USB powered 9V battery charger - Help wanted

[JaredB]

Hi, I'm doing a project and I want to know if you can buy or make a 9V battery charger that uses a USB port as the main power source (NOT a device that uses the 9V battery to power a usb device.). Specifically I want to be able to use a USB battery bank to be able to charge 9V batteries while on the go.

 

I'm not sure which catagory this falls under, so I'm using general discussion, sorry.

 

Any help with this would be apreciated.

 

Jared B

[VMaxMuffin]

USB only provides 5 V... and you'd need a power converter but then charging would be slow (assuming you're using a common 0.5/1 A port)

 

2 ports in series? Then the voltage would add...

 

(Just kidding, please don't try this)

[FizzyFantom]

USB only provides 5 V... and you'd need a power converter but then charging would be slow (assuming you're using a common 0.5/1 A port)

This is correct.

 

2 ports in series? Then the voltage would add...

 

(Just kidding, please don't try this)

Really, don't.

[JaredB]

This is correct.

 

Really, don't.

Oh thanks.

Ok then, are there devices that could do something like I want?

[DigitalHermit]

You can try a basic op-amp circuit... Not sure how this will work though... You can look through some catalogs to see if there's something that will funciton using a 5V supply...

[FizzyFantom]

Something like this may work, but I can't imagine it would be terribly efficient:

http://www.murata-ps.com/en/mer1s0509sc.html

 

If you plan to carry around a battery pack as well as making your own adaptor you should consider picking up a 12V battery (pack) and a couple of voltage regualtors. This way you could make a 12V cable, a 9V cable and even a 5V cable from this power source.

You would need more than 9V DC to charge a 9V battery (most 12V lead-acid batteries charge at around 13.5-14.5V), but as for how to make a charger like this I dont know. This forum thread may be helpful:

http://www.digikey.com/techxchange/message/12408

This may also be helpful:

https://uk.answers.yahoo.com/question/index?qid=20090916121404AApoBtZ

 

If you get a 12V battery you could buy something like this and connect it to the battery, which would allow you to charge a few different types of battery from it:

http://www.amazon.co.uk/ALL-RIDE-12v-BATTERY-CHARGER/dp/B003LII2GC

 

Batteries can be nasty things, just make sure you're careful when dealing with them.

[KemoKa]

erm... is this rechargeable battery important to you, because if you try jerry-rigging the thing and it explodes or leaks or something...

They have cheap chargers online that won't kill your battery for you, i'm sure. Just lurk around teh interwebs.