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MVVS 26/35IFS new ignition voltage

Old 08-23-2006, 03:38 PM
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Default MVVS 26/35IFS new ignition voltage

I just recently received 2 35cc and 1 26cc MVVS gassers from Pe. They have the new "lite" version MSR ignition module. A tag on the spark plug wire and the installation instructions says to use 6-8.4V. We tried to start the new 35cc engine using a 6 volt NiMh pack and it showed low voltage. It would not start. We reread the instructions and they indicate that for the lite version under the technical data listing on the back of the instruction sheet that the module requires either a 2x Lilon/ LiPol or a 6x NiCad/NiMh. We used a 7.2 volt pack and the engine started and ran fine. Am I to assume that the tag on the spark plug wire and the installation instructions are wrong and we bought 3 - 6 volt battery packs that won't work? What is the maximum voltage allowed. This is very confusing!!
Old 08-23-2006, 04:48 PM
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Default RE: MVVS 26/35IFS new ignition voltage

A 6V is a 5 cell pack. That is at the very lower operation limit, so the ignition refuses due to the slightest voltage drop in the cable harness. You need at least 6 cells, with 7 cells even better.
Old 08-23-2006, 08:20 PM
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Default RE: MVVS 26/35IFS new ignition voltage

Thanks Pe. The system will not work on 6 volts. We tested two 5 cell battery packs. One was 6.2 volts and one was 6.6 volts and the ignition would not operate. We have a simple switch harness set up with 22 ga wire so should have minimul voltage drop. We quick charged a 5 cell pack that measured 7.1 volts when we took it off of the charger and that pack worked. Do you know what the low voltage cutoff for this system is and what is the maximum voltage that it will take? I have told the guys that bought these engines that they will have to buy a 6 cell NiMh or 2 cell Lipo to power the ignition system.
Old 08-24-2006, 07:48 AM
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Default RE: MVVS 26/35IFS new ignition voltage

To avoid confusion, I quote the supplied documentation:
Lite and Standard versions: 6xNiCd/NiMH or 2xlion/lipo
pro: 9xNiCd or 3xLiPo/LiIon

!!!!!!!!!!!!!!!!!! There is no mention of Voltage! !!!!!!!!!!

A 6-pack NiCd at 6.6 volts is empty!
Old 09-01-2006, 08:50 PM
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Default RE: MVVS 26/35IFS new ignition voltage

We are learning a lot about this new ignition. I helped the guys troubleshoot the system today and find that a fully charged 6 cell 1700 mah NiMh will start and run the engine but there needs to be a clean connection from the battery pack to the ignition sytem. We found a lot of voltage and amp drop using some questionable extentions and switches. After changing out the bad wiring and switch and charging the 6 cell pack we got good performance. Just for the record this 35cc engine is very, very powerfull. The power almost scares me. The MVVS tuned pipe works to add to that power.

It is obvious that this ignition is really designed to be used with the 2 cell LiPoly packs and we will probably bite the bullet and buy one of these packs. For a 35cc engine what size would you recommend to get about 3-4 flights per session? We were thinking that a 2000 mah pack would work but don't have enough info on the system demand to make that call.

Your help will be appreciated.
Old 09-02-2006, 05:30 AM
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Default RE: MVVS 26/35IFS new ignition voltage

1.6 Ah capacity will probably do fine, since the spark energy needed has not changed, but the applied voltage is higher. I have not measured actual current draw, but expect more operating time from the new ignitions.
LiPo will need a special charger. Full voltage of two series cells will approach 9V, so 7 cells NiMH should also be a good base if one considers using conventional cells.
Old 09-02-2006, 03:37 PM
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Default RE: MVVS 26/35IFS new ignition voltage

We will use the 7 cell NiMH 1700mah packs for now. The 3D guy will probably go to LiPoly or LiIon to save that precious extra few ounces. The guy flying the 26cc on the big Ugly Stik will use the NiMH. It was a steep learning curve but we got there.

Thanks again for the help.

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