Multiple 16s 48v Modules in parallel or 1 Massive 1200lb 6p16s Battery?

[carterjohnsons25]

HELP PLEASE: Need Ninja Knowledge:

I am Making a 96cell Eve 48v Battery -1200lbs. ~85kWh

1. is it better to make one Massive Battery. IE 6p16s with 1 single 500amp BMS
2. Make 2 48v Modules 3p16s each with a 250amp BMS, then put these two modules in 2p configuration. ... or some variant of this. Such as 3 48v modules in 3 parallel
3. Make 6 16s 48v modules each with 100amp BMS for each individual module, then connect all 6 modules 6p configuration.

If you go with multiple 48v modules in parallel, how would you monitor each module? Each BMS will have its own Bluetooth. Can one app read from all the Bluetooth modules or would you need a screen for each Module? Any suggestions here?

My uneducated knee jerk is following
Multiple packs in parallel
PROs - has benefit of any one pack going bad and you can just shut it down. You are still good
CONs - Balancing with charging? How to monitor 6 48v modules

Massive Single pack
PROs - single BMS for balanced charging???
CONs - Massive high amp BMS, Many single points of failure. one cell bad could Drain or kill pack.

Thank you in advance.

 

[jwelter99]

This is an ideal config for a Batrium distributed BMS.

 

[curiouscarbon]

seconded that batrium seems appropriate for this use case.

my knee jerk 2 cents for DIYmode:

option 3 of no paralleled cells only paralleled packs appeals to me a lot from a maintenance perspective.

i have used JBD BMS before and got data from the UART serial. there's a thread nearby about adding wifi to each BMS so they all connect to a wifi access point. if you did that you'd have 6 BMS each with a wifi thingy connecting to the WiFi network on boat to communicate their data. perhaps that could work.

each BMS can independently control the charge transistors and discharge transistors, so if you select parameters carefully such as charge voltage, low voltage cutoff, balance voltage, balance delta threshold, etc. my gut says balance is achievable

hope this helps, happy to elaborate, but also be aware that i'm figuring this out as i go too.

my personal plan is to scale up using multiple JBD BMS, each connected to a pack of unparalleled cells. each pack will be paralleled (with some form of protection) with other identical packs. each BMS will be connected wired to an arduino brain via isolated i2c. i write arduino code that read each pack data and log it and activate or deactivate contactor based on state information. important to handle case where data stops arriving. important that the program notices that data stops arriving.

cheers, i look forward to more development on this project.

 

[DLTooley]

I don’t know the answer, but three 2p16s batteries would also be an option.
The three 16s BMS configuration would be simple to manage and offer considerable redundancy.

 

[John Frum]

How much continuous discharge current are you designing for?
The continuous charge current will be between 336 amps(.2c) and 840 amps(.5c).

The nec ampacity tables saw that 4/0awg is good for 260 amps with 90C rated insulation.
With fuse headroom that is 208 amps max continuous current.

 

[carterjohnsons25]

seconded that batrium seems appropriate for this use case.

my knee jerk 2 cents for DIYmode:

option 3 of no paralleled cells only paralleled packs appeals to me a lot from a maintenance perspective.

i have used JBD BMS before and got data from the UART serial. there's a thread nearby about adding wifi to each BMS so they all connect to a wifi access point. if you did that you'd have 6 BMS each with a wifi thingy connecting to the WiFi network on boat to communicate their data. perhaps that could work.

each BMS can independently control the charge transistors and discharge transistors, so if you select parameters carefully such as charge voltage, low voltage cutoff, balance voltage, balance delta threshold, etc. my gut says balance is achievable

hope this helps, happy to elaborate, but also be aware that i'm figuring this out as i go too.

my personal plan is to scale up using multiple JBD BMS, each connected to a pack of unparalleled cells. each pack will be paralleled (with some form of protection) with other identical packs. each BMS will be connected wired to an arduino brain via isolated i2c. i write arduino code that read each pack data and log it and activate or deactivate contactor based on state information. important to handle case where data stops arriving. important that the program notices that data stops arriving.

cheers, i look forward to more development on this project.

I am leaning heavily towards

6 16s 48v packs, each with its own BMS.
or
3 32s 96v packs each with its own BMS.

This way I never have to parallel at the cell level. I have read that parallel at cell level is better. but it creates lots of points of failure and I loose the ability to monitor each cell individual.

Trying to understand why parallel at the cell level seems more recommended. Any thoughts from the crew?

How much continuous discharge current are you designing for?
The continuous charge current will be between 336 amps(.2c) and 840 amps(.5c).

The nec ampacity tables saw that 4/0awg is good for 260 amps with 90C rated insulation.
With fuse headroom that is 208 amps max continuous current.

