Hi ToraDog,
Not sure who coined the down under thing, probably a Northerner. 😁
Yeah the sun down here is a bit on the hot side in summer, I am happy to hear you and your wife enjoyed your stay in AU.
I am further south than Sydney.
Cheers,
Stephen.
Not sure who coined the down under thing, probably a Northerner. 😁
Yeah the sun down here is a bit on the hot side in summer, I am happy to hear you and your wife enjoyed your stay in AU.
I am further south than Sydney.
Dave and Graham,
Spot on Chaps👍
Those were my immediate thoughts as well-
1 What does he want to do with it, i.e. what is the load, how many AMPs?
2 If high current, more than 2 or maybe 5Amps with a few, the cost of a higher current Booster is almost certainly more than a decent 3S Lipo.
3 Maybe a 10 cell NiMh would be a more cost effective alternative?
Or even a 12V SLA if the boat/ship is of a size and type to cope with the weight.
4 A Buck Converter is voltage reducer AKA Step Down Converter and is a type of Switched Mode power supply.
The output voltage is proportional to the ON time of the switch.
The name 'Buck' is derived from the inductor which opposes (or Bucks🙄) the incoming supply voltage, especially as it changes, i.e. switches ON/OFF! A characteristic called Back EMF, i.e. opposing voltage or voltage drop across the inductor and hence the voltage at the output to the load is less than the battery input voltage. The inductor stores energy in a magnetic field and when the supply is switched off the field collapses and discharges it back as Back EMF and reverses the polarity across the inductor. Thus the nett voltage supplied to the load is always less than the battery voltage; i.e. battery voltage minus voltage across the inductor. Efficiency is 90+% as power is not dissipated as heat as in a classic passive voltage divider of series resistors.
(Incidentally Back EMF is the characteristic that Brushless ESCs use to know where the rotor of the motor is in relation to the stator coils, simply said, it detects the Back EMF from the last stator coil energised when it is switched off and knows which one to energise next😉 This is why you can not drive two brushless motors from a single ESC. The poor ESC would probably go schizophrenic trying to figure out which motor is where and telling it what🤕 I ain't tried it to find out what happens - and I don't propose to without a research grant😉)
In a Buck Converter the inductor and switch (MOSFET transistor) are in series with the load with a capacitor in parallel as ripple filter at the output. Thus the switch simply switches the supply V from the battery ON/OFF. A diode rectifier (or transistor in modern types) is connected from the switch output to ground.
Still with me so far? Or all gone to sleep😉
As Dave says to increase voltage you need a Step Up Converter, colloquially known as a Booster. Basically the same components are used, but in a different circuit configuration.
Here the inductor and rectifier are in series with the load. A capacitor is in parallel with the load (converter output) as before. But here the switching device is connected from between the inductor and rectifier to ground.
When the switch is on the output of the inductor is shorted to ground. Thus the current flow through the inductor stores energy by creating a magnetic field. The polarity of the inductor is opposite to that of the battery.
When the switch is off (open) the current reduces as the load is now in circuit.
The magnetic field collapses to provide energy to maintain the current flow, thus reversing the polarity of the inductor, so we now have two 'batteries' in series thus increasing the output voltage. Yahoo, something for nothing😀
Nope, 'old yer 'orses! There is the slight snag of Conservation of Energy, in this case Conservation of Power. P=IxV (current times voltage). So if you increase the voltage the current must reduce to conserve the power level. There ain't no such thing as a 'Free lunch'🤔
It should now (I hope) become fairly obvious that to build a voltage Booster capable of the high currents needed to drive current thirsty high power motors is going to require some hefty high current and expensive components, an extreme case being those used in electric cars to boost battery voltage to reduce the number, weight and cost of the on-board batteries!
Hence those commonly available for model builders generally have low current capability of a few Amps.
BTW; there are also combo circuits, Buck-Booster and CUK, a special type of Buck-Boost with low output ripple voltage and reduced EMI, but that's a whole new bucket of worms😝
Here endeth the Basic Electronics lecture for today😁
Healthier than sleeping tablets!
