Matt83

I just got an ebike, fat tire with the bafang 750w rear hub and the intelligent control module. It has a feature where you hold the + button and the headlight turns on. It's a single led that's running on battery voltage (48v). It's ok for casual night riding but I want more light, as well as my rear light to be connected to the circuit. My plan is to run an 18w 12v led light up front, and run it in series with 3 eagle eye led lights in the rear, this would bring the 48v down to around 12v. My only concern is can that circuit handle the added wattage I want to pull.

Has anyone had experience adding more wattage to built in lighting circuits on e bikes?

Cloudedsanity

Hey Matt88,

On here looking for help on lights as well so I'll mention what I would look at based on your question.

Amperage draw (Amps=W/V) is what you should pay attention to - if the amp draw is "near to or greater than" the wires rated amperage capacity, then the wire gets hot, you have a voltage drop and also run the risk of fire in severe cases.

My suggestion would be to determine amp draw of the components you want to add and then find any other components on the same wire or circuit which also draw against that individual wires rated capacity. Combine all amperages together and then compare that to the wires rated capacity.

If you don't know the wires rated capacity - try to find out the wire size, type of wire (twist, solid, etc) and the conductor material, likely copper. The length of run from the power source (battery / junction box) is also important.

Look online for wire charts which will detail average amperage capacity by foot, by type, and by conductor

If you spend the time to do the research, you will know exactly where you are at, and what you can add.

Good Luck,

Matt83

Thanks for the input on the wire. I'll look into the wire size, and hopefully it's not too small, I'm only going to be pulling 2-3 amps max. If the wire size is rated high enough for the amperage I'm going to be pulling is it safe to assume the rest of the circuit is rated the same? Being that The circuit is switched through the main LCD control screen.

Matt83

Well one thing for sure is the light that came with my bike is only good for lighting up the sidewalk, it's in need of an upgrade for sure.

It sure was fun being out on the bike at night though!

2old

Don't think this will help since I haven't ridden my ebike at night and wouldn't ride on the street at night in "the OC", but my wife and I ride MTB off road at night with Lezyne 750 lumen rechargable headlights (about $100) and they provide plenty of illumination; also, there are much more powerful systems now. Doesn't solve the problem of a stop light.

Robert C

I put a cheap magic-chine clone, with a defuser lens, on the front. It is powered by a voltage regulator going to the main battery. It works reasonably well.

Matt83

Tapping into the main battery and running a switch is my backup plan, but I really like the concept of turning on the lights from the main controller-one less thing mounted on my handlebars.

The wire gauge is 18 or 20 so it should be able to handle the few amps I'm going to draw from it. I'm just waiting on the red led lights to come in then I'll mock wire it all up and give it a go.

Dunbar

You could always wire up a relay and use the the controller + button to switch the light on/off. However, you wouldn't think that LED's are going to draw that much current.

Cloudedsanity

hey Matt,
Looks like some good input from others...
Have you figured out what the amp draw is on the components you want to install? LED's draw is quite less than the chips rated wattage. I would contact Dave at Draco-products on Ebay - he has been a source of information & parts for me. Likely he has a bulb which can replace the standard one on your bike, increasing the lumens exceptionally.

Also, if the light draw is on the same circuit as the LCD screen, please make sure you don't overload that circuit. Tapping into the main battery or junction box is a good idea. If you use a relay (as suggested) you can have the signal wire connected to the circuit which comes on when you turn on the main controller - it would accomplish what you desire without adding workload to the existing circuit. Just make sure you use a fuseable link, circuit breaker or fuse inline with the main load wiring for light.

Mike

fietsbob

Schmidt and other European makers of Hub dynamo powered LED lights offer a DC version of their lights
to run off the same battery that the motor uses..

Matt83

Thanks for all the great info! The light wire is not coming out of the main LCD, so I'm assuming the lighting switch is built into the motor controller. I'm going to use a 6 LED light that can run on 12-30v and a brake light for trailers that runs on 12-24v. I'm going to run them in series to bring the voltage down to 24. Also running the lights on a higher voltage than 12 drops the amp draw. I should be pulling somewhere around 1 amp.

Matt83

Here is a picture of the lights I'm going to use. The headlight should mount right up where the original is, I'll have to fab a bracket for the tail light.

Matt83

Well I had some interesting results when I wired up the lights for testing. When I would turn the lights on they would flash on for a second that's it! So im guessing the circuit has some type of built in overload, that's great because if I find a setup that works I would assume I'm not overloading the circuit. So I tried using another led light in series then it worked! So there is an issue with the tail light, I'm guessing it's not rated at 24v as stated. The 2 led lights were both rated at 24v.

I included a picture of the lights on, powered by the bike. On a side note I'm now torn between what light to use. One is a spot light with OK side to side throw, the other is a flood that really lets me see all around well, just not quite as far.

So I made some progress, I just need to work on a solution for the tail light.

Matt83

I should receive the red led eagle eye lights I ordered tomorrow. Hopefully by this weekend I will have a solution for my headlight. I plan to run 3 of the eagle eye lights in series with the led headlight, this should bring voltage down to 12v.

Matt83

I decided to go with the flood light, it lets me see more of my surroundings. I made a bracket and it will bolt on right where the original was. I also ran wires to the rear seat for the tail lights. I'll figure out how to mount those when I get them.

Matt83

I ran into an issue with the eagle eye lights, the wires that they come with are a very small gauge, maybe 24 or smaller... so running them in series with the main led is not an option because those wires cannot support the amperage.

I have now completely ditched the idea of running the lights in series. I placed an order for a voltage regulator that will take 48 V drop it down to 12 V . It is small enough I'll find somewhere to mount it on my down tube . It has a three amp output more than enough to power my headlight and taillight .

Matt83

Now that I'm running a dedicated 12v for my lights I went back to my original idea of using a brake light for my tail light, and I mounted a couple of the eagle eye lights on the frame just to make myself seen more at night. Here are some pictures of the brackets I made and how I mounted them. I'll update more when the regulator arrives and I get that mounted.

Matt83

I've been busy but finally had a little time to tinker with the lights and again hit another road block... this time I throw in the towel.. I got the 12v converter in the mail, hooked it up and.....nothing. It seems that the converter trips the built in fuse in the light circuit.

I have officially given up on running the lights through the main controller. I am now working on wiring the converter straight into the main battery voltage and running a dedicated switch for the lights.