How many Parallel 12V230Ah (Built-In 200A BMS) Safely & Practically?

[sun_of_a...]

Hello,

Thanks for the forum! This is regarding these: "LiTime 12V 230Ah Plus Low-Temp Protection LiFePO4 Battery, Built-In 200A BMS, Max 2944Wh Energy"

How many of these can be safely and practically put in parallel for a 12v battery bank? I've got 16 of them I was going to put in 4s4p, but thanks to the forum, I'd like to explore other scenarios now.

I'm leaning away from 4s4p because of the issue of imbalance among the cells. Does that issue just start coming back with 12v parallel in this case? Then there's a 24 volt bank to consider. I'm trying to minimize the imbalance potential now, and that's the nature of my question at this point. Thanks.

One practical issue with 12v is cable size. Note, PV would not necessarily need to go directly to this battery bank, nor would AC necessarily need to come directly from it. Maybe those are secondary issues.

The question now is how many of these can I safely and practically (wire size, buses, fuses, etc. Other?) put in parallel? And if anyone has a rough estimate of the cost of cables, fuses, buses, etc., it would be appreciated too.

Thanks for the forum!

 

[rodrick]

battery voltage should be native for the system for best results ie 24 volt for 24 volt system, that being said you can use a battery balance unit to keep each battery in series balanced so you are going to have to decide which voltage you are going with and get the required balancers this is a example of a 24 volt equalizer

EQ-24/2 24V Battery Balancer, balances 2 x 12V batteries in series. – Watts247 Wholesale

watts247.com

 

[sun_of_a...]

battery voltage should be native for the system for best results ie 24 volt for 24 volt system, that being said you can use a battery balance unit to keep each battery in series balanced so you are going to have to decide which voltage you are going with and get the required balancers this is a example of a 24 volt equalizer

EQ-24/2 24V Battery Balancer, balances 2 x 12V batteries in series. – Watts247 Wholesale

watts247.com

Hi rodrick. I'm getting the idea from the forum that best practice is simply not to put these batteries in series at all, so that's why I'm exploring one big 12v bank. I can have other battery banks at different voltages with different batteries.

Do you think a 24v battery bank of these 16 batteries using 8 battery balancers like you posted would be as stable and resistant to imbalances among the cells as a 12v bank of 16 of them in parallel, or two banks of 8 in parallel each?

Thank you!

 

[rodrick]

Going with 16 in parallel just doesn’t sound like a good idea to me and I would check with the manufacturer on how many can be put in series and parallel they should have a recommendation most do
becouse you already have the batteries I think you are going to have to go with the balance units and a lot of manufacturers say 4s4p is max so 2s8p may not be a option unless you make 2 separate banks of 2s4p and use them individually
do some more research on the manufacturer recommendations and limitations

 

[sun_of_a...]

Going with 16 in parallel just doesn’t sound like a good idea to me and I would check with the manufacturer on how many can be put in series and parallel they should have a recommendation most do
becouse you already have the batteries I think you are going to have to go with the balance units and a lot of manufacturers say 4s4p is max so 2s8p may not be a option unless you make 2 separate banks of 2s4p and use them individually
do some more research on the manufacturer recommendations and limitations

Manufacturer says 4s4p with these is okay, but forum generally says not, so there is no theoretical limit to parallel, but at some point the wires just get too big and it becomes impractical. What is that point? "Eight is Enough!"?? All 16? The answer is out there. Thanks.

 

[Rocketman]

Mis read post - so original answer doesn’t apply

 

[sun_of_a...]

Mis read post - so original answer doesn’t apply

Yep, I think you were talking about building my own batteries. I already have 16 of these LiTime 12V 230Ah batteries. How many in parallel safely and practically? Thank you. There's an answer.

 

[Rocketman]

You can put a bunch of 12v batteries in parallel.

Just land them on a battery bus bar. A Victron PowerIn w/fuses added (see YouTube), would be ideal (because you can sting several together). Be sure and use equal cables - equal length, size, etc.

