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What's on your TCW IBBS Backup Battery?

snoop9erdog

Well Known Member
What makes sense and what is too much?

TCW 6AH= 8A Max Continuous all outputs and 12a Peak Transient

When considering the load analysis:

Both 10" screens, GEA24, GSU 25, GTN 625, GAD 29, & Autopilotw/507 = 8.55 amps and more than max continuous. Critical to stay below 8a?

Both 10" screens, GEA24, GSU 25, GTN 625, & GAD 29 = 7.63 amps

Only one 10" screen, GTR 200B, GEA24, GSU 25, GTN 625, GAD 29, & Autopilotw/507 = 7.15 amps

G3X Instl Manual provides interconnect for both screens, GEA 24, and GSU 25 with regarding to the TCW.

Thoughts?
 
The less you draw off the IBBS the longer it lasts.
My belief was it was emergency back up only. Only items meeded to keep me alive.
GDU-PDF, GEA and GSU are the only items I have on mine. I want ot be able to keep it upright and get it on the ground. I have an e-buss with quite a bit more but that is if I lose the alt and am running off of the battery only. IBBS is last resort.
 
Thx Mark. Love your 9.

Have you been satisfied with the TCW battery? It senses main battery voltage and then kicks on, correct?

Do you do as the manual says....power up everything first and leave ON?
 
Concur with Jeff, plus the GAD29. No need to power both screens , let alone the autopilot. If I?m in the soup, I?m getting on the ground. If I?m VFR, I?d kill the 625 and whatever else I could to make my destination if able.
 
I agree. Great comments Shane and Jeff. A G5 with it's own backup battery is in the plan as well.

I'll likely take the gtr200 off and have a handheld comm for backup. The autopilot would be nice since it's amo load is minimal compared to other LRU's. I may add it but can shed it easily to conserve power if need be.

1 screen on the TCW is probably the way to go. I'll power up the other side thru the GAD 27 "keep alive power".
 
1) EarthX ETX900 Main Battery for the whole airplane.

2) TCW Battery for the PFD, GTN, GEA, and GSU in accordance with TCW's drawing:

https://www.tcwtech.com/IBBS-12v-6ah_GTN & G3x.pdf

3) G5 with it's own backup battery.

Having the GTN on there is interesting and presents a pretty heavy load on the TCW, when transmitting the unit may draw more than the 4 amps listed (10 amp breaker on the com side and 7.5 on the nav side) and generally uses 18ga wire to support that current flow. The feed thru CB on the TCW is shown as 10amp to carry everything?

Personally... I use the back-up battery for PFD, ADAHRS, GEA24 only.
If you really want a GTN or com on a backup I would use a separate TCW for this or larger backup source.
 
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Having the GTN on there is interesting and presents a pretty heavy load SNIP...

The GTN-650 is a power hog. If you must rely on a backup battery then dump the GTN-650 from the backup battery load, leave COMM #2 on the backup battery. Now add the backup battery(s) for whatever EFIS system you have.

Sorry to beat a dead horse, but shifting from a plethora of backup batteries to just two PC625s or similiar provides options for better redundancy and electrical reserves.

Carl
 
I have a GTN 625.....so no comm. Specs say it uses 1.8 amps.....max 2.8 (but I believe that applies to the 650 as well)

I'll only have one GTR200B for my comm. If i'm in the soup shooting an approach, wouldn't the priority be to keep the GTN for navigation over having the comm? Would have a handheld as backup for comm.

Explain your duel battery system Carl. I'm assuming you run off a main batt, then have diodes/switch to trickle charge and activate the second/backup? In this setup...is it far superior to a TCW because of the additional endurance AH capacity? Expound.

If my main Alt goes TU...I have at min an hour on main batt until it goes to min voltage to trigger the TCW...at which point I'd have at least 45min - to 1hour with the IBBS to get on the ground. More if I pull a few breakers and a =m able to shed the GTN. Depending on how much I've already flown prior to the electrical issue.....I'm probably going to start having fuel issues before I run out of electrons. ?? No?
 
Ed,

PM me your email address and I?ll provide details on the dual battery install. It is flying on four RVs over the last decade and has proven itself.

Carl
 
Dual Main Battery Sys

Hello Carl,

I?m very interested in your system. I?m still at the the ?canoe? stage, but starting to think ?bout the wiring, among other things.... Thanks

Charlie
 
Thx Mark. Love your 9.

