General Battery Question - Voltage vs Available Capacity?

shop deals on amazon
Advertise with us
rocket sok
Shop deals on ebay
The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
GregGleason

GregGleason

Well-Known Member
Joined
Nov 13, 2009
Messages
4,674
Reaction score
45
I have a general question on determining the health of a battery, namely batteries used for flight electronics.

For example, I plan to fly my MAWD with a tiny 9V battery. Obviously, the available capacity of those batteries are a lot less than the standard 9V, so the margins are smaller. So other than testing the voltage with a DMM (which I have), is there another test that should be done to check the overall health of a battery?

I plan to fly these batteries once. I am just wondering if there is a way to check it to see if it is up to the task before placing it in the rocket.

Greg
 
It really depends on the battery chemistry. Some have a clear relationship between open circuit voltage and state of charge, some don't.

Also, as batteries get smaller their internal resistance tends to go up, which means the current they can deliver into a given load tends to go down. This is probably more critical in your application.
 
Suggestions will be dependent on the type of battery, can you be more specific? Exactly what battery are you using? Make, model, etc...
 
GregGleason said:
This:

https://www.amazon.com/Vinnic-Alkaline-Battery-GP-10A-L1022/dp/B007TLGE0I


View attachment 245707

Greg
Click to expand...

Greg,

Are you planning on firing deployment charges with this battery? If so, I strongly suggest you use something different. This kind of battery is not intended to deliver high current pulses. One of your spec sheets lists 15ma (15 thousandths of an amp) as the maximum current pulse this battery can deliver. That is nowhere near enough to fire any e-match on the market.
 
Last edited by a moderator:
cvanc said:
Greg,

Are you planning on firing deployment charges with this battery? If so, I strongly suggest you use something different. This kind of battery is not intended to deliver high current pulses. One of your spec sheets lists 15ma (15 thousandths of an amp) as the maximum current pulse this battery can deliver. That is nowhere near enough to fire any e-match on the market.
Click to expand...

The MAWD has a nice big capacitor to deliver to the output events and thus can use this battery. No problems. Been using them for years.

To test, I just put a voltmeter on the battery and if it reads 8+ volts, it should work. You can probably get 2 or 3 flights from one battery, but I use them just once and throw away. They are dirt cheap - around $1.00 ea when purchased in bulk.
 
Buckeye said:
The MAWD has a nice big capacitor to deliver to the output events and thus can use this battery. No problems. Been using them for years.

To test, I just put a voltmeter on the battery and if it reads 8+ volts, it should work. You can probably get 2 or 3 flights from one battery, but I use them just once and throw away. They are dirt cheap - around $1.00 ea when purchased in bulk.
Click to expand...

Ah. Fair enough. Didn't know about the cap. Carry on! :grin:
 
I would be tempted to run a full up test including time on the pad. So think about having the altimeter and charges a wired up, turn it all on, and let it sit or a half hour like you were at a busy launch then make sure it will fire the charges. This way you know that with a fresh battery you can be good for a while.


Mark Koelsch
Sent from my iPhone using Rocketry Forum
 
markkoelsch said:
I would be tempted to run a full up test including time on the pad. So think about having the altimeter and charges a wired up, turn it all on, and let it sit or a half hour like you were at a busy launch then make sure it will fire the charges. This way you know that with a fresh battery you can be good for a while.
Click to expand...

Better yet, do the same test two or three times (with the same battery - including the 1/2 hour 'wait time' (each test)) or until it *won't* fire the charges - so you'll have an idea of just what your margins are.

-- john.
 
GregGleason said:
This:

https://www.amazon.com/Vinnic-Alkaline-Battery-GP-10A-L1022/dp/B007TLGE0I


View attachment 245707

Greg
Click to expand...
You want to read the fine print in both datasheet. One of the batteries lists a 38 mah capacity and the other lists a 62 mah capacity so there appear to be some differences in the internal construction of the (6) button batteries inside the GP10A/L-1022.

Both claim these capacities are obtained by draining the battery to 4.5 volts through a 15KOhm resistor so you want to measure the voltage across the battery draining thru a 15 Kohm resistor. If the voltage is 8.0 volts or higher, the battery is ok for use in the MAWD, if not, use it in a non-critical use like a garage door opener.

