Getting 12 volt from 48 volt supply?

[ericmark]

My e-bike is 48 volt, my tyre pump is 12 volt, battery encapsulated, is there an easy way to drop volts?

At moment I rely on an aerosol can to reflate tyres when out, touch wood, never needed to use it, but bike has a 12 Ah 48 volt battery, can't think of any way to use it, maybe one one else can?

 

[RandomGrinch]

I have no idea if its efficacy, but you could try something like:

https://www.amazon.co.uk/HOMELYLIFE-Voltage-Converter-Waterproof-Regulator/dp/B09Q1Z94GQ

 

[SFK]

Search for "DC to DC converter"
And select one that covers 50V and 12V
And has a wattage (or current) rating that matches your inflator.

This one is likely over rated (wattage wise) for your needs

DC-DC 8-60V to 1-36V 15A 200W Step-down Converter Buck Voltage Power Module | eBay

To enhance heat dissipation up to 200W. The maximum peak output is current 15A. Overcurrent protection: Yes (the output current exceeds (15A) current maximum sample protection only). Type: Non-isolated step-down module (BUCK).

www.ebay.co.uk

 

[SFK]

And I would say that random Grinch suggestion is likely better than mine as encapsulated and fixed voltage.

 

[JohnW2]

My e-bike is 48 volt, my tyre pump is 12 volt, battery encapsulated, is there an easy way to drop volts? At moment I rely on an aerosol can to reflate tyres when out, touch wood, never needed to use it, but bike has a 12 Ah 48 volt battery, can't think of any way to use it, maybe one one else can?

The DC-DC converters that have been suggested are the obvious approach.

However, roughly how much current does your tyre pump draw at 12V?

Kind Regards, John

 

[chivers67]

buy a small pump! wiggle pumps!

 

[RandomGrinch]

And I would say that random Grinch suggestion is likely better than mine as encapsulated and fixed voltage.

...although your suggestions are a lot cheaper!

 

[Mottie]

buy a small pump! wiggle pumps!

Yep. That’s what I have in my undersaddle tool bag. I have one like this: Surely a lot smaller than a 12v compressor.

 

[chivers67]

i have one that fixes to my bottle cage...

 

[Harry Bloomfield]

Why not an ordinary hand cycle pump?

A 12v 3amp series regulator is cheap and the fact they waste current would not be much of an issue for short use, but the last I was involved with were only speced to 30v. No doubt the 30v limit will have improved since then, or run two in series.

 

[DetlefSchmitz]

Trying to find one last week as it happens. Very hard to source a components at the moment. *Very* few have 48V input capability. I don't think the time to blow up a tire is short enough to ignore heating effects. And for linear regulators running from the same sort you can't run them in series.

 

[Harry Bloomfield]

And for linear regulators running from the same sort you can't run them in series.

Floating ground, in the middle?

 

[SUNRAY]

My tyre inflater is 12V 45A a surprising number are in excess of 10A.

I'd have thought a hand pump would be fine for the rare times they need pumping up.

 

[Harry Bloomfield]

My tyre inflater is 12V 45A a surprising number are in excess of 10A.

Not come across any with that sort of demand on 12v, the only 12v ones I have seen plug into the ciggy lighter socket.

I'd have thought a hand pump would be fine for the rare times they need pumping up.

I agree, it only takes a minute with a hand pump. Out of curiosity, a few weeks ago I tried one of those bike pumps where you stand on the base and operate with two hands - to blow up a car tyre. It was perfectly doable.

 

[JohnW2]

My tyre inflater is 12V 45A ....

Good grief! My car one claims to be 6A (at 12V) and I think all the car ones are designed to be plugged into the ciggy socket, which is usually/often fused at 10A. How do you power your 45A one?

Kind Regards, John