Re: Battery Charging Station
 

Yes. A fuse blew at the Boilermaker regional one year, and lots of people had no power.

If teams are limited to 4 amps apiece, it's going to cause problems if anyone wants to run a shop vac. That's not an unheard of practice.

Re: Battery Charging Station
 

I'm surprised that the people setting up the regional don't bring in a 10 kW generator! That's weird because they probably know that there will be a great power usage. The only power problems we experienced were the lights going out during the Las Vegas regional, which I do not know about!

Re: Battery Charging Station
 

Yash, you're going to go talk to the folks who run the Arizona Regional about how much it costs to run a regional, and how hard it is or isn't to get that funding. You're also going to talk about past Arizona Regionals in the Coliseum, same topic. (I'm hoping some of them happen to see this and go find you to make sure.)

Once you do that, you'll understand exactly why they don't bring in a much bigger generator at this time, even if they know there may be a huge power issue.

If it works out OK this time, then we'll all have been saying the sky was falling. If it doesn't, or barely works, then I'm sure that increasing the size of generator will be very high on the list of priorities for the next event.

Re: Battery Charging Station
 

This actually occurred because teams were using the upper limit of available power from the generator. Coupled with the warm temps that year, the electrical distro finally broke down and was too hot to go near for quite a while. It took out the pits and the FCS computers as well. Thankfully it occurred near the end of the competition day.
Putting in higher power generation carries higher distro costs and increased liability insurance. That is of course if you can find one locally.

Re: Battery Charging Station
 

Can't you hook up the pits to the cars? You may be able to generate a kilowatt!

Re: Battery Charging Station
 

Please elaborate. What do you mean?

How far do you expect a single kilowatt to go? Consider the power used by a battery charger, an electric drill, a soldering iron, a laptop computer, a shop vac, etc.

Re: Battery Charging Station
 

Quite a bit over here in the US. We use 120 volts, so that would be equal to 8.3... Ah. For those on 240v, you would get 4.15.

Anyways, now I really think we are getting off topic so we should create a new thread, like "Power in the Pits"

Re: Battery Charging Station
 

Your car's engine has enough power for many kilowatts (>100 kw), but the alternator and electrical system isn't designed for powering stuff. Some cars have an inverter built in, but their usually rated for only a few amps, so the alternator, charging system, and battery don't get damaged.

Teams also use a ton of power. We have an ancient computer that draws 450 watts while running video, three monitors, two pretty high power projectors, a few hundred watts of lighting, 10 robot battery chargers, and 3 drill battery chargers. We've also run all this plus a shop vac, sawzall, mini band saw, and mini bench grinder all at the same time. We don't typically run all this at the same time, but it's happened before. That's quite a few kilowatts.

Re: Battery Charging Station
 

Car and light trucks (pickups and full-sized vans) have alternators that have current ratings in the range of 80 to 120A, depending on the vehicle, giving you about 1 to 1.2 kW of output power. That rating is only a peak rating for when the alternator is charging the battery after the battery was used to start the vehicle. It is very likely that the continuous current rating would be half of the stated peak rating or less so you will only get around 400 to 600 W continuous. No, the manufacturers are not going to tell you what the continuous rating is since they play the specmanship game.

All the motor driven power tools you use in your pits will have some sort of current rating printed on them if they meet the UL safety standards. The starting surge current will be several times (3 to 6 X) higher than that continuous current rating printed on the case of the tool. I blew out a 2 kW inverter running such loads off my trucks batteries during Hurricane Rita.

Re: Battery Charging Station
 

Let us not forget the resistive losses of the wire at 12 volts. In vehicles you are talking a few feet at most while trying to bring that inside you are now talking 50-100 feet. Welding cable is needed to prevent the drop from being excessive.

Re: Battery Charging Station
 

In this case, wouldn't you step it up to 120/240 volts at the generator/battery/etc, and use the high voltage instead of the low voltage? Also, wouldn't you need gauge 6 wire or so, for the current traveling at 120volts?

Re: Battery Charging Station
 

No. Most wiring in your house is (probably) 14 gauge. Your microwave is probably 12 gauge. Wire gauge has a lot more to do with current than voltage.

Re: Battery Charging Station
 

Aaaaaaand here's why:





I love it when I can answer questions with material that was already said in the thread.

Re: Battery Charging Station
 

#6 at 100 amps will drop 0.1 volt for every 2 feet of length. At 100 feet that is 10 volts. (remember you have to calculate for both the red and the black wire.) While at 220 volts that represents a mere 0.045% at 12 volts that is 83% drop in voltage. The wire size in a residential home is calculated on the voltage loss expected in a particular length and then fit to the breaker size. Many circuits in a typical house are 15 amp breakers fed with #14 wire. If you look at typical spec sheets, appliances are designed to run down to about 90 volts.