Building a go kart size Aerial Atom

[JTSpeedDemon]

I know very little about electric karts, but my one input is:
SLA'S ARE FRIGGIN' HEAVY!!!
And I know that from my ham radio experience!

 

[Functional Artist]

Hey FA

You just need to get with the times and go lithium. Either get some 18650s and build a pack with some vruzend connectors or buy some factory built packs from a hybrid or electric road vehicle.

I paid $500 for a single LG Chem battery pack out of a Chrysler Pacific hybrid minivan. Its 16s1p 45ah, weighs 40lbs. Can do over 200amps continuous or 400amps peak. For your current draw you'd see very minimal voltage sag.

You would need a BMS and a charger as well.

---------- Post added at 04:16 PM ---------- Previous post was at 04:04 PM ----------

Oh yeah, FA what you proposed will help you, but only fractionally.

Your idea would increase the capacity of one of your 5 batteries. Let's say that capacity increase is enough to stop the voltage sag for THAT battery. The other 4 batteries will still have the same voltage sag so you'll theoretically reduce your voltage sag by 20%

1) my ElMoto (electric motorcycle) is powered by a 2kWh lithium battery pack (from a Chevy Volt)

2) building homemade lithium packs scare me
...too many variables (differing cell capacities, different resistances etc.)

IMO one would need a bunch of (really) closely matched cells
...& also, some good equipment, to verify them as such, to "safely" proceed

3) I really like your kart
...but, I build a lot of karts & find it kinda hard to justify $500.00 for just the battery pack
…& then/plus a BMS & charger

4) OK, makes sense
...adding (1) cell to a (5) cell battery pack would/may reduce sag by 1/5th

 

[Bmr4Karts]

1) my ElMoto (electric motorcycle) is powered by a 2kWh lithium battery pack (from a Chevy Volt)

2) building homemade lithium packs scare me
...too many variables (differing cell capacities, different resistances etc.)

IMO one would need a bunch of (really) closely matched cells
...& also, some good equipment, to verify them as such, to "safely" proceed

3) I really like your kart
...but, I build a lot of karts & find it kinda hard to justify $500.00 for just the battery pack
…& then/plus a BMS & charger

4) OK, makes sense
...adding (1) cell to a (5) cell battery pack would/may reduce sag by 1/5th

2) I agree. I'm sticking with factory built packs like my LG Chem. They are built for Chrysler Pacifica hybrid minivan.

3) Thank you.
You gotta pay to play. On my last run I was pulled an average of 90 amps over 10 minutes and max current is over 200 amps (meters max). I'm running 60 volts, so that's 5 batteries in series just for the voltage. To handle the current I'd probably need 3 or 4 sets in parallel. That's a ton of space and weight.

I don't run a BMS. I discharge down to a safe voltage while driving and check the individual cells. Two hard runs so far and the cells drain together within 20mv. I then charge with a hobby charger with individual cell balancing.

 

[Functional Artist]

I got my Aerial Atom kart out over the weekend

I've been thinkin' about (maybe) doin' a couple of modifications (I've learned a bit more, since I built this kart, back in 2018)

First off, the "dash bar" is way too low (it just barely clears my knees & I'm not a big guy)
...& maybe check out the steering a bit (I don't remember incorporating the Ackermann concept)

Left knee

Right knee

It's a blast to drive
...but, I'm just worried that "if" ya hit something "it wouldn't be pretty"

* As I'm get older, Ima thinkin' a lot more about the "what if's"

Well, let's do something about it

Here is the "back side" of the old dash bar

Ima thinkin', maybe something like "this"

Wow! that'll give us lots more clearance

 

[Functional Artist]

I made up a dashboard (out of a piece of plastic from the back of, an old TV)

This one will still have a PZEM-051 "power meter"
...but, Ima gonna add a digital speedometer too (like I installed in the Hell-raiser kart)

Yup, I cut that dash bar right off, like I didn't even like it (JK I actually thought about it several times before I did it)

Quite the difference between the (2) dash bars

The (2) dashboards are quite different too

My weapons of choice

Cut 'er off with the cut-off wheel (being careful NOT to damage the "main bar/frame" on the kart)

Cleaned 'er up (a bit) with the rough grinder

Then, used the fine (40 grit) sanding disc (like it never happened)

 

[Functional Artist]

