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Message
Apollo 13 question re: batteries
Posted on 4/22/25 at 10:13 am
Posted on 4/22/25 at 10:13 am
Wife had this on last night when I came to bed, and as usual, I got caught up in watching it and went to sleep later than intended. But something stood out to me that I've noticed before, but never asked on here.
The movie makes a huge deal about them being limited to the 20 amps of power or whatever, and they are desperately trying to start things up in a certain sequence to save as much power as they possibly can. And Ken Mattingly even says at one point that they should us the batteries from the LEM (I think that's the one) and asked if they could reverse the flow of power so that they could get the additional four amps that they need to restart everything.
But the whole time in the ship, the astronauts are jamming to a tape player playing music that is (presumably) running on battery power. Now, I don't know what the battery situation looked like in 1970, so I'm assuming there were a couple of AA batteries powering the little radio. And we see the batteries dying near the end when the music is droning and slowing down.
Question:
Knowing they were desperately low on amperage and power, why in the world would they be wasting batteries in a tape player when they could be using those batteries for the extra power they needed? I believe they end up using battery power from the LEM anyway, so surely the batteries in the tape player could have helped. And we already saw them figure out how to put a square peg into a round hole for the CO2 filter situation. Surely NASA could've figured out a way to utilize those batteries as well.
Any ideas as to an explanation of this? Did I miss a line of dialogue that explains this or something? It just always bugged me that such a huge deal is made about not having enough power to get home, yet the tape player is floating around playing music for hours (days?).
The movie makes a huge deal about them being limited to the 20 amps of power or whatever, and they are desperately trying to start things up in a certain sequence to save as much power as they possibly can. And Ken Mattingly even says at one point that they should us the batteries from the LEM (I think that's the one) and asked if they could reverse the flow of power so that they could get the additional four amps that they need to restart everything.
But the whole time in the ship, the astronauts are jamming to a tape player playing music that is (presumably) running on battery power. Now, I don't know what the battery situation looked like in 1970, so I'm assuming there were a couple of AA batteries powering the little radio. And we see the batteries dying near the end when the music is droning and slowing down.
Question:
Knowing they were desperately low on amperage and power, why in the world would they be wasting batteries in a tape player when they could be using those batteries for the extra power they needed? I believe they end up using battery power from the LEM anyway, so surely the batteries in the tape player could have helped. And we already saw them figure out how to put a square peg into a round hole for the CO2 filter situation. Surely NASA could've figured out a way to utilize those batteries as well.
Any ideas as to an explanation of this? Did I miss a line of dialogue that explains this or something? It just always bugged me that such a huge deal is made about not having enough power to get home, yet the tape player is floating around playing music for hours (days?).
10
Posted on 4/22/25 at 10:16 am to CocomoLSU
Were 2 AA batteries even a drop in the bucket for what they needed? Or even convertible to use with the ship?
This post was edited on 4/22/25 at 12:28 pm
Posted on 4/22/25 at 10:21 am to CocomoLSU
Is there a place to plug AA batteries into a space shuttle?
Posted on 4/22/25 at 10:21 am to CocomoLSU
Your question is why didn't they use AA batteries from a tape player to power a spacecraft?
Posted on 4/22/25 at 10:23 am to jlovel7
quote:
We’re 2 AA batteries even a drop in the bucket for what they needed?
Quick google search says this:
quote:
An AA battery typically has a capacity rating of 2 to 3 ampere-hours (Ah). This means it can deliver 2 to 3 amps of current for one hour. However, the peak current a battery can deliver for short periods can be higher, potentially over 2A.
So I honestly don't know. Also I am guessing at the type of batteries in the tape player.
quote:
Or even convertible to use with the ship?
That's what my CO2 filter comment was for. Seems like they surely could've come up with some sort of way to utilize the battery power.
Just seems like with power at such a premium, you'd want to utilize any-and-everything you possibly can.
Posted on 4/22/25 at 10:27 am to boxcarbarney
quote:
Your question is why didn't they use AA batteries from a tape player to power a spacecraft?
No. I'm not saying they could power the whole thing with a couple of small batteries. But they just needed a small extra bit of power to be able to turn everything on that was needed. My question is why wouldn't they use every single thing at their disposal to draw power from. They even use battery power from the LEM (I think). And all they needed was:
"All we're talking about here is four amps" - Ken Mattingly
Admittedly, I am ignorant to how power works, how power is drawn from things, volts vs. amps, etc. Thus my question. There very well may be a very easy explanation for this, I just have never seen one.
Here is the scene:
quote:
Ken Mattingly: [after another power-up simulation fails] I know this sequence works, John.
John Aaron, EECOM Arthur: The sequence looks good, we're just over budget on the amperage.
Ken Mattingly: By how much?
John Aaron, EECOM Arthur: Three or four amps.
Ken Mattingly: Goddamn it, John! Is it three or four?
John Young: Four.
John Aaron, EECOM Arthur: Four!
Ken Mattingly: [sighs] Four more amps...
[He ponders for a moment]
Ken Mattingly: We know they have some power left in the LEM batteries, right?
John Aaron, EECOM Arthur: Yeah.
Ken Mattingly: We have an umbilical that provides power from the Command Module to the LEM.
John Young: Right. It's a backup for the LEM power supply.
John Aaron, EECOM Arthur: I'm listening.
Ken Mattingly: So, reverse it. Reverse the flow and see if we can draw these four amps from the LEM batteries before we cut it loose. Why can't we do that?
