Battery charging is spot on!!!

[pythos]

I had just finninshed one attack wave on a convoy off of Japan. It is late 42 and I am in command of a Tambor class boat.

Following the attack and run away, I am parelleling the convoy's last known course. At first I was going at full speed. I checked my battery level and noticed it was charging really slowly if at all, so I dropped to standard (still about 12 knots), and saw a small jump in the charge rate, then out of curiostiy I dropped it down to 2/3 (or the step below standard) and saw a bigger jump. Then it dawned on me.

The devs did their homework, just like they did with SH3.

With the German boats for battery charging one engine was dissconected from the prop shaft, and left connected to only the generator, leaving one prop stopped or "windmilling". This was simulated in Sh3 quite well.

With SH4 the same is done with the 2 engined/ direct drive S-boat. When charging one prop is stopped.

Now the newer fleet boats had four engines, none directly connected to the drive shafts, instead they were connected to a generator which in turn was connected to either the batteries, or directly to the drive motors. When traveling at slow and charging the boat would be proppelled by one or two engines, while the other two or three would charge the batteries. At standard it was two engines connected to the motors, and two to the generators. Then at full three driving one charging. At full all four would be driving, with a little bled off for charging, and at flank, no charging.

In SH4 this is simulated quite well. You will also notice there is no increase in speed when the battery indicates fully charged, like you get with the older or german boats. Also, while charging both propellers are turning.

I have to say, I am impressed.

[SteamWake]

Are you saying that the batterys recharge faster when the helm is set to 2/3 in lieu of flank ?

Seems a bit counter intuitive.

[tater]

Well, when surfaced you'd expect them to run all engines. If you want the boat to move at 1/3 speed, the other engines would be charging until the batteries were topped.

It's a little odd, there should be a difference between when you click the recharge batteries or not button. If set to recharge, I'd assume all engines would run, and any power produced NOT used to propel the boat at the ringed up speed would charge.

When the button is off, I'd expect the boat to only run as many diesel engines as needed to produce the power needed for the ringed up speed. If you have the boat set for 5 knots, I'd expect one engine running I think.

tater

[SteamWake]

Well in the boats where an engine is dedicated to charging duty it (that engine) would charge at whatever rate it was set for.

The speed of the other engine would be irrelevant.

I do know that diesel engine generators are controlled to run at a constant speed and adjust throttle according to load to maintain that speed. However that is because they have to produce a consistant 60 cycles per second regardless of load. In order to charge batteries the alternating current would have to be converted to direct current so that cycles per second would not be critical and basically the faster you can spin the generator the more 'juice' you can get out of it.

[pocatellodave]

I have been having a hard time with fuel conservation,but I'm doing much better now thank to a lot of help from other skippers.I use the Strict range mod,and this gives me nine knots at ahead standard,and it is the most efficient speed for mileage.I try to stay on the surface as much as possible,with battery charging off when applicable.My greatest wish would be that we skippers could determine the number of engines we wished to run on,and charge batteries.I'm pretty sure I read where skippers would run on only one engine to conserve fuel.Please someone correct me if I'm wrong.I know running with two engines for propulsion,and charging with two was S.O.P.Maybe a mod like I mentioned isn't out of the question.I thank all the people that gave me a hand with using fuel more frugally.
Pocatellodave

[Tom C]

In order to charge batteries the alternating current would have to be converted to direct current ...

I read somewhere, FleetSubmarine.com I think, some comments suggesting that WWII diesel-electric surface ships had DC/AC converters but submarines did not, all-DC. Does anybody know for certain?

[Sailor Steve]

This would indicate that the motors and generators were all DC.
http://www.maritime.org/fleetsub/elect/chap1.htm#1F

[SteamWake]

This would indicate that the motors and generators were all DC.
http://www.maritime.org/fleetsub/elect/chap1.htm#1F

Oh goody I get to give Steve a hard time :p

No such thing as a DC generator :know: the windings output either a pulsing dc current (0 to +) or an alternating current (- to +). Then that is 'recitfied' to DC.