Also coming out of that use a Class T fuse rated to your main trunk cable size - like 4/0 cable and a 400a Class T fuse. I would also install a Victron Smartshunt or BMV712.

That would make a long lasting 12v battery.

Because imbalances can still occur, Quarterly or so (to start with), you need to test to make sure each battery is getting its absorbation charge (hopefully you have Bluetooth in those batteries).

 

[Samsonite801]

Hello,

Thanks for the forum! This is regarding these: "LiTime 12V 230Ah Plus Low-Temp Protection LiFePO4 Battery, Built-In 200A BMS, Max 2944Wh Energy"

How many of these can be safely and practically put in parallel for a 12v battery bank? I've got 16 of them I was going to put in 4s4p, but thanks to the forum, I'd like to explore other scenarios now.

I'm leaning away from 4s4p because of the issue of imbalance among the cells. Does that issue just start coming back with 12v parallel in this case? Then there's a 24 volt bank to consider. I'm trying to minimize the imbalance potential now, and that's the nature of my question at this point. Thanks.

One practical issue with 12v is cable size. Note, PV would not necessarily need to go directly to this battery bank, nor would AC necessarily need to come directly from it. Maybe those are secondary issues.

The question now is how many of these can I safely and practically (wire size, buses, fuses, etc. Other?) put in parallel? And if anyone has a rough estimate of the cost of cables, fuses, buses, etc., it would be appreciated too.

Thanks for the forum!

My RV system has six 4s packs in it (1680Ah), with Overkill 120a BMSs, and works fine. Just use a BMV-712 battery monitor to get a single SoC % number on the gateway, and I couldn't be happier.

Some BMS companies say certain particular BMS models can't be paralleled (not sure their logic why not), but Overkill don't have this limitation.

Each BMS has a bluetooth module on it so I can easily check on pack-level (periodic health check), but generally I never log into them but once a month since the BMV-712 provides all the information I usually care about.

 

[rodrick]

Being manufacturer allows it 4s4p would be the cheapest way to go with one active balancer to do all four Banks I think that's the way I would go it would cut way down on wiring

 

[sun_of_a...]

You can put a bunch of 12v batteries in parallel.

Just land them on a battery bus bar. A Victron PowerIn w/fuses added (see YouTube), would be ideal (because you can sting several together). Be sure and use equal cables - equal length, size, etc.

Also coming out of that use a Class T fuse rated to your main trunk cable size - like 4/0 cable and a 400a Class T fuse. I would also install a Victron Smartshunt or BMV712.

That would make a long lasting 12v battery.

Because imbalances can still occur, Quarterly or so (to start with), you need to test to make sure each battery is getting its absorbation charge (hopefully you have Bluetooth in those batteries).

Thank you. These batteries each have a Built-In 200A BMS but no bluetooth. Is there an affordable external bluetooth monitoring device I can put on each battery in this large 12v battery bank so I don't have to disconnect them all to test them quarterly? Thanks.

 

[Samsonite801]

Thank you. These batteries each have a Built-In 200A BMS but no bluetooth. Is there an affordable external bluetooth monitoring device I can put on each battery in this large 12v battery bank so I don't have to disconnect them all to test them quarterly? Thanks.

There was a time when I was testing two 16s battery packs which had non-managed BMSs on them (so no bluetooth), in which case I also then installed two JK Active Balancers onto them (one per pack), and the JK Active balancers have built-in bluetooth on them (can at least read cell voltages, but not read BMS alarms or protection alerts or anything). Note, that doing this requires a second set of balance wires going from the new JK Active Balancer to each cell.

As far as what @rodrick says about 'to go with one active balancer to do all four Banks', is this possible? Is there such a thing as an active balancer that can wire to all cells consisting of 4s parallel packs? I don't know, could something like the Neey balancer do this? I haven't yet heard of a balancer that can be wired to all cells within multiple parallel packs. Perhaps he could chime in with more info about that if there is something like that.

