BYD packs — one year on — survey
- Thread starter BarkingSpider
- Start date
iamrich
Solar Addict
Thanks! I have watched that one about 10 times (seriously). The still shot of the video I think is enough, but I just want to make sure I understand. I am basically duplicating the picture above on both sides of the pack and to the same bus bars on each pack? So a wire into each top bus bar of each cell going to the same bus bar/cell on the 2nd pack?
I plan to use a similar wire/fuse, but I am with a connector so I can separate them for maintenance if needed.
Off to watch that one again.
Yes, that's basically the idea. You want to parallel connect the cells with the same voltage together. Do make sure the cell voltages from both batteries are similar before bundling them together so you don't get fireworks unintentionally.Thanks! I have watched that one about 10 times (seriously). The still shot of the video I think is enough, but I just want to make sure I understand. I am basically duplicating the picture above on both sides of the pack and to the same bus bars on each pack? So a wire into each top bus bar of each cell going to the same bus bar/cell on the 2nd pack?
I plan to use a similar wire/fuse, but I am with a connector so I can separate them for maintenance if needed.
Off to watch that one again.
jasonhc73
Cat herder, and dog toy tosser.
Don't get your hopes up, expect about 160ah usable.
Take the cover sides up.
Attach a wire to each cell of the pack to the same spot on the other pack. That is really all there is to it.
iamrich
Solar Addict
Yes, that's basically the idea. You want to parallel connect the cells with the same voltage together. Do make sure the cell voltages from both batteries are similar before bundling them together so you don't get fireworks unintentionally.
How big do you think the wiring needs to be? It looks like David used 12awg with 30amp fuses, but I can't figure out why. Seems like the lines he showed all had under 1 amp (0.29 was the biggest number I saw) going through them.
iamrich
Solar Addict
Ouch... Hopefully I get luckier than that.
I am not sure in the end it's worth the effort or extra cost. Maybe you should wait until you get the cells and see what condition they are in before making plans to parallel them from the start.
I agree with @jasonhc73. There is a usable range on these packs, and if you stay within the range, the cells are reasonably tight. At least for me, above 3.4V, the runners sort of take off, but there isn't much up there anyway.
I agree with @jasonhc73. There is a usable range on these packs, and if you stay within the range, the cells are reasonably tight. At least for me, above 3.4V, the runners sort of take off, but there isn't much up there anyway.
iamrich
Solar Addict
Right now I have the lofty goal of pulling about 600 watts a day for exterior lighting from this setup.
Well, and not electrocute myself or fall off the roof, but these are not deal breakers...
Well, and not electrocute myself or fall off the roof, but these are not deal breakers...
jasonhc73
Cat herder, and dog toy tosser.
600 watts? That's not much. But you don't have the "correct units".Right now I have the lofty goal of pulling about 600 watts a day for exterior lighting from this setup.
Well, and not electrocute myself or fall off the roof, but these are not deal breakers...
600 Wh maybe?
600 watts for 24 hours is about 14kWh
600 watts for 12 hours is about 7kWh, so using the two packs in a 24V setup will give you 6 to 8 kWh.
Each pack is good for a solid 3 kWh @ when used between 53V and 48V. They get pretty wild if you don't have active balancing above 53V and below 48V. @pjones chart really shows a good bit of info there. Take notice about noon time when the V barely goes up such a tiny bit, and causes all chaos with the mV difference.
Study my voltage chart to help understand why there is no good reason to try and charge above 90% anyway.
LiFePO4 Battery Voltage
Sheet5 How to Find Happiness With LiFePO4 (Lithium-Ion) Batteries <a href="https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/">https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/</a> These are big graphs, SCROOL RIGHT -----> for more info about HIGH V...
When you get your packs, charge them, to say 26.8V then just let them sit a day, so you can see where they self-discharge to. This is the same as me charging mine to 53.6V. After a year of use I understand now that that is just a pipe dream and not to even try to get them there, they are perfectly fine charging to 53.1V.
53.1V/26.5 is about 75% SOC.
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Mine were...on that ship.
iamrich
Solar Addict
sorry, 35w load for 14 hours. Basically x5 7 watt lightbulbs outside
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jasonhc73
Cat herder, and dog toy tosser.
