9-Volt Batteries - Part 1 : The Tear Down - Battery No.1 thru No. 5

[ksaves2]

Easy - I avoid launches with long pad wait times.....
Sure - if it sat on the pad for hours or took a long time to recover, then perhaps a new battery.
Only real load on your typical FC while it waits is all the beeping.

Well yeah but if you want to launch at a major affair, one is stuck with the pad number that sponsoring club uses. Might take awhile to get one's rocket off. In the meantime can see some interesting projects launch.

Plus, I've never lost a rocket that had a nominal flight at one of those launches. Somebody usually finds it.
Shoot, I've found other fliers rockets and if I didn't meet them walking towards me out in the field, I turned the rocket in to the LCO or RSO's table so the flier could get it back.

Ummmmm, the really BIG projects that came down close to me while out in the range, I'd fold up the man-sized parachute as best I could and put the massive nosecone on top of it so the rocket didn't get dragged across the field by the wind and set a surveyor's flag up that I always carried in my pack. The owners always appreciated that when I pointed them towards their project.

Kurt

 

[mh9162013]

Plus, I've never lost a rocket

The Powers-That-Be:

"Hold my beer..."

 

[cls]

If these are needed, they should be on the PCB.

Mmmm, no. Please look up SMT resistors, by size, and watts.

If they are not on the PCB, you have a design that is not compatible with the high-current LiPo's can source.

Most designs can accommodate a variety of power sources.

Use a 9V and don't throw more components to cover up yet another issue with using LiPo's

Thanks for sharing your idea, but it doesn't apply to everyone. This is model rocketry, among 2 people, always 3+ ways of doing something.

 

[ksaves2]

The Powers-That-Be:

"Hold my beer..."

O.K.,

That's a fair comment. I've lost my share of modrocs but the larger projects with Rf trackers in them the recovery rate is 100% for me. That includes a lawn dart with a GPS tracked rocket. Of course the tracker died on impact but the last position 50 to 100 feet in the air brought me to the fin can sticking out of the ground. Was a small I think 2 inch diameter cardboard tubed rocket with the electonics in the nosecone. It disappeared on launch, tracked it, didn't see it or any events and then no more packets coming in when it hit. No one saw it either.

Scrolled through the list of positions and went to the last known position. Wandered around for 5 minutes and found the fincan sticking out of the ground. Dug it out and left the dead electronics/dead tracker in the field. It was too deep to get the N/C out. Sliced off the fincan and used it on another project. I found out it was a battery problem on the deployment device. Tracker had its' own battery hence gave me a last location. The switch on the N/C backplate was off for the deployment device! Long story and it was an early MAD unit with no aural indications.

As far as rules making is concerned, I stay on the side of criticizing them and not making them!
Kurt

 

[prfesser]

Yes, I think often the "heavy duty" batteries are actually a somewhat improved version of the old carbon zinc cells that ruined so many of my toys as a kid.

Hans.

Not just "often," "always". Alkaline cells are significantly more expensive to produce than carbon-zinc (LeClanche) cells. "Super Heavy Duty" cells that don't include "alkaline" on the label...aren't alkaline.

LeClanche cell technology is pretty much 'mature', hasn't changed significantly over the last few decades. It would be interesting to see if today's Super Heavy Duty would outlast the batteries that dad would have used in his flashlight, half a century ago.

 

[prfesser]

Now might be a good place to ask about the construction, chemistry and performance of the old photo flash battereis. Was there ever 9 volt photo flash battery?

According to Wikipedia, the main difference was that photoflash cells had a higher proportion (1:1) of manganese dioxide to carbon in the "filler" material than did regular carbon-zinc cells (3:1 up to 10:1).

Photoflash cells could provide high current for a short time, after which the unwanted ions would (slowly) diffuse away from the cathode and desired ions could migrate toward the cathode. I think that only took a few seconds.

Considering the application of photoflash cells, I doubt that 9V PF cells were made. Their capacity would be awfully low, and the basic idea of a PF cell was "lots of current", meaning "lots of cell material."

 

[tsmith1315]

I remember reading where some "authorities" used to write to change the battery with each flight!

