"will Ultracapacitors Save Start-stop Systems From Consumer Wrath?"

[Paladin4Elio]

Start-stop systems, which switch off a car's engine while it's stopped to boost fuel efficiency, are now entering the U.S. market in serious numbers.

Many European makers, including BMW, Mercedes-Benz, and MINI, are fitting them as standard on 2015 models, and there are more to come: By 2022, some forecasts expect start-stop to be included on more than half of U.S. vehicles.

But car buyers often dislike the feature, which is not only unfamiliar but can also send vibrations through the car when the engine restarts.

Worse, some early data appears to show that the beefier lead-acid starter batteries that enable the system to restart the engine dozens of times a day may need to be replaced more frequently.

That has led some analysts and electronics companies to suggest that start-stop systems will soon include not only the advanced-glass mat (AGM) batteries but also a small ultracapacitor to ease the power draw on those batteries.

More at:
http://www.greencarreports.com/news...s-save-start-stop-systems-from-consumer-wrath

 

[CheeseheadEarl]

While not used for start-stop systems, there's one company that I know of making ultracap start systems for heavy trucks. Most big rigs use 3-4 lead acid batteries for starting the big diesels as well as powering more and more electronics, and creature comforts with the engine off.

This system uses one ultracap for starting, and the other batteries are replaced (ideally, regular batteries work, but not best) with AGM deep cycle batteries for "shore power" needs.

Link: http://www.maxwell.com/esm/

I think a smaller version would sell well to pickup owners with heavy electric loads - winches, snowplows, etc. Replace the main with an AGM deep cycle, and a smaller ultracap mounted where space allows for starting. Commonly they use large, heavy dual batteries in most of these applications. My personal plow truck has only one battery, and when I'm done moving snow, it needs some charger time.

 

[carzes]

While not used for start-stop systems, there's one company that I know of making ultracap start systems for heavy trucks. Most big rigs use 3-4 lead acid batteries for starting the big diesels as well as powering more and more electronics, and creature comforts with the engine off.

This system uses one ultracap for starting, and the other batteries are replaced (ideally, regular batteries work, but not best) with AGM deep cycle batteries for "shore power" needs.

Link: http://www.maxwell.com/esm/

I think a smaller version would sell well to pickup owners with heavy electric loads - winches, snowplows, etc. Replace the main with an AGM deep cycle, and a smaller ultracap mounted where space allows for starting. Commonly they use large, heavy dual batteries in most of these applications. My personal plow truck has only one battery, and when I'm done moving snow, it needs some charger time.

I love new technologies, and think it's great to push things in new directions, but to be honest, I don't see anything here. It's kinda smoke and mirrors and a new way of using what car audio 'enthusiasts' have known for a long time. Not that the system might not get your engine started under certain circumstances, just like it would give you the extra kick to rattle the windows six blocks away with your 'awesome' car stereo, but these applications are just taking advantage of a capacitor's ability to discharge VERY rapidly, providing a very high current surge for a VERY short time. As in mili-seconds. When a lead-acid battery is discharged beyond a certain point, it can no longer supply large current levels for things like turning starter motors. So a whole stack of large capacitors can charge up slowly and then supplement the current output of the battery for a couple seconds, which hopefully is enough to get you started. But that's it. They can only act as a current buffer for the battery, not a replacement.
In terms of any kind of energy storage application, the increadibly low power density of capacitors makes them TERRIBLE. My questions for such a system would be: A. How much do they want for a box of capacitors? B. What are the electronic specifications of that box? ( I notice there are NO specs discussed on the company's web page). C. What makes these capacitors so 'ultra'? (Once again how about some specs?)
I hate to come off sounding critical, but I'm just smellin' some snake oil here.

