just a quick thread to build 2 simple packs of 6S/10P to make a nice 12S/10P
cells : samsung 40 T 4000mah 35A in 6S/10 P (25,2V/40 000mah)
enclosure : plastic box IP56 240x190x90mm (perfect fitting)
No BMS for charge et discharge
simple spot welding machine from amazon for eur 50
now a new toy from ISDT battair …a bluetooth device so you can check voltage via bluetooth anytime (never unplug) from android/ios …usd 5 on amazon for 6S device
now regarding charging …the product from ISDT are extremelly good, very reliable and cheap.
I will post later the product I used for charging.
I dont like BMS even when bypassing for discharge , proper RC charger with latest chip are doing a much better job
this ISDT Q8 smart charger is amazing 500w 20A , you can charge the pack in 2,5 hours (from 3,45V to 4,20V) on 10A which is the maximum for these cells![IMG_0247.HEIC|375x500]
but you need an external source for powering the charger from AC current… to be fun and geeky you can use an HP DPS -1200FB 1 A
on 240V you get output of 12V 100A for less then usd 35 (second hand on ebay)
I will send more details of the HP power supply but you can power various lipo chargeurs at once in a very effective way
On 12V you can charge 25v batteries
Finish product !
You will need a série cable made of 2 XT90 and 1 QS8 with fuse to hock up to VESC for a 12S 40 Ah
Indeed you can the same for 2x7S or 2x8S these chargers handle both up to 8S
So you divide the risk of your pack in case water come in . I believe you balance the best way possible your pack and control each cell .
Removing the BMS and possible fail and expensive power supply
which from reviews seems to be good, though I’m not sure what it can do in terms of nickel thickness and other materials such as copper which seems harder to spot weld,
Heyho. The Battery looks good but i think there is a weak point at the end of the main wires. Half of the whole current goes through the nickelstrip between 5th and 6th cell.
For example: If you are using 100A the strip has to carry 50A, which a 0.15mm nickelstrip would not endure very long.
Do you remove your packs from the plastic enclosures to access the balance plugs, every time you charge? I guess that keeps the plugs safe, provided the plastic case is watertight.
No doubt a hobby charger will balance just fine. One benefit of a BMS is that you don’t have plugs with 13+ pins sitting very close to each other that you need to waterproof/access. The risk of shorting pins and catching fire is a concern.
This business of high powered batteries in a saltwater environment is fraught with challenges
option. Do you know of a siimilar one for 7s. Looks Like battair doesn’t offer a bigger one.
