large road legal electric go kart build. need help!

[Inwo]

just bare in mind i will in the future set them up for 96 volts, but leave them in 48v form for the bms and charging, that should be ok correct?

Don't understand. This one is 12s but future builds will be 24s?
Suggest you do 2s 2p for the 4 12s modules right away.

New model bms-24 is in production. As is a matching 24s charger that works with bms.
New model has display in a separate enclosure and Bluetooth communication thru android.
Sneek peak:

 

[falshami]

if i understand what you are saying, you will in the future allow them to function for 96v but allow the, to do their work and control at 48v?

my future builds will probably be 12s 48v if i decide to build something slightly more mass produced, but for my own build, i do want to do a 96v build, so i will end up converting my stuff too 96v when i get the change to buy a 4th battery.

i would love to see what your new BMS systems comes out as!!

If we are miss communicating feel free to call me!

my biggest confusion now is , am i going to be able to use two 48v chargers to charge my 96v pack? will my current BMS work? or am is tarting from scratch?
i have a charger that has two output ports that charge 1200w 50.4 volts each

 

[falshami]

falshami, did you ever find out what the gearing ratio is in that differential/final drive box ?
Or what rpms the motor runs up to ?

sorry for not replying to this, the gear ratio in the gear box is nearly 1:1 , maybe something like 1:1.14

 

[falshami]

weird thing ive noticed... so every time i do a fairly good drive cycle, say 15 miles. when i got o recharge it, its been able to charge a bit higher up it used to top out at 6100 wh, now shes currently charging up to 6780 wh, and at an efficiency of around 200ish wh per mile... thats an extra 4 miles per charge. what gives? why is my capacity increasing? is the battery breaking in? or is the charger learning what it can do with the battery?

 

[fechter]

If the batteries were new, unused cells, then you might be seeing capacity increase from the batteries getting "broken in". From what I can tell, you might see an increase in capacity for 3-4 cycles then it will max out.

 

[falshami]

They were supposedly broken in I believe they had quite a few thousand miles on them. But this is awesome they increased almost a full 1000wh from when I first bought them from 5800 to 6900wh!

 

[falshami]

So my little car that could successfully took me from home to work to home today. I charged up at work just in case. But I think its clear voltage is my enemy. Or the lack thereof.so I'm going to overvolt my motor while keeping an eye on amps etc. I think running my motor at 12 or even 15 kW is reasonable. I think I've settled on a 30kw controller the hpc500 which can do 96v at 400 amps. Now I won't be running my motor anywhere near this hard as I'm sure that would be a quick death. I want to program the controller for a maximum of 6000 rpm. Which would give me a great speed boost. But limit the output voltage of the controller to maybe 60 or 70 volts. Keeping also the amps low at maybe a peak of 250 amps at 60v or 200 at 70v. This way the motor is never over revved or overly heated. And since the front stator of my motor probably will get hotter than the rear water cooled stator. I'm thinking adding a front place to my motor that touches a large surface area and adding thermal paste and some heatsinks. Or trading my golden motor for a montegy brush less motor. In leaning forwards keeping my current motor but will probably sell my vec500.so the good news. It got me to and back today home to work. Half way through the trip the controller thermal throttled itself. Which I thought would be awful. But honestly it helped. It kept me from draining my battery super fast at excess of 300a. And it still was able to maintain a nominal 40mph. This was adequate for my drive. Now keep in mind the ambient weather was about 100 out. So it was fairly easy for electrical components to overheat. My cooling systems managed to keep my vec500 cool enough to not shut down or kill itself and maintain 40 mph. My water cooking of the motor kept the motor cool enough to touch it still. I couldnt leave my hand on it for more than 3 second but its not burning you like an engine. I'm going to look into further Cooling. More heatsinks maybe? Also dropping two teeth on my pinion gear will help. 96v is in the pipeline. I just need to get a 4th battery and figure out how to use my current 48v charger to charge my batteries while they are in a 96v configuration and keep my BMS reading at 48v ideas are always appreciated

 

[Inwo]

Leave the bms and batteries connected 24s. Use two 48v chargers. Your bms can work on 24s and control two chargers.
Makes no sense to reconfigure for charging.
I just picked up a 96v DQ charger that might be reasonable. It has a built in DC to DC which is nice. Don't know what profiles it has yet.
As you know DQ lithium chargers can be controlled directly by BMS-24.

ps.
It makes it hard to follow when talking about maximum battery volts. :wink: 12s are 44v nominal, and 24s 88v.
Dq 72v chargers can be set to 24s. I'm out of working ones though.
Have 24v, 36v, and now a 96v. I buy them to repair.

