Safe Speed Forums

I suppose so. It is just that connecting electronic power supplies in parallel, without load balancing resistors, is a definite no-no. The supply with the highest voltage tries to supply all the load and go into an overcurrent trip before the others can contribute.

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

You're still a youngster - when I was a kid, washing machines were still equipped with mangles. No diodes there

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

Electronic power supplies, yes I agree.
But batteries have inherent series resistance - the more current you pull the less the terminal voltage.
Of course, a duff cell in one of the batteries can mess up the equation

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Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

The load balancing is not a problem in this particular scenario, even without the inherent series resistance.
In this case, one battery should be strong enough to power the load, so 'current hogging' isn't actually a direct issue even if it did occur.

Added to Pete's valid point of the inherent resistance, is the ramping down of output voltage(s) over time when loaded. So even with an initial voltage mismatch (and current hogging), the voltages and individual currents will quickly sort themselves out such that the load is evenly distributed by the respective capacities - that is that the higher capacity batteries will end up automatically taking more of the load; otherwise the currents are equally shared (assuming the resistances aren't significant). This will generally hold true so long as the source technologies are all the same (all are leads acids for example).

As a bonus: the batteries need not have identical capacities when used in parallel. This is one disadvantage of having them in series. The whole series system is limited by the smallest capacity battery (and capacities reduce with lifetime), and the whole system must be shut down when that one battery becomes discharged (even if all the others have loads of spare energy left over) otherwise it will quickly become permanently damaged.
Also, the chain must be perfectly charge balanced, for the same reason. One shouldn't use a partially empty one in series with a full one of identical potential capacity.

As Malcolm rightly pointed out: a battery with a lot of cells is a very good compromise as each cell within a battery should behave identically.

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

Sadly as many of you know I am not up on the techie side of this, but I have neigh 4yrs experience of running without mains (until Dec 4th).

I know that you are looking at a system stability but I wonder if you have those crucial systems always running on 12V / 24V and then just charge up the battery all the time (trickle type charge), then when the power fails (am I not right in thinking) that the battery will just run it as it is not seeing anything different?

I am still using the 12V and battery and charger, but I now have the luxury of the charger being on all the time and topping up the batteries (linked together - forget if that his series or parallel) all the time.
This has been suggested, and it is working for me ....

I have run my laptop directly off the Kipor genny (their sinwaves are OK for laptops) directly and it is fine.
An electric start diesel genny will enable you to run it off red diesel - about 72p/l at the moment. LPG Gas is expensive - £58 (v cheapest that I can find) for a 47Kg cylinder - (in this weather it lasts 2 wks). How well it would perform on a genny I don't know but some people like it. I have seen gas genny for less and even 2nd hand one's. Personally the electric start was ideal and no effort at all.
What about you getting the gas cylinders as they are very heavy!
I have found that running leisure batteries with charger last about 2 yrs if you are lucky ...

Having got much better batteries they have performed & still do very well - I check them often and they run in a pair and seem to work fine. I do have a very good charger on them.
I am a bit concerned though that if I leave the charger on all the time (batteries are still under load) that it might damage the batteries ?
I have wondered about what I will do in a powercut .... I guess after the laptop battery runs out just get the genny going again ... it's 12V supply hates the distance to the battery bank and it has thick t&e wire too! - About 15m distance)
(I probably haven't been much help) ...

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Safe Speed for Intelligent Road Safety through proper research, experience & guidance.

Dragged this back as I found http://www.powerinspired.com/product_info.php?products_id=1691, while looking for something else naturally.

Thought it might be of interest as it is designed to use your own 12v battery array. Still not a cheap solution I am afraid.

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Driving fast is for a particular time and place, I can do it I just only do it occasionally because I am a gentleman.
- James May

Ta. 2000w should be more than enough for everywhere minus the kitchen. I did find a £4k gas generator that was 12kva. It's cheap compared to that

Better hurry-up with the genny and batteries.
Your GREEN future is coming.
And I noted on the way home this morning that diesel is now 140.9 at a station near me....and 138.9 at tesco.

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

http://www.youtube.com/watch?v=dYZqAzEuPE8

What more needs to be said!