Lol, ok then.
Each battery pack will be able to power your lights for about a week. 2 packs, about 12 days.
iamrich
Solar Addict
I will definitely follow your advice on charging. I plan to wire both packs up for a cell monitor. I know from reading all the different threads that this isn’t the best storage solution out there, but for the price ($850 delivered) and coming from the USA instead of on a boat from China I was good with it. Having so many videos and threads on the subject is awesome!
BarkingSpider
Carbon Lifeform
I have 4 BYD units in a 48v config in a 2S2P setup, I have not bothered linking each parallel cell, but instead use 2 separate 16s balancing BMS units. This avoids disassembling the packs and lots of extra wiring. As long as I dont go too hi/lo on the voltages they behave fine. They usually stay around 25mv apart but may go upto 100mv at the end of the charge. I couldnt charge much over 54v (3.4v per cell max) before they go crazy with runaway cells voltages.
I did strip off the giant heat sinks, cases, fans, etc to save weight and ground down the posts and drilled to attach the cables (see pic). That has worked well. It saves a ton of space and allows them to sit side by side much better. Look how much more space the David Poz setup uses by keeping all the original box. My cells never got hot or even slightly warm, so the heatsink and fan are not needed.
The big rotary switch (off, 1, 2 or both type) allows me to isolate any one of the 2 48v banks for charge/discharge or use both.
I have made multiple 8s connections to the cells via the builtin BYD cable for all the testing I do with various equipment. You wont need that many. You can make the connector by cutting out the socket in the original BMS, you dont need to buy anything extra.
They are connected to 2x MPP 3048 systems giving me split phase 2 x 120v / 240v that I feed to my main house panel and can run my entire house from. That finally works well.
In general, I would not recommended using these old (70% remaining) batteries, far better to buy new 280ah cells For so many reasons. Amazing how prices/specs have changed in less than 12 months. They require alot of babysitting and that will increase exponentially as they age.
Excuse the mess, its always a work in progress and my lab for testing. My production system will use new 280ah cells.
Here is todays data, its at 99% full as its been not used to power much right now, and you can see the cell voltages are staying within range, but any more charge and they go crazy. Same at the low end.
I did strip off the giant heat sinks, cases, fans, etc to save weight and ground down the posts and drilled to attach the cables (see pic). That has worked well. It saves a ton of space and allows them to sit side by side much better. Look how much more space the David Poz setup uses by keeping all the original box. My cells never got hot or even slightly warm, so the heatsink and fan are not needed.
The big rotary switch (off, 1, 2 or both type) allows me to isolate any one of the 2 48v banks for charge/discharge or use both.
I have made multiple 8s connections to the cells via the builtin BYD cable for all the testing I do with various equipment. You wont need that many. You can make the connector by cutting out the socket in the original BMS, you dont need to buy anything extra.
They are connected to 2x MPP 3048 systems giving me split phase 2 x 120v / 240v that I feed to my main house panel and can run my entire house from. That finally works well.
In general, I would not recommended using these old (70% remaining) batteries, far better to buy new 280ah cells For so many reasons. Amazing how prices/specs have changed in less than 12 months. They require alot of babysitting and that will increase exponentially as they age.
Excuse the mess, its always a work in progress and my lab for testing. My production system will use new 280ah cells.
Here is todays data, its at 99% full as its been not used to power much right now, and you can see the cell voltages are staying within range, but any more charge and they go crazy. Same at the low end.
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iamrich
Solar Addict
![IMG_E8492[1].JPG](/data/attachments/32/32473-46047ffde5cfac060d4ab4237b90e5d6.jpg)
iamrich
Solar Addict
I paralleled the two together for 12 hours (settled at 24.6v) and then charged them up to 26.7v (took all day at 20a from the LV2424 AC in). Let them sit for a day and they are at 26.6v. I don't have the solar panels installed yet so I really don't want to capacity test them until I can recharge from the sun. It is snowing today (in Central Texas) so I can't even hook up my test panel.
jasonhc73
Cat herder, and dog toy tosser.
