StratologgerCF, 2.6" rocket, what battery?

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Bat-mite

Rocketeer in MD
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I just ordered a 2.6" DarkStar from Wildman. I am going to get a StratologgerCF altimeter.

To date, I have always used 9V batteries with my altimeters, but in 3" and 4" rockets.

I am guessing that it may be time to switch to a LiPo, a coin battery, or something else that is small/low profile.

I have browsed lots of threats where folks talk about batteries, but not without any real interest until now.

So, what are your suggestions for this altimeter in a 2.6" coupler?

Thanks.
 
Best option is a 1S Li-Po. Fully charged it will be 4.2 volts the SLCF runs from 4-16 volts. I run mine and my SL100 on a 1S Li-Po and have done lots of ground testing with back to back charges and in the extreme case using dual e-matches for drogue and main my latest test was 3 tests back to back on the same battery and it only dropped down to 4.1 volts and that was probably only because it was just 4.2 when it started.

Some use a 2S however it is not required and will not give you anything more except more weight and potentially a shorter life expectancy on the altimeter. A 9volt alkaline is what was traditionally recommended for this altimeter as well as the SL100 however it will not perform anywhere near as reliably as a 1S, or as long.
 
Thanks. There seem to be a few different 1S Li-Pos in different current amounts. I have found 150 mAh, 160 mAh, 750 mAh.

Looks like they charge via USB? Is there recommended charging hardware? I truly know nothing about batteries.
 
If you don't need to save weight or volume, it's a lot simpler to stick with 9V batteries IMHO.
 
On the 2.6 inch rocket you are probably flying on a non-E motor so you have a few extra ns to support the weight of a 2s 7.4v lipo . I like smallest with a standard JST / BEC connector like this :

https://www.hobbypeople.net/index.php/hobby-people-7-4v-350mah-2s-30c-lipo-battery-bec-plug.html

I used my buddies charger until I got my own (thanks WeFly2).. seems pricey at first but Duracell 9vs are $2 + .

Kenny

2S is not required

1S JST 250mAh 25c is a good choice, here is one with a JST connector https://www.thunderpowerrc.com/Products/250ProlitePlusPower/TP250-1SP25J_2 and the same but with a Molex connector, both very secure options.

You will also need a charger, so getting set up for Li-Po is not the cheapest route as with anything you get what you pay for. There was a thread a while back on looking for an inexpensive charger and someone posted a good option. I use this one https://www.thunderpowerrc.com/Prod...-10-0-AMP-AC-DC-CHARGER-DISCHARGER-W-BALANCER my only complaint is that you cannot discharge to the storage voltage in one go, you have to discharge to a specific range then recharge back to storage rate. I believe there are many good less expensive chargers that will do this.

If you don't need to save weight or volume, it's a lot simpler to stick with 9V batteries IMHO.

9V alkaline has very poor performance due to a much higher internal resistance, compared to Li-Po chemistry for this application. Sure they are cheaper however if you want to have a better more reliable choice then move towards Li-Po.
 
9V alkaline has very poor performance due to a much higher internal resistance, compared to Li-Po chemistry for this application.
For any reasonable ematch, you need 300-800 milliamps for a second or so. I've flown the same 9V battery for ten or more flights and not gone below 9V on the cell. Lipos can produce lots more current than this application needs; so much that for some altimeters you run the risk of blowing up the switching MOSFETs.

A 1S lipo very quickly dips below 4V (they spend most of their time at about 3.8V) so you are hoping that the regulator in the SL has enough margin to operate over temperature and load. Which it probably does, but...
 
I've been using a 1S 400mah lipo for a while without issues until this weekend when the main deployment charge shorted and (I believe) the circuitry on the battery shut it down to avoid over discharging.
Good for the battery, good for not frying the altimeter, not so good for the continued operation of the altimeter in that flight. Fortunately it happened after the main deployed so the landing was good.

mikec - FYI that 1S battery easily does a flight to 6K ft. and two ematch ignitions without dropping below 4.1v under normal circumstances.

Speaking to Perfectflite support about it - they recommend a 2S, 150mah Lipo without the PCB protection. The higher voltage gives you more brown out protection and in a short event the low mah means it won't fry the altimeter while no protection PCB means the battery won't shut off and the altimeter can stay on.
 
For any reasonable ematch, you need 300-800 milliamps for a second or so. I've flown the same 9V battery for ten or more flights and not gone below 9V on the cell. Lipos can produce lots more current than this application needs; so much that for some altimeters you run the risk of blowing up the switching MOSFETs.

A 1S lipo very quickly dips below 4V (they spend most of their time at about 3.8V) so you are hoping that the regulator in the SL has enough margin to operate over temperature and load. Which it probably does, but...

My opinion is based on my experience with using them specifically with the S100 and SLCF, as well as using a 9volt with a failure. The failure was due to the alkaline's, relative, inability to recovery quickly if you happen to fire back to back. If you have a SL100 or SLCF with some flights, check the logs and post the result showing the impact the charge has on the voltage. In most cases it will drop immediately after the charge, whereas with a Li-Po remains the same.

