1088Ah 32 cell LiFePO4 Lishen 24-Volt 8S4P build, actually 4P8S as parallel connections are 1st.

michael d

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Assembly idea for you all: As I manually lifted and moved the 4 cell Lishen cells to assemble them into the 32 cell build, onto a larger base, I found they did not slide as well as I wanted. So I added a piece of the chopping mat I bought at the dollar store under each set of 4 cells connected in parallel. I put the smooth side up so the cells can be slid a bit easier. 4 cells at 5.3kg each is still 46.64 pounds plus busbars. 8 of the 4 cell packs will weigh 373.12 pounds. I bought 5/16 inch threaded rods and washers and nuts for the compression jig. This week hopefully, I will have it assembled. the Electrodacus SBMS0 arrived last week; then came the honey-do list and the holiday. I will post some pictures later.
 
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michael d

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finally, the 32 cells are all connected.

4P8S configuration; all cells hooked in groups of 4 in parallel 1st; then the groups of 4 paralleled cells are hooked together in series.

I checked voltage after each series connection.
the 32 cell battery is presently at 27.35 volts.
I changed my design to make 1 long set.
it is 63 inches long.
here is a preview picture.
I will hook 4 positives and 4 negatives to their own busbar.
I still have to make those cables. 20210909_170911.jpg
 

michael d

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did you run all parallels 1st? then the series. if you look at my last post I do 4 cells in parallel 1st. then I connect each group of 4 ins series with 4 more 2/0 cables that are about 4 inches long center to center. This evens out the current from parallel group to parallel group.
time will tell how it works. I will update as time goes by.
the engineer said to connect the cells this way.
then I will have 4 cables out of the positive end and 4 cables out of the negative end to their respective busbars.
A 400 amp class T fuse with 4/0 wires to the inverter on the positive busbar.
The 32 cell 4P8S battery was all assembled yesterday and had a 27.35 volt SOC.
I will re-snug the connections but need to get the Electrodacus SBMS0 sense wires and shunt connections done.
 

michael d

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update: I made the 8 2/0 10 inch cables (hydraulically crimped) for the main positive and main negative today. I got the 4 positive cables connected to the main positive bus bar from the 32 cell battery.😎 here are a couple of pics. had to go to get some 1/4 inch bolts ss >>>the ss lock washer cost the most $1.79 for 8 . wow.😥
 

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michael d

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wow, my title is even wrong. it should say LiFePO4.
3.2x8x272x4= 27,852.8Wh potential capacity.
they are hooked in parallel 1st then in series 4P8S.
I am planning to utilize the middle part as much as possible and stay above 25 volts most of the time.
I need someone to proofread before I post.
at any rate, I have the 4 2/0 10inch long cables hooked to a positive busbar and 4 2/0 10 inch long cables hooked to the negative busbar. the positive busbar has red insulators and the negative busbar has black insulators. I checked the voltage and it is still 27.35 volts. once I get the BMS hooked up and the busbars mounted a bit more solid >>> then I will hook up to the 15,000-watt inverter and use some of the voltage.
today (40) 250-watt solar panels arrived on a delivery truck, so lots to do before winter arrives in full force.
 

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michael d

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Catastrophe avoided yesterday!!!!be careful! always check and recheck what you are doing!
I use red for positive and black for negative for the main positive and main negative cables respectively. but when in a hurry, mistakes can be made. Lucky for me I had a 400 amp class T fuse holder in place without the fuse in it. This acted as a break in the wire so no electricity could flow through the 1088Ah 32 cell 24-volt battery build.
why was this important to my mistake? as I was adding the 500 amp Deltec shunts I found that I had them on the negative end of the battery and needed them on the positive end of the battery for the SBMS0.
more importantly >>> the major mistake was I had the negative directly shorted to the positive with busbars and large cables but the fuse holder did not have the fuse>>>> whew hoo >>>> thank you, Lord!!!!
I had to remove the shunts and bus bar on that end move them to the other end, make new cables for a slightly different length setup. But this missing 400 amp class T fuse saved my (XXX) from a huge dangerous arc and possible fire.
I color code and label as much as possible. but I only had red 2/0 cable so the 4 reds which normally would be black for negative eluded me, >>> what alerted me was the battery cells that I labeled clearly with a piece of red tape on the positive end and a label maker white label that says positive. I did this on all of the Lishen 272Ah cells after an accidental arc about 10 months ago. I will show a pic of the negative end. and maybe you can see what I mean.
the problem of covering up the battery cell terminals when assembling is you can lose orientation more easily of what is positive and what is negative.
Lucky for me; This disaster/catastrophe was
avoided!!!!!
 

