DIY Batteries (1 Viewer)

[Raul]

This is my latest home brew with envision 305ah cells. Internal resistance are very close and not far of the EVE premium cells.

I still need to crimp some lugs, and fit the DC Breakers. I used the old JK bms on both, very reliable tried and tested bms.

 

[pappajohn]

Curious .....
Why do you have coils on the link wires rather than being cut to actual length

 

[Lenny HB]

Curious .....
Why do you have coils on the link wires rather than being cut to actual length

At a guess he used all the same length cables as the coils get bigger as you go along.

 

[oldiesontour]

Balance wires all same length My guess

 

[MisterB]

or he just used the balance wire cables already attached to the BMS. if youre building your own batteries, sometimes its better to leave the cables the existing length, in case you change things after a time. you can then swap out other bms's to other builds and configurations.

so, Raul - what was the cost for the home brew in total ?

^{_{Subscribers  do not see these advertisements}}

 

[Montezuma]

Just out of interest, (Electrics is a black art), what is the all-up weight of that little lot, and what are the dimensions of each individual unit?

Just curious.

I would also like to ask what is the big advantage of such a set-up, but I don't want to look silly.

 

[MisterB]

Just out of interest, (Electrics is a black art), what is the all-up weight of that little lot, and what are the dimensions of each individual unit?

Just curious.

I would also like to ask what is the big advantage of such a set-up, but I don't want to look silly.

cost !! - the one shown though is a battery for home use, not motorhome as it will be 48v (16 cells @3.2v = 51.2v) a motorhome leisure battery only uses 4 cells (@3.2v + 12.8v) - the weight and dimensions of each cell can be found on lots of websites including Fogstar. RogerIvy has built one off batteries to fit into specific spaces on motorhomes for people, which is also a big advantage in building your own as they can be lots of shapes other than 'standard' battery shape.

 

[Montezuma]

All I can find is this:

• Manufacturer: Envision
• Model: ESS 72173207-305A
• Size: 71mm x 207mm x 173mm
• Capacity: 305Ah
• Weight: 5.5KG
• Maximum Discharge: 305A (1C)
• Nominal Voltage: 3.2V
• Cycle Life : 3500 cycles @ 0.5C
• Top: Screw Terminals, bus bars and screws included.
• Protection: None

These cells are ideal for compiling 12V off-grid batteries for solar, campervans, and boats. They are generally renowned for being the very best DIY battery for energy storage.

They have a lifespan of >3500 cycles and charge at 0.5C (0.05C termination current up to 3.65V) with discharge 0.5C (down to 2.5V).

These cells require connecting together with the included busbars (Nickel Plated Copper) and screws (8 nuts and bolts).

The cost is given as £69.99.

I'm none the wiser.

I wish I'd not asked.

 

[oldiesontour]

Just out of interest, (Electrics is a black art), what is the all-up weight of that little lot, and what are the dimensions of each individual unit?

Just curious.

I would also like to ask what is the big advantage of such a set-up, but I don't want to look silly.

I'm doing a 340 amp 12 v for the van all in with heater , Bluetooth and 200amp output circa £300,compare that to an off the shelf price

 

[MisterB]

All I can find is this:

• Manufacturer: Envision
• Model: ESS 72173207-305A
• Size: 71mm x 207mm x 173mm
• Capacity: 305Ah
• Weight: 5.5KG
• Maximum Discharge: 305A (1C)
• Nominal Voltage: 3.2V
• Cycle Life : 3500 cycles @ 0.5C
• Top: Screw Terminals, bus bars and screws included.
• Protection: None

These cells are ideal for compiling 12V off-grid batteries for solar, campervans, and boats. They are generally renowned for being the very best DIY battery for energy storage.

They have a lifespan of >3500 cycles and charge at 0.5C (0.05C termination current up to 3.65V) with discharge 0.5C (down to 2.5V).

These cells require connecting together with the included busbars (Nickel Plated Copper) and screws (8 nuts and bolts).

The cost is given as £69.99.

I'm none the wiser.

I wish I'd not asked.

so, weight would be 4 x 5.5kg plus whatever case you put it in, plus the BMS which are under 1 kg. so 23kg for a 12v 304ah battery approx, oldiesontour give a good example of how much you can save by building your own, its much easier than you realise.

