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JUSTNUZZA

912 uls Battery

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Just would like to know what size battery people are using in their 912uls. Dimensions, CCA and Ah would be good to know.

 

 

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Use what Rotax recommends, and especially in relation to Amp hour. That way I won't get a call from you when your system is no longer charging, as it should. Hopefully you would have only detroyed the regulator, (cheapish) and not the stator charging coils (dear $$$$ !!!)....hey it's your money, but I'm happy to take it off you !!...................Maj...ranting.gif.5470ae857812d977cdbca23fadaf1614.gif

 

 

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Use what Rotax recommends, and especially in relation to Amp hour. That way I won't get a call from you when your system is no longer charging, as it should. Hopefully you would have only detroyed the regulator, (cheapish) and not the stator charging coils (dear $$$$ !!!)....hey it's your money, but I'm happy to take it off you !!...................Maj...ranting.gif.5470ae857812d977cdbca23fadaf1614.gif

Thanks I will call rotax and see what they recommend

 

Thsnkd

 

 

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Maj, could you please expand on that? How does a higher Amp.Hour battery (I presume you were talking of higher, not lower) affect the regulator? Is it because it has a higher cranking current capability, which implies a lower internal resistance, and hence a higher peak charging current? In that case though, the regulator would just limit the charging current so I can't see that that would cause a problem. I'm not being critical - I seriously don't understand, and I'd really like to. :) Thanks

 

 

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sfgnome, I am certainly not the Rotax guy that designed the system, (actually Ducati) but as I understand it the lighting coils as they are called, only produce a relativly low amount of current, that is only designed to go into a certain amperage battery. If you run a high apperage battery something is not going to be happy, and may overheat. You do not need a higher amp battery in the system anyway, as they start just fine with the recommended one.

 

The last 912 stator change I did ran out to about $2900, including new stator and associated bits, (varies with aircraft type, and access to rear of engine). It ran a super-duper high-amperage oddessy..Like I say, it's your money ............................Maj...024_cool.gif.7a88a3168ebd868f5549631161e2b369.gif

 

 

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Don't follow your logic here Maj... a high Amp battery is its discharge/load capacity. It relates to the load it will provide, not the supply for charge. It will only take what it is given and does not suck more amps. Then it will only give what is asked not provide what it can regardless. Can you explain your reasoning a bit more? I am trying to understand where the problem would be...060_popcorn.gif.cda9a479d23ee038be1a27e83eb99342.gif

 

 

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Don't follow your logic here Maj... a high Amp battery is its discharge/load capacity. It relates to the load it will provide, not the supply for charge. It will only take what it is given and does not suck more amps. Then it will only give what is asked not provide what it can regardless. Can you explain your reasoning a bit more? I am trying to understand where the problem would be...060_popcorn.gif.cda9a479d23ee038be1a27e83eb99342.gif

Tex: I'm inclined to agree with you on this. A regulator is just that, it regulates. It is designed to limit the voltage and current supplied from the charging device to the battery. What fries regulators is running them open circuit, which is why Rotax reccomend that a large value capacitor be wired PERMANENTLY across the output of the regulator. Then if the master switch is turned off while the engine is running, the regulator still has some load to supply. The other thing that will fry the regulator is mounting it where there is no cooling airflow and mounting it with the cooling fins horizontal. Everyone knows that hot air rises, so the cooling fins of the regulator should be vertical so that if convection is the only cooling mechanism available to the regulator, the heat can at least escape upward.

 

http://www.scotthendry.com/P1080360.JPG

 

 

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Very interested in this discussion. We have just had a problem with our battery on our Texan as being too small only 8 Amp Hour, 12 volt and we have had it blow a linking bridge between the electrodes on the battery - a Cyclon Pb battery. It did this on cranking the engine to start.

 

According to our importer this is half the recommended size needed for the plane and he doesn't know why the factory fitted such a small battery.

 

My only problem is that we will need to work out a new mounting bracket for the battery.

 

Any suggestions on the smallest battery that we could fit that will provide the 16Ah needed and bracket ideas would be appreciated.

