Battery Range?

[Rudel_chw]

Hi,

I was editing a detailed cold start mission, with all checks and many audio explanations, but found out that the Viggen battery only lasted for 30 minutes (until step 38 of the procedure). Is this as per real life, or can it be considered a bug?

 

Eduardo

 

PD: This was the mission I was trying to do ... on minute 30 the battery goes out of juice

 

 

 

Edited November 8, 2023 by Rudel_chw

[razo+r]

I'd guess 30 minutes might be a bit on the short side for a battery, but then again if you need that long for startup, you might want to look into using the ground power during that time.

[Rudel_chw]

24 minutes ago, razo+r said:

you might want to look into using the ground power during that time.

 

My intended plot for the mission was to teach both alternatives: A Battery-only Cold Start; and a GPU-powered Cold Start, both last about 60 minutes due to the instructor explanations about what each system does. Guess I will have to change the plot and do only a GPU cold start  

[TOViper]

Hey Rudel!

Damnit, you spent so much time in preparing good training material, and now it doesn't work as planned.
What we maybe could do is - at least to avoid other users from making this mistake someday somewhere somehow at some stage - put this information to the manual.
I think it is worth putting this information, e.g. to the procedures chapter for cold start without groundpower, maybe as a CAUTION.
How long was the time exactly, and which systems did you turn on (or did not turn on)?
 

[Rudel_chw]

23 minutes ago, TOViper said:

Hey Rudel!

Damnit, you spent so much time in preparing good training material, and now it doesn't work as planned.

 

Hi,

The original mission had two aircraft slots: one for Cold Start with Ground Power and another for Cold Start with just battery.  What I'm now doing is leaving the mission with just the Ground Power slot and naming it "M02 Detailed Cold Start", and then copied the mission as "M01 Abbreviated Cold Start", removed all checks and steps not essential for DCS and set it to use just battery  ... so the training material is not lost and the student pilot just chooses which of the two he wants to fly (or both) ... I hope to have both ready tomorrow

 

23 minutes ago, TOViper said:

What we maybe could do is - at least to avoid other users from making this mistake someday somewhere somehow at some stage - put this information to the manual.
I think it is worth putting this information, e.g. to the procedures chapter for cold start without groundpower, maybe as a CAUTION.

 

 

Agree, just a note alerting the user that the maximum battery endurance is about 22 minutes .... my only doubt is if that value is realistic or if this is kind of a bug.

 

23 minutes ago, TOViper said:

How long was the time exactly, and which systems did you turn on (or did not turn on)?

 

let's see .. Battery ON at 8:41

Master alarm at 30:47 ... probably a low voltage alert.

Battery runs out at 31:18 .... so the total time on battery was: 31:18 - 8:41 = 22 minutes 37 seconds was the battery range ... pretty low if you ask me

 

[TOViper]

3 hours ago, Rudel_chw said:

 

Hi,

The original mission had two aircraft slots: one for Cold Start with Ground Power and another for Cold Start with just battery.  What I'm now doing is leaving the mission with just the Ground Power slot and naming it "M02 Detailed Cold Start", and then copied the mission as "M01 Abbreviated Cold Start", removed all checks and steps not essential for DCS and set it to use just battery  ... so the training material is not lost and the student pilot just chooses which of the two he wants to fly (or both) ... I hope to have both ready tomorrow

 

 

 

Agree, just a note alerting the user that the maximum battery endurance is about 22 minutes .... my only doubt is if that value is realistic or if this is kind of a bug.

 

 

let's see .. Battery ON at 8:41

Master alarm at 30:47 ... probably a low voltage alert.

Battery runs out at 31:18 .... so the total time on battery was: 31:18 - 8:41 = 22 minutes 37 seconds was the battery range ... pretty low if you ask me

 

Sounds reasonable to me (I am not an electric expert )... its just 24V with 37 ampere hours, so if you take 1.5 Ampere for 1 hour, or 3 Ampere for half an hour ... and then the battery is near its end ... (hope I calculated correctly).

edit: this calculation was total bullshid. You can take 37 Ampere for one hour, and 74 Ampere for 30 minutes, and about 100 Ampere for 20 minutes.
100 Ampere at 48V equals 4800W, or 4.8kW. Hm. Only avionics take 4.8 kW ... could be?!?!

edit2: i tested this, after battery on and nothing else the battery died after 1400 seconds, whereas after 1300 seconds the master warning came up (but with no alert message on the warning panels).

Edited November 9, 2023 by TOViper

[Rudel_chw]

18 hours ago, TOViper said:

edit: this calculation was total bullshid. You can take 37 Ampere for one hour, and 74 Ampere for 30 minutes, and about 100 Ampere for 20 minutes.
100 Ampere at 48V equals 4800W, or 4.8kW. Hm. Only avionics take 4.8 kW ... could be?!?!

edit2: i tested this, after battery on and nothing else the battery died after 1400 seconds, whereas after 1300 seconds the master warning came up (but with no alert message on the warning panels).

 

Thanks for correcting your raw initial estimate ... meanwhile I removed all the check steps of the procedure, cutting the time between Battery start and Engine Start to 17:20 minutes, only to find out that the battery at that point has not enough juice to power up the GTS, it dies 7 seconds after I flick the engine start switch 

Seems to me that the only way to edit this battery start mission is to move some steps out of order on the procedure, for example setting up the radar, rwr, and the armament ... there seems to be no good reason to have those steps (24, 37, 44, 45 & 46 on the manual) done before engine start, they could easily be done after the generator is running.

I'm a bit frustrated at the moment, so I will set the mission aside for a bit and instead focus on the detailed one, with ground power use.