The instructions for the Black Sky AltAcc actually said to use a fresh battery with every launch.

 

[4regt4]

Not just "often," "always". Alkaline cells are significantly more expensive to produce than carbon-zinc (LeClanche) cells. "Super Heavy Duty" cells that don't include "alkaline" on the label...aren't alkaline.

LeClanche cell technology is pretty much 'mature', hasn't changed significantly over the last few decades. It would be interesting to see if today's Super Heavy Duty would outlast the batteries that dad would have used in his flashlight, half a century ago.

Back when I was a kid, and before alkaline batteries became common enough to appear in regular stores, I did see a definite difference in the "heavy duty" batteries. They also seemed less prone to leak. The package for the Eveready cells had a chart showing the difference in expected life for typical applications, such as flashlights. Just higher quality materials and/or construction, I suppose.

But, still, no where close to what a modern alkaline battery will do.

Hans.

Edit: And this is getting way O.T., but the silver colored Eveready batteries seemed more prone to leaking than the yellow/blue Ray-O-Vac. You could see a difference in what was probably a cardboard gasket and/or insulator that was exposed on one end of the cell.

 

[user 30299]

I want to thank everyone for their input, their 2-cents, and their interesting stories. This is good, and this is how we learn.

I would like to hear people's thoughts on the importance of the amp levels. You have batteries in the 5 amp group,
some in the 2 amp group, and some less than 1 amp.

How critical is that amp level, compared to the voltages, for keeping the flight electronics up to snuff to
fire the e-matches?

 

[FredA]

How critical is that amp level, compared to the voltages, for keeping the flight electronics up to snuff to
fire the e-matches?

e-matches are current devices.....they work via IR (Current times resistance) heating.
They are spec'ed on how they fire by current level.
Good ones have a spec for their no-fire current, a typical fire current and an "all fire" current.

Most e-matches have an all-fire spec of 1 Amp.....provide an amp any of the batch should fire.

 

[user 30299]

one thing that nags me... not sure shorting is exactly like a real ematch. I think they are usually 1 or 2 ohms. using a small resistor limits the current a bit, not much, but more like a real ematch.

I know several fliers who are putting such ballast resistors in series with the ematches, because the FETs of certain altimeters can deliver full current from the lithium battery. once bitten, twice fried, I guess.

You're correct, the shorting is not exactly like a real e-match. But this was the only easy & consistent way,
with a multimeter, to see a basic amperage level for each battery - and see it over a period of months.

We know we need some amperage to fire the e-match. What we don't know is what each battery can generate.
A number of the battery specs, by the manufacturer, do not list this. And if they do, it's usually in a series of
performance graphs that are not user/reader friendly.

For me, the testing gave a clear picture of how the batteries differed significantly in their amperage.

The e-match typically uses a nichrome wire as a bridgewire between its two lead wires. The nichrome
wire has a super-high resistivity, many times higher than the copper lead wires. The e-match normally
only needs just under 1 amp to get the nichrome hot enough to ignite the pyrogen.

Here is the typical 5 amp battery.


Here is the typical 2 amp battery.


Here is the typical battery that is barely 1 amp.


So "technically" we can say there are two battery groups that clearly provide sufficient amperage to fire the e-matches.
Those two groups are in the alkaline class of batteries.

The question comes up about the battery's physical construction.

How much influence does it have on the battery's performance under G load?

The pictures can easily influence (or support) our opinions.

Is it the battery's construction that we really need to be concerned about?

That's a test for another time . . . .

 

[FredA]

That's a test for another time . . . .

We need a "microphonics" test.
Hook them up - provide a modest load - watch the voltage across the load with a scope and slam the battery on the table on all sides.
Any observed change in the voltage and you know you have a battery with marginal construction.

PS: Not to derail the thread - do the same with switches - see how "vibration-proof" your favorite switches are.

 

[user 30299]

We need a "microphonics" test.
Hook them up - provide a modest load - watch the voltage across the load with a scope and slam the battery on the table on all sides.
Any observed change in the voltage and you know you have a battery with marginal construction.

PS: Not to derail the thread - do the same with switches - see how "vibration-proof: your favorite switches are.