Have you been satisfied with the TCW battery? It senses main battery voltage and then kicks on, correct?

Do you do as the manual says....power up everything first and leave ON?

Hey Ed,
Sorry for the late reply. I like the TCW system and would do it again.
I have not checked the capacity with a load test in a while but this thread has reminded me to do that.
I wired per the manual with a toggle switch that is left on during all ops.
I also use an E-buss through a diode.
 
Having the GTN on there is interesting and presents a pretty heavy load on the TCW, when transmitting the unit may draw more than the 4 amps listed (10 amp breaker on the com side and 7.5 on the nav side) and generally uses 18ga wire to support that current flow. The feed thru CB on the TCW is shown as 10amp to carry everything?

Personally... I use the back-up battery for PFD, ADAHRS, GEA24 only.
If you really want a GTN or com on a backup I would use a separate TCW for this or larger backup source.

Walt,
Should one put the GMU 11 on the IBBS as well or would that be unnecessary?
 
They shipped me a TCW IBBS 3 AH as backup with my new AFS 5400. I have elected instead to use my second Pc680 as backup in case of alternator failure. If my alternator dies...I'll just flip the second master switch and bring that backup battery online. 16 AH instead of 3 AH backup. Not sure I see a need for the IBBS.
 
I have the 3ah TCW IBBS, in an IFR panel I fly IFR regularly. This is what I have...

1. GDU 370
2. GDU 375
3. #1 GSU 25
4. GEA 24
5. GPS 175
6. GMC 307 (no AP servos but to control FD, draws only mA)
7. GAD 29
8. GTX 335

Total draw is calculated just under 5A, but tests show a little less as the 3ah IBBS lasted 59 min.

I went back and forth over a couple things:
1. COM...big variable draw. Decide this is an emergency I can squawk 7700 and use my backup handheld if needed.
2. GMC 307...not needed but a nice item during stressful situation, and it draws like 180mA
3. Both GDUs...there wasn't a need but I wanted the brown-out capability during start.
4. Decided against the GSU 25 #2 because of the additional load and the GPS 175 has an AHRS feeding ForeFlight if 10^-9 rears it's ugly head

I opted for the IBBS over a second battery because of weight. The IBBS is an emergency...I have and hour to get in the ground...plenty of time in the lower 48. Of course, the way my system is designed, things would need to be pretty bad to get down to just the IBBS. Alternator and battery failure, or a significant short prompting isolating both the main and endurance buses. If you use my IBBS test to gauge my healthy battery life, I would guess my battery would last about 2 hrs longer than my fuel endurance. Thats why I didn't think there was a need for another heavy battery.
 
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COM

I have the 3ah TCW IBBS, in an IFR panel I fly IFR regularly. This is what I have...

1. GDU 370
2. GDU 375
3. #1 GSU 25
4. GEA 24
5. GPS 175
6. GMC 307 (no AP servos but to control FD, draws only mA)
7. GAD 29
8. GTX 335

Not arguing against your lineup at all... just curious as to why you want to have a transponder in an emergency instead of your COM. I am currently installing my IBBS and need to make some decisions and appreciate your help. I don't want to revert to my handheld COM during an emergency. The GTX shouldn't be required if we're down to the IBBS.... does the GTX make a big difference if we need ATC help to get back on the ground?
 
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Not arguing against your lineup at all... just curious as to why you want to have a transponder in an emergency instead of your COM. I am currently installing my IBBS and need to make some decisions and appreciate your help. I don't want to revert to my handheld COM during an emergency. The GTX shouldn't be required if we're down to the IBBS.... does the GTX make a big difference if we need ATC help to get back on the ground?

It came down to loads...the load during transmission was going to put me into a 6aH unit even without the GTX, and the transponder I can always shut off once I get the handheld spun up to talk. I also have an archer wingtip antenna and headset jacks solely for my handheld so it’s pretty much a panel mounted com...just need to switch my headset and turn on
 
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I will Have the IBBS 6ah battery.

On back-up battery
  1. PFD
  2. MFD #1
  3. GEA 24
  4. GSU 25 #1
  5. GMU 11

Not on back-up battery
  • GNX 375 -not needed, PFD has GPS.
  • Comm - not needed, have handheld.
  • A/P - I'm getting on the ground as soon as able.
 
