thinking about going lipo

[b264]

Your C rating times your Ah is what matters, so the less capacity you have, the higher C ratings you need. If you have 20Ah lipos then the C ratings can be a lot lower than 2500mAh lipos which need a super high C rating. Assuming everything else is normal.

[Mikeyrides]

Perfect👍 that just brought everything into perspective.

[Geo_Engineering_FTW]

thinking of trying Lipo as just seen @mutantbass post this on good deals. Ngl, ive never made a battery and have never understood the Wh metric, have only ever understood the configuration metric (i.e. 12s4p).

A few of questions:

1. For about £100 I get 4 of these
   
   
   
   What is this equivalent to in config terms (i.e. is it close to 12s1p)?
2. I can fit 4 of these in an enclosure, is this easy to connect them? - what tools do i need?
3. Is adding this smart BMS to them going to be difficult? (looks like a nighmare)

cheers

[Evwan]

Adding a BMS will be a bit of a nightmare, but of you have 4 of these it’s hard to call it a 12s1p. Easiest thing to “compare” it to is a 12s2p 40T pack, but they’re two very different things. Besides the BMS you just need to put them all in series.

[Geo_Engineering_FTW]

I can look on youtube for lipo guides I think, maybe even the old forum might have guide. 12s2p 40t pack is pretty solid for 100 quid.

@Evwan

but they’re two very different things

I have got this impression. Many jumpers use them, as I guess it can deliver more amps in bursts, or something. Anyway migh be a fun option to try for a small street build

[mutantbass]

Well, aren’t you fucking lucky

LIPO Charge only Smart BMS wiring Guide

Alright folks, have some time on my hands so decided to make this guide. We are going to be wiring 4x 3s lipo batteries to a smart Bluetooth LTT bms (available on https://www.lithiumbatterypcb.com/ ) in charge only to make a 12s lipo. The goal here is to be able to monitor individual cell voltages from a smartphone and charge the batteries from a charge port on the enclosure and not have to take them out every time. This is the best solution I have come up with for flying with my board and tak…

Those are equilavent to a 12s2p of Samsung 40T or molicel 42a cells. You are getting a total of 355 watt hours.

3.7v nominal x 3s x 8ah = 88.8wh per battery x 4 batteries = 355.2 watt hours.

[Geo_Engineering_FTW]

haha, fuck me. nice one

might even try a massive one for a pelicase emtb at that price.

cheers

[Geo_Engineering_FTW]

@mutantbass , just wondering, i’ve heard that Lipos get easily wrecked, because of general user negligence (like not dissipating the battery enough/too much). Does adding the BMS somehow make them more long lasting/help avoid these things, or will these issue’s with them (compared to Lithium Ion) still stand regardless of whether you use a BMS? (I know BMS just regulate/balance cells, but maybe this has a positive effect on them too?)

[mutantbass]

Keep them between 3.55v/3.6v and 4.15v per cell. They will last hundreds of cycles. People discharging their lipos down to 3v and then come complain about lifespan. Take your lithium ions to 2v per cell and see what happens.

The BMS is there so you don’t have to take them out every time to charge on a Lipo charger.

LiPos on a street board: The no-enclosure enclosure

Yeah. RC LVC doesn’t really translate to esk8. The equivalent esk8 usage would be going uphill 30 degrees full blast and emptying the battery in 20 minutes. In those circumstances, 3.5v might well mean you still have 50% battery left due to voltage sag. But for the most common esk8 usage which is very start/stop in terms of amp usage, 3.5v most likely means that you have used all your capacity and are damaging your cells.

thinking about going lipo

I exclusively use LIPOs. This is my current setup on a trampa/kaly hybrid with a bms. I also used them before on a split enclosure flexy deck. This current setup is 3s x 4 8ah each and I can take them on a plane (88wh each battery). I know it looks complicated but trust me, it is 1/10th the work of building a li-ion pack. the whole thing took me an hour while I was watching tennis at the same time. lol Here is what I have learned. Keep the battery between 3.6v and 4.15v per cell and you won’t…

[Geo_Engineering_FTW]

Excellent work here man. Will have a read and join the Lipogang

[Mikeyrides]

Watching your discharge is really important, one for lifespan and two for charging. I accidentally discharged mine to about 3.1 volts and the charger wouldn’t read it. It kept saying, “incorrect cell count”. I had to bring up the voltage to about 3.5, through a different charging mode, for the charger to recognize the battery. I only charge to 4.15v as well and get around 20-25 miles on a emtb depending my riding style. And they have massive punch​:ok_hand: the first day after getting them my board shot out from under me

Edit: I have two 13ah 6s in series.

[mutantbass]

@Mikeyrides

I accidentally discharged mine to about 3.1 volts

Do you have a lipo charger that can measure internal resistance?

[Mikeyrides]

Yeah, everything is reading normal still, internal resistance is good, cells are perfectly balancing before and after a ride and capacity is good.

[Red_souls]

Any of you guys run fuses between your lipos and VESC? Just wondering because I’m making my first board right now and confused on if I need a fuse between those, I know for sure I need one for the BMS and charge port, other then that. Got no idea where else

[poastoast]

i ran no fuse

[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)