Picking 16 cells for my first battery build, 2 @ 24V, connected in parallel

[RetiredSparky]

I am new here and wanted to ask if there was any general preference on lfp cells for diy battery build? I looked at the Amy Zheng web site with the Houston warehouse. She looks to have a good rep here. This would work for me as I live in Houston. Her web site had several choices in the 280-320ah range. I do want a large battery bank compacity. I do not know what BMS I will need yet. I do want bluetooth but have not understood much on selecting one for this battery config. Do I need to pick a BMS first? I don't think so from what I read here so far. I know they have a max amp rating and I am buying large cells. I would like to get the cells while I can. The warehouse stock is out now but will have more next week maybe. Just want to be sure I don't need to buy smaller cells to use a good BMS if that even makes sense? I only started into this about a week ago. Learning as I go.

 

[brewmatic]

There are a lot of different BMS available. So it should be a choose BMS after you get cells. But what are you going to use your battery for?

 

[RetiredSparky]

There are a lot of different BMS available. So it should be a choose BMS after you get cells. But what are you going to use your battery for?

I retired and ordered a high roof transit van a few weeks ago. I plan to convert it enough to register it as an RV and do some traveling. I picture hitting the road and visiting friends and family I have not seen in years. I also bought my lifetime pass to the BLM lands and the national park system. In the van I want an AC unit, a Microwave, a refrigerator/freezer and maybe some electric heat and cooking all at 120VAC. There will be more loads like laptop charging, Coffee pot, TV, ventilation etc. I do not want to run out of power in the van doing any of it. I am thinking a 3kw, 24V inverter tied to this battery. The van will be a few months getting built. I would like to have all the equipment picked out and ready to install when I get the van. The batteries are the one thing I am sure of so far. I pictured this system monitored and controlled by a single touch screen in the van and an app of some type for remote access and control. That will be a different post a little later. I don't wand to sidetrack my own thread here. Batteries today, yes!

 

[Steve_S]

For a 3000W Inverter, you will want to be able to deliver a minimum of 125A or better yet 150A. It is generally suggested not to exceed 250A pull from a battery bank. I run 24V, 120V coffee maker takes 52A while running (no warmer), 1200W Panasonic Inverter Microwave 75A while running. Just to give you real time examples.

There are different types of BMS and many have multiple applications. The most common ones are the FET based (no relays) and the SmartBMS' are the preferred choice because they can be programmed via a phone app and adjusted / monitored as desired. It is generally suggested to Derate them so for a 150A Usage, a 200A BMS would not be out of order. Currently the most popular ones in use are from JBD or JKBMS which are available from various sources. Features, Functions and Capabilities of course affect the cost so it is wise to really think it through.

I should point out, that depending in Inverter, Solar Charge Controller or AIO (All-In-One) units selected, there is some possibilities to have BMS' that can interact with these to make a better all around system.

It is CRITICAL to come up with a Plan because without a Plan, you have a plan to fail. Take your time, do your research, ask lots of questions and Do NOT Buy ANYTHING till you have a plan.

 

[RetiredSparky]

For a 3000W Inverter, you will want to be able to deliver a minimum of 125A or better yet 150A. It is generally suggested not to exceed 250A pull from a battery bank. I run 24V, 120V coffee maker takes 52A while running (no warmer), 1200W Panasonic Inverter Microwave 75A while running. Just to give you real time examples.

There are different types of BMS and many have multiple applications. The most common ones are the FET based (no relays) and the SmartBMS' are the preferred choice because they can be programmed via a phone app and adjusted / monitored as desired. It is generally suggested to Derate them so for a 150A Usage, a 200A BMS would not be out of order. Currently the most popular ones in use are from JBD or JKBMS which are available from various sources. Features, Functions and Capabilities of course affect the cost so it is wise to really think it through.

I should point out, that depending in Inverter, Solar Charge Controller or AIO (All-In-One) units selected, there is some possibilities to have BMS' that can interact with these to make a better all around system.

It is CRITICAL to come up with a Plan because without a Plan, you have a plan to fail. Take your time, do your research, ask lots of questions and Do NOT Buy ANYTHING till you have a plan.

Steve, Thank you for your help here. I do not think that I will really need the 3kw inverter's full potential in the van build. Buying the inverter with a 150% rating over what I need will insure it runs cool and is not stressed. I may wind up needing a larger one later as the system will be removed from the van in a few years and used for something else. I do have reasons for this but do not want to sidetrack this thread now. I will provide overcurrent protection for each battery separately and the rest of the system too as the final components need. I do want to order a large LFP battery bank now as it is a very long lead time. I started reading up on BMS options and realized how complicated a question the BMS is. I do definitely want communications with every component is the system that can be communicated with. Communication with each BMS would be better than just a battery monitor with a shunt. I will have a Battery Monitor also. Not sure that system communications will be easy after reading on this site the last few days. It seems most solar components on the market today are not built to talk to each other. Of course I just stared into this in the last few weeks or so. But that subject will be in a different thread. I do know this system will be expensive. More so if not done right the first time so I do not want to pinch pennies here. Anyway from reading your reply are you saying it may be better to build a bank of 4 smaller 24v batteries and connecting them in parallel? From what I have read on here this week 12v in series is not the best idea. It seems the BMS does not work well in that configuration. Reading that is what made me think to write this question here before buying LFP cells. I think around 600ah or more at 24v will work for me.
What are my options for BMS communications available in the market now? I have been looking to build this system with a central control display connecting it all together. I have not seen much so far that you do not have to write your own code to tie it to a central display control panel. It seems most components used by people here do not have a com port. Some that do will only communicate with the single display they made for that specific component. Seems rather short sighted of the marketing potential by manufactures. I did see a YouTube video on the Victron Cerbo unit this morning. I like what I saw as far as communication capability output to one touch screen control display. Local Bluetooth in the RV with a remote internet connection option too. Just don't know that I can limit myself to only Victron components. I plan to research this Cerbo device more after I post this reply and do lunch. What BMS has the most wildly accepted communication options? What com outputs can you get on a BMS? If the BMS communication will not tie into everything else. What BMS is available with the best control and monitoring interface of it's own? I find I need to order the two long lead items now and then select the best component options for the rest of it afterward. The one component I think I should be able to get away with doing this is the LFP cells. I would not prefer to do it except for the lead time involved.
Yea not the best plan I know.

 

[RetiredSparky]

I decided to buy one of Will’s recommended batteries retail.