I actually have one just like that. The only reason why I dont use her as a matter of routine is the issue of soundproofing in an urban area. They are not that noisy infact with a suitable exhaust system (You could easily go to sleep next to one), but you can "Feel" them over a considerable distance which for neighbors can be a great deal more disturbing! (Between them, those flywheels weigh over 1/4 of a ton! although you can get a pretty good "Ballance" on one of these there is still a significant "Ground-pounding" effect! which is difficult to eliminate )

(EDIT Re "Ground-pounding". see http://www.youtube.com/watch?v=3a6RZFHy ... re=related You will note that there is little vibration once the engine gets up to speed, but the glass still slides around all over the tappet cover indicating that though lateral movement is minimal (otherwise the water would slosh around aswell) there is significant vertical movement allowing momentary "Zero/low G" on the glass such that small lateral vibrations produce significant overall movement)

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"The road to a police state is paved with public safety legislation"

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

Though I am not sure about this particular system the problem generally with these small CHP systems (Alnog with the domestic solar/mini wind systems currently being promoted) is that they will NOT OPERATE during a power cut!!!

This (To my mind) Is about as useful as the proverbial chocolate teapot!

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"The road to a police state is paved with public safety legislation"

?

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

There is some very naughty uses of the term efficiency in that article. The 40% figure for conventional power stations is the Carnot Cycle efficiency for an inlet temperature of about 400C discharging to ambient. What the 92% quoted for uCHP is I don't know but it sure as eggs isn't a fair comparison, unless they have found a way to bypass the 2nd law.

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

It cannot be a very large generator since it only provides 1KW of electricity.
Obviously they use the waste heat to provide.....err.....heat ?
Adverts....what are they like !

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

On a similar but far smaller scale...

My work colleague and I were looking at a new chip we want to use to get 12 volts from a USB port and although we haven’t decided on one yet there’s some brilliant new devices on the market. (I’m a bit behind the times you’ll have to understand). In my day you needed a transformer but things have come on in leaps and bounds in the last 12 years since I was heavily involved with electronics.

I haven’t quite got my head around how they work, yet, although they do explain the principle of operation in the literature. It uses a series of capacitors which are alternately switched in a clever way. It's amazing what they can do these days and in such a small package! Anyone here ever used them or happen to know a good one for our application?

Sorry if it's a bit of a cheek on the topic drift scale


http://uk.rs-online.com/web/search/sear ... &R=5165354

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

The old diode multiplier in a small package.

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

I don't know, he just comes here with his damn snap shots and leaves me here like a naked nob in jail surrounded with inmates in a shower!

Care to give me more mate?

I didn't see any mention of diodes in the blurb, unless that's some kind of Esperanto for capacitors...

Tone

Where's Botach, dcb, Steve, Pete..... when I need you????

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The views expressed in this post are personal opinions and do not necessarily represent the views of Safe Speed.
You will be branded a threat to society by going over a speed limit where it is safe to do so, and suffer the consequences of your actions in a way criminals do not, more so than someone who is a real threat to our society.

Stand back for an expert. What you are probably looking at is a "Boost Convertor". You pour current into an inductor which stores the energy in a magnetic field. You then discharge that energy into a load. Because the voltage you get out is related to the rate of change of current rather than the input voltage you can either increase (Boost) or decrease (Buck) the voltage.
Wickerman gives a good explanatiion here: http://en.wikipedia.org/wiki/Boost_converter

Or you might be talking about a switched capacitor charge pump. Basically you charge several capacitors in parallel then connect them in series (so that the voltages add up) and transfer the higher voltage to an output capacitor. http://en.wikipedia.org/wiki/Charge_pump.

But you don't need to know that! Just wire up as per the data sheet and away you go.

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown

http://en.wikipedia.org/wiki/Voltage_multiplier

Used to use them years ago....when I wanted more volts but couldn't be bothered to buy a transformer for the job.
As I remember they were a bit of a pain at high current....now they run them at high frequency and have smaller caps..

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The world runs on oil, period. No other substance can compete when it comes to energy density, flexibility, ease of handling, ease of transportation. If oil didn’t exist we would have to invent it.”

56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing

Indeed. It is the much higher switching frequencies - hundreds of kay - which make modern power supplies so compact. The amount of iron you need in the inductors is so much less than what you need at 50Hz

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When I see an adult on a bicycle, I do not despair for the future of the human race. H.G. Wells
When I see a youth in a motor car I do d.c.brown