I think it would be more fun if we did something like this to slam the batteries.




(We just need a run of linear rail and maybe some compressed air. lol )

 

[user 30299]

Here is a basic breakdown (grouping) chart of the batteries, along with preliminary graphs of the volts
and amps between May and December of 2022.

The amperage is from the first 2-second "shorting". The subscript "2" on the "A" means I read the
amps after 2 seconds. There is a similar amperage chart with a subscript of "19" meaning I read the
amps after 19 seconds; 2-second short + 15-second recovery + 2-second short.

Once we put the chart and the graphs together, that's when the Codes jumped out at us along with
the grouping. The grouping is "subjective" but it does help you put things in a simple perspective.

The great thing about the Codes is they're always printed on the battery case and packaging,
and it's an industry-standard code too. This allows you to easily determine the battery's basic
construction of the cells.

 

[cls]

PS: Not to derail the thread - do the same with switches - see how "vibration-proof" your favorite switches are.

yep! gave up on switches a long time ago.

 

[FredA]

yep! gave up on switches a long time ago.

Some do pretty well -- others do not.
Just like 9V batteries, one needs to do some investigation prior to use.

 

[cerving]

...

PS: Not to derail the thread - do the same with switches - see how "vibration-proof" your favorite switches are.

+1 for electronic switches... virtually vibration-proof.

 

[dhbarr]

Clearly the only sane thing to do here is add a 7th cell to get high volts / high amps 10.6V here I come!

 

[user 30299]

Clearly the only sane thing to do here is add a 7th cell to get high volts / high amps 10.6V here I come!

That's a snap. We just need to get some input on the best epoxy for the job.

I'll let you be in charge of that project.

 

[Scott_650]

So for us troglodytes who bitterly cling to our 9V batteries the Rayovac Fusion looks like the best compromise of construction vs. performance. The fact that I can use my monthly coupon at my local Ace Hardware just seals the deal…though I promise not to pay the clerk with a check

Seriously, this has been a great thread - big shout out to QFactor and everyone who contributed! I completely “get” that LiPos are better, lighter, smaller, more powerful but, and for me this matters, not using LiPos elsewhere means I need more (all be it low footprint) “stuff” to properly care for them, one more factor to deal with when I don’t have that much experience with rocketry electronics to begin with - conventional 9V batteries are “set it and forget it” tech for me.

Everything I have to start with dual deployment beyond my JLCR can use a 9V battery and every rocket I’m going to fly that way is plenty big enough and has plenty of lift capability to handle the weight. Grabbing a fresh pack of 9Vs before a launch takes away one more variable I don’t have to deal with. And it’s not like I don’t have plenty of smoke/CO detectors to use them in after a couple of flights. LiPo batteries are a down the road if I pursue more complex electronics thing, for now 9Vs are good enough to do the job I need them to do.

Thanks again Q!

 

[FredA]

+1 for electronic switches... virtually vibration-proof.

They just trade that for many other problems - another HARD PASS.

 

[Rocketjunkie]

I want to thank everyone for their input, their 2-cents, and their interesting stories. This is good, and this is how we learn.

I would like to hear people's thoughts on the importance of the amp levels. You have batteries in the 5 amp group,
some in the 2 amp group, and some less than 1 amp.

How critical is that amp level, compared to the voltages, for keeping the flight electronics up to snuff to
fire the e-matches?

The current capability is critical. Many put 2 ematches in parallel. Only the high current batteries will reliably fire them. It's good to see the Amazon ones are high current, will order some next Amazon order for testing. Again, I got at least 10 flights before the voltage got below 9.2V. The rectangular cell stack got 1 or 2 uses. Energizer Ultimate Lithium has 3 3V cells and will last at least as long as the other high current batteries but they are very expensive.

 

[user 30299]

Back on Post #74 the graphs & chart show three distinct groups. What is interesting is to see how "tight" the numbers
appear to be within a group yet maintained across the manufacturers. With so little data there is no way to look at this
with a statistical analysis (which would take the fun out of this), but there appears to be little to no variations across
the manufacturers.

