Liion batteries

[Roy1]

I was wondering if any of the members made their own lithium batteries. I had been pricing batteries and they are very expensive and some of the vendors are very sketchy as well. I figured it might be cheaper in the long run if I made them myself, so I just made myself a new 6s2p 8400 liion battery. I used 21700 size batteries and a 60A 6s BMS. The batteries are about $5 apiece and the BMS card was about $20. The nickel strips were free and it didn't take too long to hot glue together and weld up. I did go ahead and buy a welder for $75 though. I got probably got about $90 in the materials, but I think I have a better battery. Forgot to mention that the batteries have a max discharge of 45A and I am using it on a Leopard 4082-1400kv. I also bought 4 more cells in case I ever wanted to convert the battery to 8s. Do you think this battery will properly power the motor and does anyone foresee any problems with my setup. This my first one so got my fingers crossed. I had purchase two 5000ah batteries a year ago and one has already bit the dust. They are the pouch type (do not like these). Anyway thanks for any help.

[jkflow]

Build my own battery backup system, small scale with LiIon. No I wouldn't use them for what you have in mind. Motor is rated at 2400W which is roughly 100A on 6S and they are more than happy to pull ~240A during peaks. They will overload your battery and it will degrade quickly.
By all means, I have no idea what type of application you have in mind but can't use that motor at rated power or burst.
You would need ~ 4 of your battery setups in parallel.

[Roy1]

Build my own battery backup system, small scale with LiIon. No I wouldn't use them for what you have in mind. Motor is rated at 2400W which is roughly 100A on 6S and they are more than happy to pull ~240A during peaks. They will overload your battery and it will degrade quickly.
By all means, I have no idea what type of application you have in mind but can't use that motor at rated power or burst.
You would need ~ 4 of your battery setups in parallel.

Thanks I will take your advice and move it to a 6s4p setup instead. I appreciate your advice.

[Speed2]

It have decent lipos out they that can deliver the power needed for that motor and I think they are reasonable priced.

SMC is a brand that sells powerful cells. The cheaper smc cells can supply the power that the your motor needs.

Does $75 or $80 sound bad for a 6s that can supply 200amps?

Then they have more powerful cells that cost in the $150 to $200 range that will handle over 300 amps but those are over kill for a 1400kv 4082. 6s batteries.

[Bande1]

you can get a set of cheap lipos on amazon that will do 150A output for under $60. It doesnt seem to make sense building a pack when it can only do 45A output. that is comically too small for a boat which usually do in the 150A-175A range.

https://www.amazon.com/Socokin-Conne...f-a2c47c48c32f

It have decent lipos out they that can deliver the power needed for that motor and I think they are reasonable priced.

SMC is a brand that sells powerful cells. The cheaper smc cells can supply the power that the your motor needs.

Does $75 or $80 sound bad for a 6s that can supply 200amps?

Then they have more powerful cells that cost in the $150 to $200 range that will handle over 300 amps but those are over kill for a 1400kv 4082. 6s batteries.

its a good deal but you cannot push 200A on 6s with that motor. You will fry your wires first of all. you'd be running at 4200w. you maybe could do that for 3 seconds max. You cannot race or anything. that motor is really a hot 4s motor.

when you look at batteries look at the weight. SMC batteries weigh a lot more because theres more actual battery there for the rated mah. batteries on amazon lie constantly about their weight. the ones I linked above probably weigh 30% less than what they state in the ad. You basically get what you pay for. SMC cost more but you get more.

[Roy1]

I guess I didn't give you guys enough info. I looked up how to calculate the available amps for a battery and it was (rated amp for battery X Ah of pack = total available amps. If this is wrong please let me know. That being said, I calculated that my battery rated at 45A X 8400ah = 378 amps. Once again if this is wrong, please let me know. As for the motor, I looked up the specs on it and it is rated for up to a 10s battery. I am quoting hat without going back and looking it up, but I know it is at least an 8s. I just want to make sure that this is going to work. Thanks for input.

[Roy1]

Build my own battery backup system, small scale with LiIon. No I wouldn't use them for what you have in mind. Motor is rated at 2400W which is roughly 100A on 6S and they are more than happy to pull ~240A during peaks. They will overload your battery and it will degrade quickly.
By all means, I have no idea what type of application you have in mind but can't use that motor at rated power or burst.
You would need ~ 4 of your battery setups in parallel.

I forgot to mention that the batteries are setup in a 6s2p 8400mah battery. This will yield a 378A available for use. The formula I found was discharge rate of battery (45A) X total amp capacity (8.400mah) = 378amps which will handle the motor. Am I doing something incorrectly?

[Bande1]

I forgot to mention that the batteries are setup in a 6s2p 8400mah battery. This will yield a 378A available for use. The formula I found was discharge rate of battery (45A) X total amp capacity (8.400mah) = 378amps which will handle the motor. Am I doing something incorrectly?

yeah thats wrong. the best lipo batteries output a real world 30-35c continuously. your math has them at 45c. to understand what a battery can actually output you have to accurately measure the internal resistance at nominal voltage and room temperature. Most budget batteries are in the 15c-20c range.

