Will this work and safe ?

[new off grid]

Hi everyone
My 5 years old 48v/15s ( 15 cell in serial )/ 200 amp Lifepo4 pack is running strong
just added 1 more pack, same Lifepo4 but it's 16S
they are 3.2v different and I've been trying the best to connect them together automatically, but no success yet
this's my new try, please tell me it's doable or total messed up, safety wise ppl
thanks all in advance !
I will buy 1 cell, 272 Ah/3.2v, such as this one

Lishen 272Ah 3.2V LiFePO4 Prismatic Battery - Grade A

Explore the pinnacle of battery technology with the Lishen 272Ah 3.2V LiFePO4 Prismatic Battery - Grade A. This state-of-the-art battery is engineered for superior performance, offering a massive 272Ah capacity and a stable 3.2V nominal voltage, perfect for high-demand applications. With its...

18650battery.com

and connect it directly onto my 15s battery, externally, in serial
my goal is to turn the 15s to 16s so that it can work together with my new 16s batt
just hook it up, no any new BMS, no nothing
what you think ? workable ? the old whale will smoke this little baby in seconds ? will the 15s BMS feels something wrong and stop working ?
as long as it works, and safe , I do not mind to replace this 1 cell add on anytime if needed
Great day ppl

 

[42OhmsPA]

Hi everyone
My 5 years old 48v/15s ( 15 cell in serial )/ 200 amp Lifepo4 pack is running strong
just added 1 more pack, same Lifepo4 but it's 16S
they are 3.2v different and I've been trying the best to connect them together automatically, but no success yet
this's my new try, please tell me it's doable or total messed up, safety wise ppl
thanks all in advance !
I will buy 1 cell, 272 Ah/3.2v, such as this one

Lishen 272Ah 3.2V LiFePO4 Prismatic Battery - Grade A

Explore the pinnacle of battery technology with the Lishen 272Ah 3.2V LiFePO4 Prismatic Battery - Grade A. This state-of-the-art battery is engineered for superior performance, offering a massive 272Ah capacity and a stable 3.2V nominal voltage, perfect for high-demand applications. With its...

18650battery.com

and connect it directly onto my 15s battery, externally, in serial
my goal is to turn the 15s to 16s so that it can work together with my new 16s batt
just hook it up, no any new BMS, no nothing
what you think ? workable ? the old whale will smoke this little baby in seconds ? will the 15s BMS feels something wrong and stop working ?
as long as it works, and safe , I do not mind to replace this 1 cell add on anytime if needed
Great day ppl

1st off - I think that's a knockoff site and I've never heard of them.
This is the real and reputable 18650 Battery Store. https://www.18650batterystore.com/collections/lifepo4-prismatic-cells

Your idea might work but it will not work without replacing or modifying the BMS, some BMS are "smart" and can take a range of cells in series if wired properly.

How do you plan to connect the new cell?
Are your current cells welded bus bars?
Is the internal resistance the same?
Is the cell height the same?
Care to share photos of what you're working with?

 

[new off grid]

1st off - I think that's a knockoff site and I've never heard of them.
This is the real and reputable 18650 Battery Store. https://www.18650batterystore.com/collections/lifepo4-prismatic-cells

Your idea might work but it will not work without replacing or modifying the BMS, some BMS are "smart" and can take a range of cells in series if wired properly.

How do you plan to connect the new cell?
Are your current cells welded bus bars?
Is the internal resistance the same?
Is the cell height the same?
Care to share photos of what you're working with?

like I said, just connect it outside, external, in serial without open the 220 lbs beast cover
hook the 15s batt Negative to the new cell Positive
then the new cell Negative + original 15s Positive out to load
this's 5 year old batt, almost 2000 Cycles on it, still pretty good thou
but I do not treat it as diamond, not so care about anything else,
as long as it work, and trying to squeeze it 'til out of juice
been transferring power manually nightly between them, tired of it already

 

[wpns]

, It should work, but there will be no battery management for that new cell, no way to keep it in balance, and no way to shut it off for over or under voltage.

 

[new off grid]

, It should work, but there will be no battery management for that new cell, no way to keep it in balance, and no way to shut it off for over or under voltage.

As long as it works, and do not burn anything down, I'm happy
I do have 2 levels of all voltage/current... protection for the whole system, except this new baby
so if anything happen to this, it's easy to replace and not so expensive
once again, hope you're right friend
can't wait to try it tmr
lets see
thx for ur input

 

[wpns]

and do not burn anything down,

You know that’s what the BMS is for, right?

