BYD 24V Powerwall

[Solarwanabe]

Anyone have any experiece with how the BYD reconditioned powerwall batteries hold up? I know they are used but what lifespan should I expect?

 

[GVSolar]

I have 4 of the the 24v Techdirect/BigBattery pre-assembled wheeled units - I am rating them at 3kwh per unit. They are wired in parallel to an Schneider Conext SW4024 system and three solar arrays totaling 4.5kw. The units have been in operation continuously for about 4 months - and are operating flawlessly. The units were charged/discharged separately - and capacity tested - before installation. I am totally off-grid so dependability is key for me. As to the expected lifespan - difficult to say - but so far I am impressed. Caveat: I am using conservative charging specs - 27.2 bulk, 26.7 float, 26.4 bulk recharge reset, and I have plenty of charging capacity. I routinely run 1kw AC, washer/dryer, refrigerator, microwave, tv and associated household loads. I also have a Chevy Volt which is currently fully charged. Your mileage may vary, of course. Best.

 

[GVSolar]

There's a great deal of info on those batteries in this thread (and many others), both good and bad:

Bigbattery.com coupon code: "diysolar" for 10% off BYD 3kWh LiFePO4 Packs

"Big battery" is the same business as "tech direct" (popular ebay battery store). I just signed up for their affiliate program, and they have BYD packs. Most of their batteries are super cheap, but they are cobalt based packs. NMC and Lipoly. I am going to make a very long video about the...

diysolarforum.com

 

[Solarwanabe]

I have 4 of the the 24v Techdirect/BigBattery pre-assembled wheeled units - I am rating them at 3kwh per unit. They are wired in parallel to an Schneider Conext SW4024 system and three solar arrays totaling 4.5kw. The units have been in operation continuously for about 4 months - and are operating flawlessly. The units were charged/discharged separately - and capacity tested - before installation. I am totally off-grid so dependability is key for me. As to the expected lifespan - difficult to say - but so far I am impressed. Caveat: I am using conservative charging specs - 27.2 bulk, 26.7 float, 26.4 bulk recharge reset, and I have plenty of charging capacity. I routinely run 1kw AC, washer/dryer, refrigerator, microwave, tv and associated household loads. I also have a Chevy Volt which is currently fully charged. Your mileage may vary, of course. Best.

Thanks for the info. Will's video said they had a 65A breaker. If so, what is the best size wire to run to the inverter? How much is the nominal draw (their specs say max discharge is 350A)?

 

[Prefersdirt]

Good thread. I saw Will’s video and have been wondering about doing the same thing. If I bought 2 of the battery backs, I could keep things at 24v but have greater capacity?

I

 

[GVSolar]

I wired to parallel busbars using the #6 Anderson connectors that TechDirect sells. From the busbars I run 4/0 to the inverter with appropriate fusing and disconnects. My system has some significant loads but having 4 units keeps my charge/discharge amps per unit well within bounds.

 

[Solarwanabe]

Great info. Did you buy the Schneider MPPT and Inverter prewired or build it yourself? I'm thinking along the same lines because I want to be able to manage the the battery charging from AC if solar does not provide enough on snowy/cloudy days. Right now I have a subpanel that I plug my generator into. I would like to use it for my input for the critical loads. Do you run a well pump off this system?

 

[GVSolar]

Built it myself from all Schneider Conext components - AC & DC switchgear, SCCs, Combox, System Control Panel & SW4024.

My well pump is run from a SW4024 too - a old Trace/Xantrex one - almost 20 years old. It was the precursor to this system - it puts out a pure sine wave 120v - I use a Trace transformer to kick it up to 240v for the well. It was the system I replaced with the Conext. Now I use it to pump water only and as a maintenance backup for the house.

As to the current Conext system: it has very powerful DC charger - and it does AC coupling - which allows me to increase total power generation without adding more batteries or exceeding the max power rating of the SW4024. 1.5kw of my panels are AC coupled - tied in from the roof of my barn. If you do go with Schneider read up on the manuals and the programming - all that flexibility comes with a higher study threshold. The MPPT SCCs have been bulletproof - and the Combox/SCP interface & graphics are compelling.

I've had the Schneider SW system running since November 2014 - originally with lead-acid batteries. I was really glad to see them go (actually the Trojans replaced the decade old batteries in the well pump system). The BYD Powerwalls are far and away superior - the lifepo4 chemistry is made for solar.

As to longevity - I've been off-grid for 30+ years - and as you can see I'm committed to using equipment that lasts. So far, so good. (My 30 yr old Arco M75 panels still run a 24v water pump for a stock tank in the pasture).


Best of luck to you.