Recommended: power your lights using DC-DC step down transformer

[LazyViking]

Last year I rigged up my MagicShine lamps togethether with a step down DC-DC transformer powered directly from my Agattu battery.

I can thoroughly recommend this solution. It's really effective and practical.

I bought my transformer on e-bay for under £10. Sent from India.

My first transformer got wet and on my second attempt I have moved the installation from the bottom bracket up to the handlebars.

The lights come on as you put the battery in the bike. I added a switch in case I want to leave the battery in the bike without the lights on.

The transformer get it's power from a cable which I have attached to the contact plate.

I have two "900 lumen" 5W MagicShine lamps at the front, and a 3W MagicShine flasher at the rear. They run on about 7V. I planned to add a connection to my trailer too, but this would be a bit much for one transformer (rated at 2A?). Connections to the lamps use cables supplied by MagicShine too.

The original Agattu dynamo lights are still on the bike as a backup.

--LazyViking

 

[tillson]

I'm really interested in this and it is something that I have been considering for a while. Any details about the transformer and pictures of the connections to the battery connector would be appreciated.

 

[LazyViking]

Parts list

Here is the transformer I found on ebay:
LM2596 DC-DC Step Down Adjustable Power Supply Module

For example:
LM2596 DC-DC Step Down Adjustable Power Supply Module on eBay (end time 27-Feb-11 14:19:18 GMT)

(At this price, buy a couple.... delivery takes several weeks).

Front lamp:
$76.85 - HA-III Cree SSC P7-C (SXO) 3-Mode 900-Lumen LED Headlamp Set (4*18650 included) - SSC Flashlights

Rear lamp:
$57.60 - Magicshine MJ-818 HA-III SSC 42180U 3W 3-Mode LED Bike Tail Light Set (4*18650 included) - Bike Lights

And some cables/adapters:
$3.12 - 5.4mm Male to Female Extension Cable for SKU 29489/30864 (100cm) - Flashlight Accessories
$3.13 - 5.4mm Male to Dual Female Adapter Y-Cable for SKU 29489/30864 (25cm) - Flashlight Accessories

You will also need a cable from the bike battery terminal plate to your transformer, and some way of keeping the transformer watertight, eg. a little plastic bag and PVC tape. Some cable ties will keep the cables fastened nicely.

I've mounted the back light under the back seat using a custom bracket made from some 1mm aluminum sheet. The standard bracket is not much use.

See fleccs page describing which battery terminals are which. The terminal plate is easily removed if you have a torx screwdriver set and philips (PH2) screwdriver.

Add a switch before the transformer and it's probably a good idea to add a fuse too

Disclaimer: don't do this unless you are sufficiently qualified

 

[banbury frank]

dc to dc

Hi I use one off these on 48 volt to 12 v 5 amp they also do a 5 volt output

18V 19V 20V 22V 24V 48V DC to 12V DC 5A voltage reducer on eBay (end time 22-Mar-11 16:32:22 GMT)

also http://www.ebikes.ca/store/photos/LED_LightKit.jpg

http://www.ebikes.ca/store/photos/Lumen_Dual.jpg



Frank

 

[tillson]

Thanks for the links chaps. It was the battery connections that were of slight concern. I should have thought of flecc's pages and sipped from the font of knowledge.

 

[aseb]

DC to DC Multi-Purpose Voltage Converter $19
It's small, covers led light voltages, and lots more.
Voltage input range: 4.5V to 60V
Voltage output range: 1.2V to 30V
Current: 3A

 

[jbond]

Have a dig around in your box of old 240v-5v or 240v-12v power plugs. Take them apart and they should work fine with 36v or 48v inputs.