Workin' on "placement" of the new dash bar

...then, got 'er welded "in place"

...& double checked the "fitment" of the dashboard

 

[Functional Artist]

While I've got 'er "torn apart" let's work on the steering

* In this pic, the tie rods are disconnected from the pitman arm

* It's pretty kool with how the back of this kart is designed
...where she can "stand up" on her tail

I first checked where the Ackermann "angle" need ta be
...with a string, tied to the center of the rear axle

This kart has forward facing spindle arms
...so, to do the Ackermann "adjustment", we need to bring the outer tie rod end "out more" (technical term)
...but, there's not much room, between the tie rod end & the tire, ta move it "out more"

So, were gonna have ta do the adjustment, in the center, on the pitman arm

* This kart currently only has a (1) hole pitman arm
...so, I had ta make up a new one with (2) holes

First, I drew 'er out on a piece of 1/8" steel
...& drilled some holes

Cut out the "main piece"
...& redefined the shape a bit

Cut 'er some more
...& did some roundin'

To keep the tie rods "in alignment" the pitman arm needs to "wrap around" a bit
...so, I did some bendin'

Then, I put 'er on the kart
...& installed the tie rod ends
...but, the Ackermann "effect" seemed ta be backwards (worse not better)

 

[Functional Artist]

It looks like we need ta "criss-cross" 'em
...so, I had ta make up some longer tie rod ends

* Then, I found that my double hole pitman arm "clashed" with one of the tie rod ends
...so, I had ta make another (2) hole pitman arm, with more "clearance" (still clashes just a bit)

Also, to help illustrate the angles, I put a piece of cardboard under the front tires

...& drew out the angles with the tires turned in both directions

First, I drew a line along the outside of the tire to establish a "straight edge"

So, when doing a right turn the right tire "is" the inside tire (& should turn more)
...& with the right tire turned at "full right", it measured ~3 3/4" (from the straight line)

...but then, when turned at "full left" it only measured ~2" (when turning left, the right tire "is" the outside tire & should turn less)

* Yup, this seems ta be more correct
...because, the inside tire "should" turn at a sharper angle than the outside tire


To help "illustrate" it even more, I extended the "lines" & painted 'em


I also, did a video to help show "all of this"

 

[landuse]

Looking good FA!! Just out of interest.....would the batteries on the kart still be good after all these years/ Do they just need to be charged?

 

[Functional Artist]

Looking good FA!! Just out of interest.....would the batteries on the kart still be good after all these years/ Do they just need to be charged?

Hey pal,
How have you been doin'?
...& thanks!

Well, I try ta connect the charger to them, about once a month, while in storage

When I got 'er out, (1) of them seem ta have went "bad" while sitting
...but, upon further examination I found that the (1) that "went bad", was actually damaged

It had a crack in the bottom
...& some of the "gel" seemed to have "leaked out" (technical term)

* I guess the Liquid Electrical Tape, that I used ta try-n-seal 'er up, didn't "do the trick"

So, I replaced it with another (like/also used) cell
...& charged 'em up

Now, the pack seems ta "work" OK
...but, ya can tell their getting "old" & weaker

It was good ta hear from ya
...'cause we miss ya

 

[landuse]

Hey pal,
How have you been doin'?
...& thanks!

Well, I try ta connect the charger to them, about once a month, while in storage

When I got 'er out, (1) of them seem ta have went "bad" while sitting
...but, upon further examination I found that the (1) that "went bad", was actually damaged

It had a crack in the bottom
...& some of the "gel" seemed to have "leaked out" (technical term)

* I guess the Liquid Electrical Tape, that I used ta try-n-seal 'er up, didn't "do the trick"
View attachment 133276
So, I replaced it with another (like/also used) cell
...& charged 'em up

Now, the pack seems ta "work" OK
...but, ya can tell their getting "old" & weaker

It was good ta hear from ya
...'cause we miss ya

Oh ok. At least you didnt have to replace them all.

