HI-TECH go kart

S

sabongi

100 W
Joined
Nov 19, 2009
Messages
139
Hello guys, i´m planning on building a electric go kart with the latest and most efficient electronics possible. I have decided for 12 Thunder Sky - LiFeYPO4 - TS-LFP40AHA batteries, giving me fully charged 63V and 40Ah. But i´m still searching for a Brushless highly efficient DC motor of approx 10KW and a controller for it. Can you guys give me suggestions? It needs to have high efficiency >90% and low weight! Something like a agni 95 motor but brushless!

Tks!
 
If you seek efficiency, you want a battery with low Ri, as the energy lost in voltage drop is lost efficiency in the system.

In a kart where minimal weight is everything, I would look for alternate battery options. Your battery will weigh as much as a complete proper racing kart.

For a motor, perhaps the mythical 10kw goldenmotor PMBLDC they said they have in stock, but haven't listed on the website yet? There seems to be a big gap in BLDC motors in this size range with >90% efficiency. Few brushless motors seem to be able to match the brushed Agni motors. I'm not personally a fan of brushed motors, but I gotta give them credit for doing such a great job on brushed motors.
 
liveforphysics said:
If you seek efficiency, you want a battery with low Ri, as the energy lost in voltage drop is lost efficiency in the system.

In a kart where minimal weight is everything, I would look for alternate battery options. Your battery will weigh as much as a complete proper racing kart.

For a motor, perhaps the mythical 10kw goldenmotor PMBLDC they said they have in stock, but haven't listed on the website yet? There seems to be a big gap in BLDC motors in this size range with >90% efficiency. Few brushless motors seem to be able to match the brushed Agni motors. I'm not personally a fan of brushed motors, but I gotta give them credit for doing such a great job on brushed motors.
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golden motors claim max efficiency 87,6% while agni 93%... impressive for a brushed motor...
 
Depends on your budget and what you want to do..

If safety is not priority #1 :twisted: .. RC lipo is the lightest and best performance option, you have to be VERY carefull with charging these and use them properly, check the battery section of the forum for all the information you need to know..

LiFePo4 does have a bit more of a safety margin if you screw up but weighs a bit more. Headway is one brand PSI is another that can deliver better performance vs the TS cells..

A few guys on here have built carts with A123 ( dewalt 36v powertool packs ), check the video section for some of that..
 
Ypedal said:
Depends on your budget and what you want to do..

If safety is not priority #1 :twisted: .. RC lipo is the lightest and best performance option, you have to be VERY carefull with charging these and use them properly, check the battery section of the forum for all the information you need to know..

LiFePo4 does have a bit more of a safety margin if you screw up but weighs a bit more. Headway is one brand PSI is another that can deliver better performance vs the TS cells..

A few guys on here have built carts with A123 ( dewalt 36v powertool packs ), check the video section for some of that..
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i have plenty of experience with lipos from RC´s, that´s why i was looking for LifePo4 :D
 
People seem to like the headway cells. A couple more C than thundersky but still LiFe.. if you're looking for a switch from RC bats like you say. Not as cheap as thundersky for the capacity you get though. May be a good idea to figure out your capacity needs first as that can narrow or open your options.
 
If you already have experience with Lipo from RC why would you want anything else? Unless that experience has been negative. But you probably already have all the charging equipment already for these, so why not? Have you checked out the Astro 3220? not 10 kw, but lighter and certainly cheaper than the Agni. I guess the first question you should ask is what is your budget...

Please post pics of smoky burnout in the cul de sac of your nieghborhood. 8)
 
vanilla ice said:
People seem to like the headway cells. A couple more C than thundersky but still LiFe.. if you're looking for a switch from RC bats like you say. Not as cheap as thundersky for the capacity you get though. May be a good idea to figure out your capacity needs first as that can narrow or open your options.
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yep, that's where i ask help for you megawatt guys!
Using a 10KW BLDC golden motor and 72V how much Ah would i need for approx 15 min runtime???
 
etard said:
If you already have experience with Lipo from RC why would you want anything else? Unless that experience has been negative. But you probably already have all the charging equipment already for these, so why not? Have you checked out the Astro 3220? not 10 kw, but lighter and certainly cheaper than the Agni. I guess the first question you should ask is what is your budget...

Please post pics of smoky burnout in the cul de sac of your nieghborhood. 8)
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i saw many lipos puffing and heating altough they were one of the firsts, not the 30/40C generation. I get worried about over discharging when using lipos...
About the budget, this is a pretty long time project and things usually take 45 days to get to brazil, so no rush and no tight budget...
 
You would need around 80ah worth of thundersky for 200amps. Thats bulky and heavy but it would get you a long 24 minutes of run time under a constant 200 amp load. So with on/off/partial throttle use its probably too much capacity and weight for what you need.
 
Not to mention even with the light 3c load on TS cells, they will still have considerable voltage drop. Lipo really is your best option for a kart for weight, power, and size. It may lose out slightly to TS in cost, but the advantages are more than worth it in my opinion.
 
sabongi said:
ok, i'm going for hobbycity.... 3 6S in series...
Click to expand...


The 40C cells can do 200amps each, but I think for roughly the same money you would be a lot happier with the performance and range if you went with 2P on 5Ah cells to give you 10Ah capacity. This would let you run something like the cheap 25C cells, have better performance, twice the run-time, and only a small weight penalty.
 
liveforphysics said:
sabongi said:
ok, i'm going for hobbycity.... 3 6S in series...
Click to expand...


The 40C cells can do 200amps each, but I think for roughly the same money you would be a lot happier with the performance and range if you went with 2P on 5Ah cells to give you 10Ah capacity. This would let you run something like the cheap 25C cells, have better performance, twice the run-time, and only a small weight penalty.
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can you help me estimate runtime on a 10Ah setup? If i consider a average 100A that would take me 6min runtime, is this right?
 
I agree, i'd get the cheapest cells if it allows you to run a bigger capacity pack. Even 15c is fine if you're running enough of them.
 
sabongi said:
liveforphysics said:
sabongi said:
ok, i'm going for hobbycity.... 3 6S in series...
Click to expand...


The 40C cells can do 200amps each, but I think for roughly the same money you would be a lot happier with the performance and range if you went with 2P on 5Ah cells to give you 10Ah capacity. This would let you run something like the cheap 25C cells, have better performance, twice the run-time, and only a small weight penalty.
Click to expand...
can you help me estimate runtime on a 10Ah setup? If i consider a average 100A that would take me 6min runtime, is this right?
Click to expand...


Yep, on paper it would be a 6 minute runtime if you averaged 100amps. This would mean 100% DOD (depth of discharge) on the cells though, which is pretty rough on them. I like to plan around only using 80% of the capacity of the cells, so I know they can do lots of cycles. Just as a general rule of thumb, I also only like to hit the cells with 1/2 of the C rating they are able to pulling. This just keep the voltage sag to a minimum.

They have some really cheap 25C 6s5Ah packs right now, $53/each I think. If you only need 5mins of runtime, running them 2P would work out well, if you want a full 6mins of runtime, I would run them 3P.
 
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