My 1200w/48v EBike Build

[Handy Andy]

Opted to order a 48v-12v converter for the headlight, proper scooter horn, and a set of 12v LED tail/marker lights. I also ordered a motorcycle style switch as well for these.

Eww, I would not, you can do better with calculating and using drawing resistor current than to use the linear dropping converter - it will be drawing power all the time, sucking your battery dry until it got to 12 volts.

LED lamps are lightweight - just a larger value resistor Wattage? Usually 1 watt rating is sufficient especially about 100 ohms or more -

The Horn? A relay or lamp (light bulb like a 921 or 194) in series to draw down current thru it then to the horn to keep it's own coil buzzer system seeing less voltage, and current - using the 48V system.

The objective - as I see it, is to keep the 48 volts for your bike, don't worry so much about the accessories - they should do ok with limited life-cycle duty times of 10 - 25% - but LED? Heck, a simple resistor with a good wattage rating will drop the voltage and current to a safer level and you don't have to fiddle with the linear aspects of the 12V converter.

Unless of course you're thinking of using some BRF300AN from @kopcicle for that extra boost for your radio...(ahemn...)


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[CB590]

Eww, I would not, you can do better with calculating and using drawing resistor current than to use the linear dropping converter - it will be drawing power all the time, sucking your battery dry until it got to 12 volts.

LED lamps are lightweight - just a larger value resistor Wattage? Usually 1 watt rating is sufficient especially about 100 ohms or more -

The Horn? A relay or lamp (light bulb like a 921 or 194) in series to draw down current thru it then to the horn to keep it's own coil buzzer system seeing less voltage, and current - using the 48V system.

The objective - as I see it, is to keep the 48 volts for your bike, don't worry so much about the accessories - they should do ok with limited life-cycle duty times of 10 - 25% - but LED? Heck, a simple resistor with a good wattage rating will drop the voltage and current to a safer level and you don't have to fiddle with the linear aspects of the 12V converter.

Unless of course you're thinking of using some BRF300AN from @kopcicle for that extra boost for your radio...(ahemn...)


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The issue I have is most motorcycle LED or regular bulbs are rated for the 12v range and not 48v. Also when power is off on the battery with main switch on side of battery it cuts everything so there would be no draw.

I ordered in 2 motorcycle turn signals already for the rear forks and have 2 more coming for the front.

I am grabbing that little bag today for the 7ah battery and will initially try that. If I can get it mounted up I will probably return the 48/12 inverter to Amzn unused.

 

[Handy Andy]

I just didn't want the weight factor, and all that battery slinging around under you in that frame. The balance and gyro effects will be most pronounced when you are starting and stopping - it can become too top-heavy - then what...?

 

[CB590]

I just didn't want the weight factor, and all that battery slinging around under you in that frame. The balance and gyro effects will be most pronounced when you are starting and stopping - it can become too top-heavy - then what...?

Copy that. I'm also not very savvy when it comes to figuring out resistors and such though. So either I do the 7ah SLA or the 48-12 adapter.

 

[Handy Andy]

The converter, you cant use it. UNLESS you know how much current it draws to operate at idle - its' constant draw it uses to supply any 12 volt unit it will supply. It will drag - drain - down the 48 volts like a hungry baby sucking power as a constant current until it's no longer available - because the potentials of in to out are equal, no current flows - but you have only 1/4th of your reserve left after that converter pulled it down to the 12 volts.

Until you know how the converter will drain that battery - Unless stated otherwise - the (any) converter is not a high impedance device when idle - it has to draw some current to stabilize the voltage output it's rated for.

 

[CB590]

So I put the 48/12 on. Says like .01 amp no load draw.

Also did front white marker with amber signals and the better 12v scooter horn. Rear is red marker with amber signals. Simple led flasher.

Still need to fix the spaghetti.

 

[Shockwave]

One cheap source of free used lithium ion batteries is the recycle box out in front of your local Lowes store. Most cells in those packs are still good and just went below the voltage that the stock charger could recover them from. If they even light an led when you press the test button, they are probably good. Get enough 18650 cells to make whatever you want and buy an inexpensive battery management board for the pack on eBay or Amazon. That will help compensate for any unmatched cells if you can't build what you want from a single pack.

 

[338_MtRushmore]

One cheap source of free used lithium ion batteries is the recycle box out in front of your local Lowes store. Most cells in those packs are still good and just went below the voltage that the stock charger could recover them from. If they even light an led when you press the test button, they are probably good. Get enough 18650 cells to make whatever you want and buy an inexpensive battery management board for the pack on eBay or Amazon. That will help compensate for any unmatched cells if you can't build what you want from a single pack.

I thought everyone recycled those batteries at amazon. They will even send you a new battery first, but you have to pay a hefty core until you return the old one.

 

[Shockwave]

Just pulled a Husqvarna pack out the the recycle bin at Lowes with 90 good 18650 cells in it. They were the expensive 2900ma ones too. Cells had dropped to 3.5 volts and would not recover with the stock charger. Came right back to life once charged with another that ignores the low voltage charge inhibit function.

 

[CB590]

Managed to get a rear rack that fit the fat tire for $30. No worries the load will be way under the alleged 50#. Waiting on incoming brake light that will work off the brake lever (switch).

 

[CB590]

I've learned by putting 110 miles on it to and from work a few things.

I need to move the rear side lights back as my heel catches them once and awhile.

Check for anything lose weekly.

The ride is cool at night when it's less than 50' F and you don't own gloves.

Doing 15-20mph avg will get me to work and back with about 50% battery left on avg. I do one section of road at full 25-28 to keep ahead of the flow thru a 30mph zone because it has no shoulder at all and people don't know how to drive near a bike.

The new gel seat is way better than the BMX factory seat for long rides. (Pic was pre rack install last week at work lunch)

 

[TM86]

Those gel seats are nice on a long ride.

 

[CB590]

LED tail/brake installed using rear brake handle to activate a switch for brake light

 

[CB590]

Got rid of the twist 7 speed. Put on a thumb shifter. Basic mad max. Tons of compliments. And questions.

 

[CB590]

Next build for the new business I'm trying to do. Kiss budget build ($45 used bike) as the advo piece.

Just headlight, tail, and horn on this.

Same 1200w/48v kit (not fat tire, just 26"). Mock up today. Waiting on the motor to get here.