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Ignition system voltage

Old 08-06-2008, 10:32 AM
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BaldEagel
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Default Ignition system voltage

Sorry to ask this guys as I know it has been asked before, but do you know the maximum voltage that can be put through the ICU units, I understand that Two LiPo come off the charger at 8.4 volts for the S unit and that a three cell LiPo will come off the charger at 12.6 volts for the P unit, what I am looking for is guidance on using LiFi cells (A123) at 3.6 volts each off the charger so what it all boils down too is:
Can the S ICU unit take 10.8 volts? Three cells @ 3.6 off the charger.
Can the P ICU unit take 14.4 volts? Four cells @ 3.6 off the charger.

These cells will settle too 3.3volts after a short time so the three cell pack would be at 9.9 volts the same as a six cell NiMh its the extra voltage off the charger that I am worried about, same with the four cell pack except 13.5 volts as a nine cell NiMh.

I suppose I can answer my own question by putting a voltmeter on a six cell and nine cell pack straight off the charger that would give an indication of what the ICU is designed to take, I will do that now.

Mike
Old 08-06-2008, 10:46 AM
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Default RE: Ignition system voltage

Ok fresh off the charger my sub C cells are at 1.42volts each that means that a six cell pack is at 8.52volts and a nine cell pack is at 12.78 so the potential for over voltage on both units is at 2.3 volts on the S unit and 1.62 volts on the P unit fresh off the charger, and an extra 1.38volts on the S unit after the batteries have settled down and an extra 0.5volts on the P unit.

Hope its clear to you chaps.
Mike
Old 08-06-2008, 05:13 PM
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Default RE: Ignition system voltage

Mike,
Worry about the low voltage instead. The ICU is designed for LiPo cells! So if you want to use different cells, be sure to meet the low voltage requirements with whatever cell type you choose to use (LiPo low voltage cut-off). The Lipo High voltage for the type (L,S,P) is safe. If You use different batterie types, use in line high current diode(s) to take the excess voltage as compared to LiPo and cross check against the expected low voltage limits.
That way you will play safe, But am sure you already knew that? Then there is the quite standard 10% excess voltage upper margin as in all electrics. Use that at your own risk though.
Old 08-07-2008, 06:29 AM
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Default RE: Ignition system voltage

Pe
Thanks ever so much for your answer, could you expand on the high current in line diode(s) for me.

I am not worried about the low voltage with the A123's as they can be very quick charged on the field, what concerns me is using a potential fire hazard (LiPo) in a petrol plane, a very high loading landing (crash) could have dia concequencies in a crop field, I carry an extinguisher with me now days.

Mike
Old 08-07-2008, 04:32 PM
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Default RE: Ignition system voltage

A diode has a few parameters to take into account.
One is the absolute voltage drop, at say 100 mA.
The other is the voltage drop at about 5A (5000 mA).
You want to be the low current drop at 0.6V or more, whilst the high current drop should be 0.8V or less! Take the problem to the electronic's store, and they will know how to address it, using their manuals.
Old 08-21-2008, 11:53 AM
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Default RE: Ignition system voltage

Copy of an e-mail from MVVS:

Hello,

Yes the ignition ICU - P is able take 14.4 volts. You can not go over 16 V.

Best regards

Lukas Chymek
Technical Support / Technick√° podpora

MVVS, spol. s r. o.
tr. Kpt. Jarose 35
60200 Brno
Czech republic


I have sent this to Pe, but he is not well at the moment so may not have a chance to post this, therefore I am posting it on his behalf.

Hope you are back to full fitness soon Pe.

Mike
Old 09-17-2008, 05:24 AM
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Default RE: Ignition system voltage

Further to the above, my new S type ingnion unit for my 45 has a lable on it that says, 6.5 - 8.4 volts, I have sent an e-mail to MVVS asking the maximum voltage that the unit can take, this I expect to come back too me as 8.4 volts as per the lable, but will post what answer I receive back from them.

Mike
Old 09-17-2008, 09:20 AM
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pe reivers
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Default RE: Ignition system voltage

I hope the ignition will allow 3x A123 cells. I do not particularly like LiPo.
Thanks for asking Mike.
Old 09-22-2008, 05:42 AM
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Default RE: Ignition system voltage

Reply from MVVS on the ignition voltage on the S unit.

Hello,

S ignition till 10V there is not problem. 11V is Top line.

Best regards

Lukas Chymek
Technical Support / Technick√° podpora

MVVS, spol. s r. o.
tr. Kpt. Jarose 35
60200 Brno
Czech republic

Bottom line is the S unit can take up too 11volts so a 3S A123 battery should be OK, fresh off the charger would be 10.8 volts.

The Pro unit can take up too 16volts so a 4S A123 battery should also be OK, fresh off the charger would be 14.4 volts.

Hope this helps all.

Mike
Old 09-22-2008, 06:30 AM
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pe reivers
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Default RE: Ignition system voltage

Thanks Mike.
Very good info.
Old 09-22-2008, 06:30 AM
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BaldEagel
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Default RE: Ignition system voltage

Reply from MVVS on the ignition voltage on the S unit.

Hello,

S ignition till 10V there is not problem. 11V is Top line.

Best regards

Lukas Chymek
Technical Support / Technick√° podpora

MVVS, spol. s r. o.
tr. Kpt. Jarose 35
60200 Brno
Czech republic

Bottom line is the S unit can take up too 11volts so a 3S A123 battery should be OK, fresh off the charger would be 10.8 volts.

The Pro unit can take up too 16volts so a 4S A123 battery should also be OK, fresh off the charger would be 14.4 volts.

Hope this helps all.

Mike

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