Max will be ~0.33c or 250 amps.

For this pack 1c is 840amps. Yikes.

There is a chance if I one day add a second 96v 24kw motor that I would draw at 450amps which is still less than 1c.

 

[John Frum]

Max will be ~0.33c or 250 amps.

For this pack 1c is 840amps. Yikes.

There is a chance if I one day add a second 96v 24kw motor that I would draw at 450amps which is still less than 1c.

96 / 16 = 6
6 * 280 = 1680

1c is 1680 amps
.5c is 840 amps
.33c is 554.4 amps

 

[John Frum]

Hold the phone there is no practical way to run a 96 volt trolling motor off of a 48 volt battery.
Are you thinking about putting the 48 volt batteries in series?

 

[curiouscarbon]

Hold the phone there is no practical way to run a 96 volt trolling motor off of a 48 volt battery.
Are you thinking about putting the 48 volt batteries in series?

they bought 96 cells 280Ah

96cell/16S=6 packs

96v

 

[John Frum]

they bought 96 cells 280Ah

96cell/16S=6 packs

That was my understanding but then he brought up the 96 volt trolling motor.
So it could be 3 sets of 96 volt batteries each constructed of 2 48 volt batteries in series.

 

[curiouscarbon]

originally they wanted a 96v system but maybe now targeting 48v due to component availability

sorry if any of this in error

96v

 

[time2roll]

I would go with 3x 32s and run the three batteries in parallel.

 

[John Frum]

I would go with 3x 32s and run the three batteries in parallel.

what bms would you use?

 

[carterjohnsons25]

96 / 16 = 6
6 * 280 = 1680

1c is 1680 amps
.5c is 840 amps
.33c is 554.4 amps

Its a 96v Pack, Not 48v

32 280ah cells in series = 1 96v 280ah Battery. 3 of these Batteries in parallel would be 280ah * 3 = 840ah at 96v.

Your math is correct for 48v. Which this is not. If I create 48v Packs, they would have to be in series to create 96v. Don't get to add the AH when in series.

Believe my numbers are correct for 96v. It will run at 150 to 250amps, 96v which is about .33C for a 840ah 96v battery.

Hold the phone there is no practical way to run a 96 volt trolling motor off of a 48 volt battery.
Are you thinking about putting the 48 volt batteries in series?

Correct. You would need to center tap a 96v pack to run a 48v motor. Bad idea. This is a 96v Controller for a ME1616 DC motor. Need 96v

I would go with 3x 32s and run the three batteries in parallel.

The more I read / research. this seems to be the winner. Just need to find the 32s 96v BMS. Have some leads, but all Alibaba so nervous.

Here is the top contender at the moment

High Current Ant 10s To 32s 150a 200a 300a Li Ion Lifepo4 Lto Smart Bms With Bt - Buy Ant Bms,Smart Pcb,Bms Product on Alibaba.com

High Current Ant 10s To 32s 150a 200a 300a Li Ion Lifepo4 Lto Smart Bms With Bt - Buy Ant Bms,Smart Pcb,Bms Product on Alibaba.com

www.alibaba.com

the 32s 96v 300amp version does 120 continuous and 300 peak
- This would get me 360amp max continuous, 900peak from the 96v pack since 3 of them in parallel. If I ever add a second motor, I will have to go with a BMS/Contactor options as many EV use. This can be added later when/if needed.

what bms would you use?

Correct. this is the dilemma with 96v solution. you exit the realm of standard equipment.

Here is the full thread for this project. Extreme details if interested.

96v Solar Cabin Cruiser Project - Full Solar/Shore/Inverter/LifePO4 - Discussion and Progress

Starting this thread to document the full Solar Boat Conversion Project. Always looking for good advice. The Concept 1) I will eventually be converting a nice 40 Cat from Gas to Electric. Needed a project boat to experiment on first. 2) I found this 23 foot boat for $1800 + Trailer delivered...

diysolarforum.com

 

[toms]

Trying to understand why parallel at the cell level seems more recommended. Any thoughts from the crew?

The capacity of a large format prismatic cell is determined by how many individual cells are put in parallel.

For example, a 200ah CALB LFP cell is the same as two 100ah CALB LFP cells, just twice the paralleled cells in a bigger case.

If you buy two 100ah cells and parallel them, only your busbar connection gives a greater chance of cell failure than using a single cell.

 

[John Frum]

HELP PLEASE: Need Ninja Knowledge:

I am Making a 96cell Eve 48v Battery -1200lbs. ~85kWh

Its a 96v Pack, Not 48v

 

[MartyByrde]

Did you ever end up building this? How’d it go?