Need ideas for BMS for 24s 34p LGD1

[220volf]

Hi! I want to build large bike battery 24s 34p LGD1 (It will be about 80 lbs Need your ideas about bms because D1 have higher voltage than usual 18650 liion. This BMS must be reliable because there are many cells and all of them can broke.

So my second question is what bms usually do when one of cells break? Is it switch off whole battery or one broken cell pack and I can ride with less voltage?

And third question: is there way to join multiple batteries each with his own bms? I can use one at a time, naturally. But can i do parallel or serial commutations?

 

[atomek1000]

Hey, why do you want to use this weird cells? Why not 3500mah 18650s with normal 4.2 termination current?

And about your question you will be 100%ok using different/the same packs in series eg 24v+36v but total capacity will be the capacity of the worst battery pack
So you have 3packs - 11ah + 13ah+ 15ah but will be able to use only 11Ah because at that point bms from first battery will cut power completely.

Using packs in parrarel is slightly more complicated, you must keep them at the same 'health' and SOC to use them. If you don't do so they won't function properly(risk of different internal resistances is that batteries will try to balance each other all the time)

 

[Wheazel]

I use those cells in a 18s26p config in my cargobike, but to prolong lifetime I never considered making a 4,35V solution for them.
Infact part of the decision was my hypothesis that a 4,35V "capable" cell would do well if charged to 4,15 or 4,2v.

I use the adaptto bms for that bike and think I have the chargevoltage set to 4,15V now. Works great.
Do you really need to charge to 4,35V? I fell that if you wanted the last bit of capacity, you wouldnt have choosen D1s in the first place as of the year 2016.

 

[220volf]

Hey, why do you want to use this weird cells? Why not 3500mah 18650s with normal 4.2 termination current?

Because of D1 price!

 

[220volf]

1. Imagine than I have some serial packs with different capacity and ont of them fully discharged. Can BMS disconnect only discharged pack making my battery work with less voltage?
2. Can I use multiple batteries each with his own BMS serial ar parallel?
3. Mybe there is a controller that can use muliple batteries?
4. Does somebody know how tesla bms works? I heared rumor that it can disconnect broken cells or packs.

 

[okashira]

How about two model s modules converted to 12s in series. That would be 24s37p and water cool/heatable

Iirc, the D1's have crappy cycle life

 

[220volf]

How about two model s modules converted to 12s in series. That would be 24s37p and water cool/heatable Iirc, the D1's have crappy cycle life

Is there way to buy tesla packs? This is surprise for me!

 

[220volf]

The D1's have crappy cycle life

I have info that d1 lasts long (700-800 cycles) on lower discharge rates like 0.1-0.2c. If I have huge battery, then I have low current on cell. That's my plan

 

[Wheazel]

Yes the D1s have decent cycle life if not charged fully and kept at low dischargerates.
But that said they are not in line with the better options of today.

Okashira has a salethread about tesla batteries in the for sale section.
In the past Ive seen him sell lose cells, custom packs and modules.
His stock has been going up and down depending on finding donorcars I think.
Personally never bought any tesla cells.

If we look at cyclelife for my cargobike, I have traveled ~2900km with it since I built it july 2015. Which has been 3moths riding and the rest winterstoring.
And for that the average is 30-35 shallow cycles. I will probably not have to replace the battery because of it going bad. (fingers crossed)
But more likely want to replace it in a few years due to better tech alternatives.
Its mostly up to the application, and I think you are on the right track for this specific cell.

Also keep in mind that the chargerate most likely have abig effect on cyclelife as well.
As seen in recent testthreads of other 18650s.

 

[okashira]

How about two model s modules converted to 12s in series. That would be 24s37p and water cool/heatable Iirc, the D1's have crappy cycle life

Is there way to buy tesla packs? This is surprise for me!

Yes, we have about 6 modules left. We sell individual cells and modules (6s74p or 12s37p).
We also make packs but not taking orders. Too much backlog not enough labor.
The current cells are from a 2015 car built in September with only 1k miles. Cells are 99% new capacity.
How much are you paying for the D1's?

 

[liveforphysics]

Anytime you can make use of an OEM part like a Tesla module, it's definitely going to be the least hassle for best results.

 

[220volf]

How much are you paying for the D1's?

New D1 about 2.8$ with all fees. What's the price for tesla module? Where are you from? What about transfer to Russia?

 

[okashira]

No shipping to Russia. Sorry.

 

[220volf]

No shipping to Russia. Sorry.

Why no? Maybe there are variants to ship throught third country?

 

[okashira]

I take it back. I should be able to ship to St Petersburg.
You will want to make sure you're pre-approved to receive the shipment so customs doesn't keep it. I'd give you a contact for that.
You would need to pick it up in St Petersburg.

 

[220volf]

I take it back. I should be able to ship to St Petersburg.
You will want to make sure you're pre-approved to receive the shipment so customs doesn't keep it. I'd give you a contact for that.
You would need to pick it up in St Petersburg.

Sorry, I dont understand you at all. You took back packagge or you took back your last words about shipping?

 

[okashira]

I mean, I can ship to St. Petersburg. But 100% payment in advance is needed, and you need to visit St. Petersburg customs to get pre-approved to receive the crate before I ship