Ideas for cheap 48v batteries?

[slayer666]

Buy, build, steal?
Wondering what the least expensive but, still workable way to get 48v lifepo4 batteries is. I see Server rack batteries all the time but they seem like they're about twice as much as a regular battery. What would be the downfall? Lack of communication? Don't really need communication, some say. What other ideas do you guys have about how to get your hands on batteries inexpensively. The batteries are what's killing my build. Extremely expensive.

 

[rodrick]

Best bang for the buck is diy especially if you are wanting a large capacity a 280 Ah battery with bms will run about $1500 plus a little more for whatever you decide on for a case which could run as little as $50 to 500

 

[SparkyJJO]

Money vs time
DIYZ is the cheapest but the most time consuming (especially the first one). How much time depends on how much of the DIY you're doing. DIY kits like the Luyuan box are probably the best balance of money vs time.

 

[wpns]

Don't really need communication, some say.

Some are wrong. Unless you only want the batteries to last a year or two. And then your ‘too expensive’ argument is stood on it’s head.

 

[jorby]

You need at least a bluetooth app to see what is going on with cell balance. Closed loop comms with the inverter are optional though.

Edit: if you are using sealed batteries (which contain a bms) to make a bank.

 

[SparkyJJO]

Some are wrong. Unless you only want the batteries to last a year or two. And then your ‘too expensive’ argument is stood on it’s head.

Pretty sure there are lots of people here running with no comms for years and their batteries are just fine. It is a little more complicated than that.

Comms have pros and cons. Let's not make sweeping (and inaccurate) statements like this.

 

[Shaw1984]

I run 3 banks of Eve 280ah on 100Balance BMS with no comms. Pretty simple and has been flawless for a year and a half on my Solark 15k. About to add 4 more banks of Rept 280ah with the same BMS for 100kwh of storage.

 

[yabert]

get your hands on batteries inexpensively

Maybe not for everyone, but I have a way to put my hand on batteries and be paid for...
Short story: Buy a crash EV.
Let say you find a 5-10k$ crash EV with a 60-100 kWh battery. Dismantle the car, sell parts. Dismantle the battery, use half (or less) for you and sell the other half (or more).
Many time you can end with a free battery.
Lot of work, often 12S NMC chemistry (45V), it's not for everyone.

 

[fuzzmunky415]

I've been waiting on another Eco-Worthy/DCHouse sale...that is a stacking coupon on top of an existing %off markdown. Still undecided on the rack mount, though I see the appeal, but running with comms seems rather pointless if you have basic BT/screen status access, so I've been leaning towards the DCHouse metal case cells:

48V 100Ah LiFePO4 Golf Cart Battery Metal Case with Bluetooth Battery Monitor RV | eBay

You will receive 48V 100AH Lithium Battery. It can be used for more than 4000 cycles. 48V Lifepo4 Lithium Battery. 12V Lifepo4 Lithium Battery. 24V Lifepo4 Lithium Battery. Small Size Lifepo4 Battery.

www.ebay.com

I'd likely get one with the charger, then add additional cells as budget and sales occur.

Vid showing a slightly older version of this battery:

 

[wpns]

Pretty sure there are lots of people here running with no comms for years and their batteries are just fine. It is a little more complicated than that.

Sure, but pretty sure we see another instance of imbalance in sealed comms-free cheap batteries on a weekly basis here.

Comms have pros and cons. Let's not make sweeping (and inaccurate) statements like this.

Not talking about inverter/battery comms, just a way of seeing cell voltages and balance function and maybe make settings changes, though those can go wrong too.

 

[slayer666]

I watched a couple of videos of Will prowse and he didn't even use a case or insulation or anything. He just taped the cells together and added a BMS and set them on a Shelf. In another video, he didn't even take them together. He left them spaced on purpose. It looks pretty damn easy to me. How do I choose a BMS? I was thinking of starting with a 16 cell 320 amp battery.

 

[42OhmsPA]

You absolutely want insulators between and around the cells
Compression vs loose vs restraint is a rabbit hole. I would never run loose, restraint at a minimum.

I like JBD BMS, the only negative I've found is lack of active balancing in most if not all models.

I run Class T Fuses on each pack.

I attached a couple photos of racks I've built; they aren't pretty but they function. It's been a few years of open loop with no issues or signs of degradation; buy an inverter/AIO with a reliable USER profile and you'll be fine once you program the BMS and inverter/AIO correctly.

Search for the big blue box from @Zwy ; one of the nicest DIY builds I've seen here and all open loop.

Communication with BMS to see what cells are doing is a must, not so much with inverter communication.

 

[slayer666]

You absolutely want insulators between and around the cells
Compression vs loose vs restraint is a rabbit hole. I would never run loose, restraint at a minimum.

I like JBD BMS, the only negative I've found is lack of active balancing in most if not all models.

I run Class T Fuses on each pack.

I attached a couple photos of racks I've built; they aren't pretty but they function. It's been a few years of open loop with no issues or signs of degradation; buy an inverter/AIO with a reliable USER profile and you'll be fine once you program the BMS and inverter/AIO correctly.

Search for the big blue box from @Zwy ; one of the nicest DIY builds I've seen here and all open loop.

Communication with BMS to see what cells are doing is a must, not so much with inverter communication.

Isn't a lack of balancing a bad thing?

 

[42OhmsPA]

Isn't a lack of balancing a bad thing?

Yes. The JBDs have passive balancing, it works but it's slow and not as efficient as active. Passive bleeds power, at low current, as heat. Active transfers from cell to cell.
The passive works fine if you top balance your cells before putting them in series.

 

[SparkyJJO]

Sure, but pretty sure we see another instance of imbalance in sealed comms-free cheap batteries on a weekly basis here.

Not talking about inverter/battery comms, just a way of seeing cell voltages and balance function and maybe make settings changes, though those can go wrong too.

And we've seen plenty of comms connected batteries being imbalanced too. Comms sounds good on paper - I thought it was a great idea at first - but its implementation I think leaves a lot to be desired. It doesn't seem to always fix imbalance at all.