 

[falshami]

OK so my charger can charge two 48v batteries at the same time as it has two charge ports. Are you saying I can do that still? Also my batteries charge up to 4
50.4 volts. So that would be 44v nominal? Sorry for the confusion! This would mean a 96v controller couldn't work for me?

 

[Inwo]

Depends on the specs for both.
The charger would need to have isolated outputs. Do you have a link?

The controller should list high and low voltage.

 

[falshami]

i need to see if they are isolated, i believe they are. it is a vicor charger at 48v, im going to go look up the specs and model number, how does this bms handle two chargers? i only had one relay shut off lead?

 

[Inwo]

It can easily power two relays.
Are you using an ac ssr?
One may handle both, or add another. Inputs in series or parallel.

 

[falshami]

i didnt even realize that i could just wire it to do two relays, however my vicor should manage to charge both just fine as they do seem to be independent, as long as my outlet can handle it. another update, my battery is now charging to over 7200Wh to me this is simply amazing, i am so happy to have gotten a realistic extra nearly 5 miles out of my pack . i had a little more playing with my vehicle today and honestly running it a bit harder i got about 220wh per mile instead of my average 212wh, im pretty stoked about this personally. i need to figure out what else i can do to keep the controller a bit cooler when its over 100 outside.... its just scary to my vehicle throttled like that though it does maintain 40 mph. i think a bigger controller leaving it severely under powered will be better off im thinking. this buggy is really turning out to be tons of fun. this week i will get my under body panels to hopefully help aerodynamics a bit, and also my 12 tooth gear, we will see what she manages to do with a 12 tooth gear instead of the 14 tooth. i just need to find out another way to bring up my 0- 8 acceleration. it would make traffic easier.

 

[falshami]

so good news ans bad news. Solar works swimmingly, it was charging me up at between 3.2 amps and 5 amps, amps would stay at 5 if the car had been moving and cooling the panels off.. bad news... on the way to work she started to cut out then finally just stopped moving.. my thoughts are a loose wire or a bad controller... but why would the controller go bad after only 60 miles and ive kept my heat low... im quite perplexed. i thought it was the key ignition but it didnt help. it must be a wire since it would go for a little bit then cut out all together again, then i couldnt get her going and had to tow her home, making me late for work. she seemed a bit down on power though today as well right out the gate. but then picked up nice and hard when moving, so that might just be in my head. also a fuse replacement didnt help... is there a way to reset these controllers ? other than just a reprogram

 

[galderdi]

Again, all of this is sounding very familiar. I think you are progressing well through your (expected) teething issues.

I suspect the controller has shut down as a safety to protect something. Maybe a cell or two are out of balance.

I had a similar issue which I eventually put down to my BMS over heating. I had them in a sealled box to protect them from the elements. Since then I have added two fans and vents to circulate air through the box. I've not had any issues since then.

 

[falshami]

I'm going to check this out. Doesnt the BMS system just balance everything on its own? I'm sure the controller was dead cool since it had only done a quarter mile. I'm going to check what you've just reccomended right now and see what happens s

 

[Inwo]

As far as I know this bms is only connected for charge control. Not discharge control. It does have a display that shows cell levels.

 

[falshami]

So after checking the car. I tried a new throttle and its responding again but only at full on or full off. And the BMS is no longer reading watt hours. On becoming quite concerned as to what this could be. I'm going to see if a reflashing helps?

 

[falshami]

another update, i think the controller may have just failed? i tried a reprogramming and it works again, but it works either throttle full on or full off, which means i am at a loss, i dont know why this would happen and ive tried two throttles. and nothing, just full on or full off. also golden motor customer service is absolute garbage , if it is broken im probably going to have to eat this. i dont have the skills to repair this unit saddly if that is the case. any suggestions? also this failure comes after only 60 miles of driving, thats insane.

