Cheap 4kwh LiFePO4 batteries from Battery Hookup
- Thread starter Will Prowse
- Start date
I'm thinking of doing the same thing, I know I could get by with just one battery pack, but with the price shipping I'm thinking I'll buy two, and be able to run a airconditioner.
I just received my Meanwell PSP-600-27 power supply from Amazon at an amazing $35 and in two days time. That is no longer available on Amazon (cheapest right now is $125) but Alibaba.com has these in lots of 1 unit for between $35-$55. Of course, it will take a month to get them. I also found a spec sheet from the manufacturer showing how to parallel up to 4 of these power supplies to increase current. https://www.mouser.com/datasheet/2/260/PSP-600-SPEC-806243.pdf . So can anyone tell me why I cannot just use this power supply alone to charge up my single test BYD battery? and then parallel them to charge up my parallel connected 4 - 6 BYD battery pack at 27 volts and 88 amps? for a cost of about $150?
OK. I want to use 4 of these for my battery bank. Can you recommend a couple charge controllers that can accommodate my 4700w solar array? My array is divided into two separate feeds.
j
My inexperience ignorance.
Keith C
Ahhh, the sharks have him.
You shouldn't because:
It has no current adjustment. So it has no constant current setting. You can't, say, set it to 10A and the peak voltage you want to charge to and let'er rip. Instead you will hook it to the battery and it will try to force the battery to exactly what the supply's output is instantly. Likely tripping the supply's own protection while going out of regulation.
You can weasel it by measuring the battery voltage and setting the supply's to the exact same voltage.
Then you MUST put an ammeter in series to see what's happening. Use a meter with a 10A or more current setting. Once that's in place the supply is set to the battery voltage you can power it up. Use safety glasses, (of course), as you're messing with big power here. If you're using a typical meter with banana plugs do not go over about 3 amps as the cords and bananas can't cut it.
Slowly turn up the voltage adjust on the Meanwell PSP-600-27 while watching the ammeter. Don't exceed those 3A. Have at it. Make sure you FREQUENTLY check each cell to make sure you aren't taking one over the cell max. You essentially need to play human BMS for the next umpteen hours. Set alarms on your phone don't forget. Do not go to sleep during the process. Check wire temps occasionally.
Thanks for the input. I have a ToolKitRC M8S charge controller that takes 7 - 30 V DC input and allows full control of charging voltages, has a cell balancing while charging function, and allows me to control amps as well. I think my MeanWell PSP-600-27 power supply can drive this charge controller. I have drained my test BYD battery to 22.4 v and am ready to charge it back up for the first time. I plan to set the cutoff voltage at 28.8 v (3.6 v per cell). What charging amp setting should I use the first few cycles to test capacity of this nominal 220 Ah battery? The charge controller amperage can be set from 1 - 18 amps.
Keith C
Ahhh, the sharks have him.
I can't speak for the ToolKitRC M8S charge controller but it looks like it would work for you. Let us know how it goes.
FINALLY! I am charging up my first BYD battery. Here is my setup.
A MeanWell PSP-600-27 power supply is feeding 29 v at up to 22 amp into the ToolkitRC M8S balancing charge controller. The balance wire harness is self made with #14 wire and machine screwed into the holes of the BYD cell busbars. The M8S is set to charge up to a cell voltage of 2.55 v as a first stage cutoff using 10 amp of current. Keeping it low on this first cycle. The negative output of the M8S goes through a 250 amp shunt meter to the battery. The positive output of the M8S goes through a relay/fuse switch which functions as an on/off switch to the battery. It took only two hours to get all 8 cells to the same voltage with a delta of 0.019 v, down from 0.203 v when battery was empty. That all looks positive to me so far. Next step is to see how long it takes to charge up to the 28.4 v cutoff point and end of stage one charging. Any comments? Suggestions?
A MeanWell PSP-600-27 power supply is feeding 29 v at up to 22 amp into the ToolkitRC M8S balancing charge controller. The balance wire harness is self made with #14 wire and machine screwed into the holes of the BYD cell busbars. The M8S is set to charge up to a cell voltage of 2.55 v as a first stage cutoff using 10 amp of current. Keeping it low on this first cycle. The negative output of the M8S goes through a 250 amp shunt meter to the battery. The positive output of the M8S goes through a relay/fuse switch which functions as an on/off switch to the battery. It took only two hours to get all 8 cells to the same voltage with a delta of 0.019 v, down from 0.203 v when battery was empty. That all looks positive to me so far. Next step is to see how long it takes to charge up to the 28.4 v cutoff point and end of stage one charging. Any comments? Suggestions?
