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New boris bus breaks down
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New boris bus breaks down
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New boris bus breaks down
On Mon, 19 Dec 2011 10:28:03 +0000
Roland Perry wrote: In message , at 09:50:09 on Mon, 19 Dec 2011, d remarked: Oh dear. Not off to a good start then. http://www.lbc.co.uk/new-routemaster...dy-photo-48777 Sounds like the battery went flat. Who knows. Probably the hybrid drive system still has some issues to sort out. On the radio they said it was going northbound so perhaps they already knew about the problem and were trying to get it somewhere to sort it out but didn't make it. B2003 |
New boris bus breaks down
wrote in message
On Mon, 19 Dec 2011 10:28:03 +0000 Roland Perry wrote: In message , at 09:50:09 on Mon, 19 Dec 2011, d remarked: Oh dear. Not off to a good start then. http://www.lbc.co.uk/new-routemaster...dy-photo-48777 Sounds like the battery went flat. Who knows. Probably the hybrid drive system still has some issues to sort out. On the radio they said it was going northbound so perhaps they already knew about the problem and were trying to get it somewhere to sort it out but didn't make it. I speculate that the range-extender hybrid drive is designed for stop-start operation, with the engine having lots of opportunities to charge the battery when the bus is picking up pax or stoppd in traffic. Regenerative brakes will also help keep the battery charged in stop-start traffic. The engine may not have enough continuous output for the bus to go long distances at relatively higher speeds on a motorway. It's also possible that the battery wasn't fully charged at the start of the journey. I wonder if, in normal operation, it's planned that the batteries will be fully topped up overnight in the depot? According to the Autocar review of the bus, the 4-cylinder diesel generator has a max power of only 182bhp (which is less than my car), which is used not only to charge the battery, but also to power the air compressor for the brakes and steering. The battery is rated at 75kWh. |
New boris bus breaks down
On Mon, 19 Dec 2011 11:26:32 +0000
Roland Perry wrote: The circumstances (and some of the comments) are consistent with the drive system becoming overloaded or overheated as a result of sustained high speed. I guess you mean the bit where it says "They claim the bus is not designed to drive as far as Luton and therefore it needed a break". To me that sounds like a bit of spin to disguise a problem. I can't believe the hybrid system can't cope with doing 20 miles on a motorway without overheating. That would just be **** poor engineering. Also it would've taken a week to drive it from the factory in nothern ireland. B2003 |
New boris bus breaks down
On Mon, 19 Dec 2011 11:37:34 -0000
"Recliner" wrote: According to the Autocar review of the bus, the 4-cylinder diesel generator has a max power of only 182bhp (which is less than my car), which is used not only to charge the battery, but also to power the air compressor for the brakes and steering. The battery is rated at 75kWh. Its quite enough to move a double decker on the relatively shallow inclines of a motorway even accounting for losses in converting to electical power. Most buses arn't rated at much more than that anyway. If it can't cope with steady running on a motorway with loads of nice cold air to keep it cool god knows how it'll manage in 30C in summer slowly cooking in a london traffic jam. B2003 |
New boris bus breaks down
wrote in message
On Mon, 19 Dec 2011 11:37:34 -0000 "Recliner" wrote: According to the Autocar review of the bus, the 4-cylinder diesel generator has a max power of only 182bhp (which is less than my car), which is used not only to charge the battery, but also to power the air compressor for the brakes and steering. The battery is rated at 75kWh. Its quite enough to move a double decker on the relatively shallow inclines of a motorway even accounting for losses in converting to electical power. Most buses arn't rated at much more than that anyway. If it can't cope with steady running on a motorway with loads of nice cold air to keep it cool god knows how it'll manage in 30C in summer slowly cooking in a london traffic jam. You're assuming that it overheated, rather than my guess that the battery was running low. I presume that they run the engine for optimum economy, rather than for max power. |
New boris bus breaks down
On Mon, 19 Dec 2011 11:55:54 -0000
"Recliner" wrote: You're assuming that it overheated, rather than my guess that the battery was running low. I presume that they run the engine for optimum economy, rather than for max power. I shouldn't make any difference. Once the battery is flat it runs off the engine just like every hybrid car ever built. B2003 |
New boris bus breaks down
wrote in message
On Mon, 19 Dec 2011 11:55:54 -0000 "Recliner" wrote: You're assuming that it overheated, rather than my guess that the battery was running low. I presume that they run the engine for optimum economy, rather than for max power. I shouldn't make any difference. Once the battery is flat it runs off the engine just like every hybrid car ever built. This is a range-extender hybrid, unlike most existing hybrid cars. In other words, it's more like the Volt, not the Prius (ie, not all hybrid cars are the same). So the only drive to the axle is from the 174bhp motor, powered by the battery, with the generator just acting as a part-time charger, which runs at optimum revs when it runs at all. If the engine isn't charging the battery as fast as it's discharging, the bus will have to stop or slow down for long enough for the charge to accumulate again. Autocar comments that the engine needed to run most of the time during its short road test, probably because it wasn't getting much benefit from regenerative braking, unlike on a normal bus route. This does suggest that the engine isn't really up to powering the bus for a sustained run at motorway speeds (unless the engine is pushed hard, which would destroy the excellent economy and green claims). Wright claims 11.2mpg for the Boris Bus, compared to 8.6mpg for Wright's Gemini 2 Hybrid (and 4.3mpg for a Citaro G bendy bus). The CO2 figures are also much better (640g/km, compared to 864 and 1300, respectively). |
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