Electronics > Power/Renewable Energy/EV's
Safe Sodium Batteries battery pack
federico:
Hi Everyone.
I would like to create the battery pack for the electric longboard that i am designing,
but I am very afraid of using a lithium pack, I would like to create my pack with the new sodium batteries 8)
I know it's not very convenient because they have a low capacity compared to lithium, but I prefer to sleep safe knowing that it will never catch fire.. :scared:
I found these batteries:
https://hakadibattery.com/products/hakadi-sodium-ion-3v-26700-battery-3500mah-brand-new-rechargeable-cell-for-e-bike-diy-12v-24v-48v-battery-pack?variant=41884768141517
https://srikobatteries.com/product/sodium-ion-26700-3-0v-3-2ah-9-60wh-3c-rechargeable-battery/
My brushless engine is the following:
https://flipsky.net/collections/e-skateboard/products/flipsky-bldc-belt-motor-6354-140kv-2450w-for-electric-skateboard
Which absorbs max: 65Amp...
The motor controller (ESC) works from 14 to 60Volts.
With these batteries I was thinking of creating a pack like this: 13S 2P
Row of 13 batteries in series, put in parallel with another row of 13 batteries in series.
What should I have about 48Volt and about 6AH?
I'm not so interested in the range, (I don't travel much) as that the engine has the energy to work at its full power,.
Is my pack ok with these sodium batteries? do you think with these batteries i will have the necessary power in terms of current discharge, etc..?
I'm confused, Before I waste time/money I ask for help from you who surely understand more than me... |O
Sniper1:
--- Quote from: federico on November 11, 2024, 12:36:21 pm ---Hi Everyone.
I would like to create the battery pack for the electric longboard that i am designing,
but I am very afraid of using a lithium pack, I would like to create my pack with the new sodium batteries 8)
I know it's not very convenient because they have a low capacity compared to lithium, but I prefer to sleep safe knowing that it will never catch fire.. :scared:
I found these batteries:
https://hakadibattery.com/products/hakadi-sodium-ion-3v-26700-battery-3500mah-brand-new-rechargeable-cell-for-e-bike-diy-12v-24v-48v-battery-pack?variant=41884768141517
https://srikobatteries.com/product/sodium-ion-26700-3-0v-3-2ah-9-60wh-3c-rechargeable-battery/
My brushless engine is the following:
https://flipsky.net/collections/e-skateboard/products/flipsky-bldc-belt-motor-6354-140kv-2450w-for-electric-skateboard
Which absorbs max: 65Amp...
The motor controller (ESC) works from 14 to 60Volts.
With these batteries I was thinking of creating a pack like this: 13S 2P
Row of 13 batteries in series, put in parallel with another row of 13 batteries in series.
What should I have about 48Volt and about 6AH?
I'm not so interested in the range, (I don't travel much) as that the engine has the energy to work at its full power,.
Is my pack ok with these sodium batteries? do you think with these batteries i will have the necessary power in terms of current discharge, etc..?
I'm confused, Before I waste time/money I ask for help from you who surely understand more than me... |O
--- End quote ---
Simple answer: NO not even close
Long: cells have 0.5C rating so 1.75A per cell , in practice u should be fine with 3A from what i understand
For your rated 65A max current u will need like 20 strings or 6-7 strings if you go with absolute max rating
As for cells in series 13 is ok tho u can add a few more BUT i would not go over 16-17
Questions?
Hydrochloride:
Surely I must be missing something. With 26 cells, it seems like you're going to have very little runtime.
I imagine you’re not asking for the maximum power of the motor, but doing the calculations just to request 1/4(constant) of what the specifications state: 2450/4 = 613W (rounded).