Otherwise, a main shunt like a Victron shunt or BMV can give global view via bluetooth, but not on cell level.

The last potential possibility, is that if your BMSs have a UART serial connector on them, there may be some possibility that a bluetooth-to-UART module, or a USB-to-UART module could be installed, it's possible that a common app like XiaoXiang, perhaps even Solar Assistant or something could talk to the BMS if it just had a UART interface on it, but that is not a guarantee (that they would speak the same protocol or language), and would be hit-miss, try at your own risk, depending on how much time you want to spend or money you'd want to save on parts vs your time.

I finally just ditched the idea of running non-managed BMSs and broke down, bought some JBD BMSs for everything (which came equipped with bluetooth-to-UART adapters on them already and work with XiaoXiang app out of box).

 

[rodrick]

You would need an active balancer for each series set so a total of four balancers on that 48 volt I should have been clear

 

[sun_of_a...]

Okay, thanks rodrick, samsonite, others. Good night.

 

[zanydroid]

(which came equipped with bluetooth-to-UART adapters on them already and work with XiaoXiang app out of box

What direction does bluetooth-to-UART work? Does it provide a UART to a BMS that is Bluetooth only? Or the other way?

 

[740GLE]

You would need an active balancer for each series set so a total of four balancers on that 48 volt I should have been clear

For a set of 4 12v batteries in series (48v bank) only 3 balancers are needed not 4.

Battery Balancer - Victron Energy

Equalize the state of charge of two series connected 12V batteries using the Battery Balancer. Find a Victron Energy dealer near you.

www.victronenergy.com

 

[rodrick]

For a set of 4 12v batteries in series (48v bank) only 3 balancers are needed not 4.

Battery Balancer - Victron Energy

Equalize the state of charge of two series connected 12V batteries using the Battery Balancer. Find a Victron Energy dealer near you.

www.victronenergy.com

Didn’t know victron balancers could be set up like that but after looking at the diagram I see how they are wired once again victron impresses me with the versatility and engineering

 

[Samsonite801]

What direction does bluetooth-to-UART work? Does it provide a UART to a BMS that is Bluetooth only? Or the other way?

The serial data travels both directions... But only the BMS has a UART port and no native bluetooth or USB...

My JBD 200a 9-24s BMSs I bought that say they come with bluetooth, really don't have it actually on the main board, when I got them in the mail, and same with my Overkill 4s 120a BMS, they just have a 4-pin UART port connector on the BMS board, and this bluetooth module pigtail is plugged into it, and dangles off of it (right out of box)...

Example:

Help with JBD BMS--voltage for BT module

Hi, would really appreciate it if someone can check something for me. If you have a JBD BMS and have a bluetooth module on it, can you check the voltage on the VCC pin for me? Is it 12v, 5v or 3v? I have a 13s unit, and a bluetooth module that I want to connect to it, but checking the...

diysolarforum.com

In fact, Overkill even sells a USB version of the UART adapter to plug into that same port (can't have USB or bluetooth option at same time, just one or the other).

Example:

USB Module for BMS – Overkill Solar

overkillsolar.com

With the USB version of the adapter, you can plug the BMS into a Solar Assistant RPi.



Either version of the adapter just uses a hardware bridge chip which makes like a USB or bluetooth to UART protocol bridge to allow bi-directional serial data to travel via a serial com port.

how does usb serial to uart work - Google Search

or

how does bluetooth serial to uart work - Google Search

The reason I mentioned all that is because my old BMSs (Bellhope) 200a 16s, they had no bluetooth, but they did have UART ports on them, so I had always wondered if I could've plugged in an adapter and made it work with one of the common apps available, but I just decided I didn't have surplus time to tinker with that, ditched those BMSs (sold them for $100), and just bought some JBD instead. And if I can't get those to work very well with data comms through Solar Assistant or this solution ( https://www.patreon.com/posts/82923237 ), I have some Seplos to try as well later..