John Aaron, EECOM Arthur: [Looks at John] We don't have a procedure for that, do we?
John Young: You're gonna lose a lot in the transfer, Ken.
Ken Mattingly: Yeah, yeah. But all we're talking about here is four amps.
This post was edited on 4/22/25 at 10:29 am
Posted on 4/22/25 at 10:35 am to CocomoLSU
You are missing the other important part which is volts. The AA battery is only (at most) 1.5v. Amps x Volts = Watts. They are basing the additional amps they needed based on whatever volts the capsule ran off of - which was assuredly more than 1.5v
This post was edited on 4/22/25 at 10:39 am
Posted on 4/22/25 at 10:46 am to BigBinBR
Considering they were in a tv studio the whole time makes this point moot
The military dropped them into the ocean to simulate their safe return home
The military dropped them into the ocean to simulate their safe return home
Posted on 4/22/25 at 10:51 am to CocomoLSU
Did they show them using AA's? Because most portable cassette recorders in 1970 were using D cells. (And they went through them very quickly.)
Posted on 4/22/25 at 10:52 am to CocomoLSU
quote:
John Young: You're gonna lose a lot in the transfer, Ken.
this could be an issue as well.
if you "lose a lot in the transfer", you may not accomplish anything at all by pulling from the radio batteries.
Posted on 4/22/25 at 10:54 am to nicholastiger
quote:
Considering they were in a tv studio the whole time makes this point moot
The military dropped them into the ocean to simulate their safe return home
I was going to put the caveat that it doesn't matter, because space isn't real
Posted on 4/22/25 at 11:07 am to Fewer Kilometers
quote:
Did they show them using AA's? Because most portable cassette recorders in 1970 were using D cells. (And they went through them very quickly.)
I don't believe so. Thus my comments in the OP about being unsure of battery information in 1970.
I got this from google's AI:
quote:
In 1970, a D-size carbon-zinc battery typically had a capacity of 4.5 to 8 amp-hours (Ah). This means it could provide approximately 6.25 amps of current for about one hour, or 1 amp for about 6 hours, and so on. The actual amperage a D battery could provide would depend on factors like the brand and the specific demands of the device it was powering.
This post was edited on 4/22/25 at 11:10 am
Posted on 4/22/25 at 11:21 am to jlovel7
quote:
We’re 2 AA batteries even a drop in the bucket for what they needed? Or even convertible to use with the ship?
Most likely, that radio was powered by a couple of C batteries. Probably even 4.
OP has a point -- from my old RadioShack Science Fair Electronic Kit days -- you could easily adapt those batteries and radio to put out electricity instead of consume.
Posted on 4/22/25 at 11:29 am to CocomoLSU
quote:
Any ideas as to an explanation of this?
Yes, these are the size and quantities of the batteries on Apollo
PDF Source
This post was edited on 4/22/25 at 11:30 am
Posted on 4/22/25 at 11:34 am to Floating Change Up
Transistor radios used 9 volt batteries. And if you made the mistake of falling asleep with your radio on, you woke up to a dead battery.
Posted on 4/22/25 at 11:41 am to Dam Guide
quote:
Yes, these are the size and quantities of the batteries on Apollo
PDF Source
Interesting.
So using the larger of the LM batteries, it looks like one battery was roughly 16" x 9" x 10" and had 400 amp hours. I'm not sure how that translates to "amps" needed in the movie though. But if it is 1:1 then you'd need 1/100th of that power to achieve what they needed (4 amps). So a small battery (let's assume D batteries based on what someone said above) outputs 4.5 to 8 amp hours (from my google result above).
So unless I am reading that wrong, it seems like they could have achieved their 4 amp need by using the batteries in the tape player. Does anybody agree/disagree with that?
Posted on 4/22/25 at 11:57 am to CocomoLSU
From a search it seems like they were issued Sony TC 50 cassette player/recorders starting with Apollo 7, which appeared to run on 3 double A batteries per a pic of the label/instructions
Pic of the service manual of EBay
EBAY
Pic of the service manual of EBay
EBAY
This post was edited on 4/22/25 at 12:01 pm
Posted on 4/22/25 at 11:59 am to CocomoLSU
quote:
So unless I am reading that wrong, it seems like they could have achieved their 4 amp need by using the batteries in the tape player. Does anybody agree/disagree with that?
It wouldn't have done anything and could have started a fire. It's a dumb idea.
Posted on 4/22/25 at 12:14 pm to CocomoLSU
quote:
But they just needed a small extra bit of power to be able to turn everything on that was needed. My question is why wouldn't they use every single thing at their disposal to draw power from
A) the guys in the space craft would have no way of knowing that the guys in the simulator were down to needing 4 amps. They didn’t even know Ken was working on it until then.
B) the guys in the simulator did not know all they needed was 4 more amps until the end of the process when it was crunch time.
It also took several people working for hours? To figure out how to create the CO2 scrubber to that foe radio batteries they would have to know well in advance that it might come down to that to create some kind of umbilical if that was even feasible. But given they can reverse transfer from the LEM it would seem unnecessary anyway. Nice try though
This post was edited on 4/22/25 at 12:17 pm
Posted on 4/22/25 at 12:25 pm to CocomoLSU
This discussion has me looking through the old Radio Shack Catalogs from my youth, so thank you for that.
Radio Shack Catalog Library
Radio Shack Catalog Library
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