Breakers are not switches in the true sense of the word especially where DC and high currents are used, if they were then they would be sold as a Switch-breaker. Can you use it as a switch? Sure. Will it hold up being used as a switch maybe not! Don't take my word for it, check with the manufacturer. Engineers will specify a DC rated switch and a separate DC rated breaker (or fuse) for each power circuit. The electric vehicle kits that are being sold today have a DC interrupter of some type to positively disconnect the power from the controller in the case of emergency. If you use a breaker as a switch in place of this device you risk in an emergency flipping the breaker and having the connection stay stuck closed. Beware. Remember the guy who strapped a Rocket booster to his Chevy Impala not realizing there was no "OFF" button to a rocket booster, once started it runs until the fuel runs out (myth or real Darwin award winner - posthumous)... if the controller faults do you want to have the bike run until the battery charge runs out?
DC unlike AC causes difficulties in disconnecting from the power. If you were to put yourself across 115V AC it is not too difficult to break the connection, the fact of DC being steady voltage (no swing from 115V positive to 0 to 115V negative) breaking away is difficult if not impossible (someone may have to physically bump you out of the circuit), the same with switches and breakers. Just look at DC rated switches, the DC rating is much less than the AC rating because of this issue. I have used a very large breaker (250 A DC) as a switch with a very large fuse in 72V battery based systems and had no issues YET. Peace. Jeff On Wed, Mar 19, 2008 at 9:20 AM, damon henry <[EMAIL PROTECTED]> wrote: > > > Your understanding and mine or the same. Perhaps Jeff Blamey was thinking > of AC versus DC ratings. I have one of these circuit breakers in my truck > and expect it to be able to break full pack current at full voltage (80 > volts of BB600 Nicads). Of course, I also have a fuse and a main contactor > which should be up to the task as well and retained my clutch for a physical > disconnect. > > damon > > > ________________________________ > Date: Tue, 18 Mar 2008 23:58:32 -0600 > From: [EMAIL PROTECTED] > To: [email protected] > Subject: Re: [ElectricMotorcycles] eBay: Airpax 150 Amp 80 Volt DC Circuit > Breaker (old discussion revived) > > > > I noticed these are still up. I also reviewed some of this discussion, to > try and understand the potential safety issue of using a circuit breaker. > > Jeff Blamey: > > Don't mistake a DC breaker for a DC disconnect. A DC disconnect has a > positive break capability up to the rated capacity. > > What's the use of a breaker if it doesn't have a positive break capability? > Isn't that it's purpose to begin with? > > Jeff Blamey: > > A dc disconnect is a positive shut-off with contacts meant to make/break > large current, a breaker could become stuck (or unreliable as a shut-off) > and with the current these batteries hold, watch out! > > Isn't that the reason for an arc interrupt current (AIC) rating? I checked > the original breaker this discussion was about, ebay item: 290058376726, and > it's rated at 10,000. Does this mean it can break 10,000 amps, or am I > missing something? > > Regards, > Andrew > > > On Sat, Mar 24, 2007 at 6:42 PM, Mike <[EMAIL PROTECTED]> wrote: > > I was poking around eBay, waiting for the spray paint to dry on some > ebike parts, and found this: Airpax 150 Amp 80 Volt DC Circuit > Breaker with a buy it now for $5. Item number: 290058376726 > > # DC Circuit Breaker > # Maximum Voltage 80 Volts DC > # Rated Amperage 150 Amps > # Trip Amps 180 > # Delay 52 > # Auxiliary Switch N.O/N.C. 10 Amp 250 Volt AC > # Panel Mount > # Approximate Dimensions 1-1/2" Wide x 2-1/2" Long x 3-14" High > # New Surplus > > Dunno if anyone is interested or not but I thought I'd run it up the flag > pole. > > -- > > The Electric Motorcycle Portal > http://www.electricmotorcycles.net/ > > Electric Motorcycle Listserv > http://www.electricmotorcycles.net/listserv > > > > ________________________________ > Climb to the top of the charts! Play the word scramble challenge with star > power. Play now!
