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lithium vs lead acid for gokarts Answered

For electric go karts, which one is better (for the money)? Lead acid is by far much much cheaper, but it is much much heavier. With a heavier battery you need a stronger frame, which weighs even more. With all of this weight you need an even stronger motor to push it all. With lithium you can build a lighter, cheaper frame, and power it with a weaker and cheaper motor and still obtain the same speeds. Lead Acid batteries take up about 1/3 the weight of a gokart with rider (1/3 being the driver, and the other third being chasis and motor and such). Reducing the weight by about a third (honestly, lithium, batteries weigh like nothing) could have huge performance improvements. So, does spending more money on batteries, and saving money on chasis and motor equal out to spending less on batteries and more on chasis and motor?

17 Replies

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12V (author)2009-06-08

lithium batteries are more inclined to explode under high load.

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Gjdj3 (author)2009-05-12

I'm pretty sure that the lithium batteries will be way more expensive. So expensive, that any weight reduction won't make up for it. You might find a good deal somewhere though. Where have you been looking?

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guyfrom7up (author)Gjdj32009-05-13

ebay, deal extreme, google, surplus sites, wholesale sellers you know, the usual ;)

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lemonie (author)guyfrom7up2009-05-13

(and like Gjdj3 - resize you avatar to "square" and it's head won't get cut off)

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guyfrom7up (author)guyfrom7up2009-05-13

the robot seems a little skinny now, doesn't he :P

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lemonie (author)guyfrom7up2009-05-13

Yea - looks like it should! (still a bit "porky" though) L

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lemonie (author)2009-05-12

I think the electric (battery) speed record was set with NiMHs (a lot of them).
60mph is a lot, the power needed to overcome drag is proportional to v3 or something similar. You'd want 5Kw at least I'd think?

L

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guyfrom7up (author)lemonie2009-05-12

Is there a way to calculate friction based on weight, and shape (for wind resistance)? I'm just wondering if cutting back on weight is really worth it for extra money.

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lemonie (author)guyfrom7up2009-05-13

Weight will generally affect acceleration, braking, the frame construction, and handling. If you've got good bearings and wheels it's not that much of an obstacle to top speed. You'd be wise to use regenerative braking if you can, to conserve some energy, but that's extra work.
To calculate friction / drag is hard - you'd be better trying to find data for similar things and making assumptions.

L

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guyfrom7up (author)lemonie2009-05-13

ok, and I'm banking on regenerative braking as my main source of breaking, cause I think it's actually simpler than other forms of breaking!

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guyfrom7up (author)guyfrom7up2009-05-13

wrong type of break in that last sentence of mine :P

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guyfrom7up (author)2009-05-12

oh, and how many watts or horse power do you think I'll need? I weigh about 115 (let's just say I way 150 so there more room), and lets just say the cart weighs 350 with lead acid batteries. Do you think 3.2kW is enough, or not even close? Oh, I guess I also have to give speed I want... I kinda want to go really fast, like 60 mph :D. Yeah, I don't think 3.2kW is enough... does anyone know where to get decent motors for cheap?

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caitlinsdad (author)2009-05-11

Have you priced out lithium vs lead-acid yet and is it even available for the consumer for the size that you will need? The cost of lithium for small power tools is about 3 to 4 times the price of regular batteries and that's only in 18volts with milliamp draw.

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guyfrom7up (author)caitlinsdad2009-05-11

I've been searching around, but I can't really get a bench mark price. Some places are way more expensive than others, but I'm not 100% sure the capacity of some of these batteries. Some are really cheap fakes that only have half the capacitor as advertised, and it's hard to keep that into account. Also, I've been thinking of building my own lead acid batteries to save money (any thoughts?)

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caitlinsdad (author)guyfrom7up2009-05-11

I dunno, has anyone tried to salvage junk car batteries and resurrect them? I don't know how one goes about replenishing the plates. And you're messing with acid and gas release and toxic landfill...

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