battery recharge question:historic

[brett25]

I noticed in SH3 that I am able to recharge the battery without moving the sub, as long as the engines are running and im in recharge mode. Does anyone know if this is historically correct? Did the uboats have a gear that disabled the propeller shaft allowing the engine to stiull spin the shaft to recharge the batteries withput having to be in motion?

[Task Force]

I noticed in SH3 that I am able to recharge the battery without moving the sub, as long as the engines are running and im in recharge mode. Does anyone know if this is historically correct? Did the uboats have a gear that disabled the propeller shaft allowing the engine to stiull spin the shaft to recharge the batteries withput having to be in motion?

I belive when U boats are rechargeing they use one engine to spin one prop and the other to recharge.:yep: so, i believe if the were stopped, they would have 1 engine rechagreing and running and the other stopped.

[ryanglavin]

Task force is correct. they would also run extremely fuel efficient-like, by running 1 diesel through both electrics to run the boat. that was a solid 4 Kts.

[brett25]

ok thanks that makes sense. do you know of any good books covering the engineering and mechanics off the uboat?

[Jimbuna]

Recharging batteries whilst stationary is not realistic...but simply a glitch in the game that has not been addressed thus far.

[ryanglavin]

ok thanks that makes sense. do you know of any good books covering the engineering and mechanics off the uboat?

One book, a biography on Wolfgang Luth goes into detail about the IXD2. Clay Blairs' Books go into alot of detail, if you read both front to back, (done that 4 times here :yeah:)

[brett25]

Recharging batteries whilst stationary is not realistic...but simply a glitch in the game that has not been addressed thus far.

@jibuna , do you know if this was because the crew typically did not do that, or is it because its not possible mechanically speaking.

@ryanglavin thanks for those suggestions

[Task Force]

I would think its mechaniacly possiable... running one engine while while not turning the prop shaft... Abit like a car in park I guess, its still rechargeing the battery by turning the alternator but isnt moveing the wheels...:hmmm:

[ryanglavin]

I would think its mechaniacly possiable... running one engine while while not turning the prop shaft... Abit like a car in park I guess, its still rechargeing the battery by turning the alternator but isnt moveing the wheels...:hmmm:

The thing is, that I learned from my research on a Honors Lit paper in 9th grade (I write alot about submarines), that the diesels were directly connected to the electric engines which were connected to the Propeller shafts. Keeping it stopped wouldn't work because you would need the diesel engine to power the electric engine to get it recharged... Unless you found a way to cut a line to the propellor shaft, and i don't think you would want to do that.

[Jimbuna]

@jibuna , do you know if this was because the crew typically did not do that, or is it because its not possible mechanically speaking.



See below....http://imgcash6.imageshack.us/img144/8426/lookherewd0.gif http://imgcash6.imageshack.us/img144/8426/lookherewd0.gif http://imgcash6.imageshack.us/img144/8426/lookherewd0.gif
http://imgcash6.imageshack.us/img144/8426/lookherewd0.gif http://imgcash6.imageshack.us/img144/8426/lookherewd0.gif
The thing is, that I learned from my research on a Honors Lit paper in 9th grade (I write alot about submarines), that the diesels were directly connected to the electric engines which were connected to the Propeller shafts. Keeping it stopped wouldn't work because you would need the diesel engine to power the electric engine to get it recharged... Unless you found a way to cut a line to the propellor shaft, and i don't think you would want to do that.

[Sailor Steve]

The problem I have with that is that it also means that you would never see one prop not turning while you recharged. If they disengaged one engine from the propellor shaft while recharging, then it follows that if one was recharging and the other shut down then you could indeed be sitting still while recharging (if you so chose).

[Jimbuna]

The problem I have with that is that it also means that you would never see one prop not turning while you recharged. If they disengaged one engine from the propellor shaft while recharging, then it follows that if one was recharging and the other shut down then you could indeed be sitting still while recharging (if you so chose).

Sorry Steve but you've lost me here (might be experiencing one of my rare sober moments).

Do you mean the game should always show at least one prop turning?

