i've actually got, rather then just take the suppliers word for it? Perhaps im a bit sceptical.

Nominal voltage?
Max charge voltage?

It could be a Lithium ion as its cheaper and mis advertised? But also prone to explode! Although fully encased in metal case. Also not what i ordered.

Again, LFP is lithium ion.

If i connect to existing Lifepo4 batts what complications can i expect?

Probably nothing, because it's probably LFP.

Ie can you mix the 2 types together?

Depends on the cell count and target voltage.

I welcome your comnents
Thanks

Open it up and take pictures. Post here.

 

[Gray17]

Thanks for replies Guys,
The battery comes with 5 years warranty, however thats voided if i break the seals and open it up, not sure I'd risk that as couldnt then return it if need to, also reading the booklet again its doesnt give any nominal voltages, but upper says do not charge above 58.8v cells 3.65v max, lower 46.4v , these are different to the current lifepo4 are set ie 58v upper 44v lower.
Obv being a proper power wall it has an electronic on/off switch and RS 485 and 232 and CAN comms, plus an LCD display. Got it out in the open today its mega heavy found a plate at bottom see photo Mmm!
Hopefully someone can tell me what ive got? Still nowhere does it say lifepo4 like my other batteries do.

 

[wpns]

Yeah, it’s 16-cell LFP, go ahead and hook it in parallel with your others.

 

[Gray17]

Thank you for the reply, thats good to know. Perhaps im just being over cautious. To be honest dont really
understand the differences.
Googled it, it states both Lihium Ion and lifepo4 use lithium iron as the medium but have different +cores which is what makes the lifepo4 more expensive and less prone to explode.
What i cant understand is why the new battery doesnt say thats what it is so theres no misunderstanding.
I also googled the Company who manufactures them Future- RE the uk site says doesnt exist, the chinese site says its an insurance seller?
Very strange!

 

[wpns]

Thank you for the reply, thats good to know. Perhaps im just being over cautious. To be honest dont really
understand the differences.
Googled it, it states both Lihium Ion and lifepo4 use lithium iron as the medium but have different +cores which is what makes the lifepo4 more expensive and less prone to explode.
What i cant understand is why the new battery doesnt say thats what it is so theres no misunderstanding.
I also googled the Company who manufactures them Future- RE the uk site says doesnt exist, the chinese site says its an insurance seller?
Very strange!

Umm, OK, but if you don't trust us when we tell you that the specs are the same and it can't be anything but a 16S LFP battery and you can safely connect the new and old batteries in parallel, then please check out that <other> forum that will give you a different answer you can trust.

 

[Gray17]

Hi thanks for reply, but think youve misunderstood what i said, not that i don't trust people on the forum i do, its the sellers misrepresenting their products i dont necessarily trust ie calling a battery one thing but could actually be a cheaper version of it, which could cause an explosion. Why? To make more profit.
Think its prudent to ensure it is what it's supposed to be!
I totally believe the new battery will work perfectly with the others, which is great to know, thanks But theres also the cost too, you think youre getting a lifepo4 at a good price, but actually not that good if its lithium ion, rather then whats its advertised as.
So my question is really, have i actually got what i paid for ie A 48v 100ah 5.1kw Lifepo4 battery (Lithium Iron Phosphate) or a cheaper Lithium Ion (Iron)?
Think theres a lot of people newbies and others too that dont fully understand the differences between the various batteries, their benefits and pitfalls of each.
But at the end of the day you should get what was advertised and you paid for. Thats fundamental.

 

[sunshine_eggo]

Hi thanks for reply, but think youve misunderstood what i said, not that i don't trust people on the forum i do, its the sellers misrepresenting their products i dont necessarily trust ie calling a battery one thing but could actually be a cheaper version of it, which could cause an explosion. Why? To make more profit.
Think its prudent to ensure it is ehat its suppised to be!
I totally believe the new battery will work perfectly with the others, which is great to know, thanks But theres also the cost too, you think youre getting a lifepo4 at a good price, but actually not that good if its lithium ion, rather then whats its advertised as.
So my question is really have i actually got what i paid for ie A 48v 100ah 5.1kw Lifepo4 battery (Lithium Iron Phosphate) or a cheaper Lithium Ion (Iron)?
Think theres a lot of people newbies and others too that dont fully understand the differences between the various batteries, their benefits and pitfalls of each.
But at the end of the day you should get what was advertised and you paid for. Thats fundamental.

The nominal voltage, capacity and charge voltage are consistent with LFP. It is impossible for what you fear to be "lithium ion" to have that nominal voltage and kWh capacity.

This is a typical case of crappy Chinese documentation/labeling. It's not the first time I've seen it on here.

Accept the prior assertion of LFP and this one, or don't. It's up to you. If you're not going to accept it. Please go complain elsewhere.

 

[Gray17]

No that fully explains it, now i understand how thats arrived at, i can fit safe in the knowledge its all correct and is what its,supposed to be.
Many thanks to all