I finally found the vintage kart I was looking for my EV conversion.

[Functional Artist]

Um...do us both a favor, the next time you go into town
...take a Tesla (or a Volt or a Bolt or there's a bunch of them, now) for a test drive

Just to knock it off of your bucket list (you can thank me later)

They don't have mufflers
...but, what they do have is (well...get back to me/us...on that)

 

[Bmr4Karts]

Hey functional...I'm 76 years old....I will have gas available for the rest of my life. My poor grandkids will be forced to drive those humming pieces of crap that , Jeez don't even have mufflers. What kinda car is that ? Tree huggers will never enjoy life, because there ain't no such thing as ozone !

 

[EpsilonZero]

Again, this was with the controller at 60% battery current. So now I'm going to bite the bullet and just get a eight 6s 10000mah lipos and run those packs as 4s2p for ~96v 20Ah. With that I'll be able to crank the battery current up to 100% and max out the controller.

Aren't those 22.2v packs? That will get you 88.8v max rather than 96v. You could do a 4s1p with 6s 20Ah Turnigy packs too if you want to make it less complex. Then again, you won't be maxing out the motor... Obviously you should do at least 4s2p(6s 20Ah packs) for 40Ah and double the maximum current!

 

[Bmr4Karts]

Aren't those 22.2v packs? That will get you 88.8v max rather than 96v. You could do a 4s1p with 6s 20Ah Turnigy packs too if you want to make it less complex. Then again, you won't be maxing out the motor... Obviously you should do at least 4s2p(6s 20Ah packs) for 40Ah and double the maximum current!

22.2v is nominal for 6s lithium. You may be thinking of Lifepo4 which is less. I'm going with four 6s packs in series which is 24s, likely 3 set of that in parallel. Charged to 4v per cell is 96v max, 88.8v nominal. I charge to 4.1v but that's not a huge difference.

 

[Bmr4Karts]

Caught a sale at Amazon and got these packs for 20% off, sixteen 6s 8000mah packs. I’ll be running them in a 4S4P configuration which is then 24S 88.8 volts nominal and 32Ah. The packs are rated 120C which is complete BS. My controller is 500A max 200A continuous so I only need the packs to do ~16C max and 6.25C continuous so I should have a decent amount of wiggle room.

I tested a single pack with a constant 75 amp draw and it heated up to 120F. I won’t be pulling that much continuously per pack so I should be good there also.

I’ve been making EC5 hook ups and balance lead harnesses to prepare for all this. I’ll be shrink wrapping each group of 4 parallel packs and each group will always be hooked up to a parallel balance harness.

 

[EpsilonZero]

Update?

 

[Bmr4Karts]

Update?

Got tied up waiting for additional parts, a family vacation, starting my toddler in day care and subsequently dealing with the whole family getting sick, and figuring out how to manage all my battery connections.

I'm bundling 4 packs together into a single brick of 6s 32AH with parallel balance leads but keeping all the discharge connectors separate. Designed a wire guide that keeps the connectors together so I don't mix them up in the kart. Also made the harness that goes in the kart. Idea was to be able to plug all 4 EC5 connectors in at once but that takes more force than I was expecting so I'm changing it to two pairs each bundle.

I then need to move a couple things on the kart so the 4 bundles all lay flat under my legs.

 

[Bmr4Karts]

She’s a runner. Competed the battery and figured out mounting. 32AH of the lipos was just the right amount. I can run hard for 15 minutes and the packs are barely warm while the controller is slightly hot and the motor is about as hot as it should be. Can place my hand on it but it’s at the limit of not being painful.

After those 15 minutes the cells are all sitting around 3.8v which is perfect. I’ll still put them on the charger for a 3.85c storage charge though.

I also installed 4 Batt Airs which Bluetooth cell status to my phone. Makes it super simple to check.

This was my 2nd run with the new packs. First run the 4 gauge phase wires were kinda hot so I replaced them with some left over 0 gauge from my car audio days.

Used Strava on Apple Watch to track the ride. Said top speed was 57 mph but I don’t trust that. I bet it’s around 50.

 

[Functional Artist]

Very Kool!

Um...only ~15min on a 90V 32AH pack?
...or was that just "this" test?

How is the acceleration? (0 to 50MPH in?)

What is the Amp draw?
...& how about the Voltage drop?

Video?

 

[Bmr4Karts]

Very Kool!

Um...only ~15min on a 90V 32AH pack?
...or was that just "this" test?

How is the acceleration? (0 to 50MPH in?)

What is the Amp draw?
...& how about the Voltage drop?

Video?

Hey FA.

I have to get my meter attached for volts and amps. I haven’t recharged yet to see what I burned today but yesterday I burned 17AH in 19 minutes.

I’ll bring along my phone for some acceleration data next time. It’s probably under 5 seconds to 50mph.

 

[Bmr4Karts]

Oh yeah. I left a lot of rubber in the clubhouse parking lot. Hope that doesn’t cause me trouble.

 

[Bmr4Karts]

Got some data.

Voltage sag is around 5-6% and my meter shows I pull around 280 battery amps max. This is with the controller set to 65% battery amps though while I dial in the settings with the more powerful batteries. I still get the "3-2 Reset Error" which can mean any of the following.