But technically you are correct it was called a DC generator.

http://farside.ph.utexas.edu/teaching/302l/lectures/node91.html

Take a look at the sign wave at the bottom its a pulsing dc current. But then again the batteries dont care if its pulsing or not. As long as the pulse is always positive. A negative pulse would be a very very bad thing indeed. Ever seen what happens when someone trys to jump start a car and gets the leads reversed ? Lets just hope your no where close.

The amount of stored energy in a lead acid battery is really quite amazing.

[-Pv-]

Regardless of the theory, the slower you travel on the surface, the faster the recharge time in the game.

Here's the results I made and posted using patch 1.2 in April:

Endurance test results.

Installed game had no diesel, power, battery, or crew mods. No mods to any submarine model or components.

Platforms:
(I) 1942 Porpoise leaving Midway using a saved game on my 3rd patrol. I've been carefully building up my crew skill (assuming those graphs and numbers aren't totally meaningless.)
Eng Room Crew Efficiencies- I=.93, II=.94, III=.98
Weather: 5m/s dir 44
Sub Heading 250

(II) 1944 Balao Leaving Midway using one of the default patrol missions.
Eng Room Crew Efficiencies- I=.88, II=.88, III.88
Weather: 5m/s dir 0
Sub Heading 270

Procedure:
On Surface set depth to 70 ft 1/3 speed "Ahead Slow" 11 knots.
Passing 50 ft set speed to 1/3.
Upon reaching 70 ft, mark the time, mark the map, and set speed 2 knots (both text and voice confirm 2 knots.)
Cruise at set depth/speed using 1024 TC until battery reaches 2% or Oxygen warning of 95% CO2 (whichever comes first.)

Results using Porpoise:
2% batt, 95% CO2 = 76.95nm, 48 hours

Results using Balao:
4% batt, 95% CO2 = 91.4nm, 48 hours
Continued until battery reached 3% and 98% CO2 (Crew death at 99% CO2)
Distance = 95.1nm

Procedure for battery charge time:
Surfaced at battery depletion times described above. Mark time from charge lcon changing to bright until icon changes to dark automatically.

Recharge times:
Porpoise- Speed set to 1/3 on surface = :49 min
Porpoise- Seed set to Full on surface = 2hr:47 min

Balao (based on 4%Batt/95%CO2)
Speed set to 1/3 = 1hr:16 min
Speed set to full = 2hr:18 min

Ran same tests using Silent Running. No difference. This setting apprently only affects noise/detection/repair and does not affect CO2 generation or machinery/power savings.

-Pv-

[SteamWake]

Good research. Have you compared it to 1.3 ?

Also is this a 'vanilla' install ?

It still seems counter intuitive that the slower you run the faster your battery charges.

[tater]

The sub is propelled by electric motors. They take power. The power can come from the batteries or the generator directly.

Any power made by running a generator (a diesel engine) that is NOT used by the screws is available to be put into the batteries for later use.

[SteamWake]

The sub is propelled by electric motors. They take power. The power can come from the batteries or the generator directly.

Any power made by running a generator (a diesel engine) that is NOT used by the screws is available to be put into the batteries for later use.

This may be so but if you ring up for flank wouldent there be more 'excess' power as opposed to ahead 1/3 ?

My basic reasoning is that the harder the engine is running the more power is being put out wether its applied to the screws or the batteries.

[tater]

Well, the interface is limited. You are ringing up SPEED, RPMs on the screws, not the engines.

Wehave to assume on the surface that the sub runs all 4 engines until charged up, then only as many as are needed for the target speed after that.

[tycho102]

The sub is propelled by electric motors.

I thought Gato and Balao class were direct-drives, with a generator coupler. I'm pretty sure electric motors weren't used yet. We've had a thread on this topic before on the SH3 side. All electrics didn't start showing up until the early 50's.

