Building a high Amp output battery question

[maarkmohamed]

Yea its going to be for a electric dirt bike, just trying to figure out exactly everything i need right now. You guys have shown me many options i have to figure out which is best.

 

[999zip999]

Again asking about the exact controller and the exact motor.
Yescom 1,000 watt dd with dilled covers.

 

[shaglord]

What about running a higher voltage and fewer amps = equal watts.

Good for a high performance (limited range) EV build. Thinner cables, smaller controller components

What about two wheel drive?

 

[izeman]

Again asking about the exact controller and the exact motor.

Why would that matter? He's just asking for advice on battery building, and he gave info about max amps and voltage.

 

[999zip999]

It all in the complete design . Like to see the whole picture. As mistakes and confusion have already been straiten out. Don't what to haul in the back on a trailer.

 

[Chalo]

The only reason why I'm not willing to use other batteries besides the 18650 is because I know how to assemble and work with 18650 cells, theres countless videos on them which makes it easy for me.

Prismatic cells with threaded terminals are infinitely easier to deal with than 18650s. I have used the Panasonic 25Ah prismatic cells as used in VW and Ford hybrids. It has unimpressive energy density, but huge current capability, and it's a piece of cake to build into packs. I think you'd still need 2P pack architecture to reach 500+ amps.

You seem to want maximum discharge rates north of 30A/cell for the little guys. Customary means of tabbing and welding them are nowhere near being suitable for such current. What's your plan?

 

[999zip999]

I saw your packs and like them but hard to fit on my style bike and a little heavy.

 

[maarkmohamed]

Being realistic right now, if i build a 26s 14ah battery, it would be a bit above 96v nominal 100+ hoc, and each cell would put out 20 amps continuous that would leave me with almost 27kw continuous. If i push the battery a bit and draw 25 amps from each cell which i could do for a few seconds even draw 30 amps from the cells for a few seconds which has been tested, id be pushing 30+kw into the 40kws. Now with a bike thats going to be less than 200lbs im really really being overkill. the alta redshift which is like 270lbs says they have a maximum output of around 20kw. And people who ride it say they dont even use the highest mode much because its too much power. So i think i should be realistic with the power im looking for and not be dumb. 20+kw of power continuous should be plenty.

 

[maarkmohamed]

Also if someone could confirm this for me. at 26s the nominal voltage would be about 96, when its fully charged (HOC) would the voltage be 4v x the 26 cells in series? so something like 104v?

 

[izeman]

Also if someone could confirm this for me. at 26s the nominal voltage would be about 96, when its fully charged (HOC) would the voltage be 4v x the 26 cells in series? so something like 104v?

Not ALL 18650 cells are the same, but as a rule of thumb you can calculate with 3.65V nominal on the conservative side (up to 3.75V some others say), and up to 4.2V for fully charged.
So 26s would be 95V nominal and 109V fully charged.

 

[maarkmohamed]

Also if someone could confirm this for me. at 26s the nominal voltage would be about 96, when its fully charged (HOC) would the voltage be 4v x the 26 cells in series? so something like 104v?

Not ALL 18650 cells are the same, but as a rule of thumb you can calculate with 3.65V nominal on the conservative side (up to 3.75V some others say), and up to 4.2V for fully charged.
So 26s would be 95V nominal and 109V fully charged.

thank you for clearing that up

 

[999zip999]

The hard part is making a series buss bars to handle the current in the 18650 format.

 

[izeman]

The hard part is making a series buss bars to handle the current in the 18650 format.

Drilling single stranded copper wire as used in home installation is how the guys building power walls do it.

 

[Bullfrog]

maarkmohamed....so you plan to build a 26s1p battery using 18650 cells?

It can be done BUT you are not going to have much capacity at your high amperage. Lets assume you use HG2 cells which are capable rated at 20A and 3 Ah. That means you will have 520A and 3 Ah...you will be able to go really fast for a couple of minutes and your batteries will be dead.

Voltages...is the push on the charge very similar to the pressure in a water pipe.

Amperage is the quantity of charge...very similar to the volume in a water pipe.

Amp Hours is how long you can maintain a charge flow...sort of like how big is your water tower supplying the pipe.

Watts is just Volts X Amps...or power. To some extent you can increase voltage or increase amperage and achieve more power.

Nice thing about increasing voltage is you don't need huge wires...the heating is proportional to the amperage squared X resistance. Voltage is not part of the equation. BUT high voltage makes things dangerous.

I have been looking at building or buying an 18650 based pack to run a bike on and chase a land speed record and I came to the conclusion that it is not reasonable to get there with an 18650 based pack...and I am only looking for around 100A.

Anything is possible given enough time and money but that doesn't mean you should do it.

I am now looking into LiPo packs and just wiring them together in series an parallel to get the power I need.

I'd suggest you consider some of the options others have posted...you won't pull as much of your hair out :lol: .