No speed gain after stopping battery recharge

[shegeek72]

Likely has been asked before, but something I always wondered about SH4 (unlike SH3): why doesn't the speed increase after turning off battery recharge?

[Spraug]

Because that's not how it works, what happens is that the fuel consumption goes down. Because the speed you set is the important variable and charging comes second, the engines are mainly used for propulsion and only the remaining capacities beyond that are used for charging. This means that during charging engines run at less efficiency and at a higher than with full batteries and therefore fuel consumption goes up until the batteries are charged.

Depending on the mod you are using there is a button that gives you maximum range at your current speed. This will vary drastically depending on whether or not you are recharging at the time. Can't remember if the button exists in plain vanilla, but I think not.

[TorpX]

I get a speed boost. Maybe because I'm in a S-boat.

Anyway, I think if you are trying to go at high speed, you should see the difference.

[Spraug]

Interesting!!! I've never had that. Maybe it's the S-boat as you said (wrote).

[ETR3(SS)]

Different propulsion systems as compared to a U-Boat. Fleet boats used a diesel-electric system. What that means is a diesel engine was coupled to a generator that generated electricity. That electricity in turn was used to drive electric motors to propel the ship. So the faster you wanted to go, the more generators you would bring online to provide more power. Typically there were 4 Diesel Generators on the boat (2 for the P Class). The more you brought online for propulsion, the less there was for battery charging.

As for U-Boats AND the S-boats, they employed a direct drive system. The diesel was directly providing propulsion power to the shaft(s). When you needed to recharge your batteries, you would clutch one out to a electric motor. That motor now becomes a generator and you lose speed as you're down to single shaft propulsion. Boats of this propulsion configuration typically had 2 Diesel Engines onboard (the Type IX may have had 4).

[TorpX]

I was testing my mod set-up, to make sure everything was kosher, and did a little test with the battery charging speed.

class ____________ max. speed __________ w/ battery charge
S-18 ____________ 13.5 kn. ______________ 10.5 kn.
S-42 ____________ 12.75 ________________ 10.0
Porpoise _________ 20.0 _________________ 19.25 to 19.5 *
Gato ____________ 21.5 _________________ 20.5 to 20.75 *

* batteries charged at very slow rate

The speed for the battery charge was checked at 50% battery capacity, and again at 90%. That is why there are two figures for the diesel-electric boats. Note that while going at flank speed, charging was very slow for these boats (as we would expect). I tried the Gato at 1/3, and it seemed that charging didn't reduce that speed (as it shouldn't). This may explain the confusion over the matter.

The difference between 20 and 19.5, or between 21.5 and 20.75 may seem trivial, but it takes 8 times the power to obtain 2 times the speed, so the difference is greater than it appears at first glance.