Starting Car with external battery [Archive]

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ChrisS

01-21-2008, 02:57 AM

Was wondering if there is a rule against starting your car with an external battery. A number of teams were doing this at the FSAE Australia comp, the fact that some of them were trying to hide they were doing it makes me think it might be a slippery slope.

Any thoughts?

ChrisS

01-21-2008, 02:57 AM

Fyhr

01-21-2008, 04:09 AM

I dont think this is a problem so long as it can be done in a safe way, i.e quick connector at the back of the car.

During endurance at the driver change, the car needs to be able to restart according to:

"5.7.7 Endurance Vehicle Starting/ Restarting
The vehicle must be capable of starting / restarting without external assistance at all
times once the vehicle has begun the heat. If a vehicle stalls out on the track, it will
be allowed one (1) lap by the car that is following it (approximately one (1) minute)
to restart. If a vehicle has a restart problem at the end of Driver Change, it will be
allowed a further two (2) minutes to restart the engine. If restarts are not
accomplished within the above times, the car will be deemed disabled and scored
DNF for the heat."

exFSAE

01-21-2008, 01:32 PM

Nothing wrong with it. Smart way of doing things IMO.

Of course you still need an onboard battery and would be crazy if you didn't have one (spin/stall in enduro = F'd). The idea is for starting you're just connecting the battery to an outside supply of juice (jumper box) so during all those heavy cranking cycles at a competition you dont wear down the battery prematurely.

Otherwise you start deep cycling the battery, having to charge it constantly, and eventually wearing it dead.

Biggy72

01-21-2008, 02:12 PM

I can't seem to find any pictures of it all together, but we have a car battery on our wagon with our tool box and whatever else we need to drag around with us. Then we just have a pair of jumper cables with the normal alligator clips on one end and a plug on the other end that goes into a plug on the car. It's pretty simple. I think Brian talked about it more in a post about batteries in the another section of the forum.

Having the plug on the car also makes it much much easier to charge the onboard battery since it's right out in the open.

VFR750R

01-21-2008, 02:33 PM

i don't know anything about them, but the quick disconnect fittings nascar teams use on batteries are pretty slick, and i'm sure you can get them pretty reasonable.

exFSAE

01-21-2008, 02:57 PM

Yep. I saw at least one team at FSAE Detroit 07 with that setup, VFR. Quick disconnect for a jumper box right on the outside of their frame/bodywork. Was slick.

flavorPacket

01-21-2008, 03:09 PM

we've had it for 6 years, no problems.

Brian S

01-21-2008, 06:55 PM

Here is our set up.

Connector on the car, a bunch of places carry them, I think we got it from McMaster.
http://sae.wsu.edu/files/extpower/IMG_3068.jpg

Battery box on the wagon, normally has a car battery with side terminals in it.
http://sae.wsu.edu/files/extpower/IMG_3071.jpg

Cord:
http://sae.wsu.edu/files/extpower/IMG_3072.jpg

http://sae.wsu.edu/files/extpower/IMG_3073.jpg

Kirby

01-21-2008, 07:14 PM

I don't know why you got the impression that teams were trying to hide it at FSAE-A. I certainly saw most teams "jumping" from an external battery for some of the events.

There is a really good reason for doing so aswell.

rjwoods77

01-21-2008, 07:34 PM

I just wanted to comment that those anderson type connectors are a god send for quick jumps. I am currently freezing my balls of in -31 degree C weather in Kapuskasing Canada for cold weather testing and have jumped cars about 10 times today with those. If you are going to do an external plug in setup like that then this exact plug is the one to run with.

ChrisS

01-22-2008, 03:36 AM

I got the impression that teams were trying to hide the fact when one team member was seen leaning on their car wearing long sleaves and with a backpack on. Closer inspection showed that he had a cable running from the backpack down his sleave to the power plug on their car.

I can see the advantages of using an external battery to start a car, however we are designing these cars for amateur racers and it seems highly unlikely they would start their car with an external battery. Plus several teams are clearly doing it to save weight and using batteries that can't provide sufficient starting current for long periods.

However, my team will probably start doing this from now on at comp as it seems to be the norm now. I just wanted to see what other teams thought of this.

