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Great point. I am building to fit into an RV battery compartment. The battery tray is 21" x 28 5/8". The vertical clearance is 20". I am trying to build batteries that 1) use the maximum volume of the compartment available, 2) have a weight that I can handle and 3) have some failure...

I solved my problem with some help from another site. Basically, I could not tell a temperature change during charging because my charging capabilities are limited to about 30 amps. Also, the delta v was stopping the charge early. I charged very slowly using an active balancer until I got my...

32650 LFP cells I bought at Battery Hookup. https://batteryhookup.com/ They have two 32650 cells listed: 5000mAh and 6000mAh. I am using the 6000mAh cells.

When I started to charge my new complete battery, my section variations were off by somewhere between 30mv and 120mv, as I remember. I did not worry about the exact amounts. I had planned to bring the battery up to a full balanced charge over several charge cycles. On the last charge cycle...

The First 21P4S Battery Making the Heavy Current Connections I want my internal battery connections to be able to carry high currents without heating. Copper is the best readily available conductor. But I do not have the machinery to weld copper. My solution is to use copper 12 awg wires to...

I built a 2P4S prismatic battery with an estimated total capacity of 560 Ah. This is not my first build. I am using the android app to monitor the BMS, an iCharger X8 for charge controlling, and a Fluke 87V meter to check the other two voltage readings. Of the Five batteries that I have built...

I just completed my 3rd battery build and have run into a problem. I think I have a bad cell and want to verify my findings and approach before I tear the battery apart. My build is a 21p4s battery using 6000mAh 32650 cells. This should give me a 126 Ah battery by calculation. The first two...

All good suggestions. First check I made was to verify sensing harness connections end for end. I did both resistance checks with the wires lifted, and voltage checks with the wires attached. My first assumption when errors occur is that I made the error. The charge, discharge and charge...

This posts covers some of my research and tools that I used. The attached pdf has the complete8 page document and the attached spreadsheet is the one I use to do my battery design. This is the first large battery that I have built. It has tested out at around 135 Ah and supplied 110 amps...

Section 4 The First 21P4S Battery Electrical Circuit Fundamentals and Laws The construction of this 212P4S battery is a massive series/parallel circuit. And always the laws of electricity developed by Geog Ohm and Gustav Kirchhoff will apply. The two laws that every circuit designer should be...

I think that we need to state some dimensions to be ale to verify calculations. Sometimes different assumption lead to different figure which leads to pointless conversations. The 32650 cells measure 1.25 dia by 2.75 tall. This gives me a volume of 3.37 cu-in. We are close to agreement...

I think that I forgot to add the words" to my house" when I mentioned my solar install. My bad if I caused a misunderstanding. The Installation described is a grid tie system on my home. This means that if the commercial power supply goes off line, my system shuts down. I am pretty sure...

Happy Holidays to all. I hope this post finds everyone healthy and safe, and to those that are suffering or have family members suffering, I send you my prayers. I have decided to open a post in the show and tell forum in the next day or so and describe my journey, my thoughts, my successes...

I am using the 32650 6000mAh cells from Battery Hookup in a 21P4S build. Using a iCharger X8, I charged the battery to 3.65 volts per cell and reduced the charge rate when the cells reached 3.55 volts to 1 amp. The iCharger reduced the charge to an even lower rate and the battery balanced out...

Battery Build Project Section Three Proof of concept. I decided to build a smaller version of my final battery for testing, etc. After briefly considering building my own welder, I decided to purchase a kWeld welder. I found it to be an excellent tool, but it does have its limits. I tried...

My projected charging plan is to look for every opportunity to add to the battery charge as well as looking what and where we expend energy. In my youth, I carried tents and canoes in the Quetico / Superior parks and thoroughly enjoyed myself. I also canoed and camped on the Spring River and...

I have built a 21P4S LFP battery using 32650 6000mAh cells from Battery Hookup. This build calculates out to be a 126ah battery with a maximum continuous current of 378 amps. Since I intend this battery to be part of a house battery group in an RV, I chose to design for 120 Amps continuous...

Battery Build Project Section Three Basic Layout and Assembly For the first large battery, I have chosen a 21P4S flat assembly. This will use 84 cells, and give me a 126aH battery. I purchased pieces two pieces of HDP 1/4" thick plastic and some 1/4" acrylic squares. I arranged the bottom...

I am using the 120A BMS from Overkill Solar.

Initial Welded Connections and Top Balancing Making the Initial Welded Connections and Top Balancing These two pictures show the initial connections made on the battery. The strips that connect the positive ends of the cells are 0.3mm by 8mm nickel. At this point I am making connections to...

I made a decision several months ago to investigate and build a 12 volt 100ah sized battery for an RV. I was recovering from shoulder surgery and had plenty of time on my hands. After completing my first build, I decided to document what I had done. I am going to split this project into a...

I look forward to your analysis. A little of my background. I am an Elevator Mechanic. I began as a Field Engineer in 1981. Your last statement, "Unfortunately, when it comes to stuff failing it is not if, it is when" is a statement that I have seen proven over and over again for 40 years...

With regards to my solar build, maybe some background will explain my thought processes and decisions. Some are interested in history and points of view, others may just want to skip to the conclusions. In the 70s I had a converted van that I used to camp in at times. The deep cycle battery...

My next post goes into the final building phase. During my testing, I was able to get a pretty steady 111 amps for about 1 hour. The limit on the current draw was due to my inverter and load and not the battery. During the test, I was looking for any signs of conductor/connection heating...