[brett25]

I found this manual covering recharging protocols: http://www.uboatarchive.net/BDUOrder2.htm (this article needs some deciphering from some of you who can)

and this more general article which seems to indicate the boat needed to be in motion during a recharge: http://www.uboataces.com/uboat-type-work.shtml

At greater depths, the U-boat is driven by electric motors using electricity drawn from giant internal batteries. When these are depleted, they must be recharged. This is done by traveling on the surface, or while snorkeling at periscope depth. The diesel engines are used to turn the electric motors so that they act as dynamos (generators) to recharge the depleted batteries. For rapid recharge, both diesel engines would be clutched onto the electric motors. For maximum range, one diesel engine would be clutched to an electric motor – which in turn acted as a generator to drive the other electric motor. Both propellers were turning in this way with only one diesel running.

here is a good article on uboat batteries: http://www.uboat.net/articles/id/54

[Sailor Steve]

Well, I spent 20 minutes researching and typing a long post explaining what was just said above, including links to both u-boat sources and US sources (US boats had the diesels connected directly to generators, which provided electricity to either run the motors or to charge the batteries) only to find that I had been logged off by the system and the whole thing was lost.

Sometimes I hate this server.:damn::damn::damn::damn::damn:

Anyway, the US stuff is all here.
http://www.maritime.org/fleetsub/elect/chap2.htm#2A

[Jimbuna]

Which takes me back to my post @#5....the propellor would be moving which would mean the U-boat should not be stationary........but the game allows for recharging of the batteries to take place whilst the boat is at a standstill.

I think....not really sure anymore.....what was the original point again? http://www.psionguild.org/forums/images/smilies/wolfsmilies/wacko.gif

[ryanglavin]

Hey jim, where'd you get the hands?

[Leandros]

Which takes me back to my post @#5....the propellor would be moving which would mean the U-boat should not be stationary........but the game allows for recharging of the batteries to take place whilst the boat is at a standstill.

I think....not really sure anymore.....what was the original point again? http://www.psionguild.org/forums/images/smilies/wolfsmilies/wacko.gif
I've read the articles of the links above and one thing I wasn't aware of became clear to me. The diesels are not connected to the propeller shafts, but driving them through the electric engines. That's fine. I was a little surprised, though, as this means that there would be no propulsion, not even on the surface, if the e-engines were damaged. I suppose this was done to save space and weight.

OTH, it doesn't seem clear to me whether the propeller shaft/propellers could be disconnected from the engines or not. A gearbox. Or maybe adjustable propeller pitch. To me it sounds unlikely that batteries couldn't be charged while lying still. Since the e-engines themselves were the battery charging generators, driven by the diesels, the axles would then swirl while charging. This would also take up/diminish energy for the actual charging. And the boat would move.

Can anyone point specifically to a source which says this.

[ryanglavin]

I've read the articles of the links above and one thing I wasn't aware of became clear to me. The diesels are not connected to the propeller shafts, but driving them through the electric engines. That's fine. I was a little surprised, though, as this means that there would be no propulsion, not even on the surface, if the e-engines were damaged. I suppose this was done to save space and weight.

OTH, it doesn't seem clear to me whether the propeller shaft/propellers could be disconnected from the engines or not. A gearbox. Or maybe adjustable propeller pitch. To me it sounds unlikely that batteries couldn't be charged while lying still. Since the e-engines themselves were the battery charging generators, driven by the diesels, the axles would then swirl while charging. This would also take up/diminish energy for the actual charging. And the boat would move.

Can anyone piont specifically to a source which says this.


I usually get all my information from Clay Blair's books.
He usually has facts about how the boats worked.
I was also reading in a book that U.s. Submarines had a giant cable leading out of the batteries, and If you touched it, you would literally be incinerated in under 0.1 seconds because of voltage. If that got messed up, you probably couldn't even move the boat. If a loose screw got into the cage that the cable was housed, you would probably not be able to move the boat either.

[Sailor Steve]

Which takes me back to my post @#5....the propellor would be moving which would mean the U-boat should not be stationary........but the game allows for recharging of the batteries to take place whilst the boat is at a standstill.

I think....not really sure anymore.....what was the original point again? http://www.psionguild.org/forums/images/smilies/wolfsmilies/wacko.gif
Why would the propellor be moving? In the u-boats the diesel is clutched either to the generator or to the propellor shaft, not to both. The engine that is doing the charging is not driving the boat, so if they are both charging or if the non-charging one is shut down, the boat won't move.

[Jimbuna]

Why would the propellor be moving? In the u-boats the diesel is clutched either to the generator or to the propellor shaft, not to both. The engine that is doing the charging is not driving the boat, so if they are both charging or if the non-charging one is shut down, the boat won't move.

I simply cannot imagine the momentum of travel being sacrificed....why not utilise the momentum to travel toward some intended destination.

The only scenario I can imagine would be if you were lying in wait along an expected convoy route, but even then wouldn't you be submerged to maximise your 'listening' means via the hydrophones.