Pete M

01-22-2008, 06:26 AM

I think it's a bit of a dangerous crutch personally. If your car won't restart reliably on its own, then aren't you taking a big risk in the enduro driver change? How light are everyone's batteries? Ours is 2.2 kg and the car has never not started due to a flat battery (except that time the alternator wasn't plugged in, LOL). I mean, most of the bikes these engines come out of surely start pretty reliably, right?

exFSAE

01-22-2008, 06:34 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ChrisS:
I got the impression that teams were trying to hide the fact when one team member was seen leaning on their car wearing long sleaves and with a backpack on. Closer inspection showed that he had a cable running from the backpack down his sleave to the power plug on their car. </div></BLOCKQUOTE>

That is pretty funny.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I can see the advantages of using an external battery to start a car, however we are designing these cars for amateur racers and it seems highly unlikely they would start their car with an external battery. Plus several teams are clearly doing it to save weight and using batteries that can't provide sufficient starting current for long periods. </div></BLOCKQUOTE>

Ehhh. The idea is ROUGHLY that we're designing these cars for an amateur racer. Most amateur racers though don't have or need carbon composite monocoque chassis, $10k of data acquisition, semi-active suspensions, 4-way dampers, telemetry, custom-made ECUs and traction/launch control, etc etc. Up until early 2000 or so I'd say the competition was much more "simple" but has gotten very technological very quickly among the top teams.

If a team is doing something smart to save weight, good on em. Though its ballsy to be playing with low overbuild factors when it comes to power. You don't wanna be THAT guy who didn't finish enduro because your car ran out of juice on lap 15 because you wanted to save the 1/2 pound on a lighter battery.

When our team ran that QDC/jumperbox setup we went with a HEAVIER, dry cell, deep cycle battery. Robust electrical systems and plenty of cranking and driving amps are crucial, particularly when its a cold ass Detroit morning doing cold starts, or repeated starts for different events.

Thats just my $.02

And just because another team is doing it doesn't mean its the best solution, I dont care who they are. A lot of people fall into the trap of save-weight-at-all-costs. By all means design things well and efficiently using weight, but you absolutely cannot sacrifice on-the-track reliability. Look at the past few years. You can beat a lot of top name teams just by finishing all the events.

ben

01-22-2008, 07:26 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ChrisS:
however we are designing these cars for amateur racers and it seems highly unlikely they would start their car with an external battery.
</div></BLOCKQUOTE>

Every club race paddock I've ever been in is full of jump batteries on trolleys. I'd always viewed it as a standard piece of racing equipment and not at all "professional" as opposed to "amateur"

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ChrisS:
Plus several teams are clearly doing it to save weight and using batteries that can't provide sufficient starting current for long periods.
</div></BLOCKQUOTE>

That's their prerogative and provided they have enough cranking power to restart and finish the endurance it's entirely legal.

Plus as exFSAE has pointed out, the "weekend racer" is a roll playing fiction for the purposes of the cost and presentation events.

Play the game vis a vis the static events and build the best racecar you can within your budget is still the only way to approach the comp IMO.

Ben

Biggy72

01-22-2008, 08:05 AM

If our car is running continuously for the first half of the endurance it was no problem to start up on it's own for the second half.

The only time we really ran into trouble was when we were continously running the water pump while running the fan while starting the car over and over and over again while running the wireless. I'm trying something different with the water pump situation this year, but the one we had last year was a beast any way and drew wayyy too many amps.

screwdriver

01-22-2008, 04:01 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by exFSAE:
Ehhh. The idea is ROUGHLY that we're designing these cars for an amateur racer. Most amateur racers though don't have or need carbon composite monocoque chassis, $10k of data acquisition, semi-active suspensions, 4-way dampers, telemetry, custom-made ECUs and traction/launch control, etc etc. Up until early 2000 or so I'd say the competition was much more "simple" but has gotten very technological very quickly among the top teams.
</div></BLOCKQUOTE>

That's just because people like me nowadays have the prospect of actually getting a job with an automotive company these days. So we do like to butt in on the FSAE Teams. http://fsae.com/groupee_common/emoticons/icon_wink.gif
Besides what's wrong with that when there are companies who are willing to support us with that.

On the topic at hand, I can't see anything wrong with supporting the battery outside the enduro. Still the car should be able to start itself. If it isn't, something is wrong (cooling-system design, long starter cables, short-circuits).

Kirby

01-30-2008, 09:42 AM