12 v to 48 v boost converter for 48 v electric bike

[BobK]

A boost converter is not the same thing as an inverter. There is only a single coil, rather than a transformer and the output is DC (with ripple.)

Bob

 

[Harald Kapp]

Thanks. Are there more efficiency circuits for DC to DC inverters than the class B amplifier type?
The type that uses a pair of transistors feeding a center tapped transformer.

Tha standard circuits use switched transistors, not linear amplifiers (as a class B amp is). You also don't need a transformer, simply a coil (inductor) if you do not require potential separation (isolation) as is the case here. There are a few accepted standard topologies for DC/DC converters, see e.g. here.

For Akbar's 48 volts one would need about 68 plus volts into a bridge rectifier?

Why's that? A bridge rectifier drops ~1.2 V ... 2 V, depending on the type and the load. Allowing for 1V...2V of ripple that makes max. 52 V peak at the input of the rectifier.
With an boost converter optimized for the application things are different again as no transformer is involved, only an inductor, and waveforms are different from a transformer based inverter.

 

[Poppy Ann]

I'd be very wary of the claims of ah rating and warranty in a "cheap" battery.
Personally never seen a warranty extend beyond 12 months and even then, chockerblock full of conditions.
I doubt there would be any warranty if you are using it in the application described given the risk of deep cycling a standard battery (if that is what it is)

Exide are not a cheep battery and I would expect them to stand by their batteries warranty it is not unusual for a battery company to give a 3 year warranty on a car battery the problem is with what you are using it for I worked on many battery driven machines and when trying to work out battery requirements you have to accept that if you need 40 amps at 48 volt which is = to 1920 watts to get the same amount of power from a 12 volt battery you would need a 160 amps battery and that is if you could get a 100% converter which I doubt you could find, what is the reason for changing it from the 48 volt to 12 volt? if it is due to the fact you want to change it from Lipo to lead acid due to the cost then you would have to accept that charging it would take a lot longer, you can charge lipo batteries several times faster than lead acid batteries.
if you are set on using a lead acid battery then you will want to look out for a high discharge battery or what most people call golf cart batteries, wheel chair batteries or mobility scooter batteries also do not forget that it will be at least double the weight of a Lipo battery for the same power.

good luck with the project

Regards Poppy Ann.

 

[(*steve*)]

Thanks

I feel the unbridled need to ask you if you like Wensleydale cheese.

 

[Audioguru]

Pulse-Width-Modulation is efficient because the output transistors switch on and off quickly and do not waste a lot of power making heat. A class-D amplifier uses PWM but here a transformer can stepup the voltage.