IR calculator
https://www.radiocontrolinfo.com/inf...lipo-c-rating/

The liion website says they handle 1-2 amps continuously with 6a peak. That makes their real world C rating around .45....as in 1/2 of 1c. Again the ones I linked earlier are real world 40x more powerful. why is that? because 18650 cells are lithium-ion. We use lithium polymer. A totally different battery for totally different applications.

[Roy1]

These batteries have been verified at 45A and on a 8400mah 6s setup they are rated to supply 378 amps. The 45A is the max discharge per battery.The motor is rated for up to 10s, I double checked. I am not trying to prove I am right just get the facts on something I am not 100% sure, thats all.

[Bande1]

These batteries have been verified at 45A and on a 8400mah 6s setup they are rated to supply 378 amps. The 45A is the max discharge per battery.The motor is rated for up to 10s, I double checked. I am not trying to prove I am right just get the facts on something I am not 100% sure, thats all.

first of all, a leopard 4082 is about 2200w rated or so. maybe could handle 2600w continuous lapping. 10s outputs around 6000w. in no way, shape, or form is that a 10s motor just because a motor can technically handle 10s voltages doesnt mean it can handle the current of 10s. 10s motors are 56mm in diameter, the size of a beer can.

this is an actual 10s motor
IMG_20230727_095857 (1).jpg

according to liion's website the Molice 21700 cells output 45A max, which would be about 10A continous. you have 2 in parallel. that is 20a continuous output. 90A max short burst output. which makes them 10c peak, 1.2C continuous. the cheapest lipo packs are 10x more powerful.

[Roy1]

I agree with you 100%, I had gone to two different websites and one had it at 5s-10s and another had it at 5s-9s. Finally went to Leopard's site (should have gone there first) and there it was 4-6s. That is a big ass motor. I got one on a scooter that is a 20s, but doesn't have the rpm's. Thanks for the info.

[Bande1]

I agree with you 100%, I had gone to two different websites and one had it at 5s-10s and another had it at 5s-9s. Finally went to Leopard's site (should have gone there first) and there it was 4-6s. That is a big ass motor. I got one on a scooter that is a 20s, but doesn't have the rpm's. Thanks for the info.

4s at 175A with decent batteries equals about 2500w. which will make that motor pretty warm. 6s at 175A is 3650w which will fry that motor. it will fry a 4092 also. to really utilize 6s you need like a 40107 TP motor that can handle 4,000w. That way the batteries and motor are matched for each other.

[Roy1]

I understand, maybe I will make it a 4s battery instead. By the way I looked up what the max discharge rate was for the p42a 21700 through Liion and through Molicell and it states that the maximum continuous discharge rate is 45A. It is supposed to be constructed for high discharge applications. I wonder why Leopard would state that it is rated for 6s though, now the 2200kv one was 4s, but the 1450kv was 4-6s. I guess I am a little confused. I think they achieve the same amount of power, one with voltage and one with amperage. Thanks for input. Have you tried making batteries in the past?

[Roy1]

Forgot to mention, just for kicks took my Porter-Cable 20V battery off of my drill and wired it up to a X-60 connector and it ran the boat pretty well.

[Bande1]

get us some pics of that!!

[Roy1]

What one do you recommend on Amazon for $55. I will take a pic of it, took a broken drill battery connection and hooked it up just curious.

[jkflow]

Motor voltage is only a recommendation. Mainly driven by max rpm. I run my 2200 on 6S all day.
Max rpm is typically driven by bearing rpm rating etc.
For boat applications, you typically want to be in the 25-35k rpm but I frequently ignore that as well, really depends on what you want to achieve.

[Bande1]

Motor voltage is only a recommendation. Mainly driven by max rpm. I run my 2200 on 6S all day.
Max rpm is typically driven by bearing rpm rating etc.
For boat applications, you typically want to be in the 25-35k rpm but I frequently ignore that as well, really depends on what you want to achieve.

big boats = low RPM
speed run boats = high RPM
oval racing 25k-30k RPM

why? because its where the prop size is optimized.

[Roy1]

I took a pic, was going to make a video but too much trouble. It works though used them a few times when batteries were dead.20231125_094754.jpg20231125_094801.jpg

[Bande1]

https://www.amazon.com/HOOVO-7-4V-Co...zcF9hdGY&psc=1

[Roy1]

I looked at the batteries Bande1 listed and they are LiPo bats which are 3.2 volt, I would have to get three of them to get the same voltage. I like LiPo bats they are more economical for sure, but for sheer power liion is a little better 3.7 volt. I do know that if you step up the voltage, you will decrease your amperage use. That is why electric heaters are cheaper to operate if they are 220V.

[Roy1]

By the way Bande1, I went back to Leopards website and found out my motor (1450kv) and the 1650kv are rated for 33 volts (8s). In addition some of the lower kv motors are rated for 10s. So the website I had looked at was right it is 4s-10s, it just depends on the winding, which makes sense.