Circus Clown Car

[Casalino]

Edit.
Hello everyone.
I hope your wonderful community can help me.
I just got a 72v 5.5hp motor “Dinasty it” slow ev.
And want to turn it in to a clown car but before I go get 6 flooded batteries I’m thinking lithium.
It doesn’t need to go far or fast, just enought to enter the circus, do about 3 laps inside a 45 feet circus ring and exit, that’s it.
Will there be a suitable lithium alternative?
It calls for 6 12v 100ah flooded batteries but I’m thinking maybe lithium 72v 30ah?
-All the horns, water, lights, etc will run from an stand alone 12v battery.
-By the way, I’d been running solar on a 24v system in my motorhome for close to a decade now.
Any help/advise would be greatly appreciated.

 

[sunshine_eggo]

Hello everyone.
I hope your wonderful community can help me.
I just got a 72v “Dinasty it” slow ev.
And want to turn it in to a clown car but before I go get 6 flooded batteries I’m thinking lithium.
It doesn’t need to go far or fast, just enought to enter the circus, do about 3 laps inside a 45 feet circus ring and exit, that’s it.
Will there be a suitable lithium alternative?
It calls for 6 12v 100ah flooded batteries but I’m thinking maybe lithium 72v 30ah?
-All the horns, water, lights, etc will run from an stand alone 12v battery.
-By the way, I’d been running solar on a 24v system in my motorhome for close to a decade now.
Any help/advise would be greatly appreciated.

The issue with electric motors is that they have a massive surge at startup. Lead acid doesn't care, but the BMS in LFP batteries will cut discharge if discharge current limit is exceeded. Most are limited to 1C continuous with very brief surges, and the cells themselves have similar limits.

I expect it's almost impossible to get a 30Ah LFP battery to discharge more than 30A.

LFP make for garbage starter batteries. They are only "drop in" for lead acid in power storage applications.

30Ah of LFP could "run" an electric motor of about 2-3hp, but it wouldn't start it.

 

[Crowz]

Cute looking car from watching youtube vids on it. As mentioned the surge will not work well with 30ah lifepo4's.

 

[sunshine_eggo]

Assuming perfect conversion, a 5.5hp motor is about 4125W.

4125W/76.8V (nominal for 36S LFP)= 61A

Assuming 5X surge, you would need batteries capable of delivering 300A for several seconds.

Alternatively, you could try to measure this with a high quality clamp DC ammeter, though it might not capture the true peak. It would give you a place to start.

Unless you're running several laps a night, 7 days a week, LFP may not be cost effective. LFP is most beneficial when you're cycling frequently and using most of the capacity with deep discharge. For brief usage with low discharge depth and infrequent cycling, they generally aren't the best choice.

 

[MisterB1959]

Could you repurpose an EV battery off a car? As you say, you don't need it to power the vehicle for miles, just potentially one mile, so a 'failed' EV battery might work for your needs?

 

[sunshine_eggo]

Could you repurpose an EV battery off a car? As you say, you don't need it to power the vehicle for miles, just potentially one mile, so a 'failed' EV battery might work for your needs?

IMHO, this would present an even greater challenge as a suitable BMS would need to be installed. Once you start counting > 16S, your BMS options get very limited. I doubt the OP wants to spend $1K for an Orion BMS on top of the battery costs... not to mention becoming competent with the Orion BMS (not notoriously user friendly).

 

[MisterB1959]

IMHO, this would present an even greater challenge as a suitable BMS would need to be installed. Once you start counting > 16S, your BMS options get very limited. I doubt the OP wants to spend $1K for an Orion BMS on top of the battery costs... not to mention becoming competent with the Orion BMS (not notoriously user friendly).

as you suggest, the OP may not wish to spend lots, but then again he might not need to ....

9kwh ( 175ah ) 2022 Hyundai Battery - BMS For 48v Sunsynk Hybrid Inverters | eBay

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of course, we dont know if this is a 'professional' project, in which case it might be well worth spending the extra if its a long term project ..

 

[sunshine_eggo]

as you suggest, the OP may not wish to spend lots, but then again he might not need to ....

9kwh ( 175ah ) 2022 Hyundai Battery - BMS For 48v Sunsynk Hybrid Inverters | eBay

Find many great new & used options and get the best deals for 9kwh ( 175ah ) 2022 Hyundai Battery - BMS For 48v Sunsynk Hybrid Inverters at the best online prices at eBay! Free delivery for many products.

www.ebay.co.uk

of course, we dont know if this is a 'professional' project, in which case it might be well worth spending the extra if its a long term project ..

The OP needs a 72V system.