Random: 18650 cell motorcycle battery?

[Storx]

Today was a beautiful day and i had the day off, so i figured i would take the motorcycle out for some riding, 2007 KTM 450 exc, well its plugged into a battery tender, but when i went to start the bike it barely turned over 1 time and then was completely dead, so i swung out the kick start and kicked started it, drove the bike for about 5 hours today just enjoying the beautiful day and when i got home the battery was just as dead as it was before.. going to pull the battery out, but i think its done for.. i bought it from local motorcycle shop about 18months ago and after a quick phone call found out it only had 12month warranty.

Anyways, since i have SOOOOO many cells between 1800-1700mah, was thinking of whipping together a pack in a 4s configuration to replace the battery, wanted to ask you guys what you thought about it.. the battery in the bike is an 12v 55cca 4ah battery.

 

[Storx]

Think im gonna try it out before going out and buying a new motorcycle battery, took the old battery out and hooked it up to the Imax B6, i think its shorted internally because the imax immediately goes into an voltage error condition without even trying to do anything in the menus.. just connecting the battery puts it in the error condition and there is a spark when i connect the lead from the imax to the motorcycle battery...

I checked the output on the bike to make sure it had an output to charge the battery and idle it sits at 13.87v and revving it peaked at 14.25

just comparing the cells to the old battery i can build one roughly the same size as the motorcycle battery in a 4s5p configuration, to bad 5s5p wouldnt work because it comes out nearly identical in size to the motorcycle battery, but i may put some pieces of wood on both sides so it fills in the battery holder better for a secure fit.

 

[Hillhater]

4S 5P would mean each cell would have to be able to feed 11 amps to meet than 55 CCA level !
that is not likely with used laptop cells !....at least not for many fractions of a second and with likely 50% voltage drop !
I would think you would need to have at least 10P to have a fighting chance of a workable battery

 

[Storx]

from my understandings of lead acid batteries, they are only about 50% efficient, so only about 28 cca is really the output... figured the output of this battery is comparable....

I finished it up tonight, will try it out tomorrow.

 

[Hillhater]

Lead is very good at putting out amps...its capacity (Ahrs) where lead never gives its full rated output....unless you use a very slow 20hr discharge.
But see what happens
Remember though, even if those 18650's do manage to start the bike, overloading them like that will kill them very quickly.

 

[Storx]

Lead is very good at putting out amps...its capacity (Ahrs) where lead never gives its full rated output....unless you use a very slow 20hr discharge.
But see what happens
Remember though, even if those 18650's do manage to start the bike, overloading them like that will kill them very quickly.

i dont think the battery is going to see that many amps honestly, just looked up the starter in the ktm catalog, its rated at 410watts max.....

 

[Storx]

oh ya, its 4s6p, average mah for all 4 strings is 13.1ah

 

[Storx]

Well it was a success, soldered it up lastnight, then installed it this morning using 2 large copper bolts... bike started up perfectly without any issues, actually the fastest ive ever heard the motor turn over.. i put my device on it to measure amps during startup and it was 16.1amps as the max after 5 starts back to back.. the headlight is the brightest its ever been...i discharged the battery down to 14.2v lastnight.. took forever before installing it.. right now i have it plugged into my battery tender and its pumping 14.8v into the pack.. gonna keep an eye on it tell the tender indicates full charge before i store the bike away with the tender on it.. may just leave it off during storage since this pack has way more ah then the old one had..

 

[999zip999]

At 14volt the battery is almost drain. At 4.2 x4= 16.8volts. Brightest you ever had the lights.

 

[okashira]

NCA should work great for a lead acid replacement in 4s. Since they are good down to 2.0V per cell usually without damage.
I've been running a 12p4s pack from Model S cells in my Ford Cmax for months now. Works great.
I tested the same pack starting up a 6.0L V8

 

[999zip999]

I wonder how many volts your headlight can take before it becomes a Roman candle ? Lvc 3.5 x 4= 14 volts.

 

[Hillhater]

Well it was a success,
....... right now i have it plugged into my battery tender and its pumping 14.8v into the pack.. gonna keep an eye on it tell the tender indicates full charge before i store the bike away with the tender on it.. may just leave it off during storage since this pack has way more ah then the old one had..

Unless that "Tender" is specifically designed to work with Lithium, I would not suggest using it at all !
And as mentioned 14.8v is not a charge voltage for a 4S pack.

 

[999zip999]

Good lifepo4 is a better match, but you alternator must stop at 14.5 volt not higher.

 

[amberwolf]

I wonder how many volts your headlight can take before it becomes a Roman candle ?

I run a 1980's Honda scooter headlight (on SBC) and a 1985 Ford LTD headlight (on CB2) on a 4s EIG NMC pack, 16.4v fully charged; haven't burned one out yet with it, daily commuting running all lights day and night. (same thing with various other automotive and motorcycle turn signal and tail/brake lighting, both incandescent and LED).

Dunno what modern stuff can take, but the old stuff does ok with it.

 

[TheBeastie]

Looks like 4S is a good amount for motorcycle lead battery replacement.
According to this video this guys motorcycle alternator charges up his battery at over 14volts when in high RPM.
https://youtu.be/p6GnwkCXPi4?t=119
http://www.electrosport.com/technical-resources/technical-articles/how-motorcycle-charging-system-works

Voltage ranges for 18650 cells are quite wide and the further away you are from 4.2 volts the happier and longer lasting the cell is going to be..
14v / 4S = 3.5v each per cell (happy)
15v / 4 = 3.75v (each cell still happy)
From my experience 12.00volts on lead batteries means its at the low unhealthy end of its range and I think most ICE vehicles would be happier using something on a slightly higher voltage but are stuck with the old system.
https://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery#Voltages_for_common_usages
When a lead cell is being charged via its built in alternator its suppose to get and I quote "Typical (daily) charging: 2.37–2.4" 2.4 x 6 = v14.4 is what is typically going through the wiring on an ICE motorcycles main battery terminals.

According to drkangle with the Samsung 29E 18650 the bulk of its capacity at 3.6volts area.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=76048#p1148581

 

[999zip999]

What's the highest voltage will your alternator will put out ?
How much voltage can a common old style headlight take ?
How much capacity will the pack have charged to 14.4v as a 4s ?

 

[okashira]

What's the highest voltage will your alternator will put out ?
How much voltage can a common old style headlight take ?
How much capacity will the pack have charged to 14.4v as a 4s ?

When I want a range boost, I charge my c-max pack to ~15.7V. No issues with that.
The DC/DC in the car totally shuts off and the 12v system runs off the pack for a good 30 min. Saves 400W or so.

 

[Solarpower]

Are you still starting your KTM with the 4s pack Storx? If so, how has it been working for you?
My Suzuki Burgman 400cc is only in use a few times a month, so my lead acid battery is not the healthiest one I think I welded together a small 4s6p pack and hooked it up with some jumper cables to the old battery. The old battery was around 12V and would not start the bike, but the "booster pack" made it spin like it does with a new battery! I am just wondering if I should remove the old battery, or if I should use the 4s pack as a booster. I have easy access to the battery compartment, so it would be quick to plug it in and out...

 

[flippy]

I would just get some a123 cells and trow the lead in the bin. And then you are running the pack at the proper voltage.