My 12v 280ah build thread

[Sipma02]

Inspired by the other build threads around here, I thought I would start my own. I'm learning as I go, so this might be a long process. These will eventually be the main house batteries for my wife and I's 2006 T1N Sprinter conversion. According to our max energy calculations, 280ah at around 80% discharge should get us 3 days of usage. We will start with this, and if it ends up not being enough power, I will get another 4x 280ah cells. Currently planning on a Kisae DMT1250 DC DC charger and Chargery BMS. But at this point, I'm happy to be convinced of anything

I ordered 4x 280ah LFP cells from XUBA 2 weeks ago, so now the waiting begins. I expect to see them around September

Thanks Amy!

 

[Craig]

Good luck I think you are on he right track with your components so far.

 

[grey nomad]

Hi Josh
I'm planning on building a similar battery for my 16 ft caravan.
Was going for a smaller 2 bank of 12V 100ah but saw the good price of theses 280ah cells from XUBA.
It's just the price of freight that is expensive.
Will be watching how you build goes.

 

[Sipma02]

Hi Josh
I'm planning on building a similar battery for my 16 ft caravan.
Was going for a smaller 2 bank of 12V 100ah but saw the good price of theses 280ah cells from XUBA.
It's just the price of freight that is expensive.
Will be watching how you build goes.

I think even with freight it's a good deal, especially if you have higher loads or want to stay off grid longer. I paid under $500 for my cells, will probably be under $700 after enclosure, BMS, wire, etc. Thats about the same price at lead acid at half the weight, no off gassing, faster charging, more amp draw, almost everything better (or so it seems)

 

[Luthj]

That pack may fit under the passenger seat even.

What are your peak current needs?

 

[grey nomad]

Was that under $500 including freight. XUBA have the 280AH listed for $476 for 4 cells plus freight $363.

 

[Sipma02]

That pack may fit under the passenger seat even.

What are your peak current needs?

I thought about it, and I think it will. But I think I'm on track to convince my wife to let put an 8" or possibly 10" subwoofer there. Gotta prioritize

Currently estimating around 140-150 amps peak, including 80% inverter inefficiency. This will be from a Vitamix blender, so no more than 3-4 mins at highest power. We do use that almost daily. All of our other power usage is at most 30-40 amps.

Was that under $500 including freight. XUBA have the 280AH listed for $476 for 4 cells plus freight $363.

Yes, $482 was the total cost including shipping. I was stoked!

 

[Electric Personality]

Here is mine before tidy it up. In a group 31 plastic box, which is now mounted to a camper. Plywood on bottom. Cells wrapped tightly with filament tape. I worry a bit about the buss bars, and not compressing the cells, but works for now. Ignore the lipo reading on display, it is only used temporarily to eyeball the cells. I also doubled up the buss bars since this picture. 250 amp switch breaker is mounted on outside of the box on the negative bms output.

 

[Gazoo]

Here is mine before tidy it up. In a group 31 plastic box, which is now mounted to a camper. Plywood on bottom. Cells wrapped tightly with filament tape. I worry a bit about the buss bars, and not compressing the cells, but works for now. Ignore the lipo reading on display, it is only used temporarily to eyeball the cells. I also doubled up the buss bars since this picture. 250 amp switch breaker is mounted on outside of the box on the negative bms output.

I like it but isn't a 250amp breaker too big? How many amps do you intend to draw from the battery and have you sized your wires accordingly? I have no idea what your intended use is.

 

[Electric Personality]

I like it but isn't a 250amp breaker too big? How many amps do you intend to draw from the battery and have you sized your wires accordingly? I have no idea what your intended use is.

It may be too big. It is only a 200 amp bms. I just put it there as a catastrophic breaker. Going to be using a 3K inverter, but only 1800 watts worth of it, not going to try and pull full output on it. 1/0 wires that run about 5'.

 

[Sipma02]

Exciting. Received my cells last week. All of them right at 3.28v.

They came very well packaged in 2 seperate boxes (on back to back days), I just put them in the same box so I can store/move them easier. I've got a pretty busy next few weeks of working on other stuff in van, but I hope to order a Chargery unit soon to get this baby wired up.

Main conceptual hurdle right now is figuring out what I'm going to do for a battery box. I want to be able to expand and add 4 cells in the future if I want. Considering CNC cut steel plates and welding them together, but I might just stick with wood. TBD!

