Speedometer/Tachometer solution

#1
Anyone have a Speedometer/Tachometer solution for minibikes that they've implemented? Ive got some motors that have the governors removed and though it would be a good idea to atlease install a Tachometer to know when im reaching the RPM threshold (besides the usual way of finding out :rolleyes:)
 
#2
There are several on ebay that will work for SINGLE cylinder engines and the prices is very good. Make sure to read the description as most are for 2-4 cylinder engines.
You want the Induction feature for the Tach. The Spedo may have a small magnet you place on the front wheel and calibrate.
Most use a 12 volt DC battery for power.
This has features you may never use.
http://rover.ebay.com/rover/1/711-5...0001&campid=5335845805&icep_item=283662267193

Now if you want to keep it simple you will need a spedometer for a bicycle and a separate tachometer/hour meter for a single cylinder engine.
 

DaddyJohn

Well-Known Member
#3
There's all sorts of combined tach/hour meter devices on eBay for cheap.
They usually have a little battery inside to power them, and you wrap a wire around the spark plug lead.
 
#6
I have found with the small hr meter/tachs that instead of wrappin the wire around the plug wire, tap into the hot side of the kill switch to get a more accurate readin. Has anyone used a gps speedo yet?
 

Li'l Popeye

Well-Known Member
#8
Here are some pics of the installation of the speedometer/tachometer on 1 of the minibikes.

^This is the meter. I got it from AliExpress for around $25,-, incl shipping. It's a tachometer (dial) and speedometer (digits) in one. It can be set to km or miles. It needs a 12V powersource. It can also indicate your lighting, blinkers, gearselection (from neutral, to sixth gear) and also an odometer.


^First I did some quick wiring to see if the tachometer would function with this type of engine/ignition.


^The wiring diagram that came with the meter from AliExpress. A lot of function that I will not use, but it was just $25,-.


^This is where I hooked up my remote kill switch wire. I also used this wire for the "speed signal wire". And it works.


^Make sure to have good ground, from battery to engine and to meter. Otherwise it will not function.


^Engine running at idle and the tachometer works fine. So I continued the installation.


^I placed a small 12V 2,9Ah battery, a fuseholder with 5A fuse, a batterycharger connection and a small on/off switch.


^View from the bottom.


^I made some mounts for the meter. The meter came with rubber mounts.


^The speedometer/tachometer came with a sensor and 3 magnets to measure speed. I have milled some blind holes in the front brake rotor for the magnets.


^At first I had installed 3 magnets, as I thought the reading would be more accurate. But in my case I get the best (solid and steady) reading with just 1 magnet installed. That's why I have removed 2 magnets. I also turned the magnet over, because of it's polarity. Now the speedometer works great. The meter can be set with number of magnets and tire circumference to get an accurate reading.


^Batterycharger connected.


^Battery charging.


^The speed sensor installed, with the bracket that came with it.
 

Li'l Popeye

Well-Known Member
#10
Well. The small batteries I used, can not resist the vibrations, I guess. I have 2 dead batteries by now after just 15 miles. I have ordered Li-ion cells and will try something with those.
 
#11
What is the voltage at max RPM?
That battery should not have died. SLA batteries are pretty tough and are used in portable medical equipment that really get abused.
I used one for 8 years with no issues before it sulfated up and died.
 
#15
Yea, it is possible the battery boiled out. You can pry off the vent cover and look inside. If the glass mats or plates are clearly visible, the battery is toast.
This is one reason I went with 18650 batteries as the charger for them is "smart" and very cheap. Each cell is controlled for charge/over charge/too low voltage. A test function shows if there is a low/bad battery. All in a very small package.
I've posted several photos of how I did it.
 

Li'l Popeye

Well-Known Member
#16
Yea, it is possible the battery boiled out. You can pry off the vent cover and look inside. If the glass mats or plates are clearly visible, the battery is toast.
This is one reason I went with 18650 batteries as the charger for them is "smart" and very cheap. Each cell is controlled for charge/over charge/too low voltage. A test function shows if there is a low/bad battery. All in a very small package.
I've posted several photos of how I did it.
Ok, I have ordered 18650 cells of 3350mAh and they should arrive tommorow. Also a battery holder for 4 cells in serie. That would give me about 12-16V. Speedometer is 8-18V. For charging I will have to take them out, because I will charge them with a Nitecore Digicharger D4 (also ordered). I'm not comfortable to make my own battery packs with BMS, yet. First let me see if this will function.
 
#17
Should work just fine. I have dropped down to 3 batteries and they will work the battery charger, head light, tail light, cell phone charger just fine.
 

Steve73

Active Member
#18
Ok, I have ordered 18650 cells of 3350mAh and they should arrive tommorow. Also a battery holder for 4 cells in serie. That would give me about 12-16V. Speedometer is 8-18V. For charging I will have to take them out, because I will charge them with a Nitecore Digicharger D4 (also ordered). I'm not comfortable to make my own battery packs with BMS, yet. First let me see if this will function.
why not just use a sealed small motorcycle battery? i use one i got from chrome battery works great...
 

DaddyJohn

Well-Known Member
#20
I use these for my led headlights and taillights. Got them off eBay and they have a separate charge port and a switch so nothing needs to be disconnected to charge it.
I've used those same eBay polymer lithium ion battery packs in various sizes for several projects. Very handy and affordable...

One thing to note, they have power input and output pigtails. There is also a switch and LED indicator light built into the pack, and the switch simultaneously allows charge into the charge connector, and also out the output connector. So, unless you unplug the output (which isn't hard to do), whatever you have hooked to the battery pack will be powered-up while you're charging it. Not a big deal, just a minor detail. You can get past it if you want to take the pack apart and rewire it to always have connectivity into the charge port, and just switch the output. If you're worried about the charge port always being live (which it already is, as originally wired, with the switch on), you can add a diode to prevent current backflow.
 
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