Are DC-DC converter using a lot of battery

[cwah]

Are DC-DC converter using a lot of power?

Hello there,

I've found a DC-DC converter for my 74V lipo:

Zenid e-Bike Parts

I'd like to use it so my battery can also be used for my lights. It has 90% efficiency.

I'm wondering if I plug that with my batteries if that may uses a lot of my battery? Does that worth it?


ps: I've also found this DC-DC converter but I'm not sure which one is the best between them: DC 72V to 12V 10A convertor

 

[Scottyf]

There is a loss but it's hardly worth noting though.

In the end I just used 18650 cells to make up a separate battery for my lighting as it was easier and cheaper plus less cabling for lighting. But the step downs really are quite energy efficient.

 

[cwah]

That's what I'm doing now, but I'm sick of removing my light every time I park my bike.

Also, I always forget to charge my light batteries and they are often out of light.

So I prefer to directly integrate that with my bike.

 

[cwah]

I'm thinking about using high density led as light:

HobbyKing R/C Hobby Store : High Density R/C LED Flexible Strip-Yellow (1mtr)

So no one will steal that

 

[rog_london]

Replying to your original header about 'using a lot of battery':

I'm sure it's obvious, but don't forget to wire your converter into the switched side of the battery - in other words, it needs to get turned off when you park the bike. That's because it will draw a small standing current even if the lights are turned off, and while that won't matter for the hour you may be riding, it definitely will matter if it's powered when the bike is parked overnight, for example.

Also, the '90%' efficiency rating quoted for such an item generally applies when you're drawing close to the rated load of the converter, and will not be quite so good if you're drawing well under the rated load. However, I doubt that will be significant.

Rog.

 

[cwah]

Thanks for your answer rog. I purchased the converter, will use it for my bike