Battery Recommendations

I have one of these: https://perfectflite.com/ut2a.html which I am using to ignite a 13mm BP motor using a Quest Q2G2 igniter.

Thus far I have only been able to achieve this using a typical 9v “Transistor” battery, i.e. “The Copper Top”.
I’ve tried a couple of different types/brands of 9v photocell/camera batteries but apparently they can’t supply the necessary current to get the job done.

Does anybody know of a type/brand of battery that is smaller/lighter than the Typ. 9v Tran. battery that could supply the same current output?

If so; I’d appreciate a source for same.

The 9v will fit in the space available but the weight is excessive.

What you describe is a nearly perfect application for a small Li-Po battery. There's a bazillion different versions available. It will be far smaller and far lighter than a regular 9 volt battery, and will be able to deliver several amps of current to light your Q2G2. Good luck.

These will work 1 (or maybe 2) in a PerfectFlite MAWD. Perhaps it will work in this as well.

https://www.amazon.com/dp/B007TLGE0I/?tag=skimlinks_replacement-20

Greg

Hobbyking.com has all you need. A single cell LiPo will run a StratoLogger CF and will fire a Quest Q2G2 igniter.

Any 200-300 mah 20 C LiPo is fine.

Bob

https://www.hobbyking.com/hobbyking...300mah_2S_45_90C_Lipo_Pack_US_Warehouse_.html

I know nothing about these LiPo batteries but this seems to fit the bill as per Bob; though It states 7.4v which is midrange operating voltage for my timer. I’d prefer something closer to the 9v but I’m having zero luck wading through the 10x27^63 varieties listed here.


So will this work?

And why does a battery have four lead wires?

And what does 45c discharge mean?

And what kind/type of charger will I need?

And who invented liquid soap and why?

boomtube-mk2 said:

https://www.hobbyking.com/hobbyking...300mah_2S_45_90C_Lipo_Pack_US_Warehouse_.html

I know nothing about these LiPo batteries but this seems to fit the bill as per Bob; though It states 7.4v which is midrange operating voltage for my timer. I’d prefer something closer to the 9v but I’m having zero luck wading through the 10x27^63 varieties listed here.


So will this work?

And why does a battery have four lead wires?

And what does 45c discharge mean?

And what kind/type of charger will I need?

And who invented liquid soap and why?

Click to expand...

LiPo Primer.

Nomenclature:

3.7 volts nominal (4.2 volts fully charged) = 1 cell = 1S

7.2 volts nominal (8.4 volts full charges = 2 cells in series = 2S (Replaces 9 volt battery)

10.8 volts nominal (12.6 volts full charges = 3 cells in series = 3S (Replaces 12 volt battery)

Power and charging cables.

There a 2 wire bundles on most LiPo battery packs.

1.) The heavy red and black wires supply the battery power.

2.) The other bundle is the power balancing charger cable. It is designed to be used with a LiPo charger and insures that all the cells are fully charged independently and prevent over or under charging.

3.) You need a LiPo charger. I recommend purchasing a charger that works on 1S to 4 S packs (minimum) and can work from you 120 volt wall plug at home and a 12 volts power port in your car. Costs are the same.

Battery Ratings:

LiPos are rated for current delivery as well as voltage.

A 2S Lipo is listed as 7.2 volts nominal and has a milliamp- or amp-hour rating. A 300 mah battery is rated to deliver 300 ma for 1 hour. That is the 1 C rating.

If a 300 mah battery is rated at 10 C it can continuously deliver 3000 ma or 3 A until the battery is discharged. The time it will to this is the 1 / the C rating of the battery, in this case, 1 / 10 = 0.1 hour = 6 minutes. If the rating was 45 C, the battery could deliver 45 C = 13.5 amps for 1/C = 1/45 hours = 0.0222 hours = 1.33 minutes. Most batteries have a maximum charge rating in C as well. If this battery is rated for a 2 C charge. You can charge the battery a 2 x .3 = 600 ma = 0.6 amps and the charge time for a fully discharge battery would be 1/C = 1/2 = 0.5 hour = 2 minutes. Some batteries also have a burst rating. This is the current that the battery can output for 5 seconds without reducing the capacity. Most of the time the burst current is twice the steady state current rating.

Lastly, neither of the current rating describe the short circuit current. LiPo batteries have very low internal resistance so even a 300 mah battery might put out over 100 amps on a short so you have to be careful not to short the battery.

Don't care who invented liquid soap. It's mostly water so it's more expensive than bar or powdered soap........

Bob

FWIW - a single 3.7V 70 mAh Lipo can fire Q2G2's. Tested it a number of times. Including the use of a tiny Arduino timer that ran off 3.3 V.

