BYD 24V LiFePo4 Battery Modules

[SolarRat]

These are also used in BYD transit Buses.

There's a lot of different rumors out there about busses and solar farms but how are you so sure these were used IN the busses? Pics? Links?

I think these were to store power, either from the grid at off peak hours (like they do in China) or from solar. Then, banks of these may have charged the busses, but I really don't think these look like they were made for actually powerering the busses...it's just seems like a very inefficient package for use IN a bus...but who knows? And why are "they" so secretive about it?

 

[Darkstar]

It's

 

[Picasso]

And why are "they" so secretive about it?

First BYD's came with BYD stickers. Now all of them have external stickers removed when shipped out. I suspect someone is not happy about this and since some cells DO show signs of heavy use. BYD pulled these packs because of problems and not some closing of a solar plant. From the 6 units I have 1 is MUCH newer vs the others, also some of the BMS units being active and passive. Seems to tell me a story of attempting to correct cell drift, finding some bad cells, replacing those packs with newer....and giving up and replacing them all.

 

[jasonhc73]

There's a lot of different rumors out there about busses and solar farms but how are you so sure these were used IN the busses? Pics? Links?

I think these were to store power, either from the grid at off peak hours (like they do in China) or from solar. Then, banks of these may have charged the busses, but I really don't think these look like they were made for actually powerering the busses...it's just seems like a very inefficient package for use IN a bus...but who knows? And why are "they" so secretive about it?

Every connector on the BYD pack is an automotive connector.

 

[SolarRat]

Every connector on the BYD pack is an automotive connector.

As opposed to what? It's DC, and the largest manufacturers of DC components are in the automotive industry. I use a lot of automotive/marine weatherproof components in all my projects because I've bought them in bulk cheap over the years, and they work great. BYD's main suppliers are no doubt in the automotive industry, so them using automotive connectors would be no surprise, as they are easy to obtain and relatively cheap.

In China all the electric busses are charged at local charging facilities that store off-peak grid power in large battery banks (peak rates in their big cities are astronomical). They need to charge and discharge very fast at high C rates (hence the "overkill" of heat sinks and fans these things have). Rough life for sure, so as soon as a few batteries start failing they replace the whole bank. Replacing them a year or three early actually saves them money in downtime and maintenance cost.

I've looked over BYD's site and the batteries they use in busses look nothing like these...more compact and they are water cooled. Although they may just be the newer models.

 

[nwillitts]

so,are these things junk?
how long will they last?

 

[jasonhc73]

so,are these things junk?
how long will they last?

If I can run my entire house for 24 hours straight, they are more than adequate. That is with zero charging, and an artificial limit I set as 48V as the minimum, not 40V they are capable of.

 

[nwillitts]

hey jason,installed those panels yet?

 

[Picasso]

so,are these things junk?
how long will they last?

I am still happy with the 6 I got and the price I paid. I expect to use them for 3-4 years and replace with larger cheaper cells. cheaper vs lead with none of the downsides. I'm offgrid so Id love MORE buy more BUT Im going to move to 300v+ so I can use pack intact ev batterys as better high voltage inverters hit the market.

 

[cobratom]

Has anyone tried threading the terminal posts and using a twin nut arrangement?

 

[GVSolar]

My pre-assembled BYD units from TechDirect (w 130amp BMS) arrived yesterday. Beautifully packed for shipping - delivered from a lift gate truck with no damage. I'll be posting some pictures and preliminary impressions later this week.

 

[nwillitts]

mine is scheduled for this coming friday.

 

[steviep19]

GVSolar, I'm pretty sure I bought the same battery pack as you from TechDirect. I've had mine for about 1.5 weeks now and so far I've been really impressed. The BMS on it is very good.

I know a couple people had purchesed just the cells, and TechDirect sells the BMS they used in this unit standalone for about $65. The only thing I didn't anticipate with the battery bank is just how much it weights. It took quite a bit of work to get it down the stairs and into the basement...lol

 

[nwillitts]

GVSolar, I'm pretty sure I bought the same battery pack as you from TechDirect. I've had mine for about 1.5 weeks now and so far I've been really impressed. The BMS on it is very good.

I know a couple people had purchesed just the cells, and TechDirect sells the BMS they used in this unit standalone for about $65. The only thing I didn't anticipate with the battery bank is just how much it weights. It took quite a bit of work to get it down the stairs and into the basement...lol

can you access the BMS via software?
you got 1 or more?

 

[jasonhc73]

Has anyone tried threading the terminal posts and using a twin nut arrangement?

DavePoz sourced the actual connector, it is a spring lock type clasp, about $38 each.

When dismantled, the post is just connected to a giant busbar that all the cells are welded to. You could probably pretty easily cut some threads and directly use the posts.

I spent $7 on a 5 foot long 1/2 inch L copper pipe. I cut the pipe about a hand width length for each post, smushed one end, drilled a hole, and hammered it onto the post.

In hindsight, cutting the post with a tap would probably have saved me a few hours.

 

[cobratom]

DavePoz sourced the actual connector, it is a spring lock type clasp, about $38 each.

