thinking about going lipo

[Red_souls]

You haven’t had any problems?

[sleepless]

@Mikeyrides

one for lifespan

While we’re talking about lipo pouch packs vs other options, and since this is one of the main threads that pops up when searching “lipo”, I’d like to highlight lifespan as perhaps the biggest drawback to be aware of (other than safety concerns). Generally well treated lipo pouch packs seems to handle a couple hundred cycles, while well treated li-ion cylinder packs seem to handle 4-7x that. Depending on intended use, replacement costs should be factored into the decision.

On the other hand, as most people already know, the discharge rating and discharge curve (voltage sag) are much better for lipo pouch packs than li-ion cylinder packs.

Lipo pouch packs vs li-ion cylinder cells (18650s, 21700s, etc) is almost an apples to oranges comparison, with substantially different ideal use cases. See the battery basics thread with general characteristics of each:

LiPo (typically LCO chemistry, 3.7V nom, 4.2 - 3.6v safe range, polymer gel electrolyte)

General Characteristics:

Cycle_Life: Poor (50-300 charge cycles)
Energy_Density (Specific Energy): Good (100–200 Wh/kg) - Heavier for a given capacity than li-ion / roughly 2x the weight for the same range
Discharge_Rate: Excellent - Highest discharge rates / C rate (“punchy”). Can get much higher discharge on smaller packs if not concerned about range. (10-25C actual / 200A+)
Charge_Rate: Average (1C typical, 3C maximum)
Voltage_Curve: Good - Flatter curve / minimal voltage sag / maintain a higher voltage under load for longer
Cost: Average. Easy to purchase, widely available
Quality: Average - more prone to swings in manufacturing quality, dimensions, and weight
Safety: Poor - Most sensitive to piercing / blunt damage / thermal runaway. Requires hard case for safety. Easily damaged by discharging too far (will unbalance rapidly below 3.6V.
Operating_Temperature: Average, 5 to 50°C charge (damage will occur if charging at over 60°C)
Aging: Poor- easily damaged if left above recommended storage charge for '3+ months
Packaging: pouch packs come in compact ‘bricks’ of varying sizes, encased in a semi-flexible shell. No standard size exists. Easy to replace / swap / carry extra backups, but added complexity of multiple battery packs.
Cell_Balancing: Requires a BMS or balance charger to eliminate state of charge (SOC) mismatch. 
Note: Inaccurate manufacturer C rating is very common (typically around 2-3x exaggerated)
Examples: Gens Tattu, Turnigy Nano-Tech, Turnigy Graphene, Venom, MaxAmps

Read the more detailed lipo thread here: thinking about going lipo
Read the Tattu lipo thread here: Does anyone have experience with Tattu lipo batteries?

Lipos are safe if you maintain them well. If not, they can puff and cause fires. A lithium ion (cylinder) battery pack like discussed below can still burst into flames if you wire it wrong or don’t protect it but are generally safer and easier for beginners. They can give slightly more voltage (power) but also sag faster.

Li-Ion (typically NMC/NCA chemistry, 3.6V nom, 4.2V - 3.2V safe range, liquid electrolyte)

General Characteristics:

Cycle_Life: Good (1000-2000 charge cycles)
Energy_Density (Specific Energy): Excellent (160–260 Wh/kg) lighter for a given capacity 
Discharge_Rate: Good (250-430 W/kg) - CDR largely depends on cell and manufacturer (15-35A continuous typical)
Charge_Rate: Average (1C typical, 4C maximum)
Voltage_Curve: Average - Depending on cell, can have significant voltage sag in the last half of the discharge (voltage curve)
Cost: High - significant upfront cost includes individual cells plus the materials and labor to build a finished battery pack with BMS electronics, although individual cell prices have steadily decreased over time.
Quality: Excellent - Extremely tight manufacturing tolerances by large global brands ensure high quality cells. Tend to be higher quality packs than LiPo when assembled by a quality builder
Safety: Average - sensitive to physical damage and short circuiting. Requires hard case for safety.
Operating_Temperature: Good, 0 to 60°C charge, -40 to 60°C discharge
Aging: 0.35% - 2.5% / month. Good - better at sitting for long periods of time unused.
Packaging: cells come in cylindrical steel canisters of precise dimensions, with overpressure vents (most common: 18650 = 18mm dia x 65mm L, 21700 = 21mm dia x 70mm L)
Cell_Balancing: Requires a BMS to keep cells balanced
Note: Tend to be over the limit for air flight (99 Whr), aka cannot travel with an assembled pack.
Examples: Molicel P26A and P42A, Sony Murata VTC5D, VTC5A, and VTC6, Samsung 30Q, 30T, and 40T, LG HG2 and HG6, Sanyo NCR2070C and NCR20700A

