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Simple Diy 48v lifepo4 battery bank

Gauranga108

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Oct 5, 2020
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Hi I am fairly new to the forum but have been interested and dealing with solar for a few year, so please bare with me. I currently have a 3.1 kw solar array with a midnightclassic 150 charger and a magnum ms4448pae with Magnum mmp175-30d mini panel. This currently runs a small house with a well pump. I will attach pdf files corresponding to those items. I am phazing out of my old 8 lead acid crown 430ah battery bank and looking to go with a simple diy 48v system. My system build should be straight forward and probably will be to most of you but the only factor is my 230v 30 amp 1.5 hp franklin submersible well pump. My lead acids never had a problem running them but recently I purchased a meritsun 10kwh hour bank from alibaba but for the luck of me I have not been able to get it to run the well pump...everything else no problem. Link to that thread I posted earlier regarding troubleshooting.https://diysolarforum.com/threads/new-48v-200ah-10kwh-battery-troubleshooting.13094/
Ling story short i will be selling it. That being send at max draw the well pump before it flips its own breaker would draw 30 amps at 230v which I calculated to be just around 160 DC amps for the inverter to need to produce this (considering the startup amps of the well pump). Other than that my loads are basic and my 4400 watt inverter does great. I would like to make this beafy with larger bus bars or doubled up factory ones so that i can pull plus 160amps continuous without harming them.. My system was easily able to recharge the meritsun 200ah 10kw powerwall so I was leaning towards 280ah cells but may have heard that wasn't the best. Need advice on full battery bank build including cells with alibaba links if possible, bms or multiple bms if two strings in parallel, bus bars, case for system if you have creative ideas if not I can manage ?, and anything other that is nessary to have a simple, safe Reliable system. In advance thank you all.
 

Attachments

  • 64-0032-Rev-A-MS-PAE-Series.pdf
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  • spec_sheet_classic_back (2).pdf
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Considering alibaba pricing i have a good size budget so don't let price stop you from posting if you have any good or better options
 
OK well if I go with those cells what about reliable bms rated to handle 160 amps continuous as well as proper bus bar size? Any thoughts.
 
Before you do anything, I would suspect your BMS, your batteries are probably fine especially since you say your LeadAcid handled the load.

To confirm this I would bypass your BMS and connect your inverter directly to the batteries.
Then check if your well pump works. If it does (which I suspect it will) you save yourself a lot of money.

I had the same problem with an AC unit not starting. The BMS was not up to the task.
Your inverter will cut out at LVD and save your batteries in any case.

Let me know what you find.
 
Your inverter will cut out at LVD and save your batteries in any case.
I was thinking as you were but got stumped by this:
That being send at max draw the well pump before it flips its own breaker would draw 30 amps at 230v which I calculated to be just around 160 DC amps
What would cause the pump's own breaker to trip if the inverter went into LVD?

OP: What is the amp rating of the pumps own (internal?) breaker?
 
30 amps is the wells internal breaker or in this case its got its breakers in a control box. When I put a clamp meter to test current on the wires coming from the pumps control box while running the lead acid bank it averaged out per leg just as franklin says its should around 11 amps to 11.5 per leg. But upon start up (hint the high 30 amp 230v breaker) it spiked to around 26 - 28 amps per leg but it happened so fast so its hard to get an accurate reading without some other electronic curret logging device. I was also feeling the same way about using the rs232 port to mess with the bms but I have a feeling Meritsun would voide my warranty (whatever thats worth) or worse just not give me the information to do so. The battery is rated i believe at 1c so technically it should be able to do 200amp continuous in theory but I am sure like dzl said the will probably set it to .5 c making sense why there website says 100 amps continuous. But I am also wondering if that also means the busbars are undersized as well as the wires coming off the bms and or the bms itself. I didn't want to restart my troubleshooting thread in this build out ...lol ? I guess we're going with the flow here.
 
Well pump breaker was never breaking just batteries bms with SC CODE ( sort circuit protection
 
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