I also fly redundant e-matches, so 2 e-matches per channel and I have yet to get a flight back with less than 4.1 volts remaining on my SL100 or SLCF. 3.7-3.8 is actually about a 50% charge for a 1s Li-Po so if that is what you are getting then I would say that the battery was not fully charged to start with. My testing and flights have been extreme when it comes to Li-Pos. I have literally connected a fully charge, 4.2 volts, 1S Li-Po to an SL100 with a featherweight mag switch, turned it on to run the diagnostics, turned it off and left if for a couple days to see the draw or net effect of the mag switch, then proceeded to run 2 back to back both main and drogue tests with dual e-matches and the voltage never went below 4 volts.

I agree that a Li-Po can damage the MOSFETs that is why it is important to not over specify the size, hence my recommendation for a 1s over a 2s. This is not an opinion but factual, below is a cut and paste, (modified for this thread) from another forum member who responded to my thread on this subject back in May 2014.

"Current fires a pyro and current destroys FETs. Since ohm law always applies, the more voltage you shove through the pyro circuit, the more current it will draw. Using one cell instead of 2 means 2 times less voltage and therefore 2 times less current draw. If your e-matches work with 1 cell battery than you should go that route. If it doesn't then try a 2S battery which is also what a lot of the "9 volt transistor battery style" LiPos are."
 
Continuous discharge rate as a multiple of capacity. E.g. a 1000mah & 20C = 20amps. Charge rate is the charge rate as a multiple of capacity.
 
Also, I don't want to go huge money on this. I can probably fit a 9V alkaline in there. The LiPo charger is not looking worth it, to me.

Has anyone ever tried button batteries? Would something like this with two 2032 batteries work?

https://www.adafruit.com/products/783
 
I have not played with LiPos, but have heard that cold temps can lower their voltage. So if you fly in 40s to 50s, a 2s might be better.
 
I stuffed a 9v and a marsa 54 in a 2.6 coupler. It's tight, but it'll fit.
 
I fit a SL CF & 9 volt alkaline in my 38mm Blackhawk with no problem so with a 2.6" tube you will be fine.
 
Tim and Dave,

Did you guys use a battery holder, or did you just cable-tie the battery to the sled?
 
I just used black electrical tape. You could probably use tie-wraps since you havea bit more room.

IMG_2095.JPG
 
You guys had me confused talking about 2.6" airframes. I built two minimum diameter Blackhawk 54's with redundant altimeters and dual 9v batteries into both of them. This is a 6" coupler avbay sled:
001.jpg


I build my own battery boxes:
002.jpg


I was talking to Wildman on the phone and mentioned that I didn't think it was possible to put redundant altimeters into a 54mm rocket. He said "Sure you can", and that was all I needed. I have a bunch of dual deploy rockets, and most are redundant systems. Use a little imagination.
 
Also, I don't want to go huge money on this. I can probably fit a 9V alkaline in there. The LiPo charger is not looking worth it, to me.

Has anyone ever tried button batteries? Would something like this with two 2032 batteries work?

https://www.adafruit.com/products/783

I've used a $12 dollar lipo charger that plugs straight into a wall outlet with zero issues: https://www.hobbyking.com/hobbyking...act_2S_3S_Lipo_Charger_100_240v_US_Plug_.html
The more expensive chargers have some nice features but for simply recharging your batteries, something like that will do the trick.
 
I'm guessing it works like this one.

100_8992.jpg 100_8993.jpg


Another for a 54mm minimum. Old one where I had to put ALOT of stuff on.
You cut the sled to fit inside coupler perfectly so it cannot move up/down or end to end.
Why the cut outs are there...for eyebolt clearance.

100_9004.jpg 100_9006.jpg

You use smallest tie rods you can, here # 6
Slide the sled between them, not on them, no room robbing tubes, glued on the sled.

Think outside the box.

For really small bays [38mm] you can cut sled to fit near bottom, allowing mounting of everything on top of sled & it will still fit BETWEEN rods.Once in place it cannot move.

100_3945.jpg 100_3952.jpg

If you only need one alt......do it like timbucktoo.
 
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Wayco, how does that attach to your Av bay/bulkheads?

CJ has it right, cut your sled so that when you tighten down the lids it is sandwiched tight. My allthread fits through the gaps a little different than Jim's, but the result is the same. If you get the length just right, the sled can't go anywhere. I use small terminal blocks mounted to the avbay bulkheads, with wires soldered on through them. Mounted using hot glue. This is on a larger rocket, but you get the idea:
042-1.jpg
 
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Tim and Dave,

Did you guys use a battery holder, or did you just cable-tie the battery to the sled?

Ive got mine in an unmounted holder, zip tied to the back of the sled. In mine it doesn't fit between the all thread, so it sits cocked up over one. Would be plenty of space for another back there too.
 
I have been using 180mAh 2 cell batteries from hobby king with good results. https://www.hobbyking.com/hobbyking/store/__23135__Turnigy_nano_tech_180mah_2S_25_40C_Lipo_Pack.html and for charging I use the iMAX B6 mini, which you can get from Amazon for around $35. this charger will cycle, discharge, discharge for storage, almost every type of battery. https://www.amazon.com/Original-Aircraft-Balance-Charger-Lithium/dp/B00QQ0S5NC/ref=sr_1_1?ie=UTF8&qid=1438735805&sr=8-1&keywords=imax+b6+minihere are two altimeters in a 54mm av-bay
wrS0SiR_wav2Lc0n03gkmD3Y-XLwGvY19-TGu0dvDpY=w890-h667-no

W9XxKkzSrudXHzmbNB0396Me8suM_OVLzrG5cdxBia4=w890-h667-no
 
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