^{_{Subscribers  do not see these advertisements}}

 

[Raul]

or he just used the balance wire cables already attached to the BMS. if youre building your own batteries, sometimes its better to leave the cables the existing length, in case you change things after a time. you can then swap out other bms's to other builds and configurations.

so, Raul - what was the cost for the home brew in total ?

Hiya,
So far the cost to me for both is £2780 and just few bits to add. Thats including proper 10ka DC breakers and all the connectors ready to hook up to a buss bar. Just need couple of JK switches and done. Not bad for 30kwh of storage.
Next time I will try the cells from the NL supplier, cheaper than Fogstar.

 

[Raul]

Curious .....
Why do you have coils on the link wires rather than being cut to actual length

As others already mentioned, those are the sensing and balancing wires. By keeping same length, it will have equal resistance and also the ability to re purpose the bms without the wires being butchered, they can be re configured in a different arrangement. So the closer cell to bms ends up with excess wire that i just coil up..
Also for balancing and sensing purposes 0.5mohm difference can trow a false reading. The cells are read down to last mili volt. The original wire measures 0.5-0.6mohm including the ring terminal. If I cut, the wire resistance will be modified and not equal.

 

[Raul]

All I can find is this:

• Manufacturer: Envision
• Model: ESS 72173207-305A
• Size: 71mm x 207mm x 173mm
• Capacity: 305Ah
• Weight: 5.5KG
• Maximum Discharge: 305A (1C)
• Nominal Voltage: 3.2V
• Cycle Life : 3500 cycles @ 0.5C
• Top: Screw Terminals, bus bars and screws included.
• Protection: None

These cells are ideal for compiling 12V off-grid batteries for solar, campervans, and boats. They are generally renowned for being the very best DIY battery for energy storage.

They have a lifespan of >3500 cycles and charge at 0.5C (0.05C termination current up to 3.65V) with discharge 0.5C (down to 2.5V).

These cells require connecting together with the included busbars (Nickel Plated Copper) and screws (8 nuts and bolts).

The cost is given as £69.99.

I'm none the wiser.

I wish I'd not asked.

You need to add bms, ply, wire, lugs, ring terminals, spring washer, and breakers or fuse. Fuse it’s class T, or DC breaker. Both cost quite a bit, the breaker can be used as a kill switch as well.

 

[Raul]

I'm doing a 340 amp 12 v for the van all in with heater , Bluetooth and 200amp output circa £300,compare that to an off the shelf price

Just curious, are those cells EVE mb third generation?

 

[MisterB]

Hiya,
So far the cost to me for both is £2780 and just few bits to add. Thats including proper 10ka DC breakers and all the connectors ready to hook up to a buss bar. Just need couple of JK switches and done. Not bad for 30kwh of storage.
Next time I will try the cells from the NL supplier, cheaper than Fogstar.

That's a cracking price !! Are you still fitting solar panels for people??

^{_{Subscribers  do not see these advertisements}}

 

[Raul]

That's a cracking price !! Are you still fitting solar panels for people??

Yes still fitting them, not as much as I would like, but I do few installs. My next is a 10.8kwp Canadian Solar, off grid where this batteries will reside, along with a 10kva multiplus, generator solar chargers etc.

Note
The multiplus 2 in 5-8 and 10kva has managed Uk grid certification again, since end of March. So no more hurdles for G99- G100.

 

[Raul]

Managed to finalise the batteries, bms installed, DC breaker and bms switch. Ready for a stress test, after a initial charge and balance.

 

[wfdTamar]

I built an 8 cell 626Ah 12 volt one with a 250 Amp BMS for my home Hymer. Bought the cells direct from China.

 

[Raul]

I built an 8 cell 626Ah 12 volt one with a 250 Amp BMS for my home Hymer. Bought the cells direct from China.

EVE MB cells? They give 320to 330ah. Most tested to 320ah plus.

 

[wfdTamar]

They were from EEL Batteries (I wouldn't recommend them). EVE 304Ah which tested to be 311-318Ah each. Bought nearly a year ago, so not the current EVE cells. I did a 2P4S setup.

They were the dual bolt terminal ones, but one had a cracked weld so the whole terminal was loose. After a lot of hassle they eventually sent a replacement.

^{_{Subscribers  do not see these advertisements}}

 

[Raul]

EEL is the worst to deal with, they lie.
QSO is most reliable supplier so far and hear good things about them. A mate of mine received yesterday in Romania 64 EVE cells from QSO Quishou, at $68 plus transport, less than two months.
Same supplier used by Andy fom QZ and most US diy builders.