Solar Car Competition Batteries

[999zip999]

Maybe you get a premade auto battery from battery hookup or clearing house. Still don't know you're battery or motor needs
14s 12ah is close
Let's talk motor.
I know this is too big ah-wise but here's some of the stuff they have

Battery Hookup
51.8v 35ah 1.77/1.84kWh 14s Lithium Ion Module
Regular price$275.00
You just got to look at the different places and see what they have and get lucky

 

[e-beach]

Ok ,back to the original question about what battery. I am of the opinion that v85 has given you a very good option. I like the fact that it is LiPO for it's high C rate makes it great for racing. It is under 720 Wh to abide by the rules. It is less then 10 pounds in weight. Combined with the motor you are thinking about it will power it to 20+ Hp which is 5 times what you have now. If not that battery, something very similar is what I would use.

https://www.racepow.com/product/racepow-16000mah-44-4v-12s-30c-lipo-battery/?v=7516fd43adaa

I do have one question though, will direct drive hub motors be more efficient then what you are thinking about getting? I do not have the answer to that but there is a man on this board who probably can answer that question. His name is Luke, and he goes by the handle of LiveforPhysics. He has also built and raced one of the fasted e-bikes around here. He is a very nice guy and if you politely private message him your question about batteries, I would bet he be happy to help. His profile: https://endless-sphere.com/forums/memberlist.php?mode=viewprofile&u=7638

Also, and not to keep pounding you with aerodynamics, but, the underside of you cart could use some work to help it cut through the wind better, and a canopy in front of your driver could be helpful.

My 2¢'s

 

[PaPaSteve]

By the spec the RacePow battery should work OK and is a good price.
At 30C discharge rate it will definitely be more kick then the 15C rate of the Tattu.
Tattu has a lot more in the case then just the battery.
Keeping in mind that a throttle happy driver combined with a high discharge battery could drain the battery early in the event.

To see the current car visit their instagram page (or Facebook) ... it's a different car then what's shown the web site.
They have switched to a racing go-kart with some streamlined body panels rather than an off-road kart.
Kart racing tires are tubeless with more pliable sidewalls so I'd expect them to have lower rolling resistance.
Probably too wide and sticky for this application though.
To conserve power, switching to a narrower profile, harder compound tire might be better.
Having a data logger reveal small details like this.

Overall, the team is making good progress in an exciting new racing series.
Big thumbs up
Wishing to be a kid again

 

[e-beach]

....
To see the current car visit their instagram page (or Facebook) ... it's a different car then what's shown the web site.
......

Thanks for the lead. This cart is looking much better (more complete) then the one on their web site. These girls seem formidable for sure. No doubt they worry the boys... :lol:

I agree about the tires. I suppose if they are filled with air to the point of being rock hard it would help.

 

[PaPaSteve]

Thanks for the lead. This cart is looking much better (more complete) then the one on their web site. These girls seem formidable for sure. No doubt they worry the boys... :lol:

I agree about the tires. I suppose if they are filled with air to the point of being rock hard it would help.

For the purpose of clarity ...
Pictures your showing, I believe, is the previous car not the current car.
Perhaps Pizza17 can clear this up for the readers here.

Tire pressures ... A hard lesson learned in my bicycle racing days, too much pressure can increase rolling resistance.
Ideally for road racing the tire wants a 10 ~15% sag when the vehicle is fully loaded with driver in place.
Again, a data logger can reveal little details like this.

 

[e-beach]

.....

For the purpose of clarity ...
Pictures your showing, I believe, is the previous car not the current car.
Perhaps Pizza17 can clear this up for the readers here.

....

Well, it does have the number 1 on it.

@Pizza17... Can you show us your updated car or are you keeping it under raps so the competition can't see what you are up to?

 

[pizza17]

OK ... Thanks ... Now we're real ! ...
Car is a stunner, gets beauty points from this judge.
Went ahead and threw $100 in the pot.

Thank you so much for your donation! As first-time users of this forum, we are blown away by everyone's generosity. Your donation will be a big help in purchasing these batteries

We're still in the early stages of building this year, but so far we plan on having two teams - a first for us. One group is using the chassis from last year (the pink shifter kart on Instagram) and another group is welding a new one up from scratch. In the end, it should look like this with better tires and aerodynamics

 

[pizza17]

Ok ,back to the original question about what battery. I am of the opinion that v85 has given you a very good option. I like the fact that it is LiPO for it's high C rate makes it great for racing. It is under 720 Wh to abide by the rules. It is less then 10 pounds in weight. Combined with the motor you are thinking about it will power it to 20+ Hp which is 5 times what you have now. If not that battery, something very similar is what I would use.

https://www.racepow.com/product/racepow-16000mah-44-4v-12s-30c-lipo-battery/?v=7516fd43adaa

I do have one question though, will direct drive hub motors be more efficient then what you are thinking about getting? I do not have the answer to that but there is a man on this board who probably can answer that question. His name is Luke, and he goes by the handle of LiveforPhysics. He has also built and raced one of the fasted e-bikes around here. He is a very nice guy and if you politely private message him your question about batteries, I would bet he be happy to help. His profile: https://endless-sphere.com/forums/memberlist.php?mode=viewprofile&u=7638

Also, and not to keep pounding you with aerodynamics, but, the underside of you cart could use some work to help it cut through the wind better, and a canopy in front of your driver could be helpful.