This timer you are using has a voltage range of 4.8 to 10.5 volts. So, use a two cell (2S) Lipo batter,y which will produce 7.4 to 8.4 volts. A 2S 50 mAh pack would probably be fine, and anything over a 2S 100 mAh would be overkill (a 2S 100 mAh pack weighs about 8 grams, or 25% of a 9V battery. I'll need to weigh one in awhile when I can get to the workshop).

But you will probably have a hard time finding a 2S pack as small as that from Hobby King, you need to check with the specialist micro R/C places, I can look one or two up if you have not bought anything yet and are interested.

Now, Hobby King does sell individual Lipos that small, but you would need to solder them up yourself or have a friend who is half decent at soldering do it (On a scale of 1-10 it's about a 2 to do it, the solder tabs are a bit finicky and if you short anything you may damage the battery).

Oh, you will need a special charger for Lipos. And if the Lipo voltage goes below 3 volts per cell, it damages the battery. If you let the battery go dead, then you have truly killed it, dead-dead, it's permanently damaged. That is one of the few drawbacks, it's not like letting a Nicad or NiMH go dead and recharge.

But they are the best thing going for battery tech these days, at least for models. In my R/C flying i've gone from Nicads to NiMH's, and now LiPo's. And a lot of my non-R/C models related electronics use LiPolys now. Even the ones that need say 4.8 to 5V, I use a 2S 7.4V Lipo pack and wire in a 7805 voltage regulator to provide a steady 5 volts (Also have to do that with some R/C models whose servos will fry on 7.4V).

Thanks everybody for the info. Now that I know my @$$ from my elbow with regards to these batteries I now realize that there is a new shop in my town devoted exclusively to radio control planes, helicopters etc so I might actually be able to purchase this stuff locally.

Single 100 mAh LiPoly cells at Hobby King:
https://www.hobbyking.com/hobbyking/store/__7567__ZIPPY_100mAh_20C_single_cell_.html

We use these for a lot of R/C Rocket Boosted Glider models. Usually wired up as 2S (series) 7.4V packs, with a JST Connector.

Also, BTW, link for 70 mah cells:
https://www.hobbyking.com/hobbyking/store/__7566__ZIPPY_70mAh_20C_Single_Cell.html

And for 50 mAh Cells:
https://www.hobbyking.com/hobbyking/store/__7565__ZIPPY_50mAh_20C_single_cell.html

The 50 mAh cells are 1.8 grams each, the 100 mah cells are 3 grams each. Wiring and connector adds more.

I do not use an additional connector for balancing the cells for charging. The mass is not worth it for the kind of models we fly.

If I was doing a contest model with that timer, I'd use a 2 cell (2S) 50 mAh pack. For a model that would not be quite as critical for the mass, I'd go with 100 mAh.

BTW - Hobby King's website will cause a one-time discount offer to pop up after you have been looking at an item for a minute or two. So do not click to order quickly, wait for that one time offer. For example the 50 mAh sells for $2.38, an offer for $2.09 just popped up.

In the photo below, one of my 100 mAh 2S (7.4V) packs on the scale. Upper left, a "Zippy" 180 mAh pack from Hobby King, and below it a 200 mAh pack by Electrifly. Both are really old, I do not think they sell them anymore. But you could find someplace that sells pre-made packs this small or smaller if having individual cells soldered up into packs is not for you.

Homemade 100 mAh pack is 6.70 grams
Zippy 180 pack is 13.17 grams
Electrifly 200 pack is 13.72 grams (had an extra connector, plus the balancing connector)
The 9V batt is 34.07 grams.

- George Gassaway

George

So I purchase a few of the 70mAh cells and wire them in series to get 7.4v.

Now I have to add some form of connector; and what kind of charger do I need to get?
My local shop only has chargers for the big battery packs, way to expensive and would probably cause something as small as I need to explode.

Just so you know, in the specs for your microTimer2 it has this comment for power:

operating voltage:4.8V to 10.5 V (3.0V to 4.8V at half current rating)

I'm no expert, but this seems to imply it would work with a single Li-Po cell. No need for two in series. (As long as the current draw is low... which for Q2G2s it would be)

Food for thought?

It is frustrating that there s not an easy choice for inexpensive chargers for small Lipos, beyond 1 cell types.

For 2 cell (actually 1 cell to 6 cells), I did find this on eBay. $18.43, free shipping

https://www.ebay.com/itm/IMAX-B6-2S...100?pt=LH_DefaultDomain_0&hash=item2ed9027f1c

Imax B6 Charger

Manual:

https://www.ittgroup.ee/files/IMAX_B6_manual.pdf

There are lots of listings of that one form severla sellers. Thing is that the listing above is from China, as all the low priced eBay listings for it seem to be. So you'd have to wait 2-3 weeks (possibly more) for it to arrive.