 

Cheers

 

ROB

 

1664859956_cyclonbattery.JPG.b3634736c48b6479228d33d99fedfb03.JPG

 

700632682_Batteryterminal.JPG.af47423593c6a2d6563f4d7d2d6729a7.JPG

 

 

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Called Bert Floods and they recommend Panasonic LC-XC1221p. 21amp hour battery.

Did the same ,and got the same answer, they did say the odyssey would work but the Panasonic was better value, dint entirely fix the problem as it originated in a savvanah which have battery problems form new ( just going on what I was told ) and has damaged the sprag clutch in my 912! Straight from Bert floods, crap electrical system equals spending money fixing stuff!

 

 

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Did the same ,and got the same answer, they did say the odyssey would work but the Panasonic was better value, dint entirely fix the problem as it originated in a savvanah which have battery problems form new ( just going on what I was told ) and has damaged the sprag clutch in my 912! Straight from Bert floods, crap electrical system equals spending money fixing stuff!

I have also discussed batteries/electrical systems with BFI and the advise that MM2 was given gels with my experience. A weak battery or poor positioning requiring a long cable run can result in lower voltage available for cranking the starter which results in weak engagement of the sprag clutch. This in turn causes the sprag clutch to sustain damage and eventually it fails in such a way that the clutch disengages as soon as a cylinder fires resulting in a kickback opposite to normal direction of rotation (ie. can't get engine to start). Once the sprag clutch shows signs of this type of distress, you can expect it to slowly get worse, with the engine becoming progressively harder to start, until you reach a point where it will no longer start at all.

 

Moral of the story is replacing your battery and ensuring electrical wiring and connections are in good condition is cheap insurance against expensive engine repairs.

 

 

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P = E X I (i.e. power = current x voltage)

 

If the voltage drops due to battery overload the current will rise to compensate to achieve the power required by the starter - if the battery is still capable of producing the current then components likely to fail.

 

 

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I have also discussed batteries/electrical systems with BFI and the advise that MM2 was given gels with my experience. A weak battery or poor positioning requiring a long cable run can result in lower voltage available for cranking the starter which results in weak engagement of the sprag clutch. This in turn causes the sprag clutch to sustain damage and eventually it fails in such a way that the clutch disengages as soon as a cylinder fires resulting in a kickback opposite to normal direction of rotation (ie. can't get engine to start). Once the sprag clutch shows signs of this type of distress, you can expect it to slowly get worse, with the engine becoming progressively harder to start, until you reach a point where it will no longer start at allMoral of the story is replacing your battery and ensuring electrical wiring and connections are in good condition is cheap insurance against expensive engine repairs.

What he said!

 

 

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To add to mriya floods said any time the battery is further than the firewall then you need pretty thick leads to compensate which ,when I bought my engine it came with the savannah loom , the savannahs don't have hence I'm looking at about a grand to do the sprag clutch. I'll also replace the flywheel with a new one ,it has different trigger points for the CDI's ,that will give easier starting .

 

 

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There is no need to have this sort of drama with the 912 in any aircraft, and certainly no need to do any damage to the sprague clutch. You all mention the length of the positive lead. The ground between the battery and engine/starter is just as important to power supply. Some run an additional heavy wire from battery neg direct to a starter attach bolt. I can't believe your doing sprague clutches because of this.

 

Most damage you see to those is through incorrect oil useable, often when people use oil not recommended by Rotax especially when people use Castrol Magnatec which is silicon fortified....Maj.....054_no_no_no.gif.950345b863e0f6a5a1b13784a465a8c4.gif

 

 

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There is no need to have this sort of drama with the 912 in any aircraft, and certainly no need to do any damage to the sprague clutch. You all mention the length of the positive lead. The ground between the battery and engine/starter is just as important to power supply. Some run an additional heavy wire from battery neg direct to a starter attach bolt. I can't believe your doing sprague clutches because of this.

