how to stabilize coil voltage?

[desertmule]

i am a commercial electrician by trade..i'm trying to solve a problem i have..

i am trying to increase the lighting output on my daughters 4 wheeler..

i have installed (2)55wt/12vt lights in place of the (2)original 35wt lights..because of the added load i decided to run them through a relay with a 12vt coil..my coil voltage is coming from the stator, and through the regulator and thumb switch..line voltage for the lights is straight from the battery..

the problem is that the coil voltage is not stable..with my DMM set for AC/V i read 10.3V/56Hz @ engine idle and 14.2V/94Hz @ about 2500 rpm's..i read nothing with the meter set on DC/V..

the 12VDC coil won't close with this source..i put in a small, non-polarized capaciter(maybe too small?) to try and even things out and it makes the relay chatter(and thus the lights are dim)..

what can i do to hold this coil shut? i need a solution which is reliable and rugged..i have found a 6V relay to substitute for the 12V..

thanks for any help,
william

 

[itsmoked]

Have you tried a 12V AC relay?? Your frequencies look fine for one.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[desertmule]

thanks for the quick reply Keith...

i've Googled for a 12V AC relay and came up with nothing..the AC relay would be the easiest solution if i knew where to find one..

i also wasn't sure if the AC relay would hold with the stator power source..it's not really AC..remember, i'm a commercial(crude) electrician..
william

 

[desertmule]

i ordered a RIBU1C..a little bigger than i would've liked, but it should work...
william

 

[itsmoked]

Wait - your description didn't sink in the first time thru. Skip the AC aspect!

You're saying four-wheeler. Do you mean a "Quad" or a full size vehicle? Your mention of 'stator' leads me to believe a Quad.

You have an engine driven alternator who's output is being rectified and regulated into your battery.. Correct?

There is a problem.

The battery is supposed to be kept charged by the stator-rectifier-regulator system. There should always be 12V available unless the battery capacity has totally tanked. This means that your 12V relay should work just fine. Engine running, or not, your headlights should come on. Depending on the battery capacity for a while, or a short while.

At some point what can happen is the battery drains down to the point where the relay coil voltage drops so low the relay drops out. As soon as it does the voltage rebounds and the relay pulls back in for a moment before the voltage drops too low again. This is called "relay chattering" and destroys a relay in about 30 seconds.

Problems to check:
1) You can get this problem if the relay coil shares a part of the load circuit. The large load current acts to drop voltage as seen by the relay. It's a common occurrence if you run the switched power to the relay contacts then 'jump around the corner' to the coil.

2) The battery has so little capacity that when the vehicle goes into idle there is an immediate, significant, voltage drop.


You say the voltage isn't stable but you are measuring the direct stator output. It is just as unstable as it is in a regular vehicle that comes to idle. At idle there is very little or no charging occurring. The battery is the supply then, with only some fraction being delivered by the alternator.

#########################################

Leave the headlights off.

Charge the battery fully with a charger or the engine.

Turn off the engine.

Measure the battery voltage.
It should be around 13V certainly over 12.6V. (12V system)
Turn on the headlights using your setup while watching the battery voltage. If the voltage stays above 11V your relay should NOT be chattering. If it is you have a wiring problem.

If on the other hand your voltage drops below 11V you need to replace the battery with a GOOD battery or better, a larger battery.

Let us know what you find.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[ScottyUK]

Bear in mind that the alternator has to provide, among other things, power to the ignition system, lighting, engine management if fitted, all manner of other loads depending on the vehicle type, and still have a little bit spare to charge the battery. You've added an additonal 3 or 4 amps of load when you uprated the lighting. Is the alternator simply overloaded? 'Four wheeler' covers everything from a golf kart to Bigfoot, so a bit more detail would help. Does the alternator have a rating plate on it?


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Sometimes I only open my mouth to swap feet...

 

[desertmule]

this is a small 110cc quad i am talking about..battery is fine..

i am measuring voltage at what was the old headlight feed..my intent is to simply use this as coil voltage..a new feed for the lights was pulled from the battery and run through the isolated load side contacts of the relay..

it seems i am reading direct stator output at the old headlight feed..there is a voltage regulator(just to bleed off excessive V)..the power sure doesn't look rectified..more like a pulsed DC source which varies with engine speed..

the original headlights suffered from the same problem..they will be dim(orange) at idle and start to brighten up as engine speed increased, then dim when returned back to idle..a friend bought the same bike for his daughter and it performs the same way..it seems to be in the design..the battery is not connected to the accessory source..accessories come straight off of the regulator..

i'm going to dig deeper to see if i can figure a way to get battery power to the accessories through the ignition/run relay..the bike has a keyed switch and a wireless remote/start(which is an EXCELLENT safety feature) to make things a little more complicated..

thanks for taking the time to reply..i know it's hard to answer questions when you can't get the whole picture..

i thought this would really be simple for me..

 

[desertmule]

hey guys,

i pulled apart all the wiring harnass'..the power to the light switch did come directly from the stator and was in parallel to the voltage regulator..out of the 75+ wires on this little bike i found one switched 12vt lead...i pulled the thumbswitch wire from the stator output and soldered onto the switched 12vt..then i spent 2 hours dressing the wiring which was so sloppy from the factory..problem solved..

thanks again,
william

 

[itsmoked]

Glad you got it. Happy trails.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com