Wow, not much discharge. Sounds like a good set.
madsci1016
Solar Enthusiast
- Joined
- Oct 28, 2019
- Messages
- 91
I was just finishing my discharge test after a year and came here to make a post about my past year using them. Glad I searched first!
I have 8x in a rack to support my off-grid-ish solar install (I'm off grid till SoC falls too low, then I switch on the grid to hold out for the next days sun). They tested just under 4kWhr each originally about come cycles and cell level paralleling (with a few headways in to cover the weak ones) brought the pack to exactly 4kWhr each, 32kWhr total 2.9V to 3.65V range.
( i plan to clean up the wires someday)
I started with Batrium (never again) and it did take a few months to get them top balanced. 5 months ago I turned off balancing on the Batrium and have been experimenting going without a BMS or balancer. 5 months of daily cycles and they have stayed balanced for the most part. I narrowed my pack charge level voltage from 58V to 56.1V and found the conservative top limit removes the need for a balancer with very little capacity loss. I went from just under 32kWhr to about 30.5kWhr. That low a capacity loss is not worth the cost of an active balancer to me.
No age based capacity loss noted yet otherwise.
I have since bought a bunch of the Sony 24V packs from Jehu. They are my favorite scrap market battery right now. Supposedly new never used, bolt bus bar right on them and good to go.
I added 20 and now my overall bank capacity is just over 50kWhr with the conservative charge limit.
Overall I am happy with my BYD purchase from 2019. Wasn't anything like it at the time. Today though, yeah maybe those eve cells... Idk, i get weird wondering what corners they are cutting to get price down. That's what i really like these Sony packs right now, Sony makes good cells, right?
Dealing with Batrium issues drove me nuts, sad for every dollar I lost on that. But it forced me to reverse engineering and make my own code to integrate my SMA SunnyIsland inverters into a Victron Venus device. That's got my system running exactly how I want it too!
Up to 10KW of panels feeding this. Right now It's cycling my pack 30% to 90% each sunny day. That will have to widen up this spring... More panels on the way!
I have 8x in a rack to support my off-grid-ish solar install (I'm off grid till SoC falls too low, then I switch on the grid to hold out for the next days sun). They tested just under 4kWhr each originally about come cycles and cell level paralleling (with a few headways in to cover the weak ones) brought the pack to exactly 4kWhr each, 32kWhr total 2.9V to 3.65V range.
( i plan to clean up the wires someday)
I started with Batrium (never again) and it did take a few months to get them top balanced. 5 months ago I turned off balancing on the Batrium and have been experimenting going without a BMS or balancer. 5 months of daily cycles and they have stayed balanced for the most part. I narrowed my pack charge level voltage from 58V to 56.1V and found the conservative top limit removes the need for a balancer with very little capacity loss. I went from just under 32kWhr to about 30.5kWhr. That low a capacity loss is not worth the cost of an active balancer to me.
No age based capacity loss noted yet otherwise.
I have since bought a bunch of the Sony 24V packs from Jehu. They are my favorite scrap market battery right now. Supposedly new never used, bolt bus bar right on them and good to go.
I added 20 and now my overall bank capacity is just over 50kWhr with the conservative charge limit.
Overall I am happy with my BYD purchase from 2019. Wasn't anything like it at the time. Today though, yeah maybe those eve cells... Idk, i get weird wondering what corners they are cutting to get price down. That's what i really like these Sony packs right now, Sony makes good cells, right?
Dealing with Batrium issues drove me nuts, sad for every dollar I lost on that. But it forced me to reverse engineering and make my own code to integrate my SMA SunnyIsland inverters into a Victron Venus device. That's got my system running exactly how I want it too!
Up to 10KW of panels feeding this. Right now It's cycling my pack 30% to 90% each sunny day. That will have to widen up this spring... More panels on the way!
MountainMatt
M&M Overland Adventures
I was just emailed by bigbattery in June 2021 saying they credited my account in full for 2 of the BYD's I bought back in Feb 2020, plus shipping. Unfortunately, I have not seen a credit on my account and keep getting stone walled by BB accounting dept.
Any ideas or similar expriences?
