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BMS questions

Ok thanks I'll charge them back up and then remove the paralleling leads and measure them after a day or so
 
Keep lead acid for starting the engine. The cable structure in the engine compartment is such that the alternator and starter motor share the same cable to the starter battery. If you fit a lithium battery for engine start there are a number of issues that may/will occur.
Without current limit control, the alternator could be damaged. The lithium battery current capacity unable to start the engine. Any BMS disconnect will destroy the alternator diodes.

For the BMS look here:
They have Bluetooth but an option is an additional RS 485 port for future system integration.

Mike
 
I am building a 24v battery from lithium ion cells. got an aims 40 amp mppt charger that will be hooked up to it. also planning to use a 60A Daly 7s Smart bms. The bms and the charger have peaty much the same temp and voltage settings to prevent problems. After reading some honor stories of direct panel current frying batteries after computer controls fail i want to include some dumb redundancy in my safety features a. For Amps it's a simple, i got a 40A 12-24V circuit breaker. What i haven't been able to find is a cutoff that would prevent overvoltage. If you know something that would work please let me know. Also if you see any holes in my plan please let me know.
Thank you.
 
owerload2 said:
I am building a 24v battery from lithium ion cells. got an aims 40 amp mppt charger that will be hooked up to it. also planning to use a 60A Daly 7s Smart bms. The bms and the charger have peaty much the same temp and voltage settings to prevent problems. After reading some honor stories of direct panel current frying batteries after computer controls fail i want to include some dumb redundancy in my safety features a. For Amps it's a simple, i got a 40A 12-24V circuit breaker. What i haven't been able to find is a cutoff that would prevent overvoltage. If you know something that would work please let me know. Also if you see any holes in my plan please let me know.
Click to expand...
Welcome.

Feel free to start your own thread on your rather unique circumstance.

Where will this 40 amp circuit breaker be located? If its located after the SCC or may be fine, but before the SCC, the panels would be higher voltage than the circuit breaker is located. A couple of caveats. I don’t like audio circuit breakers and that’s what most 12/24 volt C/B I have seen are. They are unreliable. How many Amp Hours are the battery and how are you protecting that?

Does your BMS not protect from over voltage?
 
chrisski said:
Welcome.

Feel free to start your own thread on your rather unique circumstance.

Where will this 40 amp circuit breaker be located? If its located after the SCC or may be fine, but before the SCC, the panels would be higher voltage than the circuit breaker is located. A couple of caveats. I don’t like audio circuit breakers and that’s what most 12/24 volt C/B I have seen are. They are unreliable. How many Amp Hours are the battery and how are you protecting that?

Does your BMS not protect from over voltage?
Click to expand...
I was thinking puting the circuit breaker between the manual protection between Charger and the battery. Bms should protect and the charger has a voltage cut out too, but i'm thinking apocalyptic scenario with both charger and bms shorting. very unlikely to happen but i run across several videos of the aftermath of exactly that happening with iron phosphate cells. I'm using lithium ion cells from a car which means that in my case im facing a fire or possibly an explosion if that happens. As far as amp hours i don't know what it will end up at. I got an 8.8 kw car battery from ebay. not the best way to go but i paid 500 for it and its big enough to use for what i need to run some power tools at the barn. i was thinking of making several 24V battery packs somewhere around 1.5 Kw hours each. As far as staring my own thread i'm not sure where to put it, seemed like bms questions would be appropriate since im talking about safety for the battery pack. oh in case it matters i'm planning to use a 6000W aims split phase inverter with it. pretty sure it's rated at 50a possibly 60a so i figured a 60 amp bms should cover that load.
 
So I charged up the lifepo4 cells again to 3.63v in parallel.
They've sat disconnected from parallel for a day and the voltages are 3.56,3.57,3.58 and 3.59 .. strange
 
mikefitz said:
Keep lead acid for starting the engine. The cable structure in the engine compartment is such that the alternator and starter motor share the same cable to the starter battery. If you fit a lithium battery for engine start there are a number of issues that may/will occur.
Without current limit control, the alternator could be damaged. The lithium battery current capacity unable to start the engine. Any BMS disconnect will destroy the alternator diodes.

For the BMS look here:
They have Bluetooth but an option is an additional RS 485 port for future system integration.
Click to expand...

You're right Mike the alternator in the sprinter is too smart with all these sensors so if I were to simply disconnect the alternator it'd probably give me a few check engine codes.
 
owerload2 said:
I was thinking puting the circuit breaker between the manual protection between Charger and the battery. Bms should protect and the charger has a voltage cut out too, but i'm thinking apocalyptic scenario with both charger and bms shorting. very unlikely to happen but i run across several videos of the aftermath of exactly that happening with iron phosphate cells. I'm using lithium ion cells from a car which means that in my case im facing a fire or possibly an explosion if that happens. As far as amp hours i don't know what it will end up at. I got an 8.8 kw car battery from ebay. not the best way to go but i paid 500 for it and its big enough to use for what i need to run some power tools at the barn. i was thinking of making several 24V battery packs somewhere around 1.5 Kw hours each. As far as staring my own thread i'm not sure where to put it, seemed like bms questions would be appropriate since im talking about safety for the battery pack. oh in case it matters i'm planning to use a 6000W aims split phase inverter with it. pretty sure it's rated at 50a possibly 60a so i figured a 60 amp bms should cover that load.
Click to expand...
A morningstar relay driver set to monitor over charge voltage with a couple of leads to the positive and negative. It can be set to send a single to a relay such as a smart relay from chargery (they have relay sizes from 100-600 amps) could work as a interrupt device to uncouple the battery bank from any charge or discharge source. it is adjustable using a PC and the program that comes with it. but this is a rather expensive option, I think you would be in for about 350 to put it together.
 