The ToolkitRC M8S balancing charge controller is capable of measuring internal resistance. I measured the IR of each of the 8 cells of my test BYD battery and found these results: 0.4, 0.4, 0.5, 1.9, 0.4, 0.4 1.4, 0.4 mR (which I believe stands for milli-ohms ?). From some manufacturer spec sheets, my understanding is that any value < 0.8 mR is good. So what does it mean to me practically that my two cells that are 1.9 and 1.4 mR are outside this range. These are the very two cells that were the lowest in my discharging of the BYD to get it "empty". Any thoughts?
Thanks for the tip. Once the battery is charged up, I will put the IR meter on the separate balancing wires that came with the battery and see if I get a different reading. If yes, I will redo those connectors to the two cells. If not, it confirms that there is something amiss with those two cells. Then the question is how serious it is if I go 80% - 20% charge/discharge.
Maast
Compulsive Tinkerer
It'd work but you'd have to have two of them in series @ 30v each for a total of 60v
The user manual of the cheap Chinese solar charge controller I used for a portable solar generator I built last year specifically prohibited using shore power instead of solar power to drive the charge controller. It may be the Victron is a much more sophisticated piece of equipment and has no such restrictions. It might be best to check with Victron directly just to be sure. It would be very helpful to be able to use only one charge controller for all power going to the batteries. Has anyone actually done this?
Maast
Compulsive Tinkerer
Sorry, didnt finish the thought before I posted: it'd work, but dont know why you'd want to - unless you're using the charge controller to limit the current output.
And I'm not sure why you'd want to do that either since these are ~220ah cells so the 22A from the power supply is only a .1C charge rate which is a fairly low charge rate. These are honking big cells - a .5C rate is going to be 100 amps, .1C is just tickling them.
If you attach the PSP supply to a fairly discharged battery it'll immediately begin supplying its max amperage rate until you hit about 3.35v per cell, then the amperage begins to taper off until the pack voltage meets the power supply voltage and the amperage has tapered to zero.
On the byd pack I have on my bench when I attached the PS it put out 24A but the highest voltage I've gone is 27.2v (3.4v/cell). Havent gotten any farther than that as I had to unplug the PS & set aside everything for the last 5 days and drive to eastern Oregon for family matters. BTW The pack voltage 5 days later is 26.8. Not going to go higher until I can attach the active balancers and begin charging to 3.55v/cell and I'm waiting for my 9 conductor 16awg speed wire to come in before I do that.
Darkstar
Rain Wrangler
- Joined
- Dec 31, 2019
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jasonhc73
Cat herder, and dog toy tosser.
28.4V is for new cells(3.55V per cell). I am doing 56.5(3.53V) for bulk and then float at 51.2. (28.25 and 25.6)
Bulk charge them, let them absorb, see where they absorb to, and just let them sit. I bulk for at only 20 amps for all 64 cells (I have 8 packs). My 16S4P setup settles very nicely at 52.2V (26.1V). I bulk them with 56.5 @ only 20 amps, they absorb and settle at 52.2, and stay there. I just finished a cycle and did 60 hours of just sitting pretty and 52.2V is their natural degraded resting state. When I received my batteries mine was sitting at 23.3 to 23.6V, and probably out of service for over 2 full years.
Remember, these are VERY used, 28.4V is what to use for brand new batteries. Crack the whip easy and let these batteries graze on the amps relaxed. These batteries have extremely high power potential. I am getting so much more utility out them than I could have ever imagined possible, especially when you compare them to brand new pricing.
Jason: thanks for this very timely posting. I have just finished with 14 hours of charging my first cycle on my BYD battery and my anxiety level if high trying to figure out what I did wrong. I charged my one BYD test battery at 10 amps with a cutoff voltage of 3.55 per cell. It went overnight and I found it stopped out in the morning. The thing that caused my anxiety to go high is that the shunt only recorded 1.15 KwH and 40 Ah accumulation in the battery. I then reduced the amps to only 5 amps and increased the cutoff voltage on my balancing charge controller to 3.6 v per cell. It got there in 30 min more with final reading of 1.18 KwH and 44.5 Ah. Thats only 26% of the expected capacity of 4.5 KwH and 160 Ah. So I freaked out wondering what went wrong. The current settled voltage is 26.76 or 3.34 per cell.
What was your capacity for your batteries? If you could put it in terms of a single BYD expected battery capacity of 4.5 KwH that would be helpful.
I am planning to let the battery rest for a day or two and then discharge it again down to about 2.8 v per cell and recharge for my second cycle. Any suggestions and ideas?