 

[CheeseheadEarl]

I love new technologies, and think it's great to push things in new directions, but to be honest, I don't see anything here. It's kinda smoke and mirrors and a new way of using what car audio 'enthusiasts' have known for a long time. Not that the system might not get your engine started under certain circumstances, just like it would give you the extra kick to rattle the windows six blocks away with your 'awesome' car stereo, but these applications are just taking advantage of a capacitor's ability to discharge VERY rapidly, providing a very high current surge for a VERY short time. As in mili-seconds. When a lead-acid battery is discharged beyond a certain point, it can no longer supply large current levels for things like turning starter motors. So a whole stack of large capacitors can charge up slowly and then supplement the current output of the battery for a couple seconds, which hopefully is enough to get you started. But that's it. They can only act as a current buffer for the battery, not a replacement.
In terms of any kind of energy storage application, the increadibly low power density of capacitors makes them TERRIBLE. My questions for such a system would be: A. How much do they want for a box of capacitors? B. What are the electronic specifications of that box? ( I notice there are NO specs discussed on the company's web page). C. What makes these capacitors so 'ultra'? (Once again how about some specs?)
I hate to come off sounding critical, but I'm just smellin' some snake oil here.

I have no personal experience with them. Wish I knew more. I am not an electical engineer. I'd like to see one "battery" spin a cold N14 Cummins to life. I can't say it does or doesn't work, all I've heard are secondhand testimonials.

 

[Ty]

Mazda did start-stop without beefing up the battery or alternator. They stopped the engine with one piston at top dead center. When you take your foot off the brake after stopping, the engine injected fuel into that cylinder, sparked it, it spun backwards for that one stroke to build pressure in the next one where a spark spun the engine in the right direction. It was said to be pretty unnoticeable, effective and pretty cheap to add in.

 

[carzes]

I have no personal experience with them. Wish I knew more. I am not an electical engineer. I'd like to see one "battery" spin a cold N14 Cummins to life. I can't say it does or doesn't work, all I've heard are secondhand testimonials.

I've been an electronic technician for a LONG time, and I can tell you that capacitors have some critically useful properties in electronics, but power storage on any useful scale is not one of them. Might be just enough to help an engine start in SOME cases, if you have a big enough box of them, but that sounds expensive.

 

[carzes]

Mazda did start-stop without beefing up the battery or alternator. They stopped the engine with one piston at top dead center. When you take your foot off the brake after stopping, the engine injected fuel into that cylinder, sparked it, it spun backwards for that one stroke to build pressure in the next one where a spark spun the engine in the right direction. It was said to be pretty unnoticeable, effective and pretty cheap to add in.

Not sure what the point would be of spinning backward first instead of just continuing in the usual direction. One cylinder firing is the same as any other firing. And at TDC it should already HAVE a fuel charge and compression. I always was told it was BAD to spin a motor backward, though I guess I can't exactly say why now that you mention it. Anyway, I really wonder how they get the engine to stop right at the point of rotation they want it at?

 

[goofyone]

Not sure what the point would be of spinning backward first instead of just continuing in the usual direction. One cylinder firing is the same as any other firing. And at TDC it should already HAVE a fuel charge and compression. I always was told it was BAD to spin a motor backward, though I guess I can't exactly say why now that you mention it. Anyway, I really wonder how they get the engine to stop right at the point of rotation they want it at?

http://www.mazda.com/technology/env/i-stop/

 

[carzes]

I found a spec sheet on the ultracap units from maxwell, and I did some math. They DO have some fairly impressive specs for capacitors. But, for example, one large cap bank about the size of a large truck battery had a rating of 500 farads and a rating of 16 volts, which is the minimum you might consider for an automotive application. It specs out to 18 watt-hours at full voltage, or 13.5 watt-hours at 12 volts. That is about 1.125 amp hours, not getting into discharge curves and all that, which is about equal in total power output to a decent AA battery.

 

[carzes]

http://www.mazda.com/technology/env/i-stop/

Interesting system. As I understand it though it would only work on a gasoline direct injected engine. Looks like it still uses the starter motor also. Seems to be all about making the startup faster and less noticeable. The Elio motor isn't direct injected is it?