 

[Luthj]

There are two main approaches. One is size the pack to add another parallel cell. The other is to plan on a second pack with its own standalone BMS. With the ~100A drop in BMS maturing enough to be used in mass market drop-ins. I would consider that route for ease of upgrading.

Dealing with bus bars, clamping, etc, would be a fair bit of work to upgrade later on. Besides who knows what cells will be available in a few years?

 

[Sipma02]

The other is to plan on a second pack with its own standalone BMS...

...Besides who knows what cells will be available in a few years?

Fair point. Since the Chargery BMS8T can handle up to 8 cells, I'll just be using it in a 4S configuration. If we decide we want another 4, it can be wired to that BMS in a 4S2P config. I do like the idea of 2 standalone BMS's for redundancy, but I don't think I'll go that route because I like the idea of the Chargery being my one-stop-shop of battery info, especially current in and out.

 

[Luthj]

Just for clarification, the chargery cell numbers refer to logical cells in series. adding parallel cells to each group has no bearing on the logical cell count? At least that's my understanding from the manual a few months back?

Cell sizes change, so don't be surprised if you can't source a 280AH cell in the right form factor 3 years down the road.

I don't see any reason you cannot connect a second pack upstream of the chargery shunt, but downstream of the master disconnect the chargery drives.

Also, don't be surprised if the chargery isn't a very good battery monitor (coulomb counter). At least compared to dedicated units.

 

[Heap64]

Tell me more about the single Chargery doing a 4s2p layout. Is that confirmed? I saw something like that in the manual but I thought that I misunderstood it? I have decided to put my 8 cells into a 24 battery and adding a stepdown converter in my camper. Good luck with your project!

 

[Oldtoad]

Good luck.
This sounds like the way to go for me as well. Was considering 560 but 280 might be enough.
Under $500, super deal!

 

[NCblueridge]

Yes, $482 was the total cost including shipping. I was stoked!

Wow, under $500 shipped to the US for a quality 280AH pack. I may have to order one of these also at that price. I am already working on a larger house build. Who do I contact?

 

[Sipma02]

Just for clarification, the chargery cell numbers refer to logical cells in series. adding parallel cells to each group has no bearing on the logical cell count? At least that's my understanding from the manual a few months back?

Cell sizes change, so don't be surprised if you can't source a 280AH cell in the right form factor 3 years down the road.

I don't see any reason you cannot connect a second pack upstream of the chargery shunt, but downstream of the master disconnect the chargery drives.

Also, don't be surprised if the chargery isn't a very good battery monitor (coulomb counter). At least compared to dedicated units.

Tell me more about the single Chargery doing a 4s2p layout. Is that confirmed? I saw something like that in the manual but I thought that I misunderstood it? I have decided to put my 8 cells into a 24 battery and adding a stepdown converter in my camper. Good luck with your project!

Glad you two posted. I messaged @Craig, and got this response:

If you want to go 4s 2p you will need 2 BMS. I set mine up parallel then series so that you can use 1 BMS. If one of the parallel cells go bad you will know fairly fast.

So I guess 4S2P will not be an option! I may look for another BMS; if I can find a cheap (around $100) commodity BMS that has low temp, HVD, LVD, and individual cell-level balancing capabilities, I may go with that. The Chargery isn't much more than $100 that though, so if I do add a second set of 4 cells, I would have 2 Chargery BMS's, each set up as 4S. Those individual 4S packs could be paralleled together. I like the redundancy of that. The only downfall is it would cost an extra $115 or so for the extra Chargery. Probably not the end of the world for the boost in redundancy.

That would mean I would need a second shunt. Can that safely be wired to the negative side with other shunts? Is it possible to have 2 shunts? (One for the Chargery, one to monitor battery SOC?)

Wow, under $500 shipped to the US for a quality 280AH pack. I may have to order one of these also at that price. I am already working on a larger house build. Who do I contact?

I messaged Amy from XUBA, via Alibaba.com. The name of the store is Shenzhen Xuba Electronic Trading Co., Ltd. on Alibaba. I mentioned that I saw her posts on the DIYSolarForum; it's possible that contributed to the great price?

 

[Craig]

NOt an argument but why are you afraid t just parallel the batteries first and go 2p4s? I know it seems more redundant but I do not think it really gives that much more safety and creates more moving parts. Sorry I only got the tail end of this thread.

 

[NCblueridge]

Thanks Sipma.