 

[Functional Artist]

Lithium Upgrade

I got my Aerial Atom kart out
& took 'er for a (last) ride (powered by the (5) 12V 15AH SLA battery pack)

* Notice the "wicked" Voltage drop (~5V sometimes)
...but, she still scoots right along

Then, I installed the 16S 60V 15AH Lithium battery pack (made out of cells, from a Chevy Volt (electric car) module)

* I also, installed a Pre-charge circuit
...incorporated into the Circuit Breaker housing
...& mounted 'em both, right on top of the battery pack (easily accessible)

Here is a video, with more info

 

[Functional Artist]

Here is part II of my Atom Kart Upgrade to Lithium video

 

[Functional Artist]

Did anyone notice, at the very beginning of part II, the rear end of the batt pack "raised up" a bit?
...& then, "raised up" even more by the end of the video? (from ~9" up to ~9 1/2") (quite concerning)

I (must admit) I didn't
...& I was even "trying" to "watch" for any irregularities

I actually noticed, when I went to remove the batt pack from the kart, for re-charging
(it's NOT a good idea to re-charge an "experimental" lithium battery pack while still in the kart) (just sayin')

But, because of this "RED FLAG" I re-evaluated "the plan"
...& thought it best to just let it "sit" for a couple of days, instead of re-charging

Well, after a couple of days of monitoring it (visually & the individual voltage levels) I noticed that the negative (-) end of the batt pack had "shrunk" back/down into the housing, a little bit
...so, I helped "persuade" it the rest of the way
...& then, put a "strap" around it "vertically" (to help keep 'er there)

So then, after re-evaluating the situation
...going over the data
...& NOT noticing any "new" RED FLAGS
I went ahead & connected the charger & charged 'er back up (constantly monitoring the pack visually & the voltage level)
Now, Ima gonna just let 'er sit for a little bit (just ta be extra cautious)

 

[Functional Artist]

I've been monitoring the 16S 60V 15AH pack.

The voltage was 65.7V just after charging
...& an hour later the voltage had settled (~.5V) to 65.2V.

The next morning the voltage had settled just a bit more (~.1V) to 65.1V
...& has been sitting there, nice-n-steady for a couple of days.

I also, have been doing individual cell checks
...& they have been staying pretty dang close

So, NOT noticing any RED FLAGS
(the voltage levels have been staying very consistent & no noticeable swelling or raising)
I went ahead & mounted it back on the Atom kart, for another test

 

[Functional Artist]

Test recap:
The 16S 60V 15AH battery pack seems to be holding up pretty well, since the last test.
No noticeable raising or swelling

During this test, I ran the pack down to ~51.5V

An hour after the test, the pack had recovered to ~53.5V

The next morning recovered to ~54.5V
...& it has been sitting nice-n-steady ~54.5V (since)

According to the meter I used ~664Wh
...so, doing the math:
The 36 cell module, that these cells came from, was listed as 2,000Wh
...& 2,000Wh/36 cells = 55.56 Wh per cell
...& 55.56Wh x 16 cells = 888.96 Wh pack

This 16S 60V pack could have been "safely" drained down to ~48V (or ~3V per cell)
...& we only drained it down to ~51V
...so, (it looks like) we still had a couple of hundred Wh left in the pack (quite a sizable Extra Safety Margin)

Next, thing I noticed is that it seems like most of the "energy" is available
...&/or was released "in" the "top" or upper voltage range.

Because (I noticed) going from 0Wh -~400Wh, went from (fully charged) ~65V down to ~60V
...but, then, going from 59V down to 51V was only ~264WH
...& the "energy" seemed to "go" or "drain" much quicker (in the lower voltage range) too

The voltage drop seemed to be in the ~2V - 3V range
(which seems like a lot, for lithium cells, only under a moderate load)

The Amp draw averaged ~18A
...& the peak, I saw was ~35A

So, on this 15AH pack the ~18A const draw would be considered ~1C
...& the ~35A peak would be considered ~2C

Top speed seemed to be pretty consistently ~26MPH while in the 65V down to ~60V range (remember, this was an in 2nd gear test)
...then, it seemed to steadily reduce, as the voltage level went down

The Low Voltage Cut-Off "kicked in"
...& started reducing the power output at ~52V
...& then, pretty much shut the system down at ~51V

* Also, notice how the voltage meter "can" be used as a "fuel gauge"
...to let the driver know, how much is left "in the tank"
...at any "given time"
...with these type of Lithium cells (anyways)

So, that's what I got out of, watching the video, of this last test (a few times)
...let me know if you'all noticed anything, that I didn't

 

[ezcome-ezgo]

Whew, had to take a sniff of gasoline to keep from getting dizzy.