Tune in next week, same time same channel, for 'Do electrons run forwards or backwards?'.
(And this time the answer is NOT '42'😁)
Cheers all, Doug 😎
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Dave and Graham,
Spot on Chaps👍
Those were my immediate thoughts as well-
1 What does he want to do with it, i.e. what is the load, how many AMPs?
2 If high current, more than 2 or maybe 5Amps with a few, the cost of a higher current Booster is almost certainly more than a decent 3S Lipo.
3 Maybe a 10 cell NiMh would be a more cost effective alternative?
Or even a 12V SLA if the boat/ship is of a size and type to cope with the weight.
4 A Buck Converter is voltage reducer AKA Step Down Converter and is a type of Switched Mode power supply.
The output voltage is proportional to the ON time of the switch.
The name 'Buck' is derived from the inductor which opposes (or Bucks🙄) the incoming supply voltage, especially as it changes, i.e. switches ON/OFF! A characteristic called Back EMF, i.e. opposing voltage or voltage drop across the inductor and hence the voltage at the output to the load is less than the battery input voltage. The inductor stores energy in a magnetic field and when the supply is switched off the field collapses and discharges it back as Back EMF and reverses the polarity across the inductor. Thus the nett voltage supplied to the load is always less than the battery voltage; i.e. battery voltage minus voltage across the inductor. Efficiency is 90+% as power is not dissipated as heat as in a classic passive voltage divider of series resistors.
(Incidentally Back EMF is the characteristic that Brushless ESCs use to know where the rotor of the motor is in relation to the stator coils, simply said, it detects the Back EMF from the last stator coil energised when it is switched off and knows which one to energise next😉 This is why you can not drive two brushless motors from a single ESC. The poor ESC would probably go schizophrenic trying to figure out which motor is where and telling it what🤕 I ain't tried it to find out what happens - and I don't propose to without a research grant😉)
In a Buck Converter the inductor and switch (MOSFET transistor) are in series with the load with a capacitor in parallel as ripple filter at the output. Thus the switch simply switches the supply V from the battery ON/OFF. A diode rectifier (or transistor in modern types) is connected from the switch output to ground.
Still with me so far? Or all gone to sleep😉
As Dave says to increase voltage you need a Step Up Converter, colloquially known as a Booster. Basically the same components are used, but in a different circuit configuration.
Here the inductor and rectifier are in series with the load. A capacitor is in parallel with the load (converter output) as before. But here the switching device is connected from between the inductor and rectifier to ground.
When the switch is on the output of the inductor is shorted to ground. Thus the current flow through the inductor stores energy by creating a magnetic field. The polarity of the inductor is opposite to that of the battery.
When the switch is off (open) the current reduces as the load is now in circuit.
The magnetic field collapses to provide energy to maintain the current flow, thus reversing the polarity of the inductor, so we now have two 'batteries' in series thus increasing the output voltage. Yahoo, something for nothing😀
Nope, 'old yer 'orses! There is the slight snag of Conservation of Energy, in this case Conservation of Power. P=IxV (current times voltage). So if you increase the voltage the current must reduce to conserve the power level. There ain't no such thing as a 'Free lunch'🤔
It should now (I hope) become fairly obvious that to build a voltage Booster capable of the high currents needed to drive current thirsty high power motors is going to require some hefty high current and expensive components, an extreme case being those used in electric cars to boost battery voltage to reduce the number, weight and cost of the on-board batteries!
Hence those commonly available for model builders generally have low current capability of a few Amps.
BTW; there are also combo circuits, Buck-Booster and CUK, a special type of Buck-Boost with low output ripple voltage and reduced EMI, but that's a whole new bucket of worms😝
Here endeth the Basic Electronics lecture for today😁
Healthier than sleeping tablets!
Tune in next week, same time same channel, for 'Do electrons run forwards or backwards?'.
(And this time the answer is NOT '42'😁)
Cheers all, Doug 😎
Young at heart 😉 Slightly older in other places.😊 Cheers Doug
Stephen,
You all don't call anything by it's normal name...😂. BTY what exactly does "down under" refer to?