Think about it. I randomly chose a box of batteries, and randomly chose a battery out of that box. There are no
far-flung numbers, what are called "outliers", that distort the general patterns. So using the battery Code can
provide a basic assurance of that battery's construction and performance.

 

[DAllen]

Soooo...I haven't read the entire thread but has someone come up with a standard for when to switch out 9v's? Switching out the 9v every flight seems ridiculously wasteful. Yes, I do have other things I can use 9v's for like smoke detectors but I mean...come on there has to be a better way to handle this. I'm not a electrical engineer nor did I sleep at a Holiday Inn Express last night but there has to be a simple quantifiable way to determine if a 9v is still good for flight.

 

[mh9162013]

but there has to be a simple quantifiable way to determine if a 9v is still good for flight.

No, not really. The only way to truly know how much capacity (or remaining performance relative to a new battery) is to fully discharge the battery and plot the discharge curve. But then you use up the battery, soo...

I suppose you could do a quick voltage and current draw test, like the OP has done. That might be a possibility that's good enough for our purposes.

I believe you have 2 other options. One, create a schedule for when to change your battery. Maybe it's one flight, maybe it's 20 flights or 1 year, whichever occurs first. Whatever it is, make it conservative with plenty of room for battery production variance.

Two, use a rechargeable 9V battery, whether LSD NiMH or lithium. Then make sure you charge it fully as soon as possible before the launch, so maybe the night before? Also, conduct an occassional discharge test using a CBA and compare it to a discharge curve that you did when the battery was new (depending on the cell, you might need to cycle the battery a few times to break in the battery). Once the discharge curve reaches a certain threshold, retire the rechargeable battery.

 

[Johnly]

PS: Not to derail the thread - do the same with switches - see how "vibration-proof" your favorite switches are.

I've had spring contact switches physically fail during a flight, fortunately the airframe survived.
Screw activated switches where the screw threads through the two contact points have never failed me.
I'm totally sold on the FingerTech Mini power switches for use in my recovery system.

 

[FredA]

Two, use a rechargeable 9V battery, whether LSD NiMH or lithium. Then make sure you charge it fully as soon as possible before the launch, so maybe the night before? Also, conduct an occassional discharge test using a CBA and compare it to a discharge curve that you did when the battery was new (depending on the cell, you might need to cycle the battery a few times to break in the battery). Once the discharge curve reaches a certain threshold, retire the rechargeable battery.

AND:
Don't forget to re-charge to the ultimate storage level for storage after the flight.
Don't forget to check the self-discharge so that it won't die on the shelf over the non-flying season.

All these things not to forget to do - along with "conducting an occasional discharge test" is way too much - just use an fresh, well-built alkaline at the start of the season.
And if you fly the crap out it or leave it beeping for hours, replace the battery.

You don't need to make it harder than it already is.

 

[mh9162013]

AND:
Don't forget to re-charge to the ultimate storage level for storage after the flight.
Don't forget to check the self-discharge so that it won't die on the shelf over the non-flying season.

All these things not to forget to do - along with "conducting an occasional discharge test" is way too much - just use an fresh, well-built alkaline.
You don't need to make it harder than it already is.

I didn't say this was the best option for others. I just said it was an option.

Also, if you get high quality rechargeable LSD NiMH cells, they'll have very little self-discharge when in storage, even when stored fully charged. As for lithium rechargeables, you don't store them fully charged, whether 9V or most other forms.

As for recharging them after each flight, how's that any different than someone having to make sure to replace the alkaline after every flight or after every X flights?

 

[FredA]

Screw activated switches where the screw threads through the two contact points have never failed me.

i HEAR YA - POOR SWITCH SELECTION CAN BE BAD.
However those screw switches violate my personal rule requiring a tool-less and obvious disarm capability.
Another hard pass here - and another thread.

 

[FredA]

As for recharging them after each flight, how's that any different than someone having to make sure to replace the alkaline after every flight or after every X flights?

Charge before.
Charge after.
Check over the off season.
Too many touch points required.

I swap a battery once per season and never think about it again.
That's often the ONLY time I open a rocket's EBAY for the season.

How long does it take you to open the Ebay, swap/charge the battery and re-assemble?
With a rechargeable, you need to do that before and after every flight.....screw that.