 

[ScropusGobbleBottom]

I have thought about this before and decided NOT TO DO IT.
Far too much risk with an unprotected cell.
Even if you paired a single 304 ah battery in series with a 100Ah 15s pack, I STILL wouldnt do it.

 

[ScropusGobbleBottom]

Hi

Why dont you just build a 15s pack and add it to your 15s battery?

 

[new off grid]

Why dont you just build a 15s pack and add it to your 15s battery?

already bought the 16s friend

 

[new off grid]

I have thought about this before and decided NOT TO DO IT.
Far too much risk with an unprotected cell.
Even if you paired a single 304 ah battery in series with a 100Ah 15s pack, I STILL wouldnt do it.

let me go 1st and report it back to you sir, lol

 

[ScropusGobbleBottom]

already bought the 16s friend

Oh, I see

 

[42OhmsPA]

like I said, just connect it outside, external, in serial without open the 220 lbs beast cover
hook the 15s batt Negative to the new cell Positive
then the new cell Negative + original 15s Positive out to load
this's 5 year old batt, almost 2000 Cycles on it, still pretty good thou
but I do not treat it as diamond, not so care about anything else,
as long as it work, and trying to squeeze it 'til out of juice
been transferring power manually nightly between them, tired of it already

I definitely wouldn't do what you are describing, it sounds like a terrible idea.

 

[ScropusGobbleBottom]

it sounds like a terrible idea.

I like the cut of your jib.

 

[new off grid]

I definitely wouldn't do what you are describing, it sounds like a terrible idea.

I know friend
any pro will say the same, safety wise
but I'll give it a try
will prepare the best for the worst 1st thou
I will put it in the isolated area, even if it burn down, it will not touch anything within 6 ft dia
it will sits in a 2 inch thick concrete wall box with active air cooled 24/7
and then wish for the best everyday...,

 

[42OhmsPA]

I know friend
any pro will say the same, safety wise
but I'll give it a try
will prepare the best for the worst 1st thou
I will put it in the isolated area, even if it burn down, it will not touch anything within 6 ft dia
it will sits in a 2 inch thick concrete wall box with active air cooled 24/7
and then wish for the best everyday...,

Definitely put a camera on it and post the video when shtf. It will fail.
I'm far from a pro.
Good luck.

 

[wpns]

I know friend
any pro will say the same, safety wise
but I'll give it a try
will prepare the best for the worst 1st thou
I will put it in the isolated area, even if it burn down, it will not touch anything within 6 ft dia
it will sits in a 2 inch thick concrete wall box with active air cooled 24/7
and then wish for the best everyday...,

Now you’re just being silly

 

[740GLE]

Do you have a link to the two batteries you have?

 

[new off grid]

Do you have a link to the two batteries you have?

below is my 5 year old, 15s/48v/200 amp

Meritsun 48v 200ah Solar Lithium Battery 48v 200ah Lithium Iron Phosphate...

Find battery solution manufacture? MeritSun 48V 200AH Solar Lithium Battery 48V 200AH Lithium Iron Phosphate for Solar Energy System, we specialized in Products, lithium air battery...

www.meritsunpower.com

and this's my new bought, 16s/48v/100 amp

48V 100AH Server Rack LiFePO4 Lithium Battery SG48100P

Shop online for top-of-the-line 12000 Watt Power Inverters at SunGoldPower. Find reliable and efficient inverters to power up your devices. Power up your server racks today!

sungoldpower.com

got the 16s very cheap, thought be able to build a bridge to connect them automatically easily, but not, for now

 

[Badbyte]

In my opinion: Only safe thing to do for now to keep your costs down, would be to drain your new 16s pack to the same voltage as your 15s pack. Once that is done you can then connect the 16s pack in parallel to your 15s pack. Leave the settings on your inverter/charger as they were originally, do not change them.
This way both packs will work properly with their own bms, but you will never get the full capacity out of your 16s pack. since the pack voltage will be about 3.2 volts lower then what it needs to be for the 16s pack to show as fully charged.

Running at reduced capacity is better then messing about and burning your place down with an unmonitored extra cell connected to your 15s pack in series.
If you want to try something like that, then please take the cover off on your 15s pack, take a look at the bms is has and see if it is 16s capable. (as an example, my bms is 7s to 16s capable depending on how you wire it up.)
*** If no, then replace the bms with one that is 16s capable and add the new cell in series with the old batteries and connect the new bms to all cells.
*** If yes then you can wire a new cell externally in series with the old cells, connected to the original bms properly to all 16 cells and then balance it manually for the first few charges. Lots of tricky work, so if you are not comfortable doing something like this then I recommend you try the first method instead or sell off your 15s pack and buy a second 16s to be safe.