-----------------------------------
Load : Flipsky BLDC Belt Motor → 613W
Cells : HAKADI Sodium ion 3.0V 26700 Battery 3500mAh → 1cell. 3.1V*3.5Ah = 10.85Wh
If you want to hold this load for 2 hours : you need (613*2)/10.85 = 112.99 cells. → 113 cells minimum
If you want to deliver 48V with nominal voltage, that will be 48/3.1 = 15.48 → 16 cells series.
But the cells maximum operating voltage is 4V. So 16x4 = 64V. Better remove 1 to be within ESC limits.
Pack voltage that way will be from 22.5V to 60V.
Other cells in parallel strings, so that is 113/15 = 7.53 strings → 8 strings
15*8 = 120 cells
1 cell is 2.64cm diameter x 7.1cm length.
120 cells will be like a box of length x wide x height → 26.40cmx31.68cmx7.10cm. Without counting tabs for spot welding and other materials to finish the pack.
Edit : Fixed with max voltage
Sniper1:
--- Quote from: Hydrochloride on November 21, 2024, 01:35:10 pm ---Surely I must be missing something. With 26 cells, it seems like you're going to have very little runtime.
I imagine you’re not asking for the maximum power of the motor, but doing the calculations just to request 1/4(constant) of what the specifications state: 2450/4 = 613W (rounded).
-----------------------------------
Load : Flipsky BLDC Belt Motor → 613W
Cells : HAKADI Sodium ion 3.0V 26700 Battery 3500mAh → 1cell. 3.1V*3.5Ah = 10.85Wh
If you want to hold this load for 2 hours : you need (613*2)/10.85 = 112.99 cells. → 113 cells minimum
If you want to deliver 48V with nominal voltage, that will be 48/3.1 = 15.48 → 16 cells series.
But the cells maximum operating voltage is 4V. So 16x4 = 64V. Better remove 1 to be within ESC limits.
Pack voltage that way will be from 22.5V to 60V.
Other cells in parallel strings, so that is 113/15 = 7.53 strings → 8 strings
15*8 = 120 cells
1 cell is 2.64cm diameter x 7.1cm length.
120 cells will be like a box of length x wide x height → 26.40cmx31.68cmx7.10cm. Without counting tabs for spot welding and other materials to finish the pack.
Edit : Fixed with max voltage
--- End quote ---
Those numbers now look way more reasonable , you can increase the string number later , if you want more power
As for series cells yea 15 is a good call 16 might also work IF you slightly undercharge or use some devices that have static loses along the ESC power patch like some IGBT still like that that control the on/of power of a IGBT it is like 1.5V drop and with large currents u can get some good drop on cables and such but yea 15 is the safe route
janoc:
--- Quote from: federico on November 11, 2024, 12:36:21 pm ---I know it's not very convenient because they have a low capacity compared to lithium, but I prefer to sleep safe knowing that it will never catch fire.. :scared:
--- End quote ---
Don't land in the trap thinking that since you have replaced perceived dangerous liquid lithium chemistry with solid sodium and thinking you are safe. You aren't, unless you really know what you are doing. This is a high energy device and e.g. your BMS failing or battery developing an internal short e.g. because of a manufacturing defect will have exactly the same devastating effects, namely a major fire. Lead acid batteries don't catch fire either - but you wouldn't want to short a charged one!
It isn't the lithium that causes the batteries to catch fire but most often either manufacturing defects, operational abuse (over charge/discharge, short circuits) and things like dendrite growth that could cause a short circuit over a time. These things apply even for sodium batteries. The only major advantage you have with sodium is that you won't have a thermal runaway in most cases. But thermal runaway is usually only the consequence of some other problem (e.g. a short circuit), not what starts the fire unless you seriously overheat the battery.
So even with sodium batteries it is a very prudent idea to observe the standard safety precautions - never leave the batteries charge unattended, make sure there is nothing flammable around, don't abuse your battery, have fuses/BMS in place, etc.
And the most important one - buy batteries from reputable manufacturers, not some random Chinese reseller from Shenzen packaging who knows what. Poor quality batteries are the #1 reason for battery fires.
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