When dismantled, the post is just connected to a giant busbar that all the cells are welded to. You could probably pretty easily cut some threads and directly use the posts.

I spent $7 on a 5 foot long 1/2 inch L copper pipe. I cut the pipe about a hand width length for each post, smushed one end, drilled a hole, and hammered it onto the post.

In hindsight, cutting the post with a tap would probably have saved me a few hours.

Happen to have a link?

 

[steviep19]

can you access the BMS via software?
you got 1 or more?

I have not accessed the BMS software. I use a raspberryPI and the voltages from my charge controller to manage the batteries. I do have a separate battery meter on the battery bank and am getting about 4 KWH cycling it between 10 - 90%
I only purchased one but they do sell a 48v system which appears to just be two of these in series.

 

[jasonhc73]

I have not accessed the BMS software. I use a raspberryPI and the voltages from my charge controller to manage the batteries. I do have a separate battery meter on the battery bank and am getting about 4 KWH cycling it between 10 - 90%
I only purchased one but they do sell a 48v system which appears to just be two of these in series.

Did you dismantle the pack down to the cells?

I am in 48V setup, 16S4P with these, but just leaving everything intact.

 

[GVSolar]

Steviep19: Glad to hear its working so well.
Questions: What was the unit's resting voltage on delivery? Did you season (cycle charge/discharge) the battery before putting it into full service? And what is your average charging amperage? Curious about the C-rate... Thx.
Not having communication with the packaged BMS was one of my biggest concerns... so far it sounds like it is performing well for folks. But do not rely on any temperature protection from it - per TechDirect.

 

[steviep19]

Did you dismantle the pack down to the cells?

I am in 48V setup, 16S4P with these, but just leaving everything intact.

Jasonhc73, I did not dismantle it, however techdirect shows a picture of the BMS inside the case, and it's the same one they sell on their store. I'm only using the BMS as a safety net, against over charging and over discharge. When I first set it up, I had my charge controller set to 30v maximum, and it did trip the BMS over voltage system.

 

[steviep19]

Steviep19: Glad to hear its working so well.
Questions: What was the unit's resting voltage on delivery? Did you season (cycle charge/discharge) the battery before putting it into full service? And what is your average charging amperage? Curious about the C-rate... Thx.
Not having communication with the packaged BMS was one of my biggest concerns... so far it sounds like it is performing well for folks. But do not rely on any temperature protection from it - per TechDirect.

It was at 25v when I received it, which is the voltage I'm choosing as my lower limit. I did fully charge the battery before discharging from it, but it was a crystal clear day here so my solar system was able to charge it that day. I only have 2.4 kw of solar panels, and I live in Massachusetts, so the most power I can generate this time of year is 6.5 kwh, and the most amps I was able to put into the battery was about 65 amps. Also, I have the battery bank in my basement where it's always around 65 F. Hope this info helps

 

[GVSolar]

It does help - more info is alway good, thx. I plan on charging primarily from solar as well (after I charge/discharge fully once). My system will kick out up to 80amps @ 24v on a cold sunny day now - and once my AC coupled panels are online it will peak at up to 200amps - that would be across three of the BYD/TD units. I'm using a Schneider Conext sw4024 inverter and (2) MPPT 150-60 charge controllers. AC couple will use 12 Enphase M215s on REC panels. Totally off-grid system, currently FLA and looking forward to LFP.

 

[steviep19]

It does help - more info is alway good, thx. I plan on charging primarily from solar as well (after I charge/discharge fully once). My system will kick out up to 80amps @ 24v on a cold sunny day now - and once my AC coupled panels are online it will peak at up to 200amps - that would be across three of the BYD/TD units. I'm using a Schneider Conext sw4024 inverter and (2) MPPT 150-60 charge controllers. AC couple will use 12 Enphase M215s on REC panels. Totally off-grid system, currently FLA and looking forward to LFP.

GVSolar,

This is my first Lithium battery bank. My old bank is an aiging 10x90ah 12v SLA batteries. They're about 2 years old, and the usable storage is down to 120ah from the original 250. I'm hoping/thinking these lithium batteries will age better.

Just kinda curious. Why are you going to be using micro-inverters with an off-grid system?

 

[GVSolar]

AC coupling allows me to increase my available AC generating power without replacing my inverter or CCs - and 220v gives me a longer wiring distance (from my barn - best location for new panels) without significant voltage drop. It does require some careful calculation (frequency ramping, dump loads, relay switching) - but it is also very cost-effective with legacy micro-inverters. And these BYD Lifepo4 batteries have the ability to accept the higher charge rates that come with AC coupling.

 

[steviep19]

AC coupling allows me to increase my available AC generating power without replacing my inverter or CCs - and 220v gives me a longer wiring distance (from my barn - best location for new panels) without significant voltage drop. It does require some careful calculation (frequency ramping, dump loads, relay switching) - but it is also very cost-effective with legacy micro-inverters. And these BYD Lifepo4 batteries have the ability to accept the higher charge rates that come with AC coupling.

Interesting. I've never seen it used off grid, but it does make sense. Even at ~100 volts I have to run pretty thick cable from the panels to the CC.