I would love to hear from some of the Viggen experts, like @RagnarDa or @renhanxue ... because I'm unable to report this low battery endurance as a bug, since I don't know if the real aircraft was really that way.

 

 

[Rudel_chw]

18 hours ago, TOViper said:

its just 24V with 37 ampere hours

 

I know it is not the same model as we have on DCS, but the english Flight Manual Vol 1 of the JA37, says that the battery has a capacity of 22 Ah, not 37 (Chapter 1, section 3, page 23), so maybe this battery endurance is as per the real aircraft  

[razo+r]

4 minutes ago, Rudel_chw said:

 

I know it is not the same model as we have on DCS, but the english Flight Manual Vol 1 of the JA37, says that the battery has a capacity of 22 Ah, not 37 (Chapter 1, section 3, page 23), so maybe this battery endurance is as per the real aircraft  

The swedish manual for the AJS sais 34 Ah: https://tanks.mod16.org/2016/08/29/saab-aj-and-ajs-37-viggen-flight-manuals-sfi/

 

[Rudel_chw]

1 minute ago, razo+r said:

The swedish manual for the AJS sais 34 Ah

 

Ok, thanks for the data, tough it seems curious to me why the JA version would use a much smaller capacity.

[MAXsenna]

Out of curiosity. Should one be able to do a full startup check on batteries only? The included startup mission, while short, have you connect ground power, and staying on battery for 30+ minutes doesn’t seem valid to me. This is 60/70s battery tech after all, isn't it. Not sure if those batteries liked to be fully drained.
Cheers!

Sent from my SM-A536B using Tapatalk

[Rudel_chw]

50 minutes ago, MAXsenna said:

staying on battery for 30+ minutes doesn’t seem valid to me.

i reduced my time to 17:20 and the starter died on 7 seconds

[MAXsenna]

14 minutes ago, Rudel_chw said:

i reduced my time to 17:20 and the starter died on 7 seconds

Ah, missed that. To be honest, I usually forget ground power, so I haven't noticed the battery dying, yet. Hopefully Heatblur can comment.

[TOViper]

All in all, and what ever the capacity of the battery is/should be, a rework of normal procedures for the DCS Viggen could be done someday if deemed necessary.
On the other hand, 99.956721% of all DCS pilots already have/perform their own procedures/checklists, and they finally become airborne .
If you know what to do (and are trained a bit), it takes about 3-5 minutes to complete all steps (depending on what you really need) starting in cold & dark config.

IMHO it might be more important to inform pilots about the limits, and maybe give them some rough numbers, and that's it.
Situations which require the pilot to start from battery only (without having ground power available) are very seldom, but for exactly theses seldom cases a CAUTION with some little text should be enough ... pilots can read (at least this is what I heard about pilots in general ... )

[Rudel_chw]

1 hour ago, TOViper said:

it takes about 3-5 minutes to complete all steps (depending on what you really need) starting in cold & dark config.

Actually, the procedure has 48 steps between turning on the battery and switching the engine start … that leaves the task of explaining 3 steps per minute to the student pilot, and even if one can manage that it still would result on a drained battery by the jet starter  honestly no way to succeed unless I start skipping non-essential steps.

[TOViper]

2 hours ago, Rudel_chw said:

Actually, the procedure has 48 steps between turning on the battery and switching the engine start … that leaves the task of explaining 3 steps per minute to the student pilot, and even if one can manage that it still would result on a drained battery by the jet starter  honestly no way to succeed unless I start skipping non-essential steps.

What about talking about the procedure, and then let the student do the steps (and support these by showing the hightlights only and the order to do the step ...)?
Could be some sort of "train to proficiency" lesson ...

[MAXsenna]

2 hours ago, Rudel_chw said:

Actually, the procedure has 48 steps between turning on the battery and switching the engine start … that leaves the task of explaining 3 steps per minute to the student pilot, and even if one can manage that it still would result on a drained battery by the jet starter  honestly no way to succeed unless I start skipping non-essential steps.

Are the procedures actually different between ground power and battery? If no, you actually only need a long one, and then a short one for battery maybe?

Edit: Right, I re-read your original idea of two slots in "one mission" with two paths. That's actually a pretty cool idea!

[Rudel_chw]

8 minutes ago, TOViper said:

What about talking about the procedure, and then let the student do the steps (and support these by showing the hightlights only and the order to do the step ...)?
Could be some sort of "train to proficiency" lesson ...

 

Thanks, will consider this approach in case the audio-trimming that I'm currently doing doesnt work 

2 minutes ago, MAXsenna said:

Right, I re-read your original idea of two slots in "one mission" with two paths. That's actually a pretty cool idea!

 

Thanks, but with this issue I have discarded that approach and instead I'm editing two missions: M01 with an abbreviated battery-based Cold start, and M02 with a detailed cold start with every check on the book and using ground power  ... lets see how it goes 

[TOViper]

10 hours ago, Rudel_chw said:

 

Thanks, will consider this approach in case the audio-trimming that I'm currently doing doesnt work 

 

Thanks, but with this issue I have discarded that approach and instead I'm editing two missions: M01 with an abbreviated battery-based Cold start, and M02 with a detailed cold start with every check on the book and using ground power  ... lets see how it goes 

Really looking forward!

[Rudel_chw]

8 hours ago, TOViper said:

Really looking forward!

 

Hi  ... finally managed to finish editing my Abbreviated Cold Start mission, managing to use only 12 minutes of battery. Had to add a warning, because if the user distracts a bit then it can easily not have enough battery to complete the start:

 

 

I will now finish the longer version of it, using ground power. 

Cheers,

 

Eduardo