My wife and I honeymooned in Sydney and Lizard island, 33 years ago and we never felt like we were under anything...except the bloody sun! We loved your country, 😀😀😀😀
Stephen,
You all don't call anything by it's normal name...😂. BTY what exactly does "down under" refer to?
My wife and I honeymooned in Sydney and Lizard island, 33 years ago and we never felt like we were under anything...except the bloody sun! We loved your country, 😀😀😀😀
I haven't heard of a buck converter before, probably my lack of general knowledge.
Down here we call them a voltage multiplier for increasing voltage and a voltage divider for reducing voltage.
Cheers,
Stephen.
I haven't heard of a buck converter before, probably my lack of general knowledge.
Down here we call them a voltage multiplier for increasing voltage and a voltage divider for reducing voltage.
Short answer, Maybe.
Long answer, A buck converter will safely increase the voltage of any source, Lipo, SLA, NiMH, ect. However All Buck converters I have seen( for use in models) are limited to around 1.0 amp current draw. As long as the current being drawn by the load connected to the output side of the converter does not exceed it's limits, you should be OK.
Personally I try to keep the draw well within the limits, leaving room for error, mostly on my part.
Short answer, Maybe.
Long answer, A buck converter will safely increase the voltage of any source, Lipo, SLA, NiMH, ect. However All Buck converters I have seen( for use in models) are limited to around 1.0 amp current draw. As long as the current being drawn by the load connected to the output side of the converter does not exceed it's limits, you should be OK.
Personally I try to keep the draw well within the limits, leaving room for error, mostly on my part.
Nick
I was not aware that I needed to be converted.
Best wishes
Buck😉
Hi nick
Buck converters reduce the input voltage and increase the current output.
I think you mean Boost Converter.
A boost converter (step-up converter) is a DC-to-DC power converter that steps up voltage (while stepping down current) from its input (supply).
So yes they are safe to use but will not give you the same current output as the Lipo.
I have used for generating 24v for mist units but the current required is about 2amp.
If you are wishing to drive a high current motor I suspect the cost of buying a suitable boost converter, assuming such is available, would be more than another Lipo.
dave976
Hi nick
Buck converters reduce the input voltage and increase the current output.
I think you mean Boost Converter.
A boost converter (step-up converter) is a DC-to-DC power converter that steps up voltage (while stepping down current) from its input (supply).
So yes they are safe to use but will not give you the same current output as the Lipo.
I have used for generating 24v for mist units but the current required is about 2amp.
If you are wishing to drive a high current motor I suspect the cost of buying a suitable boost converter, assuming such is available, would be more than another Lipo.
dave976
Hi Nick,
Simple answer - it depends!
So it depends on the specification of your converter. Certainly there are plenty of converters available that will happily step up from 7.4v to 12v.
The other consideration is matching the current rating of the converter to what you intend to drive with it.
Also be aware that the current drawn from your 7.4v battery will be higher than the current output from the converter. So if you want an output of 1A at 12v, the converter will draw 12/7.4 A = 1.6A from the battery. Indeed, as the converter isn’t 100% efficient, the current drawn will be a bit more than 1.6A.
Hope that helps
Graham93
So it depends on the specification of your converter. Certainly there are plenty of converters available that will happily step up from 7.4v to 12v.
The other consideration is matching the current rating of the converter to what you intend to drive with it.
Also be aware that the current drawn from your 7.4v battery will be higher than the current output from the converter. So if you want an output of 1A at 12v, the converter will draw 12/7.4 A = 1.6A from the battery. Indeed, as the converter isn’t 100% efficient, the current drawn will be a bit more than 1.6A.
My usual question of the day......is it safe to use a buck converter to up the voltage of a 2s lipo battery, increasing the output from about 7.4v up to 12v. To be honest I can't really afford more lipos.
My usual question of the day......is it safe to use a buck converter to up the voltage of a 2s lipo battery, increasing the output from about 7.4v up to 12v. To be honest I can't really afford more lipos.