The GP10A/L-1022 or similar type of battery works in a MAWD because the MAWD has a large brownout capacitor and employs a capacitive discharge pyro circuit. Do not use them in a conventional dual deployment altimeter that uses the altimeter battery to power the pyro circuits because these small batteries can not supply enough current to fire an e-match and your rocket will crash. I am unaware of any other currently manufactured dual deployment altimeters that employ a capacitive discharge pyrocircuit, so these batteries can only be used in a MAWD, however they will work fine in many non-deployment altimeters that draw less than a couple milliamps current.

Bob
 
Last edited by a moderator:
bobkrech said:
You want to read the fine print in both datasheet. One of the batteries lists a 38 mah capacity and the other lists a 62 mah capacity so there appear to be some differences in the internal construction of the (6) button batteries inside the GP10A/L-1022.

Both claim these capacities are obtained by draining the battery to 4.5 volts through a 15KOhm resistor so you want to measure the voltage across the battery draining thru a 15 Kohm resistor. If the voltage is 8.0 volts or higher, the battery is ok for use in the MAWD, if not, use it in a non-critical use like a garage door opener.

The GP10A/L-1022 or similar type of battery works in a MAWD because the MAWD has a large brownout capacitor and employs a capacitive discharge pyro circuit. Do not use them in a conventional dual deployment altimeter that uses the altimeter battery to power the pyro circuits because these small batteries can not supply enough current to fire an e-match and your rocket will crash. I am unaware of any other currently manufactured dual deployment altimeters that employ a capacitive discharge pyrocircuit, so these batteries can only be used in a MAWD, however they will work fine in many non-deployment altimeters that draw less than a couple milliamps current.

Bob
Click to expand...

Thanks Bob. I understand that this battery/altimeter combo will only work in the MAWD.

I guess the LiPo batteries put out enough juice now that the big caps are seen as superfluous from an altimeter design standpoint.

BTW, I made a document that I can reference based upon your comments in another thread (link) regarding DM testing of an alkaline 9V battery.

Greg

View attachment Using a DM to Test a 9V Alkaline Battery.pdf
 
GregGleason said:
I guess the LiPo batteries put out enough juice now that the big caps are seen as superfluous from an altimeter design standpoint.
Click to expand...

You have it exactly right, Greg.

The older style batteries have high internal resistance, which prevents them from delivering lots of amps. The capacitor is used in parallel to buffer the battery and make the overall circuit see a voltage source with much lower internal resistance. With a more modern battery type, and LiPo is a good example, the battery itself has a very low internal resistance so it can really push out amps when asked and has no need for the capacitor. Make sense?

Best,
 
Also you really have to pay attention to the launch temperature when you use alkaline button cell battery stacks. For example see https://www.rocketryforum.com/showthread.php?48342-What-s-in-Your-Battery&p=470186#post470186 There are 2, 4, 6 and 8 button cell variants of this battery family supplying 3, 6, 9 and 12 volts.

On Saturday at our CMASS launch the temperature was in the low 40's, and NONE of the altimeters using this type of battery worked. NONE. (and we are talking of a half dozen different altimeters from several manufacturers and more than a dozen flights.)

Note: that all altimeters worked properly in the owners home prior to the launch.

For cooler temperatures, use batteries with silver oxide cells, or better small LiPo batteries.

Bob
 
Last edited:
bobkrech said:
Also you really have to pay attention to the launch temperature when you use alkaline button cell battery stacks. For example see https://www.rocketryforum.com/showthread.php?48342-What-s-in-Your-Battery&p=470186#post470186 There are 2, 4, 6 and 8 button cell variants of this battery family supplying 3, 6, 9 and 12 volts.

On Saturday at our CMASS launch the temperature was in the low 40's, and NONE of the altimeters using this type of battery worked. NONE. (and we are talking of a half dozen different altimeters from several manufacturers and more than a dozen flights.)

Note: that all altimeters worked properly in the owners home prior to the launch.

For cooler temperatures, use batteries with silver oxide cells, or better small LiPo batteries.

Bob
Click to expand...

Wow. Thanks for that data point Bob. I did not realize that temperatures in the low 40's would put these batteries in the "no fly" zone. Also, good tip about silver oxides and LiPos.

Could you recommend a 1S or 2S LiPo for the MAWD that is small, or at least the parameters to look for in one of these batteries that would be a good fit for the MAWD?

Greg
 
GregGleason said:
Wow. Thanks for that data point Bob. I did not realize that temperatures in the low 40's would put these batteries in the "no fly" zone. Also, good tip about silver oxides and LiPos.

Could you recommend a 1S or 2S LiPo for the MAWD that is small, or at least the parameters to look for in one of these batteries that would be a good fit for the MAWD?