Example discharge curve:

Read the P42A discussion thread here: Molicel P42A cell discussion

[poastoast]

nope

bo point, really, ig you set it too low it could pop on regular use (what i ran into when i had a fuse)

and if you set it high, then, not much use for a fuse anyways

long as you wire correctly, nothing should go wrong

[Matte.Black84]

I run an antispark with power button. It seems a low cost to reduce risk of damaging your esc.

[Matte.Black84]

Not sure if it’s mentioned further up on here but the other things to consider is getting a good dual balance charger & not go for the minimum or like me you will be buying a replacement after a few months having gotten fed up of charging each pack individually. So really you are investing in using them longer term rather than temporarily until you can afford lion.

Also, voltage alarms, they are around $5 for a basic one and are a great budget way of ensuring variance between cells doesn’t mean you end up over discharging (esc only monitors overall voltage so if enough variance between min and max it won’t start cutoff in time)

[Red_souls]

I figured that removing the case every time to charge the batteries with a balance charger would be a huge pain in the ass. So I got a BMS and a charge port so I can charge the lipos through the BMS and wouldn’t have to remove the enclosure every time

[poastoast]

i find voltage alarms tend to drain cells unevenly as it’s reading it out,

setting reasonable cuttoffs should be more than ok

[Matte.Black84]

I figured the draw is so small that this would only impact of you leave plugged in when not riding? I currently balance every charge, not sure if that’s overkill

[poastoast]

balance charging every time def isn’t overkill imo

i do have a cell checker, but only to check the state of the batteries before or after a ride, anytime in between, i use the distani’ve traveled compared to expected range and feel of thevoltafe sag/cutoff

or use a BLE module/robo to see the state of charge of the pack and go from there

[giek2000]

My 2c.

Built the below 2 batteries since May, 1st one for a street deck 10AH 10s2P with 4x 5S 5AH 40C, and the 2nd for MTB 18AH 10S4P with 8x 4.5AH 35C.

Both packs are balanced to the last digit on the BMS, x.xx5 / x.xx8 when resting at 37V and around x.xx8 / x.x12 when fully charged at 41.3V.

BMS Fully Charged set at 41.3V
Soft Cutoff 36.5V
Hard Cutoff 36V

I’ve built an external LLT BMS charger which I use to charge all my builds.

Street deck is fused with 80A amp which I doubt I ever reach. MTB deck is unfused as I wasn’t sure what my amp draw would be. Looking my VX2 it’s only 17A (per motor) going 30MPH uphill, so an 80A fuse would be more than enough.

There’s a 20A fuse soldered inline on the Charger lead (not seen).

May seem like I’m not making full use of my lipo’s but I built these with a range in mind rather than wanting to deplete them fully and see what max range was. This way my lipo’s will live a long a happy life and I get that sweet unlimited power.

[lucid_layers]

need help with wiring 6 x 2s LIPO batteries to BMS and charger

ok. nearly done now. everything is working fine. thx for checking. i did 2x 3x2s one 3s pack is soldered together and wrapped the other is connected individually. when the new bms arrives, i will change it. [20230130_184132] [20230130_184143] [20230130_184150] [20230130_184155]

I use 6 x 2s 10.000mah.
They fit easely in a eBoosted LY Evo enclosure.

They are wired to 2x 6s balancers. but I will change that to a 12s balancer when it arrives…

Batteries (299 eur for 6 pieces.):
https://www.amazon.de/gp/product/B0B58XR4V2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

BMS (25 eur):
https://de.aliexpress.com/item/4001170222603.html?spm=a2g0o.order_list.order_list_main.19.34d65c5f2lyz4A&gatewayAdapt=glo2deu

It works perfectly well for me. Lots of power, so I can test the limits of my vesc and motors.
Did not test the range, but it should be 500wh calculated.

[Red_souls]

How are the Ovonics now? I’m thinking of switching up my current 10s setup since I accidentally fucked up one of my CNHL lipos getting the enclosure off for a winter inspection and the company isn’t sure when it’ll be back in stock with the one I need, sounds like it gives the board more of a kick and better range so I’m thinking on getting a pair