 

[falshami]

another update. the controller seems to be working again, it may have just been a fluke. but it got me a round trip of nearly 38 miles today around town,i always charge when i get to work of course. it seems i do need more volts and a stronger battery pack, so i will be doing a 96v conversion at some point here and picking up another battery to have two parallel 50ah 96v packs for a 100ah 96v pack. this should allow me to set a controller to only rev up to say 5500 rpm and keep the voltage up to say 60v. this means that as my battery depletes i wont notice any appreciable speed drop as i do now at 48v. a pack at 50v is way quicker than a pack at 44v . so im hoping to be able to consistently be able to put put 60v if i so need it , or any where as low as i need and never worry about droop. my BMS continues to act funny. it no longer outputs the total watt hours in the pack but only outputs what has been charged in then erases. i cant figure out the setting for this and the amps meter continues to de-calibrate itself. i was told it may be a bad shunt. so i bought two new ones just in case . i will try them and see if it fixes my BMS. it just continues to come un calibrated and reads crazy numbers, sometimes 900, or sometimes numbers that just dont seem true. it also wont allow the pack to fully charge like it used to which makes it all the more difficult.

on a different note, the new sprocket 12tooth came in, i wont make any bets as to what it will do for top speed, but im hoping shaving 2 teeth will help me accelerate quicker. which would be heavenly, today a prius was running around with me and i just had to laugh, mainly because i know he would win. although surprisingly enough, though my take off may be bad. my passing power isnt the worst thing in the world . for a vehicle with around 16 hp and 900 pounds. it does well. the 10t sprocket i recall had loads of torque while driving and was a bit scary but top speed was just not enough. im hoping my 12 tooth balances me out

i also went ant bought some carpet foam to insulate my trunk area where the motor is to dampen noise, the motor and chain get quite loud while driving so i am hoping this will bring some noise down for me.

 

[galderdi]

Great that it is going again. I know the pain of major failures so I hope you can avoid that.

Regarding the shunt readings, I blew one of my meters a while back. So I ordered an identical replacement. I just replaced the gauge without changing the shunt and found it gave crazy results as you experienced. When I swapped in the specific shunt that came with the new gauge all was fine. Even though they were visually identical. So my conclusion is that the individual shunt and circuit must be tuned to operate accurately. Someone else with more knowledge might be able to validate this conclusion.

 

[falshami]

SO i tried the new 12 tooth gear. and it has confused me a bit more... it accelerates better for sure. topped ouit on a down hill at 48 mph. vs 51 before, and on a ormal area about 45mph. so this was promising. however the consumption has significantly increased it went from 212-220, to roughly 260 watt hours. which is kind of backwards of what i wanted. it seems to be drawing alot more amperage from my batteries now that it can rev up easier. mathematically that reduces my range a good two miles... im not sure how worth it that is. however my acceleration from 0 was not as much of a concern any more... i am not quite sure what to do at my usual 45 mph it was consuming around 350 amps. which confuses me since i have the controller limited at 300.. also the BMS is still not exactly trustworthy as far as amps being drawn , and probably wont be until the new shunt tells us if its the problem or the BMS. also added some carpet foam padding over the motor compartment and it quieted things down quite a bit. alot of the high end whine has gone away. next i will be getting bigger fans for the radiator to cool it better than the stock fans. alot of things going on!! Ideas are welcome!

 

[falshami]

new update. cant get accurate figures of energy consumption due to wonky BMS. thats in the works. however today i went ahead and started on aero dynamics. it may not seem like much , but i sealed up the complete bottom of the vehicle. which hopefully means less swirling off air in the cabin, and air moving around the vehicle more instead of through and tumbling around. i also managed to get the damn regen working.... apparently putting my tranny in forward. meant the motor had to spin backawards... meaning no regen braking in motor reverse. so i threw the tranny in reverse and the motor in forward now i get around 60 amps of regen at a good pace. and some very cool braking power i didnt have before. really excited about that. slight heat increase of course in the motor and controller due to this, but so far so good. the tranny being in reverse slightly negates my newly found acceleration... so that sucks... but were moving forward at least. i will be ordering new cooling fans for my radiator to extract more heat from the motor. i think faster fans would just be awesome, especially if i could find a PWM thermostat that would regulate speed. i also found that instead of quieting down my vehicle a bit, the new floor actually reverberated the drive train... and now things of course can be heard when they shake... awesome.. so i will probably be adding some sound deadening material under the floor boards in between the metal floor and new plastic under body. i added some small little panels to help move air around the vehicle near the wheels, small little modifications all make a difference and the buggy slowly becomes more bad ass.


does any one know if ordering a 96v controller and running it at a PEAK of say 60v , would this be possible? is this even a thing the controller can be set to do? if so i will be ordering the controller asap

 

[fechter]

You should be able to reverse the direction of the motor by swapping wires around so you can keep the trans in forward.

 

[falshami]

this is what i thought, but i also have to swap the corresponding hall sensors correct? how would i go about doing this?