Greg
Click to expand...
I didn't either, however I talked to enough folks at the launch who were having trouble that it became abundantly clear what the problem was, and they were all experienced folks so I knew it wasn't user error.

The recommended 6 button cell batteries are 9 volt/-40-60 mah batteries. I would recommend using a 3S LiPo in the 60 mah or slightly higher to minimize the weight and to mot get the 8.4 V low voltage signal from the altimeter. 3 of these batteries in series would work and not trip the 8.4 Volt low battery signal, although 2 in series would appear to meet the electronics voltage specs.

https://www.hobbyking.com/hobbyking...60mAh_1S_45_90C_Lipo_Pack_for_Mini_Vapor.html each weigh 1.7 grams and the total weight would be about 6 grams for 3 or 4 grams for 2. Even though the batteries are physically small, they still will source 5 amps, so they will recharge the MAWD cap very fast.

Bob
 
bobkrech said:
Also you really have to pay attention to the launch temperature when you use alkaline button cell battery stacks. For example see https://www.rocketryforum.com/showthread.php?48342-What-s-in-Your-Battery&p=470186#post470186 There are 2, 4, 6 and 8 button cell variants of this battery family supplying 3, 6, 9 and 12 volts.

On Saturday at our CMASS launch the temperature was in the low 40's, and NONE of the altimeters using this type of battery worked. NONE. (and we are talking of a half dozen different altimeters from several manufacturers and more than a dozen flights.)

Note: that all altimeters worked properly in the owners home prior to the launch.

For cooler temperatures, use batteries with silver oxide cells, or better small LiPo batteries.

Bob
Click to expand...

What battery and altimeter were these CMASS guys using?

I can tell you with certainty that the MAWD with A10 battery works just fine in cold temperatures. I had several successful flights in sub-freezing temps over the years, including yesterday's dual deploy flight in the chilly Midwest.

I even tested an extreme condition earlier this week. I powered on the MAWD plus A10 on my back porch and let it beep for 40 minutes in 35 deg F temps. I then simulated flight by pulling a vacuum, and it successfully fired two ematches. Note: Use proper ematches for absolute certainty in this kind of test. LEDs did not fire.

So, Greg, I think you are fine with your current battery setup. Run a bunch of ground tests with your inexpensive A10s, and you will be convinced.
 
Buckeye said:
What battery and altimeter were these CMASS guys using?

I can tell you with certainty that the MAWD with A10 battery works just fine in cold temperatures. I had several successful flights in sub-freezing temps over the years, including yesterday's dual deploy flight in the chilly Midwest.

I even tested an extreme condition earlier this week. I powered on the MAWD plus A10 on my back porch and let it beep for 40 minutes in 35 deg F temps. I then simulated flight by pulling a vacuum, and it successfully fired two ematches. Note: Use proper ematches for absolute certainty in this kind of test. LEDs did not fire.

So, Greg, I think you are fine with your current battery setup. Run a bunch of ground tests with your inexpensive A10s, and you will be convinced.
Click to expand...
The CMASS problems were with altimeters using A23 (LR1028) 12volt and A10 (LR1022) 9 volt alkaline button cell stacks from Vinnic. All I can state is that the owners said they tested the altimeters at home before they came to the field and they worked, and they failed to work at the field with these batteries.

I agree the MAWD should be fine using AG10 Silver Oxide cells as recommended in the MAWD Users Manual.

Bob
 
Buckeye said:
What battery and altimeter were these CMASS guys using?

I can tell you with certainty that the MAWD with A10 battery works just fine in cold temperatures. I had several successful flights in sub-freezing temps over the years, including yesterday's dual deploy flight in the chilly Midwest.

I even tested an extreme condition earlier this week. I powered on the MAWD plus A10 on my back porch and let it beep for 40 minutes in 35 deg F temps. I then simulated flight by pulling a vacuum, and it successfully fired two ematches. Note: Use proper ematches for absolute certainty in this kind of test. LEDs did not fire.

So, Greg, I think you are fine with your current battery setup. Run a bunch of ground tests with your inexpensive A10s, and you will be convinced.
Click to expand...

Thanks for that data point Buckeye. I did bring up the CMASS flght results that Bob mentioned to PerfectFlite's attention and he (i.e., PerfectFlite) thought there might have been something else going on other than a battery problem.

When you say "proper ematches", how do you define/test to detect if they are "proper" (BTW I'm not trying to be funny)? PerfectFlite said that the match is important also, furthermore PerfectFlite gave parameters on how to test matches of an unknown quality (destructively) to see if they were flight worthy for the altimeter.