ken morgan said:
A morningstar relay driver set to monitor over charge voltage with a couple of leads to the positive and negative. It can be set to send a single to a relay such as a smart relay from chargery (they have relay sizes from 100-600 amps) could work as a interrupt device to uncouple the battery bank from any charge or discharge source. it is adjustable using a PC and the program that comes with it. but this is a rather expensive option, I think you would be in for about 350 to put it together.
Click to expand...
350 is way less than 35k for a new barn so i'll keep that option in mind but I'm hoping to find an option that is dumb, like a basic circuit breaker that does not require an electronic control. I found some basic voltage monitoring relays that have the voltage range from 12 to 36 but the highest contactor rating on those that i could find is 15A which is nowhere near the where i want to be.
 
owerload2 said:
350 is way less than 35k for a new barn so i'll keep that option in mind but I'm hoping to find an option that is dumb, like a basic circuit breaker that does not require an electronic control. I found some basic voltage monitoring relays that have the voltage range from 12 to 36 but the highest contactor rating on those that i could find is 15A which is nowhere near the where i want to be.
Click to expand...
well the total cost of the above mentioned was about 300+- ish. you could get just the chargery relay for about 150ish and then use something else to trigger it. Either way you will need a relay and the smart relays like what they offer use less power so less parasitic drain. the morningstar relay driver can be used stand alone or coupled with any of morning stars products. they have a reputation for excellence in the remote solar field... not so well know in the home brew apps its seems probably due to pricing.
 
c3auto said:
Thank you
I will have to relocate the battery for the 12v system.

so for the 4S 12v 200Ah winston system, I am looking at a 40A or 60A BMS. I am looking at a daly one. Are these ok?

For the 8s 24v I am looking at 2x 100A BMS, again a daly brand.

The undervoltage cut offs seem a bit low. Any other BMS suggestions?

For charging I was going to get a constant current DC - DC Charger with an output voltage of 14.5V.
www.aliexpress.com

27.88US $ |Dc Dc Battery Charger 12v 24v To 12v 12.6v 13.v 14.5v Lead Constant Current 5a 8a 12a 15a 20a 22a 25a Cc Battery Charger - Inverters & Converters - AliExpress

Smarter Shopping, Better Living! Aliexpress.com
www.aliexpress.com www.aliexpress.com

The 12v battery would be the starter battery so would also be alternator charged from driving as well.

Can I rely on the BMS of the 4S 12v to stop the charge and to start charging automatically with this constant current charger or should I opt for secondary protection as well through a voltage sensing relay?

any other secondary protection ideas?

Thanks again you guys are super helpful
Click to expand...
As someone who owns both Daly and JBD, you will be much happier with a JBD brand BMS. In particular, the Daly 12v BMS have problems. The 24v and larger aren't as bad.
 
c3auto said:
My system will comprise of 16x 320ah (allegedly) lifepo4 batteries from aliexpress into a 12v, 4S4P 1280ah system


As I have 16x cells I am thinking of dividing 4 cells into a bank with a BMS for each bank, with the 4 BMS' wired parallel to each other.
Click to expand...
I am building a similar system (or upgrading my existing system with LFP from OPzV). I am sticking to 12v as that is what my original tiny system was, but as I now own a Victron Multiplus I'm not about to throw it away to increase the DC voltage (although it has many benefits).

I have ordered 32 x EVE 280Ah and they will be set up into 4 banks of 2P4S. Each with its own BMS, LCD and BT. I have just made my decision to go with JBD 4s 200Ah BMS with JBD LCD and will be ordering them tonight. I will also utilise the "Kill switch" function of the BMS to shut down any/all BMS's if required. All banks will be fused with 200A fuse to the main bus bar and then fused at 400A before going into the shunt and master DC Isolator using 3/0 AWG.

I have chosen this arrangement so I can take a bank (or two) out of service if the need arises and still operate 'off grid' normally.

I do like to be able to see all 4 banks at the same time on the screens especially if there is a fault condition. What did you end up going with?
 
I went with 2x 8s in 24v. I have a JBD LCD monitor for each 8s bank. I also got a jbd 12v 120a BMS for my original 200ah sinopoly cells which Il use the bt module with. Here's the jbd LCD I used in testing (in 4s to charge them up for top balancing). It has blue green to show the highest and lowest cell voltage
 

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c3auto said:
I went with 2x 8s in 24v. I have a JBD LCD monitor for each 8s bank. I also got a jbd 12v 120a BMS for my original 200ah sinopoly cells which Il use the bt module with. Here's the jbd LCD I used in testing (in 4s to charge them up for top balancing). It has blue green to show the highest and lowest cell
Click to expand...
Have you had any trouble/glitches with JBD?
 
c3auto said:
I haven't really used it yet only a 4s BMS for charging up the batteries to top balance but the standard android BT "xiaoxiang" app is pretty glitchy/poor.
Click to expand...
Which version of the app?

JBD / Xiaoxiang Smart Bluetooth BMS - wnsnty.xyz

Extensive information surrounding the popular JBD / Xiaoxiang smart bluetooth battery management system (BMS). Software, Guides and More.
wnsnty.xyz
 
3.1.1014 from Dec 2019. Thanks for the link I had downloaded the older one I could find on Google store
 
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