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]

Originally Posted by Sailor Steve

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 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/teachin...es/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]

Originally Posted by 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.

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]

Originally Posted by tater

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