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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'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...

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...

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...

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...

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...

If you crimp, put a zinc based antioxidant inside the crimp before you do it. It'll squeeze out of the way of the direct copper-to-copper contact and the zinc will help whatever is not making contact conduct. Furthermore it'll keep oxygen and moisture from degrading the copper-to-copper...

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...

Bit of an object lesson there: unless it says Bussman, Buss or BlueSea those knock-off thermal breakers are absolute crap and will fail an/or trip WAY below what they're supposed to be rated at. They're cheap for a reason.

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...

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 have severe doubts about buying any premade battery packs direct from china even if it is a smoking deal, the cells might be okay but the rest is pretty much guaranteed to be crap inside unless you spend a lot more. Especially when its actually cheaper still (and easy) to buy individual cells...

I've been doing a bit of testing on my own and here's a picture of the results of a .2C discharge test of my worst cell at a 100% depth of discharge. It's rated for 270AH.

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...

The weak point of the APC UPSs are the transformer heat. They can't handle extended runtime unless you do something to cool the transformers - which means glue on heatsinks w/ thermal transfer glue and add some airflow. I've got 3 1500W APC SmartUPSs modified to handle large external batteries...

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...

If you're looking at a 14.3kw battery bank you REALLY need to be looking at doing a 48V system. At those potential amperages the savings in cable will be considerable, and you can always upgrade your inverter in the future without having to rejigger your battery bank.

It's pretty difficult to 'oversize' a lifepo4 bank as there is no downsides to sitting at partial states of charge and a pretty good reason (as noted above) to stay in the 20-80% state of charge window. I can't speak to the OP but I've got a 65kwh lifepo4 battery bank w/ 9500w of panels, my...

I asked the original author and got an answer. It appears a completely full charge using current taper to find the termination point once or twice a year is sufficient. My current equipment can't do it so it'll have to be a manual "memory wipe" but at only a couple times a year this is...

We are talking about allowing them to expand, but just a wee little bit so the anode/cathodes doesnt move so much they're damaged. There is a small volumetric change when charging/discharging so we want to allow for that but not allow the cells to bloat and damage. (Really, this is a "how many...

Monitoring is a Chargery 16T with two Gigavac contactors and for balancing I went with the JK BMS (aka Heltec) 10A supercapacitor active balancer. Now that I finally got all the paralleling connections done I can permanently mount them - up until now I've been using alligator test leads to...

I've got BMS16T, mainly because it using external relays for the safety shutoffs is so much better because you can tailor the size of the relay to the size of the load AND replace them if/when they go bad. I also like the external shunt too. Finally, I love the remote panel - I've run a...

I just realized I completely boogered up the above, the Chargery ouputs 12V to the coils not a bloody 48V. I dunno, I had 48v on the brain when I was shopping. Getting old is hell. Which means I just spent ANOTHER 200 bucks I shouldnt have. I'll be returning the GV221FAX and GV241FAX for...

You're overthinking the resistor, a 20 or 30 ohm power resistor will precharge any inverter just fine and they're just a few bucks. For that matter you can make your own using .032 safety wire. It's about 6 ohms a foot.

FWIW, since panels are so cheap I've sized the array for crappiest time of year to meet our base load while we're in "conservation/bare essentials mode" and the grid is down as I dont particularly want to be sitting in the dark in the middle of winter and there is some medical machinery that...

Here is my first result, thats my worst battery and even that one put out 279AH going from 3.65V all the way down to 2.5V at .2C (ish) I dont like that cell mainly because its voltage droops .075V under even a mild 20 amp load. Also a pic of my semi torn-apart tester my cc power supply and my...

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...

When doing a copper to copper connection you should ALWAYS put a antioxidant in the connection to prevent the surface of your contacts oxidizing and adding resistance. My personal favorite is a product called Noalox.