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michael d

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added a Bue Sea disconnect switch on the negative end of the battery. All is functioning as expected. The 32 cell 4P8S Lishen 25.2 nominal volt battery is at 100 percent SOC.
this LiFePO4 battery build is a 1088Ah 27852.8 Wh potential capacity and then some.
I am running small loads with an inverter until I get more solar hooked up.
I added the disconnect switch as I had a spark trying to install the class T fuse and it spooked me a bit,(imagine the 400Amp class T fuse flying through the air if you will)! 😮
I turned on the inverter and drained the capacitors with the battery disconnected.
then installed the class T fuse without a spark. 😎
 

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Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
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just a touch of clarity with regards to how lucky you got.
Appreciate that LFP will Surge Dump at 5C eh ! IE, when a Short happens. Had you been holding "the stick" we would be sending wishes to your widow. Do the math, yes, scare yourself ! 32x272AH cells dumping at 5C Burst... that's more than a Tingle ! BTW: That amount will Vapourize a Socket Wrench and the fool attached to it.
 

michael d

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just a touch of clarity with regards to how lucky you got.
Appreciate that LFP will Surge Dump at 5C eh ! IE, when a Short happens. Had you been holding "the stick" we would be sending wishes to your widow. Do the math, yes, scare yourself ! 32x272AH cells dumping at 5C Burst... that's more than a Tingle ! BTW: That amount will Vapourize a Socket Wrench and the fool attached to it.
Yes, I was wearing gloves to insulate my hands; and yes, I have seen the arc welding capability of the DC voltage in a 24-volt battery before. yes, I definitely respect this power and I am trying to be as careful as I can be. one has to be extra careful; that is why I tell of what happened. the DIY community needs to know and it is not as easy as some would like to portray.
according to the inverter guy it was likely the charged capacitor giving feedback or a normal somewhat scary 24-volt spark. 😎 the negative and positive are about 4 feet apart. I was working on the final connection on the positive end. this 400 Amp class T fuse was installed between the inverter and the battery to protect the inverter. thanks for reemphasizing the danger! 😍
the spark left a black mark on the fuse next to where the bolt hole on the fuse is, but did not destroy it in the quick very short touch connection.
I had not got the nut on the blue sea fuse holder yet so no wrench or socket was involved in this spark incident.
 

740GLE

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Out of curiosity why the need of 15000w inverter? Electric range? AC? Have to imagine it’s split phase?

What’s the idle draw of that inverter?
 

michael d

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Out of curiosity why the need of 15000w inverter? Electric range? AC? Have to imagine it’s split phase?

What’s the idle draw of that inverter?
I have an electric cooktop with 4 burners and an electric oven also, window air conditioners at present. yes, the inverter is split-phase. on the 15k inverter; the watts on The no-load is about 36 I think --- I will have to verify that better later. says 4 watts with all turned off but likely closer to 36 watts.
this is an off-grid whole house build. I plan to use the excess solar PV to heat the house this winter with diversion heating of water and resistive heaters etc. the LiFePO4 batteries are the reserve for overnight and cloudy days. I have 4 24-volt water heating elements and other things to save the electricity generated into heat storage. I also bought 24-volt water pumps etc. the intent is to go all-electric and get off the grid completely. I bought another 32 280Ah cells that are en route at this time for another battery build. I have a welder and an air compressor and other electric tools so I do not care to be limited by small battery capacity or inverter size. more later,
I have had 2 inverters running 24/7 for the past 10 months and I will add the 3rd inverter running 24/7 shortly>>>when I get more solar panels connected.😎
 

michael d

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If/when the high-efficiency propane furnace kicks on, it has a blower motor that is 120 volt also for winter. I have a propane heater that requires no electricity to operate upstairs, but would like to get off the propane or at least reduce it to minimal use as well. more insulation will help some as well!
 

michael d

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then there is also the electric clothes dryer, another 220volt load! I bought some cement to set up more solar panel round mounts to increase the PV power.
the Electrodacus SBMS0 is balancing the 32 cell battery and there is about an 8-10 mV delta between the cells in parallel....need/want lots of electrical conveniences >>>> more power arh arh arh!
anyone who thinks a small battery is going to work with a few panels in a large whole house(for a family) off-grid is wanting to live like a hermit... not me!😎
I use the Electrodacus DSSR20's as the solar charge controllers to sets of 2 250-watt 60 cell PV panels connected in parallel at the solar array. they work great and have no problems charging the LiFeP04 battery builds. more later!
 

michael d

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ground mounts. so I can remove the snow this winter and clean it in the summer. who wants to climb up on top of a 2 story roof (winter or summer) to maintain solar panels. The ground mounting of the solar PV panels makes the most sense for me. I have 6.6 acres at this site so ground space is easy to find.😎
 

michael d

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32 cell 25.6-volt nominal battery fully charged from the 4 solar panels.
32cell (272Ah Lishen) parallel 1st, then series connected so 32Lishen cells x 272Ah x 3.2nominal volts/cell = 27,852.8 Wh potential capacity @ 1088Amps.
I have 2 used 250watt PV panels facing south and 2 250watt PV panels facing to the west.
the south-facing 2 PV panels do most of the charging as the west 2 panels are getting a lot of shade right now >>> need to cut some more trees.
every 2 panels are connected in parallel at the array, then a set(black for negative and red for positive) of 10AWG wire runs about 60-70 feet or more to the Electrodacus DSSR20 which is the solar charge controller for each set of 2 PV panels. then the Electrodacus SBMS0 controls the charging.
Each set of 2 PV panels has a set of the 10AWG wires run to the off-grid solar power shed.
next up is more panels and more array support construction. each array section supports 6 250watt PV panels at this time with unistrut and treated 2x6 frames.
 
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