Upgrade from 24V to 48v motor a success (PICS)

[garolittle]

So I finally finished an upgrade on a Razor Ground Force Drifter go-kart used by my son. I swapped out the old 24v motor and lithium ion pack for the following:

48V 1000 Watt Brushed Motor with rated current of 26.7 amps

48V charge controller

14S9P batteries using Samsung INR18650-25R 2500 mAh 18650 cells (connected with spot welder using pure nickel strips)

I added a 35 amp fuse (rated for up to 58 volts).

Finally, I added a voltage/amp meter and shunt so I can constantly monitor the power.

The results were awesome. I briefly hit approximatley 15 mph on a slight uphill road and the low center of gravity from the forward mounted battery pack allows for some fun “drifting”. I weigh 145 pounds (66 kilograms) so it looks a little odd for a grown man to be riding a kids Razor Drifter Go Kart but it is really fun. Previously, the 24 volt motor struggled to gain speed on the same road. The increase in power and speed is really noticeable. I will post some videos and pictures soon but I wanted to thank everyone again for all of the great advice.

 

[Functional Artist]

Looks fantastic

Very nice job

That's a big 'ol battery pack right there between you or your sons legs

I like your ingenuity but, homemade lithium battery packs make me nervous

(Heed, Sid's warnings) just because there is so much power in that little package

...learn everything you can about them with your son

...that way you'll both know what to watch for

...& what their capable of

PLEASE BE CAREFUL

 

[garolittle]

I like your ingenuity but, homemade lithium battery packs make me nervous


PLEASE BE CAREFUL

Yes Sir and thank you. You are correct regarding safety. I have spent many months researching the issue. While there are no fool proof methods for ensuring 100% safety with lithium ion 18650 cells I have taken many precautions.

By the way, I love your videos. I learned a lot from the famous "E Bananna" go kart videos and your shunt videos were very helpful. Thanks for sharing your knowledge.

 

[snowball]

I'm currently working on a 48V project too, what kind of screen is that and where did you source it from?

Looks pretty good.

 

[garolittle]

I'm currently working on a 48V project too, what kind of screen is that and where did you source it from?

Looks pretty good.

Bought it from amazon.com. It comes with a shunt and really works well. You just have to mount the shunt on something that keeps it from touching the metal frame. I really like it. Here is the link:

bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter Multimeter Ammeter Voltmeter with 100A Current Shunt
https://www.amazon.com/dp/B013PKYILS/ref=cm_sw_r_cp_api_oVTDAb12APEE6

 

[garolittle]

Here’s a quick video of my son in action. He loves the burnouts that are now possible from a standstill.

https://youtu.be/DLb3voRxLeY

---------- Post added at 07:05 PM ---------- Previous post was at 07:04 PM ----------

One more quick video. https://youtu.be/m5Pk7TgTe8I

 

[tinamcjittles]

Are you balancing those batteries? I'm doing something similar and going to have to dedicate a microcontroller and multiplexer just to ensure they stay even, this sounds nit-picky but some of the cells were hitting 4.6v carrying adjacent cells at 3.5v!! super unsafe; also, impedance matching is a must since these cells aren't cheap lolz good luck and sick build, super jelly of your fancy readout

 

[garolittle]

Are you balancing those batteries?

I use a Battery Management System (BMS) specific to a 14S configuration (see pic below). I also used brand new 18650 cells and I checked each battery to ensure equal voltage before spot welding everything together with pure enickle strips. Finally, I added a fuse on the negative wire as close to the battery pack as possible.

 

[tinamcjittles]

That's a work of art. What kind of range will it have with all that juice?

 

[mckutzy]

Whenever I see a batt pack like that.... It always reminds me of something like a CBU...

For ex...

Depending on how good bad they are made... Could have similar failure rates....

 

[Functional Artist]

I use a Battery Management System (BMS) specific to a 14S configuration (see pic below). I also used brand new 18650 cells and I checked each battery to ensure equal voltage before spot welding everything together with pure enickle strips. Finally, I added a fuse on the negative wire as close to the battery pack as possible.

Keep a close eye on them & periodically double check 'em


I have come across this phrase many times while during research on lithium batteries

"BMS's kill more battery packs than they protect"


I think it's for many reasons

...cheap Chinese junk

...installation errors

...incompatibility issues

...or (simply) the operator relied too much on experimental components, assemblies & applications
(& didn't do his due diligence by "keeping an eye on them")

From what I understand, a "Cell Medic" is a handy (& inexpensive) tool to help check voltages & balance of these lithium battery packs

https://hobbyking.com/en_us/hobbykingtm-battery-medic-system-2s-6s.html

They are only 6S so you may have use a couple of them or see what others are using to "double check" monitor their battery packs

 

[garolittle]

That's a work of art. What kind of range will it have with all that juice?

Not sure yet. I am installing a different charge controller this weekend but I will post a response to this question. I should be interesting since the battery pack is just over 1 kilowatt hour.

---------- Post added at 09:11 PM ---------- Previous post was at 09:07 PM ----------

...

From what I understand, a "Cell Medic" is a handy (& inexpensive) tool to help check voltages & balance of these lithium battery packs

https://hobbyking.com/en_us/hobbykingtm-battery-medic-system-2s-6s.html

They are only 6S so you may have use a couple of them or see what others are using to "double check" monitor their battery packs

I appreciate this idea and I may give it a try. I agree the BMS is a critical part of the equation and Cell Medic sounds like a good way to double check everything. I used brand new Samsung INR18650-25R (2500mAh) cells from a very reliable vendor but you make a very good point about the importance of the BMS.