On direct drives, you control fuel flow for a given load. When they slapped on the gear coupling to recharge the batteries, you'd be using the same amount of fuel for a slower shaft RPM. This is accurately recreated in the simulation -- your 1/3 and 2/3's speed is actually a fuel valve, and on pure propulsion loads, you're going to crank 12 knots. Throw on recharging, and you're doing 8-9 knots for 2/3's.

I've even noticed a 1kt difference between charging a battery at 10% and a battery at 80%, which would also be accurate.

[tater]

That might well be correct (you sound like you know more about it than I do, lol), I was answering in general as to the "counter intuitive" bit.

Are you saying they had a drive shaft out of the diesels that mechanically drove the screw? That wasn't my understanding.

tater

[tater]

This is the picture I had seen before:

http://www.maritime.org/fleetsub/elect/img/fig2-01.jpg

[Sailor Steve]

Oh goody I get to give Steve a hard time :p

No such thing as a DC generator :know: the windings output either a pulsing dc current (0 to +) or an alternating current (- to +). Then that is 'recitfied' to DC.
I just looked at the manual. What I know and understand about generators and electricity would fill a book - a matchbook.:rotfl:

[SteamWake]

Oh goody I get to give Steve a hard time :p

No such thing as a DC generator :know: the windings output either a pulsing dc current (0 to +) or an alternating current (- to +). Then that is 'recitfied' to DC.
I just looked at the manual. What I know and understand about generators and electricity would fill a book - a matchbook.:rotfl:

Heh... I just had to jump at the chance cause you are the one usually setting me straight :smug:

All in good fun :up:

[SteamWake]

This is the picture I had seen before:



Hrm... I noticed there are two sets of motors "Main motors" and "slow speed motors". Whats up with that ?

Oh .. I understand now... they have a transmission of some sort.... wow most interesting.

[Elder-Pirate]

This is the picture I had seen before:

http://www.maritime.org/fleetsub/elect/img/fig2-01.jpg



What are those engines, straight eight Detroit's?

[tater]

16s I think.

It certainly doesn't look like the diesels drive the shaft directly to me. The difference between "direct drive" and "geared drive" for these fleet boats seems to be describing the electric motor, not the diesels.

<shrug>

tater

[SteamWake]

I was kind of supprised as to how much they look like contemporary diesel generators or diesel electric locomotive (train) engines.

Biggest generators Ive ever seen actually used a turbine (jet) engine producing 12,470 volts in the neighborhood of 1,000 amps and had the capability of starting, comming up to speed, and dropping on line in the neighborhood of 3 to 10 seconds depending on the weather :hmm: . They used compressed air to get them started. Damn thing was as big as a bus ! They were at a very large hospital and provided "critical" branch power. Oh... and loud... good god !

But I digress. :oops:

[tater]

They ARE locomotive engines.

That was the idea, they picked an engine that would also be used for trains so that they could be mass produced.

tater

[SteamWake]

So what Im guessing is that fleet boats were diesel electrics very very similar to a contemporary locomotive engine.

The earlier boats had direct drive to the props and somehow were disconnected from the shafts and connected to a generator.

[pythos]

As I said, the earlier boats were direct drive, or connected to the generator, not both.

To the person who keeps saying it is counter intuitive, look at the picture provided, notice how none of those engines is connected to the propeller shaft. That is why the faster you are going the less voltage you have for charging the batteries, it's all going to the motors to make the boat go.

It is my understanding that when cruising at slow speed, two sets of engines were shut down for maintenance after the batteries were topped off, while one provided propulsion voltage, and the other ticked over on the generator to keep the batteries topped up due to the electrical draw from pieces of the boats operating equipment. (lights, blowers, gyros, ect).

The older boats I think had three settings.

1) directly connected to the props. The drive shaft passed through the drive motor/generator.

2) When operating on electrics, the diesles were disconnected by a clutch mechanism, and the motors were connected by another clutch., and drove the propellers.

