Wanted to share my battery build and get the forum’s advise on the general electronics setup.
I’ll start with the battery and ask the questions in different posts within this thread.
First, I didn’t build the battery, a friend of mine did. It’s his day job, anything involving li-ion packs, from e-bicycle to esk8, RC, etc.
12S10P SAMSUNG 18650 25R.
The cells each contain 2.5AH, and are rated 8C (!). This means that I can discharge at 2.5 * 10 * 8 = 200A which should be more than enough for our task.
Dimensions: 20.5 x 24.5 x 7 cm.
Weight: 5850 grams.
I’m using a BMS only for charging, and I asked for a special BMS that allows charging at 15A
I’m going to use this 15A charger, assuming it will go through customs. This should allow me to charge in less than 1.5 hours, which should be nice.
I’m going to fit the battery into this box (link, sorry for the local shop link). It weights 2200 grams and it is IP67 water resistant.
I followed the instructions from @pacificmeister and others in the forum, and bought a lot of equipment for installing between the battery and the motor:
- ESC (Hobbywing Seaking 130A, da…)
- Self priming water pump
- Amp meter
- Temperature sensor
- Circuit breaker
- RC receiver
- 5V BEC that works on 12S
- 12V BEC (for pump) that works on 12S (I’m actually still looking for one )
I also got a small waterproof box with transparent top.
My biggest dilemmas are:
- Should I mount everything in the same box (with the battery), or should I have a different box just for the ESC (and the two BECs, RC receiver, water pump, temperature sensor)?
- Should I transform the battery box so it has a window on top? I think I can do that by cutting a square hole on the top, and gluing a plexiglass sheet on top, keeping it tight to the box with screws.
- How do I mount the circuit break? It cuts the circuit when pressing on this button, but how can I make this button accessible quickly and safely? Can I mount it outside the box? I know it is waterproof, but still,… salty water??
Some pictures of the equipment:
I am putting the ESC separate. This is the most likely part to explode or get wet.
For the e-stop I use an albright relay for electric forklifts.
Do you mind me asking a price tag on that bad boy ?
Sure, the battery cost was 840 USD (2900 NIS), including the beefy BMS.
As always, much more expensive than any lipo solution.
Usd ? Still not bad for quality cells
What do you mean more expensive?
If you exclude the BMS li-ion should be cheaper for a similar quality pack.
Last time I checked, HobbyKing had a 6S 10Ah pack for 69$, which means you can get 20Ah 12S for 276$, this is 80% of the capacity, but at 1/3 of the cost.
Yeah i had my eye on those graphene 15C beauties for half the price for some time now… 2 bad it’s either out of stock or doesnt want to be added to shopping cart
My bad misunderstood to capacity.
Lipo 20[Ah]/276$ = 0.072 Ah/$
Li ion 25[Ah]/840$ = 0.029 Ah/$
How is lipo 5 times more expencive? o.O
I’m embarrassed, I got confused on capacity.
You got to swap numbers, to calculate Ah x $!
840/25=33.6Ah per $!!
Vs. 13.something of Lipos.
Lipo are cheaper but safety etc are to be considered also
I would love to buy 33.6 Ah for 1$
Slight diversion from the main subject but what are trusted and cheap (I know it seem like a either-or situation) source for Li-ion battery?
Lipo are not cheaper than 18650 , just need to buy at first more cell 18650 for a correct discharge rate but at the end you get a higher capacity pack and it is cheaper ( spot welder less)
Lipo is the easy way good for testing but at the end not so cheap if you built 2-3 pack yourseft of 30q or 25r …
2 people i know nearby me got 4€ deal for Sony VTC 3Ah i think. If ure in europe i can ask for a shop name, idk how marketing goes on this forum. I think shop was in Netherlands.
And which is more important, safer! I think most of “top” 18650’s have internal fuse.
Ah, I’m Canada, to bad.Anybody know about https://www.imrbatteries.com/?
Nice explanation of the inside of Li-ion cells, and why not to buy cheap or untrusted sellers.