Would 2 batteries fit?

Tips and tricks about building a car. painting it a making it run smooth.
Post Reply
BriG
Posts: 37
Joined: Wed 10. Aug 2016 00:44
Location: Bethlehem, Connecticut USA

Would 2 batteries fit?

Post by BriG » Sat 13. Aug 2016 01:55

Hello forum,

Just a question for those of you building cars, is there any way of redesigning and rearranging/ the chassis/steering/drive/electronics to perhaps fit a second battery wired in parallel to give twice the run time? Unfortunately I have yet to acquire a car of my own, so I really don't have a good perspective on just how much room there is to play with, just figured I might get some thoughts from those of you who may have considered the possibility.

And anyone that has a car/controller or two they might part with, I'd appreciate the lead. Can't wait to get started.

Thanks

Brian

Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: Would 2 batteries fit?

Post by Ned » Sat 13. Aug 2016 05:25

Brian,

I'm designing chassis to be sold on Shapeways.com .

Given the current size of the steering coil, battery, and motor, it would be possible to fit a second battery onto a customized chassis but the minimum wheelbase would 3.20" (102" at 1:32) . The original stock WB is fixed at 3.0" (96" at 1:32). I could make the WB adjustable up to 3.80". The width could be as small as 1.90".

I am sure that there are current or former members out there who would like to sell some used magracing gear. The problem is finding them.

Ned

BriG
Posts: 37
Joined: Wed 10. Aug 2016 00:44
Location: Bethlehem, Connecticut USA

Re: Would 2 batteries fit?

Post by BriG » Sat 13. Aug 2016 10:09

Thanks for the reply Ned.

I'm really impressed with everything I've seen that you've done so far with your cars. We seem to share the interest of using bodies with scale dimensions and lots of detail, something that I think really makes the 1/32 slot cars appeal to a lot of people. And to be able to have longer stints on track for me would add to the realism and enjoyment.

I imagine a lighter body and somewhat less robust chassis and steering would help compensate for the room and weight needed to carry the second battery. Are these things you've considered with your improvements? I read a post with someone suggesting improved steering geometry, which doesn't appear to be that difficult to change and which could improve turning even on a small 1/32 scale.

Another thing I wondered and I saw someone else mention, was using a smaller circuit board in the car. I'm no electronics wizard, but I would think today's technology would support that change if someone could figure it out, with the benefit of more room, less weight. I read that a certain amount of weight make the cars handle better, it would just be nice to be able to juggle things around maybe to allow those somewhat heavier 1/32 scale slot car bodies to be used without sacrificing the performance.

My search will continue for my first car(s), something will come along.

Appreciate any and all replies. I really enjoy hashing about all the possibilities.

Brian

Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: Would 2 batteries fit?

Post by Ned » Sat 13. Aug 2016 13:53

Brian, the extra weight of highly detailed injection molded 1:32 scale slot car bodies is not an issue. Generally the extra weight doesn't affect lap times. It would affect times in a drag race. The extra weight does slightly affect run time from a fully charged battery. Speaking of batteries, they are so quick and easy to change that run time is not an issue for me either. The steering coil draws significant power from the battery. So much so, that when the battery is low, you can see the car slow down when you turn the steering wheel. When not being steered, my cars will run around my track at a constant speed for more than 30 minutes. More than likely, when racing against someone, you'll crash before the battery runs out of juice.

When designing a chassis I have given a little thought to weight but none to battery run time. I have given a lot of thought to making the chassis shorter, narrower, and thinner with an adjustable wheelbase which can be attached securely to a slot car body. I have recently incorporated 1 degree of positive toe (toe in) and 2 degrees of negative camber to reduce frontend shimmy and improve handling.

Concerning a smaller circuit board, some people have been experimenting with an Arduino board. HeliumFrog knows something about this. Except in a few cases, a smaller PCB is not needed to make a shorter wheelbase for 1:32 scale. A smaller PCB and/or a smaller battery are needed to make a narrower and thinner chassis for a lot of the sports cars of the 1960's.

As you can see in the photo below, my chassis is quite a bit smaller than the stock chassis. With a battery my chassis weighs 46 grams compared to the stock chassis which weighs 56 grams. It is short enough to fit a 1/32 scale body of a 1967 Porsche 910. The full size car had a wheel base of 90.6" or 2.83" at 1:32. The width of my chassis and front track are both a little too wide to be precisely to scale.

Image

User avatar
Keld
Administrator
Posts: 412
Joined: Thu 13. Dec 2012 19:06
Location: Copenhagen, Denmark
Contact:

Re: Would 2 batteries fit?

Post by Keld » Sat 13. Aug 2016 13:57

I do not understand why anybody wnat more running time, plz tell me why.

First, all weight in a racing car is no go, the car will handle poor with just a few gram extra. bad cornering, bad accelration, bad braking. :usch

Second, the driving time: I am racing slotcars on a very high level, competitions all over europe, and the normal race time is from 3 to 10 min. before there is a lane change.
on long distance racing we drive 20 min. and that is the longest before lane change.

How long do you want the car to drive before you go to pit and make a battery change?
The cars can run for 20 min. without problems, I did ran some cars for 30 min.
You are able to change the battery in less than 10 seconds with magracing. That is fast compared to wheel change/refuel in Le Mans.
If you make a setup with some very strong magnets to grab the battery from the car and a little holder for the spare battery, I think you can make the change in 2,5 sec.
/Keld

Ned
Posts: 315
Joined: Sun 13. Apr 2014 01:02
Location: Sedona, AZ USA

Re: Would 2 batteries fit?

Post by Ned » Sat 13. Aug 2016 21:34

Keld wrote:
First, all weight in a racing car is no go, the car will handle poor with just a few gram extra. bad cornering, bad accelration, bad braking. :usch
Some members of this forum have found that slight increases in weight have actually resulted in lower lap times. One has said that extra weight in the front sometimes reduces front end shimmy and improves the reliability of lane changing.

Markus, aka Rec Craemer, who has probably built more magracing cars than anybody, says that the extra weight of a detailed injection molded body does not noticeably affect lap times. My cars with custom chassis and heavier injection molded bodies run up hill on a 25 ft straight, as fast as one with a standard chassis and lighter weight vac formed body. There are lot of variables that affect lap times in magracing. One of the most important is the traction of the front and rear tires. Stock wheels/tires, do not provide acceptable traction. Another is the amount of charge left in the battery. For very serious racing with an experienced driver, lower weight is probably better, other things being equal, as suggested by Keld.

User avatar
Keld
Administrator
Posts: 412
Joined: Thu 13. Dec 2012 19:06
Location: Copenhagen, Denmark
Contact:

Re: Would 2 batteries fit?

Post by Keld » Tue 16. Aug 2016 06:38

many years ago I also found out that a heavier car would improve the tracktion, but this was the wrong way to go, it was better to improve the tyres and the track surface, with enough grib the car with lowest weight would win.

But offcourse there is always the balance of the car, you need to have the correct weight balance between front and backend, and if you cant design a new chassis you can improve the handling with extra weight.
Many slotracers, inspecially in 1/32 are doing that, but in 1/24 where we make our own chassis and bodies, we do build in the weight balance in the design of the parts.



But if the track has no grib at all, a heavy car will get tracktion.
/Keld

Post Reply