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Finally got my 18 module BYD bank complete. It's the most polished turd you'll ever see. About 6 months of stripping, cycling, testing and correcting. 2160lbs. I ended up adding 65ish 15ah cells to correct the undercapacity cells in the modules. Each cell is paralleled with 6 gauge wire and...

I wrote this in another thread and I thought it'd be useful in it's own thread instead buried 4 pages down. You've might have read me talk about using off-the-shelf CC power supplies to charge cells. The same logic applies to every charger. Lets step through each phase of a charge cycle and...

I've been buying BIG lifepo4 cells from 5 different vendors on Alibaba in the 260-280AH size, each one weighs 12 pounds. I've taken a nasty hit on shipping by buying just one cell from each vendor but since I intend on buying another 48 of them I thought it worth the investment to get and...

Finally got it done, if it looks like a kludge it's because it is - but it still works, and pretty well at that. It'll charge up a cell, then discharge it to a load and then charge it again and just keep doing that until I interrupt it. Unfortunately my data collection is having to manually...

Took a bit but they're here. Bought it on the 12th and they arrived on the 30th. UPS tracking said the pallet actually arrived in the local area the 24th. Not too terribly bad coming from the far side of the country. Pretty good deal for $300 a pop and they gave me a 'bakers dozen' for the...

Summary: I ran a series of 6 full charge/discharge tests with/without active balancing and/or with/without adding capacity. The BYD module I tested had 1 badly undercapacity and one moderately undercapacity cell and has a unmodified 3.2kwh capacity. At a 1700W discharge rate with only active...

Probably not of much interest to anybody, but I was poking around their online store looking to pick up another couple of contactors because I was reading the specs on the ones I have and their max coil voltage was 54V. Doh! There goes another couple hundred bucks. At any rate it turns out...

This is the first and easiest DIY battery tester for lifepo4 battery cells, this is for a SINGLE 3.2V cell ONLY. If you attempt to use a 12V battery you'll melt the load, set your dog on fire and make your kids drop out of school. You have been warned. Overall cost is about $130 US which is...

Came across this as a reference in a thread, it's possibly the most useful article I've ever came across about LFP charging regimes. Evidently there actually is a well documented memory effect on LFP cells and that always holding charge voltages low to avoid overcharging the cells is...

I thought I'd just pass along a 'gotcha' I encountered on my JK BMS (also known as a Heltec) bluetooth active balancer that had me in a panic for a couple of days. Hopefully if somebody in the future searches the symptoms they'll find this post. I powered it off by unplugging the molex block...

Made a 20A/cell 8-cell charger so I can charge all the cells up to the same voltage. I was having a hell of a time getting a balanced charge for these used BYD modules so I can test them. Built my own because I couldnt find a 8 cell charger that would charge individual cells separately that...

Whats the latest best value DC-DC charger from the starter battery to the house bank? The latest I remember seeing was a 50A from Renology but that sucker is 300 bucks, is there anything out there thats a better value that doesnt require connection to the ignition switch? Havent been posting...

I've been back-of-the-envelope designing supplemental EMP and transients protection for my system using tvs diodes in conjunction with the Midnight lightning arresters (I can build them cheaper than just buying them, but they're inexpensive and the time savings is worth it). I recently saw...

I want a wind turbine to boondock at the coast but it just doesnt make sense no matter how I massage it. We've got a lot in a place called Ocean Shores in Washington, the only thing between the lot and the ocean is about a quarter-mile of sand so the wind is constant and strong averaging about...

Received 36 cells and 5 cells were either bad or marginal: 3 were completely bad with .021V 1.8V and 2.1V, the marginals had 2.77 and 2.8V - since all the others were 3.0-3.11v (almost all 3.05-3.08V with a few outliers) the marginals had obviously self-discharged and are not something I want...

One of the manufacturers that I've been corresponded with put out this video on the manufacturing of LFP cells. I thought it was very informative - if not exactly thrilling. It's about 18 mins long. In short: what makes a A cell is it doesn't self discharge beyond spec, the internal...

It seems to me there is a sudden flood of new users that are asking super-vague questions without details that seem calculated to use up as much research time for a answer-er as possible. And getting them to clarify what they're asking about is like pulling teeth. This is beyond the usual...

Cut out a bad cell 1 and spliced in a good one from a doner pack. Used 2" ratchet straps to recompress the pack and I tied them down with commercial net cord (technically called no stretch hard lay gangen twine) using what I've always called a double pulley truckers knot. You can get things...

I've been looking all over for wire that doesnt break the bank to hook up the 8 individual cells in the modules to aggregate/parallel all the cells into 16 cell groups w/ 12 cells per group to attach the Chargery cell monitor and 1S active balancer daisy chain. If I were to do it with...

Thought this might help if anybody is thinking of DIYing their own code compliant system.

Found the perfect series of metal electrical enclosures to hold all the battery paraphernalia: DC breakers, shunts, contactors, etc, etc, etc. They go from little 8 inch by 8 inch jobbies though every size and depth you can think of up to huge ones like 34x32x12. I just picked up a...

Just saw a post on the DIY battery facebook group about adding cells in parallel with individual weak cells in the BYD modules to correct for them not being up to par. I'm thinking its a pretty good idea. There'd be a good bit of trial-and-error with adding a cell, cycling it to see the...

I've seen so often here and other sites the "Is this a good battery?" question but there is no way to know unless somebody has already bought them and as far as I know nobody has done full lifecycle testing on their batteries they sell. Chinese vendor published cycle test results are at best...

Bought a stack of these on Aliexpress to even up the mismatched capacity of my BYD packs. According to online reviews their smaller ones are testing out close to capacity so I thought I'd take a gamble - that and how inexpensive they were seem worth it. When you buy 8 it works out to something...

Rerigging battery tester for the 24V BYD modules and found these used on ebay for only $28, they're usually $145 power supplies. They're perfect: current limiting AND current sharing (built to be stacked), adjustable 24-30V, and do all kind of functions we'll never use. Even after I picked up...

After a good bit of thrashing around, I'm now thinking its a very good idea to use 48v coil contactors/relays for 200A and more. The reason being is that you have a 48v source ready to hand and you wouldnt need an additional 12v power source thats burning additional juice to run. The same...

From this page https://suntiago.com/essential-information/brands-ranking/#inverters I've been considering requesting if @Amy Wan (Luyuan) would be interested in acting as a purchase agent for members of the forum for top-quality inverters manufactured in China. Trust is a precious commodity...

I just bought 17 of them (16 and a spare) for 20 bucks a pop including shipping from Alibaba. I'd swear they were around 10 bucks just a year or so ago. I went with the 1s units because when one fails I can replace just the one unit and not a 8 unit board. I wanted to save a few bucks but...

Voltage is a terrible way to keep track of SOC unless you're already deep into the 'knees' and if thats what you're trying to avoid its already too late. I suppose if you had a really LARGE bank the inputs and outputs would still keep the C rate low enough its would be sorta accurate without...

Just smoked my modified APC Smart UPS SUA1000, we had the power go out and I didnt have the cooling fan enabled because I'd turned it off and forgot about it. I need a inexpensive good value inverter/charger to act as a UPS for a while until get the Radian based whole house UPS going. I could...