But it sure is a NICE charger. I have used a charger sort of like like that, but now use one that charges 4 battery packs at a time (same kind of display and options, four times).

I did check the manual to confirm it can be set as low as 0.1 amps (100 mA), as I have done with similar chargers.

If you look for some other charger that can do 2 Cells (2S), 7.4V, then look for a charger that can charge as low as 100 mA, or 0.1 Amp. If you charge it at a lot higher rate than that, it will damage the battery. And always make sure it can do LiPo's.

As cvanc pointed out, your timer might actually work with a single 3.7V Lipo, and I did successfully test fire Q2G2's with a single 3.7V cell. Check with the manufacturer to confirm that it will work on 3.7V to fire a low-current Q2G2. If so, you could get a really cheap AA powered charger like the one below, open it up and rewire the connector socket to fit whatever you use for your battery connector. A local hobby shop has these things for sale, used, for no more than $5, maybe $2. But most hobby shops won;t tend to have used ones cheap like that. There are some cheap 3.7V chargers on eBay, that can be adjusted or set for low current.

- George Gassaway

If you already have the space and connectors for a 9V, you can use the '9V' li-po batteries. The type I use are nominal 8.4V. They weigh a lot less than an alkaline or NiMH, have a range of capacities (and weight) and chargers are not expensive or complicated. Just another option.

The Imax B6 is a great charger for Lipo's.

I picked up my B6 from Hobbyking.com

I paid $28 for my B6 - it's the genuine one - not a "clone" and was shipped from the USA warehouse.

[YOUTUBE]kziSFSQvxr4#t=18[/YOUTUBE]

Well fellow forum members, after careful consideration it now becomes apparent that I will be using a standard everyday 9v alkaline battery for this application.

Whichever way I look at it I would likely spend upwards of $30-$50 for an appropriate LiPo battery and its attendant charger.

I just can’t justify that kind of outlay for a power source in a rocket whose total price is only $25 including the staging timer.

So I’ll use the “Coppertop” and launch the rocket using Aerotech D13 motors which should have enough Oomph!!* to get the rocket airborne.

Perhaps if I build additional small two stagers that require a staging timer the cost incurred from buying a LiPo and charger would be acceptable.

Thanks for the info and help with this topic.


*Oomph!!: Highly technical rocketry term whose meaning is best left up to the experts.

I have this charger as well (the real one).
I also picked up an all-in-one plug connector so, you can connect to any type of plug without needing an adapter.

JD

scsager said:

The Imax B6 is a great charger for Lipo's.

I picked up my B6 from Hobbyking.com

I paid $28 for my B6 - it's the genuine one - not a "clone" and was shipped from the USA warehouse.

[YOUTUBE]kziSFSQvxr4#t=18[/YOUTUBE]

Click to expand...

You could still use a 9V li-po and save some weight. They cost a dollar or two more than a coppertop, but might be worth the performance gain.

Well, at least you know more about batteries like Lipos, current that different battery type can deliver, 1S 2S 3S, and other terms.

And others who read this thread may have learned something.

A charger like that iMax B6, it sure is sweet. A bit overkill for your current needs (ah, double meaning), but at some point down the road you may have some other need for a charger like that. Not just you, others reading this thread.

Anyway, be safe in your wiring set-up and procedures for prep and final arming before launch. Too many cases of people having a second stage, ejection charge, or other pyro device go off accidentally during prep or on the pad.

Would be nice to add a "final arm" switch between the + output lead and the ignitor, and not arm that switch till the rocket is moments away from countdown and launch.

Actually, the final arm switch is more than nice. That ought to be in the Safety Codes, it's that important for real safety when any electronic pyro system is involved.

Also, I like to have an LED externally visible (BRIGHT clear LED that is visible in bright sunlight) or better yet (if room and mass allow) a Peizo beeper wired permanently in parallel with the output so that when it "fires", you can see the LED and/or hear the beeper. For one, very useful for testing. More important, if you see or hear it firing before you do the final arm then you will know something is seriously and dangerously wrong, and not arm it, power it down and investigate. I do that with all of my models that have electronic firing of pyrotechnics, for test to verify the system is operating and danger warning.

For example on an R/C operated system, I do not have the pyro armed, I activate the system by R/C and listen to hear the Beeper sound to confirm it would have fired the ignitor or ejection. If successful, then I do the final pyro arm and fly ASAP.

And bench-test over and over, with an LED or little incandescent 9-12V light bulb plugged in place of the Q2G2 for a lot of the testing. But also do some real Q2G2 test firings to make sure.

Practice your real prep process for a real flight, maybe use a burned out engine casing in the upper stage so you can even realistically practice and test that the timer fires the Q2G2 when the rocket is 100% prepped like a real flight (just be SURE it is a burned out casing!)

- George Gassaway