3) When charging one prop was being driven by one diesle, and the other diesle drove the motor/generator, while being disconnected from the propeller.

For the four engined fleet boats, this was not the case. They were truly diesle electric units like a locomotive, except the power went to both batteries, or motors. A very clever design.

[-Pv-]

"...Good research. Have you compared it to 1.3 ?

Also is this a 'vanilla' install ?

It still seems counter intuitive that the slower you run the faster your battery charges...."

My install was nearly pure download version. The only changes at the time were a sim file to enable 360 deg radar and a few changes to command.cfg to enhance keyboard. No performance mods whatsoever. I've seen no indication based on patrolling in 1.3 there is any significant change to the range.

As has been stated, in WWII subs, what power wasn't used for propulsion was used for battery charging. Propulsion wasn't governed by how high the throttle is set, but by how many engines are driving the electrical system. The telegraph setting represented "turns" (RPMs) and the appropriate number of engines were taken off charging and placed online for driving the prop motors to obtain the requested RPMs.

Read some good WWII sub books where these principles are often discussed in detail.
-Pv-

[tater]

http://www.maritime.org/fleetsub/diesel/index.htm

[-Pv-]

Section 6 page 62 (where the clear diagram referenced in this thread is taken) explains the general propulsion principle very clearly in the text above the diagram.
-Pv-

[Elder-Pirate]

Well I had ask the question if the engines were straight 8 Detroit's and received the answer they were 16. Yep they were and now by this article I find some of the submarines had more than just four engines but one, two or more Auxiliary engines. Only one aux. engine on Gato type Submarine here.



FOUR GENERAL MOTORS DIESEL / GENERATOR SETS

PLUS ONE AUX. G.M. DIESEL / GENERATOR SET


USS Hardhead (SS-365) was a unit of the Electric Boat Company's version of the Balao Class submarine. Manitowoc Shipbuilding Company built submarines from Electric Boat Company plans. When commissioned, USS Hardhead was 311 feet 9 inches in length overall and had a maximum beam of 27 feet 3 inches. Her standard displacement on the surface was 1,526 tons, her normal displacement on the surface was between 2,010 and 2,075 tons, and her submerged displacement was 2,424 tons. Fuel capacity was 118,000 gallons (rated) of diesel oil, which fueled 4 main General Motors Model V16-278A, 1,600 horsepower diesel engines, and one auxiliary General Motors diesel engine...which turned generators...which made electricity...which turned four General Electric main propulsion motors of 2,740 shaft horsepower... which could drive the boat at 20.25 knots on the surface...and gave her a cruising range on the surface of 11,000 miles at ten knots (rated).


Rest of this article go here:
http://www.subvetpaul.com/Engines.htm

[PepsiCan]

They ARE locomotive engines.

That was the idea, they picked an engine that would also be used for trains so that they could be mass produced.

tater

The US did that a lot, use of standardized components to build war equipement. The Sherman tank had a standard GM truck engine. That's why they build so many of them. It was easy to do. And the Germans struggled with their tank engines for their expensive Panthers and Tigers and so lost the ground war in Europe.

[elanaiba]

This is the picture I had seen before:


Hrm... I noticed there are two sets of motors "Main motors" and "slow speed motors". Whats up with that ?

Oh .. I understand now... they have a transmission of some sort.... wow most interesting.

The two parts of the picture are not the same boat, just two different priciples.

The left hand part of the pic - the one with the slow speed motors - is a Tench class propulsion arrangement. 2 slow speed, higher HP motors are directly geared to the propellers, replacing the earlier 4 motors + transmission.

[SteamWake]

They ARE locomotive engines.

That was the idea, they picked an engine that would also be used for trains so that they could be mass produced.

tater

The US did that a lot, use of standardized components to build war equipement. The Sherman tank had a standard GM truck engine. That's why they build so many of them. It was easy to do. And the Germans struggled with their tank engines for their expensive Panthers and Tigers and so lost the ground war in Europe.

That and the literally ran outa gas :p