My 2¢'s

We're leaning toward those batteries too. Thanks for the suggestion v85!

A hub motor would be awesome! We've never worked with them before but I am sure they would be great for solar cars. Thank you for giving us Luke's information - we'll definitely reach out to him. :thumb:

 

[PaPaSteve]

Take a look at these motors.

https://www.goldenmotor.com/

The water cooled 3kw or 5kw BLDC motor could be a good choice for your use.

 

[Hillhater]

……In the end, it should look like this with better tires and aerodynamics

Hmm,? ..in addition to the wheels, There is so much in that type of buggy that you would be better off losing for a < 40 mph Solar competition ..unless regulations demand them
Suspension ?
Side bars ?
Roll hoop ?
…all just adding weight
Remember , a basic track race go kart (80-100mph) will weigh less than 90 kg ready to race.!
. Do you have to run 4 wheels ?.. if not a “tadpole) bike frame could be a good starting point.. with any decent hub motor (2-5kW) and a little aero , would have you way ahead of any of those buggys .
So its a shame your regulations are so restrictive for such a low speed vehicle, and prevent these “every day” road bikes competing.

 

[v85]

51.8v 35ah 1.77/1.84kWh 14s Lithium Ion Module

Suspension ?
Side bars ?
Roll hoop ?
…all just adding weight
. Do you have to run 4 wheels ?

For both of you, i`ll quote this:

For more information, the competition is for the high school SunChase competition at FGCU. Here is the latest version of the rules https://drive.google.com/file/d/1CeO3uGCLfs_WwGJdsU14qeGHmW8nziZl/view?usp=sharing

Pages 4-6(for battery page 7). So if i understand right (on page 6), power circuitry is motor and battery and they are limited to nominal 48V

 

[PaPaSteve]

Hmm,? ..in addition to the wheels, There is so much in that type of buggy that you would be better off losing for a < 40 mph Solar competition ..unless regulations demand them
Suspension ?
Side bars ?
Roll hoop ?
…all just adding weight
Remember , a basic track race go kart (80-100mph) will weigh less than 90 kg ready to race.!
. Do you have to run 4 wheels ?.. if not a “tadpole) bike frame could be a good starting point.. with any decent hub motor (2-5kW) and a little aero , would have you way ahead of any of those buggys .
So its a shame your regulations are so restrictive for such a low speed vehicle, and prevent these “every day” road bikes competing.

High School people building a competition vehicle to a set of rules.
400 pounds including driver as the minimum weight.
Rollbar and 5 point harness are mandatory.
It appears their newest creation will be built from scratch.
So there will be great skills to practice all the way from component selection, CAD design, machining, welding, testing to race strategy.

Nice trike you have built although it is one wheel short of fitting their rules.

 

[pizza17]

By the spec the RacePow battery should work OK and is a good price.
At 30C discharge rate it will definitely be more kick then the 15C rate of the Tattu.
Tattu has a lot more in the case then just the battery.
Keeping in mind that a throttle happy driver combined with a high discharge battery could drain the battery early in the event.

We think we're going to purchase the RacePow! Does anyone have suggestions for a charger and BMS?

 

[PaPaSteve]

We think we're going to purchase the RacePow! Does anyone have suggestions for a charger and BMS?

Model crafts don't always have a BMS onboard.
Their batteries are treated as expendables.
RacePow probably has the matching charger which likely has something of a BMS internally to maintain cell integrity during charge only.

 

[v85]

Looking at this photo of RacePow 12s battery:

i see 2x7pin(6s) balance connectors, so probably (?) need 12S JST-XH Balance Board for compact charger like iCharger X12 (no integrated power supply and XT60 ports info here):

Also new for me is AS150-U plug that looks similar to XT90, but with smart function

 

[e-beach]

What you need is a balance charger. No BMS is required for that kind of battery. Contact the battery manufacture and double check how many serial (S) groups that battery has. The information the battery manufacture tells you will need a balance charger that can handle that many serial groups.

So, if that battery is (something) P and 12S, your balance charger will need to be able handle a 12s battery.

 

[pizza17]

What you need is a balance charger. No BMS is required for that kind of battery. Contact the battery manufacture and double check how many serial (S) groups that battery has. The information the battery manufacture tells you will need a balance charger that can handle that many serial groups.

So, if that battery is (something) P and 12S, your balance charger will need to be able handle a 12s battery.

Okay, thanks for the explanation. For our competition, we have to charge while we drive with solar panels and a mppt. Do you know how we can use these batteries while doing that?

Our mppt says that we would need bms. Is there a different mppt we should consider?

 

[e-beach]

Can you link to your mppt so we can look at the specs? I will help with informed answers.