Battery advice

I am thinking about using this battery (Turnigy nano-tech 300mah 2S 45~90C Lipo Pack) for Stratologger CF's . It is 2s and by my math I can put 2 in the space of a single 9v. any thoughts ?

robertv2 said:

I am thinking about using this battery (Turnigy nano-tech 300mah 2S 45~90C Lipo Pack) for Stratologger CF's . It is 2s and by my math I can put 2 in the space of a single 9v. any thoughts ?

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Go for it I use the same ones on my RRC3

45C minimum and 300mAh will have you exceeding the output FET limit of the RRC3 by nearly 3X. You'd be far better off with a smaller LiPo like the Turnigy 120mAh 2S battery here: https://www.hobbyking.com/mobile/viewproduct.asp?idproduct=19422 so you won't blow the output circuits on the RRC3.

dixontj93060 said:

45C minimum and 300mAh will have you exceeding the output FET limit of the RRC3 by nearly 3X. You'd be far better off with a smaller LiPo like the Turnigy 120mAh 2S battery here: https://www.hobbyking.com/mobile/viewproduct.asp?idproduct=19422 so you won't blow the output circuits on the RRC3.

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Well aware of the capabilities of the battery, generally I do run with the smaller Turningy Nano-tech 2s 120mah from Hobbyking. However with the ematches I am using a good sneeze sets them off, and I haven't started messing with staging or airstarts (which if I understand correctly is where most of the dead short events come from). Not too concerned about the over-loading the FET at this point. I mainly got them for my Eggfinder TRS, even more frequently than LiPos I use the Engerizer Lithium Advanced which has a PTC built in and limits them to 5A.

Please explain to me folks. Coming from a background of running electric boats and airplanes, the battery and FET's are only going to output as much power as the load (igniter) draws on it. Is this protection in case of a short? If so, how often has this occurred?

If the igniter shorts then the battery will deliver as much current as it can, if this is more than the FETs can handle they will burn out. End result is dead altimeter, although it is often possible to get the FETs replaced.

no need for that. I use the stratologger with a 9v rechargeable, and only recharge once a year. I'm not sure what you're trying to do, but the 9v is a good combination.

the goal is redundant altimeters in a 54mm. I seldom do that in a 3inch airframe and always in 4 inch and larger. Two batteries in a single box meant for a 9v is appealing . is there 2 lower amp 2 cells that will fit ?

I use a 250 mAh 25C 1S Li-Po on both the SL100 and SLCF...no issues.

Keep in mind that a 1S Li-Po is only fully charged @ 4.2 volts, 3.7 is about a 50% charge. If you think 4.2 is too close to the altimeters low rating of 4volts, you would be surprised on how many charges that battery will fire on that altimeter, and how long it will last. I last winter I performed dual e-match bench testing, firing both main and drogue consecutively three times in a row, and the voltage dropped just under 4.2 volts to 4.1 something, can't recall. Then I turned off the altimeter, but the same battery connected for a couple of days, which in my case draws current because I use a magnetic switch. Then turned it back on and performed two more tests per channel. Post testing the battery was still well over 4 volts and would of likely fired a few more times without any issue.

Bottom line is there is no need to go above a 1S Li-Po on that altimeter.

Here is the altimeter with dual altimeters for redundancy and it is also in a a 54mm MD

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Boy!!

Very nice setup. Kurt Savegnago