Safety first above all else, stuff can be replaced but your life can not be.

 

[Badbyte]

Definitely put a camera on it and post the video when shtf. It will fail.
I'm far from a pro.
Good luck.

If you do then please sell tickets to the show, Pay Per View style could make you enough cash to buy a new system

 

[new off grid]

In my opinion: Only safe thing to do for now to keep your costs down, would be to drain your new 16s pack to the same voltage as your 15s pack. Once that is done you can then connect the 16s pack in parallel to your 15s pack. Leave the settings on your inverter/charger as they were originally, do not change them.
This way both packs will work properly with their own bms, but you will never get the full capacity out of your 16s pack. since the pack voltage will be about 3.2 volts lower then what it needs to be for the 16s pack to show as fully charged.

Running at reduced capacity is better then messing about and burning your place down with an unmonitored extra cell connected to your 15s pack in series.
If you want to try something like that, then please take the cover off on your 15s pack, take a look at the bms is has and see if it is 16s capable. (as an example, my bms is 7s to 16s capable depending on how you wire it up.)
*** If no, then replace the bms with one that is 16s capable and add the new cell in series with the old batteries and connect the new bms to all cells.
*** If yes then you can wire a new cell externally in series with the old cells, connected to the original bms properly to all 16 cells and then balance it manually for the first few charges. Lots of tricky work, so if you are not comfortable doing something like this then I recommend you try the first method instead or sell off your 15s pack and buy a second 16s to be safe.

Safety first above all else, stuff can be replaced but your life can not be.

much much appreciated your long and thru out input
your ideas are 100% spot on
I'm trying to make a lil shortcut here , just to make it work with least effort
but yeah, the risk is high
I'll reconsider my next step
may go with new cell + new BMS = new 16s pack
question thou : when 1 more cell add in , has the same 3.2 v but different AH ( will get the new 1 with higher AH than the original ), will new issue arise, safety wise ?
( I do not worry too much about performance )
thanks a lot friend

 

[Badbyte]

much much appreciated your long and thru out input
your ideas are 100% spot on
I'm trying to make a lil shortcut here , just to make it work with least effort
but yeah, the risk is high
I'll reconsider my next step
may go with new cell + new BMS = new 16s pack
question thou : when 1 more cell add in , has the same 3.2 v but different AH ( will get the new 1 with higher AH than the original ), will new issue arise, safety wise ?
( I do not worry too much about performance )
thanks a lot friend

Your 15s is a 200Ah pack, so you will need a single 200Ah LifePo4 battery, not something bigger nor something smaller to adjust for the age of your old pack!
You will have to either drain or charge the new cell so it is as close as possible to the voltage levels of the other cells in your old pack, preferably within 0.02 volts of each other.
The bms should be able to handle the rest after that.

Only question is where will you install the extra cell within your old pack??? Is there room inside the old case?

 

[new off grid]

Your 15s is a 200Ah pack, so you will need a single 200Ah LifePo4 battery, not something bigger nor something smaller to adjust for the age of your old pack!
You will have to either drain or charge the new cell so it is as close as possible to the voltage levels of the other cells in your old pack, preferably within 0.02 volts of each other.
The bms should be able to handle the rest after that.

Only question is where will you install the extra cell within your old pack??? Is there room inside the old case?

of course there's no room inside friend
but plenty around it
so I will drill 2 holes to run the wires
then, the new cell will be hang somewhere in the air
good to have something funny to look at, sometimes, lol

 

[Badbyte]

Make sure to use rubber grommets on the new holes to make sure you don't short out the new cell and bms wire goint to it. The battery will weigh somwhere between 11 and 12 lbs so secure it properly or you may run into very dangerous situations if it falls or slips off.
If you're unsure about something then stop and take a break, ask lots of questions, show lots of pics...etc, etc, etc........

Don't just take one persons word on something, since everyones setup is unique and special. What works for me, may not work for you and vise versa after all. You are never too old to learn something new, you just have to want to learn it badly enough yourself to be able to do so.

Stay safe, be smart and remember to have fun. (ps: not necessarily in that order)

 

[sunshine_eggo]

Hi everyone
My 5 years old 48v/15s ( 15 cell in serial )/ 200 amp Lifepo4 pack is running strong
just added 1 more pack, same Lifepo4 but it's 16S
they are 3.2v different and I've been trying the best to connect them together automatically, but no success yet
this's my new try, please tell me it's doable or total messed up, safety wise ppl

total messed up. don't do it.