Total non-rc question. - RC-Monster Forums

josh9mille · **Total non-rc question. -** 01.05.2011, 05:12 PM

So i got my kid a 93 phazer snowmobile for xmas as a basketcase with a bad engine but in perfect condition. I got it all together with a newer engine and runs perfectly. However the sled is electric start, and i do not have the funds right now to buy a $70 battery for it. Will it hurt the charging system if i run it without a battery? Maybe just heatshrink the end of the + battery cable? I would normally ask this question on the SnoWest forum, but it is a pay site now, and i am no longer an actual member. Any help would be appreciated, Its snowing like crazy here and she wants to go riding!

brushlessboy16 · 01.05.2011, 05:19 PM

4s Lipos.

In all seriousness It should run

I have a 90's yamaha 50cc scooter that has no battery in it, fires up without it.

You should be fine

josh9mille · 01.05.2011, 05:26 PM

Quote:

Originally Posted by brushlessboy16

4s Lipos.

In all seriousness It should run

I have a 90's yamaha 50cc scooter that has no battery in it, fires up without it.

You should be fine

Oh i know it will fire up without it, just wondering about any long term damage.

lincpimp · 01.05.2011, 05:33 PM

I am guessing the stator works fine if it starts and runs. I see no reason for it to cause any issues without a battery. I plan to make a battery for my motorcycle from a123 cells. 4s3p, 12 cells. Not going to have the mah that the stock battery has, but it should start the boke just fine. I am currently using a 3s 5kmah lipo as a "jump box" to start the bike if the battery has gone down.

JERRY2KONE · **Yes -** 01.05.2011, 05:49 PM

YES it should be just fine. Consider this. If you start your 1:1 car up and get ready to drive it, then remove the battery cables from the battery. As long as the vehicle has a good charging system it will run fine. The alternator will provide enough power for the car to remain running as long as the key remains turned to the run position. In fact in most cases the only reason you have a battery is for starting the engine.

J57ltr · 01.05.2011, 10:35 PM

You will be fine no load, no output.

DrKnow65 · 01.06.2011, 12:55 AM

sorry to disagree all, but I am a career mechanic and I've toyed a bit with small engines and no battery. You need to run a battery and here is why... it's a capacitor.

When the system is running on an altenator the battery works to smooth the voltage out. The altenator is actually outputting pulses of power, the volatge regulator is not fast enough by itself to keep every pulse at exactly 13.8v. It reacts to the slightly less fluctuating voltage of the total system (including primarily the battery).

If you doubt, take a oscilliscope to a car and look at the voltage smoothness with the battery plugged in and not. Without the battery you'll see spikes of close to 18v and lows of nearly 11v. The reason you don't see the change significantly is the dwell time of the spikes is very shory (altenator rpm X 3 @ ~30%).

Also in a small engine if the rpm's get low it has a good potential to stall, the lows drop in voltage as the output decreases and the dwell time of those lows are long enough to limit the spark output = stalling.

On a snowmobile you can get REAL stuck if you let off the throttle at the wrong time...

IMHO

JERRY2KONE · **Makes sense. -** 01.06.2011, 01:16 AM

That makes sense, so how about putting a 13v 40 or 50 amp capacitor on the battery leads? Just a curious question....

DrKnow65 · 01.06.2011, 01:29 AM

Dunno about the capacitor costs

But if you were to use even some NIMH cheapies (hack togeather two $10 packs to get 14V), it wouldn't be enough to start the mobile, but propabley enough to smooth out the voltage and keep the spark flowing at low RPM's. Cheap substitute till you get a real lead acid in there.

lincpimp · 01.06.2011, 01:46 AM

So a small engine stator and rectifier still produce spikes like a car altenator does? I was under the impression that they do not, as I know that a car altenator setup needs the battery to "smooth things out" as you demonstrated.

I thought a stator was more like a generator, put out dc, and not ac... Might be wrong here, as it still needs a rectifier to charge a std dc battery.

lincpimp · 01.06.2011, 01:58 AM

Well I did some reading and found out that dc type gerator hve been phased out almost completely. So it is likely a ac type, permanent magnet unit with a rectifier/regulator. So it will experience the spikes that DRNo mentioned.

Learn something new everyday, aint life grand!

Here is a good read:

http://www.electrosport.com/technica...g-system-works

DrKnow65 · 01.06.2011, 02:02 AM

Yah Linc, small motors don't actually have a regulator, and they are single stage, but the effect is the same. They produce an AC waveform (like a real strong hall effect sensor) and you have to rectify it. But the dwell, peaks, and valleys are the same deal. I found this same situation on the Raptor 80 I put togeather for the kids this summer. If you want it to idle correctly it takes a battery.

Some small motors just use a magneto ignition and are completely void of a charging system all togeather, but that's not what you would find on a snowmobile with an electric start...

josh9mille · 01.06.2011, 03:09 AM

Quote:

Originally Posted by DrKnow65

Yah Linc, small motors don't actually have a regulator, and they are single stage, but the effect is the same. They produce an AC waveform (like a real strong hall effect sensor) and you have to rectify it. But the dwell, peaks, and valleys are the same deal. I found this same situation on the Raptor 80 I put togeather for the kids this summer. If you want it to idle correctly it takes a battery.

Some small motors just use a magneto ignition and are completely void of a charging system all togeather, but that's not what you would find on a snowmobile with an electric start...

so there IS a difference in the stators of say a e-start phazer and one that just has a pull start? Looks like ill be trying to source a battery for it somehow....

J57ltr · 03:25 AM

I understand how it all works and although the unrectified power would seem to cause a problem it doesn't on anything but the newer engines that are completly computer controlled. the charging system on a riding lawnmower is pretty much the same as the snowmobile (we don't have them down here but we do have See doos and such. Outboard engines use them as well. The question was will it hurt the charging system, the answer is going to be no. Long term damage no. He isn't running it forever without the battery. If he wants to feel better a audio cap around .5 farads or a 1 farad cap would work great and you can get a 1/2 farad for around 15-20 bucks.

I have driven 230 miles after losing a battery that was so shorted that it could not be jumped and the pos terminal had to be removed the jump the car. then left disconnect because it would kill the engine and load the alternator. And that was at night. If he needs to use it He isn't going to kill it that's all I am saying. But if he doesn't have a battery and it does die I hope you carry cables.

Jeff