"May be caused by some transient fault condition like a temporary over-current, momentarily high or low battery voltage. This can happen during normal operation."

So I'm betting its over current. It lets me keep driving just keeps beeping until I do a power reset.

I tried doing some 50 mph pulls and realized I can only hit 50 on a full pack with my 15/64 gearing. Once the pack is off max I'm down to 47 mph. 0-40 pulls took 3 seconds on my app.

But since I always want to be able to hit 50 mph I changed my gearing to 15/53 and to keep it safe I set an RPM limit of 5800, otherwise this is a 60+mph setup on a full pack. I still have drifting power with my 9 inch wide tires and I noticed a very real MPH increase on the longer pulls. I now have to tuck my head down so the wind doesn't rip the face shield off my helmet.

Next up is to try and get the battery current limit to 100%.

I may take it to a 1/8 or 1/4 mile drag strip next year. Put my Manco 20/53 gearing on it and go for 80 mph.

 

[EpsilonZero]

Next up is to try and get the battery current limit to 100%.

I have the same reset error issue (except mine doesn't beep, ever). I am able to do 80% phase current 100% battery current and I see at least 400A from the battery. James Biggar (YouTube) has the same controller as me and got the same problem but was able to do 95% phase 100% battery. According to Fany, there are current spikes that can't be seen, but I find it surprising that it could spike that much when my shunt reads like 70A and the controller resets immediately (max settings, 100% throttle from a stop).

I messed with a lot of settings and haven't been able to get any higher phase current yet without risking resets.

 

[Functional Artist]

I'd say your pulling "too much" from that battery pack.

Wouldn't a 250A+ draw be considered something like ~8C on a 32AH pack?

Does it warm up or get hot?

If you can, try monitoring the "voltage recovery rate" after a run

It seems like the recovery rate is an "indicator" of how hard the pack is being stressed.
Slow recovery = low stress
Faster recovery = higher stress

For example:
During this test, the motor was drawing ~20A (on average) ~30A (peak)
...& that should only be considered a 1C - 2C draw on the 16S 60V 15AH pack, that I'm testing
...but, the recovery rate still seems pretty quick

 

[Bmr4Karts]

I'd say your pulling "too much" from that battery pack.

Wouldn't a 250A+ draw be considered something like ~8C on a 32AH pack?

Does it warm up or get hot?

If you can, try monitoring the "voltage recovery rate" after a run

It seems like the recovery rate is an "indicator" of how hard the pack is being stressed.
Slow recovery = low stress
Faster recovery = higher stress

For example:
During this test, the motor was drawing ~20A (on average) ~30A (peak)
...& that should only be considered a 1C - 2C draw on the 16S 60V 15AH pack, that I'm testing
...but, the recovery rate still seems pretty quick

8C is nothing for these lipos. They are rated at 100C (which is BS) but I'd say anywhere from 10 to 12C burst is safe. As I mentioned before they are barely warm while my motor and controller are reaching hot.

I did a 75 amp constant drain test on a 10AH pack of the same make before I ordered the 16 32ah packs. That 10ah pack reached 120F after 5 minutes. So around a 7.5C pull for 5 minutes and the pack held balance and recovered quickly when I was done. I do think 120F is the absolute limit but I can't pull that kind of C current constantly with my setup.

Related to recovery: When I'm done running I pull up battair to read the cell voltages and they don't need a long time to reach a steady state which just happened to be around 3.8v per cell both times so far.

 

[Bmr4Karts]

I have the same reset error issue (except mine doesn't beep, ever). I am able to do 80% phase current 100% battery current and I see at least 400A from the battery. James Biggar (YouTube) has the same controller as me and got the same problem but was able to do 95% phase 100% battery. According to Fany, there are current spikes that can't be seen, but I find it surprising that it could spike that much when my shunt reads like 70A and the controller resets immediately (max settings, 100% throttle from a stop).

I messed with a lot of settings and haven't been able to get any higher phase current yet without risking resets.

I'll have to check James Biggar out. Thanks

 

[Bmr4Karts]

Put the gearing right at 4.0 to get some more torque back
Raised the RPM limit to 6200
Increased Phase amps to 100%
Increased Battery amps to 90%
Installed brand new rear tires
Cells were at storage voltage (3.85v per cell) just wanted to do a quick test run today.
51 mph top speed (motor is hitting the limiter)
Went to do some end of run donuts and busted the chain.
Time to look into size 40 chain and sprockets

 

[EpsilonZero]

Put the gearing right at 4.0 to get some more torque back
Raised the RPM limit to 6200
Increased Phase amps to 100%
Increased Battery amps to 90%
Installed brand new rear tires
Cells were at storage voltage (3.85v per cell) just wanted to do a quick test run today.
51 mph top speed (motor is hitting the limiter)
Went to do some end of run donuts and busted the chain.
Time to look into size 40 chain and sprockets

What chain were you running, #35? If you go 100% battery amps, what can you get your phase amps to?

 

[Bmr4Karts]

What chain were you running, #35? If you go 100% battery amps, what can you get your phase amps to?

I was running #35 chain before but it was the gold racing type which is stronger than regular black type.
As for the amps I honestly don’t know. Controller is 500 amps max.