Greg
 
GregGleason said:
Thanks for that data point Buckeye. I did bring up the CMASS flght results that Bob mentioned to PerfectFlite's attention and he (i.e., PerfectFlite) thought there might have been something else going on other than a battery problem.

When you say "proper ematches", how do you define/test to detect if they are "proper" (BTW I'm not trying to be funny)? PerfectFlite said that the match is important also, furthermore PerfectFlite gave parameters on how to test matches of an unknown quality (destructively) to see if they were flight worthy for the altimeter.

Greg
Click to expand...

Agreed. Whatever was going wrong at CMASS, it was not the Vinnic A10 in the MAWD.

One thing to make sure of if using the metal clips to hold the battery (see my pic above): wrap the battery in cellophane tape to insulate it and protect from shorting.

What I meant to say is test the altimeter with the ematches you plan to use. I have some litttle lamps (LEDs? I don't know) I bought from Radio Shack a long time ago to check outputs from the altimeter. The MAWD will usually fire these lamps at room temp (dimmly), but did not fire them during the cold test. The actual ematches fired just fine.

I have success with many types of starters with the MAWD/A10: Q2G2, Newton's 3rd cannisters, MTEK, JTEK, etc.
 
GregGleason said:
Thanks for that data point Buckeye. I did bring up the CMASS flght results that Bob mentioned to PerfectFlite's attention and he (i.e., PerfectFlite) thought there might have been something else going on other than a battery problem.

When you say "proper ematches", how do you define/test to detect if they are "proper" (BTW I'm not trying to be funny)? PerfectFlite said that the match is important also, furthermore PerfectFlite gave parameters on how to test matches of an unknown quality (destructively) to see if they were flight worthy for the altimeter.

Greg
Click to expand...

Buckeye said:
Agreed. Whatever was going wrong at CMASS, it was not the Vinnic A10 in the MAWD.

One thing to make sure of if using the metal clips to hold the battery (see my pic above): wrap the battery in cellophane tape to insulate it and protect from shorting.

What I meant to say is test the altimeter with the ematches you plan to use. I have some litttle lamps (LEDs? I don't know) I bought from Radio Shack a long time ago to check outputs from the altimeter. The MAWD will usually fire these lamps at room temp (dimmly), but did not fire them during the cold test. The actual ematches fired just fine.

I have success with many types of starters with the MAWD/A10: Q2G2, Newton's 3rd cannisters, MTEK, JTEK, etc.
Click to expand...
Folks, it was not only a MAWD, but several other models of altimeters with and with out deployment capability, not only ones by PerfectFlite, so I do believe it was battery related, especially since all the fliers are seasoned veterans and all had flown their altimeters successfully in the same rockets previously using the same brand of batteries.

I absolutely agree that I see no reason why the altimeters should not have worked, but they did not. I do not know if they bought their batteries from a common source, or how old the batteries were. What I do know is that the folks said they checked out their altimeters at home before they came to the field.

So it is a mystery to me why this happened. The only thing that was a common thread is that the altimeters worked at folks homes and did not work in the field, and the only know physical parameter that was different was the temperature, and that is why I reported the observation.

I do not know how folks checked their batteries, or if they did. The only way to know for sure if your battery is good is to test the voltage delivered into a load resistor and compare the voltage value against datasheet capacity curve and not use the battery if it is below the 50% capacity point.

Bob
 
attachment.php


What brand/model altimeter is this?
 
One of the seasoned veterans who had issues with his Estes altimeter at our previous launch using the recommended alkaline battery suggested in the instructions, followed my suggestion and used the silver oxide version of the button cell and had no issues last Saturday where the temperature was more than 10 F cooler at 32 f than the previous launch.......

And BTW the use of the silver oxide variant of the button cell batteries is recommend in the MAWD manual.......for low temperatures.

Bob
 

Similar threads

Adrian A
Blue Raven batteries and current limiting
Replies
23
Views
3K
Adrian A
Adrian A
Adrian A
New Featherweight GPS phone app available for Android and iOS
2 3
Replies
73
Views
6K
jgarbus
J
cerving
The Eggtimer EZ-DD Rocket/Altimeter, a Complete Dual-Deploy Package for $100
2 3
Replies
75
Views
4K
Simon Auty
S
RocketSquirrel
I think I'm ready for my first DD...
2
Replies
36
Views
1K
Buster
Buster
RVN7
Cheers from Toronto!
Replies
2
Views
373
Hobie1dog
Hobie1dog

Latest posts

Back
Top