The MI-8 has dead batteries!

[Socket7]

So for a while now, I've been terribly confused by the operation of the standby generator in the MI-8. It appeared to be hopelessly broken. Turning it on would show a 100 amp load on it, and then a few minutes later, it would stop working without a failure message in the logs. At first, I thought that the problem was the generator, but then I considered that 100 amps is an enormous load for a helicopter that's mostly turned off, and began looking for the source of the loads. I turned off all the lights, all the inverters, and the only thing left connected to the bus were the batteries. Each battery was drawing 20-30 amps! That's absolutely crazy.

 

By turning off one of the battery switches, and turning off all the other electrics, I was able to dramatically reduce the amperage load on the standby generator, and it stopped failing! This allowed me to spend 20 minutes sitting and monitoring the voltages of the batteries. The standby generator produces 27 volts, as shown by the DC voltmeter. Each battery starts out at just about 24 volts. After about 5 minutes of being charged by the DC generator, the batteries voltage rises to 25 volts, and the load it puts on the generator drops to about 10 amps. After letting the first battery charge for 5 minutes, I connected the second battery, and disconnected the first, letting the second battery also charge for 5 minutes with similar results. I then connected both batteries, and let them both charge at the same time for 10 more minutes. After charging for 20 minutes total, both batteries read at 27v on the DC voltmeter, and were putting around 5 amps of load or less on the standby generator. With the batteries fully charged, I had no problems connecting various electrics to the standby generator for testing.

 

My conclusion is that the failure of the standby generator is accurate, and caused by the overloading of the standby generator. The overload is caused by the MI-8's batteries being almost completely flat at the start of a mission. The documentation I've found says that battery voltages should be at LEAST 24 volts, and it's only barely 24 volts. During APU startup, voltages aren't supposed to drop below 18 volts, and they drop as low as 15.

 

Some notes:

 

The use of ground power does not charge the batteries, even though it does appear to make the battery load needles (barely) move into the negative, which is supposed to indicate charging.

 

The battery load needles do not drop into the negative when being charged by the standby generator.

 

I do not believe the batteries are being charged off the main electrical systems during normal flight operation. I did not specifically test for this though.

 

After shutting off the standby generator, its voltage on the DC voltmeter actually increased to 28v instead of dropping to 0v as it should, although the helicopter did behave as if the generator was disconnected. Even after shutting off the APU entirely, the voltmeter displayed positive voltage on the standby gen position. This did not prevent the restart of the APU.

 

This doesn't really have any practical implications on gameplay, I suppose there are situations where you might want to try and use the standby generator to power aircraft systems after battle damage. If you are concerned about the issue, you can spend 20 minutes on your startup routine charging the batteries.

Edited May 2, 2015 by Socket7
because words is hards.

[GunfighterSIX]

Great work!

[Devrim]

Great catch.

...This allowed me to spend 20 minutes sitting and monitoring the voltages of the batteries...

Maybe accelerating time would have helped not to waste much time.

[Socket7]

The time wasn't wasted. I also ate breakfast and watched some saturday morning cartoons while I tested. :smartass:

[Socket7]

Did A bit more testing, and confirmed that the batteries will charge properly off the MI-8's main engine generators.

 

I then ran into a problem turning the standby generator on, while trying test it with the main engines running after charging the batteries... More testing is in order to draw anything conclusive from that. Some more info on the standby generator would be handy too.

 

The fact that the batteries will charge off the engines makes this even more of a minor issue. I need to play around more with when the standby generator will work and when it won't though. That still seems a bit mysterious.

Edited May 3, 2015 by Socket7

[Docsnuggles]

seems still not fixed. Or is it? btw, when the batteries are done, you seem to not be able to get repairs on them. I stood for repairs and nothing happened.

Edited June 29, 2021 by Docsnuggles