I'd be interested in learning of an account where a boat simply 'hovered' on the surface whilst charging the batteries.

I just can't imagine this happening in RL.

Not saying it never happened, but would like to know of it :hmmm:

[Sailor Steve]

I can't imagine doing it either. I was just addressing the question of whether it could be done.

[brett25]

I simply cannot imagine the momentum of travel being sacrificed....why not utilise the momentum to travel toward some intended destination.One scenario could be a case where the u boat was in dangerous waters, needing to travel submerged most of the time but needing eventually to discretely surface, recharge in place and submerge (where a trip on the surface could attract unwanted attention). They could have done this decks awash for more stealth. Also it could be a fuel efficient way to recharge where fuel levels were critically low, or to extend the range of the patrol

also this article points to an interesting fact that charging time and propeller speeds were inverse http://www.uboat.net/articles/id/54

When the submarine's speed is faster the time of the battery charging is longer, because fast speed needs more electric power. Opposite, when the submarine's speed is slower the time for the battery charging is shorter. In that case, slower speed needs a smaller part of the electric power and the bigger part of the electric power remains for the battery charging.so why not no rotation at all for fastest recharge. I guess the main question at this point is whether there is an example of this ever occuring during the war?

[Leandros]

Why would the propellor be moving? In the u-boats the diesel is clutched either to the generator or to the propellor shaft, not to both. The engine that is doing the charging is not driving the boat, so if they are both charging or if the non-charging one is shut down, the boat won't move.
That, I believe, is not the essence of the links above. They say that all propulsion goes through the e-engines. That is, the diesels are not coupled to the axles. Whether that is correct or not I do not know. But that is how I understand the information in the links. That said, and if it is correct, I find it strange if there is not a sort of (de)coupling between the e-engines and the axles/propellers as the e-engine as a generator for charging needs to revolve. Modern u-boats might have a different system.

If you think about it from the diesels' point of view such a propulsion system is advantageous in that these can be run on near constant speeds instead of suffering from the various stress loadings caused by the variation of stress on the propeller and axles which supplants to the diesels.

So, when under speed, and charging, one diesel would drive the e-engine driving one axle/propeller while the other diesel drives the e-engine as a battery generator (which, on low speed, also can give propulsion power to the other axle/propeller while charging) - or - one diesel drives both the propulsion e-engine and the one charging.

[Leandros]

I guess the main question at this point is whether there is an example of this ever occuring during the war?
As a commander I would certainly have liked to have the possibility to lie still on station while charging. After all, keeping station was a major part of the game - when you first got there. Any other solution i'd say would be very inflexible. Not to say that it wasn't like that. I do no not know but I would like to find out about this.

[ryanglavin]

. Also it could be a fuel efficient way to recharge where fuel levels were critically low, or to extend the range of the patrol



But wouldn't you use fuel to recharge the batteries?

[brett25]

But wouldn't you use fuel to recharge the batteries? according to the above info, you would use less fuel with less prop rotation, perhaps considerable less fuel if zero energy is going to prop rotation, not to mention the resistance of moving the sub through heavy seas

[Sailor Steve]

But wouldn't you use fuel to recharge the batteries?
Yep, and you'd use more fuel since the engines are running at low speeds while patrolling (unless of course you're chasing something) and they are run at full speed for fastest possible charging.

I don't find the inverse propellor speed 'interesting' i.e. unusual. The engines can drive the boat or charge the batteries. The more power applied to one, the less available for the other.

[Leandros]

The only scenario I can imagine would be if you were lying in wait along an expected convoy route, but even then wouldn't you be submerged to maximise your 'listening' means via the hydrophones.
I should think so, but you got to go up and charge eventually. So, should you stay in the same location or let yourself be "driven" while doing so. Another thing, while we're on recharging. Wouldn't the recharging give off more sounds if the propellers were rotating. What is easier to detect - the vibrations from the diesels or the propellers moving....I don't know....

[Jimbuna]

I can't imagine doing it either. I was just addressing the question of whether it could be done.

What if they rigged a sail to the conning tower and put a few oars over the side....."Faster faster, Caesar wants to go water skiing" :DL:03:

[Leandros]

What if they rigged a sail to the conning tower and put a few oars over the side....."Faster faster, Caesar wants to go water skiing" :DL:03:
Hmmm, would that charge the batteries....?....I suppose it would if the axles/propellers weren't disconnected.....if they could be disconnected....if they couldn't it would be heavier to row....boy, that's a serious drawback....better than rigging a sail - a windmill. That could charge the batteries....:hmmm:....hmm...we are getting somewhere now...