DC-to-DC 36v/48v to 5v/6v/12v for Accessories (Sirius Sat)

You can also run the speakers off the 5v, so you will need only 1 DC-DC converter.
DC-DC converters are not cheap, so you might want to reconsider this solution.
Just run the radio,speakers and lights off rechargable Ni-mh AA batteries, and carry spare cells in your pack.

For low amps like your application, 5v/6v voltage regulars are cheap and readily available for $1-2 dollars.

But input voltages as high as 48v are less available.
One way to get around this is to get 3 voltage regulators for each of the 12v batteries, and each regulator will take the 12 volt input and output 5/6 volts.

For $0.35, input at 35v max, Output current to 0.5A, Output voltage of 5v
http://www.goldmine-elec-products.com/prodinfo.asp?number=G13017
data sheet: http://www.st.com/stonline/products/literature/ds/2143/l7805c.pdf (look at the table for L7805)

For 6volts, get the 7806:
http://www.goldmine-elec-products.com/prodinfo.asp?number=A10483

For higher amps(claimed 3amps), use something like this:
http://www.goldmine-elec-products.com/prodinfo.asp?number=G15674

I don't want a separate battery for accessories. I am willing to pay for the convenience of a single plug-in to recharge at night. I also don't want to tap the individual 12v batteries.

I have ordered one of these http://www.dimensionengineering.com/VHVBEC.htm, but I don't fully understand how to wire it. Any advice?

Model: VHVBEC
Specifications: Input voltage: 9V to 60V (3s-14s lithium, up to 40 cell NiMH)
Output current: 2.5A (~6 standard servos, 4 digital)
Weight: 17g/.6oz (including wires)
Universal connector fits all receivers

What a great BEC and a good find. I'm not sure why you're having problems wiring it. You'd just want to tap a 48V powerline and feed it into he +/- feeds on the left side and use the receiver power on the right side for your 5V equipment.

Just remember that red is + and black is - and you should be just fine. Just don't wire it backwards!

Your local RC hobby store will have the appropriate connectors (prewired) if you don't trust your soldering skills.

Karen

p.s. I just bought this one: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250270816138
on ebay. It only went up to 40V but it's only about $15 w/ shipping. Since I plan on running my moped at 28.8V, 36V, or 38.4V (i.e., not above 40V), I should be OK.

Working on a Piaggio Boxer (mo-ped) EV conversion: http://visforvoltage.org/blog/nasukaren

Hi Karen,

Can you send me the schematic for the LM2576HVT-12-ND down-converter?
I have a 48V bicycle project and I would like to run some 12V accessories.

You can see a picture of my bike project here

http://picasaweb.google.com/scott.l.baker/LongBikeProject#

Regards,
Scott

Here's a schematic for a very simple 20V-to-60V DC input to 12V DC output.
All the parts are available at digikey.com and the
parts cost is less than $10 (not counting the circuit board).
I may decide to make a circuit board if I can find some spare time
This same circuit can be used to make a 5V DC output regulator by just
changing the LM2576HV-12 to an LM2576HV-5 and a 6V regulator can be made
by adding a single resistor to the regulator's feedback path of the
5V regulator circuit.

http://mysite.verizon.net/sierracircuit/Free-Stuff/DC-DC-12V/schematic.pdf

Regards,
Scott

slbaker,

I was wondering about some additional specs. What is the max current at the 12v output? How many watts will this DC to DC converter handle?

Thanks,
Grandpa Chas S.

Moderator Captain

The LM2576HV-12 switching regulator is rated at 3A, but the coil that I
chose is rated at 2.5A continuous current. Even so, that's 30W.
I have not built one of these yet, so I don't know how hot
the coil or regulator would get when running continuous high current.
The LM2576HV's TO220-5 case allows for a heat sink if needed.