Most damage you see to those is through incorrect oil useable, often when people use oil not recommended by Rotax especially when people use Castrol Magnatec which is silicon fortified....Maj.....054_no_no_no.gif.950345b863e0f6a5a1b13784a465a8c4.gif

Maj:

 

This is very interesting and not the first time I've seen mention of incorrect oil causing damage to the sprag clutch. From the above discussion, i get that the sprag clutch is the thing that engages/disengages the starter pinion to the flywheel. How does incorrect oil cause damage to this?

 

 

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The sprague clutch is a roller bearing-like device, that is mounted on the rear of the crankshaft itself, behind the ign stator and rotor etc. It will rotate freely one way but not the other, and this is how it engages the starter to turn the crank. Rotax states that only recommended oils be used per their latest Servive Bulletins "selection of approved oils and coolants"...They state in their heavy maintenance manual " selection or use of incorrect oil may contaminate the sprague starter clutch and cause it not to engage".

 

Only oils listed on the above current SB are approved for use. They specifically recommend motorcycle-type oils with a synthetic blend or additive, for gearbox lubrication. As you know the gearbox on the 912 is lubricated with the engine oil. In past years when they approved Castrol GPS (they no longer do) owners would go to purchase GPS, and right next to it would be Castrol Magnatec with all the nice little 'balls' on the label. Hell,..that must be better, so they would use it against Rotax recommendations. Well those little balls are Teflon fortification, and it will contaminate the sprague clutch, and cause it to kick out on start-up.

 

I have replaced several sprague clutches due to this one cause. It's a big job requiring removal of all the ign section and the rear plate from the engine case, and yes is quite expensive, especially if you have to remove the engine from the aircraft for access. Read the manuals and SBs and respect Rotaxs recommendations at all times, especially in expect to oil........in response to your question..how does incorrect oil cause damage.......it contaminates the clutch, and causes 'chatter' which damages the contact surfaces causing it not to grip as it should under load...It is my understanding that the newer ign moduals with the "soft-start" feature incorporated, together with the newer more powerfull starter has gone a long way toward eliminating this problem with contamination of sprague clutches..Maj...064_contract.gif.1ea95a0dc120e40d40f07339d6933f90.gif

 

 

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Additionally you may remember (or not) after the Gazelles came out and a lot of them went into GA type schools, with VHS regos. Some were then maintained as VH in GA maintenance organisations by LAMES who knew absolutely zip about UL aircraft or engines.

 

They would service the the 912s against Rotax recommendations with aviation grade aero-oils. Hell.....must be better than motorcycle oil right ..wrong again Jose ! No synthetic fortiforcation as required for the gearbox drive cogs. And they would die a horrible and expensive death shortly after !!................Maj....004_oh_yeah.gif.82b3078adb230b2d9519fd79c5873d7f.gif

 

 

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We have been recommended to change the underpowered Cyclon Pb battery with a very light weight Lithium ion battery (only weighs 600grams) - specs as below. As the recommended Pb acid battery is significantly heavier and larger and is going to be difficult to mount in the engine bay..

 

Does any one have any comments on the use of these types of battery with a 912 Rotax...in RA planes

 

My only worry has been the recent spate of fires with Lithium ion batteries in the dream liner and the recent CASA ruling for removal of Lithium ion batteries from the Cessna 525C's.....

 

Appreciate comments

 

PART NUMBER LTX7L-BS

 

BATTERY TYPE: High Performance Lithium

 

VOLTAGE 12 Volts

 

CCA:(cold cranking amps) 220

 

DIMENSIONS

 

Length 113mm

 

Width 70mm

 

Height 85mm

 

Terminal Height 130mm

 

TERMINAL TYPE

 

J

 

J.jpg

 

TERMINAL ASSEMBLY 32.jpg

 

OTHER FEATURES

 

WET WEIGHT

 

(with acid) 0.6 KG

 

REGULAR CHARGE CURRENT 3.6 Amps

 

USAGE Starting

 

WARRANTY

 

Private use

 

2 Years

 

 

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I do not fear the lithium batteries when used and care for correctly.

 

That battery however does not have the CCA sufficient for a 912. It will turn it over OK for a short period but will discharge very quickly which is where problems will arise. What is its capacity?

 

 

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