Not much!

I've got my GRT EFIS Sport EX and the GRT EIS 4000 on my IBBS 3ah. I bought it just to ensure that I have engine monitoring at startup. If something happens where I don't have electrons, I'll just land. My RV-8 is VFR only, obviously.
 
Quick question on backup batteries. Are you doing a dual diode connection to separate main power with backup power? I'm curious how to wire things that only have 1 power line to two sources. I'm Skyview so both HDX's have their own battery, but I'd like my 175, transponder and possibly radio to have backup options. Looking into TCW as an option for me.
 
Dual diode part number: 863-MBRF20L45CTG $1 each. Buy one for each load. 10 amps max if kept cool.
Use heat conductive paste between diode and metal surface. Connect center pin to load.
 

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The TCW IBBC backup battery has the ability to provide pass through power in addition to battery backup. So you only need one power input to the device you are connecting. There are wiring diagrams in the IBBC installation instructions that's available on TCW's website.
 
I have two of these - one of each size. I use one for my avionics - just my dual G3X system and engine monitor (no autopilot), and the other to back up my Lightspeed ignition. They work great
 
Do you all have any thoughts about feeding the GTR 20 through IBBS for COMM in case of losing the main power?
 
Do you all have any thoughts about feeding the GTR 20 through IBBS for COMM in case of losing the main power?

My IBBS does not feed my GTR 200 and SteinAir designed my avionics package interconnect.
I’m guessing it’s because of the high amp requirements during transmission.
 
One mode of IBBS operation that is rarely discussed but used every time you fly is it's ability to keep Avionics powered if/when bus voltage drops during starting.

The GAD27 has a "Keep Alive" circuit that does the same thing if the main bus is powered.

Using the capability of 2 IBBS 3Ah batteries and a GAD27 you can eliminate an Avionics bus (which is recommended by Bob Nuckholls in his AeroElectric Connection book) and be full up IFR with main/stdby alt and main batt fail (highly unlikely).

My IBBS/GAD27 system:
IBBS 1: G3X PFD1, MFD, GEA24, GSU25+GMU11
IBBS 2: GTR20-1, GTN625, GAD29, GTX45R
GAD27 KA: PFD2, GTR20-2, GMA45R

This allowed me to keep my electrical system simple.
POWER DISTRIBUTION:
1 Bussman 15401-2-0-1-0A fuse/relay panel (40 fuses, 10 relays)
Various mini ATM fuses, 2-diode/fuse for single input devices (GTR20, GTN625)
BATTERIES:
1-Earthex ETX900-VNT
2-IBBS 3aH
1-G5
ALTERNATORS:
1-B&C 460H
1-Monkworkz MZ-30L

After running the numbers this stood out as the simplest, lightest and least costly redundant electrical system. It has proved very reliable in many hours of flying my RV-10.
Note: I use mags so my engine doesn't care about electricity. Plan accordingly if you are using electronic ignition.
 
I will Have the IBBS 6ah battery.

On back-up battery
  1. PFD
  2. MFD #1
  3. GEA 24
  4. GSU 25 #1
  5. GMU 11
Not on back-up battery
  • GNX 375 -not needed, PFD has GPS.
  • Comm - not needed, have handheld.
  • A/P - I'm getting on the ground as soon as able.

My list will be similar. I previously (pre-edit) wrote that I'd probably skip the GMU and have the GAD 29 in place of the MFD, but after working on my pin to pin diagram, backing up the GAD 29 doesn't seem necessary. The GAD 29 is shown on the TCW installation docs, but all it does for me is an ARINC conversion to get NAV data from the GNX 375 to the CAN Bus, and air data back. I only have the 3ah battery, so still not sure about adding the GNX 375, but I'd like to. 1.2A typical draw though. The GAD 29 isn't a candidate for me anymore.

I think I'd rather lose Comms completely versus losing weather and traffic from the GNX 375. Like you said, there are hand-helds, but also cell phones and last, regs to follow when radios go out.

One mode of IBBS operation that is rarely discussed but used every time you fly is it's ability to keep Avionics powered if/when bus voltage drops during starting.
<snip>
BATTERIES
1-G5

I definitely like the idea of the brown-out protection, if only to keep my wife from asking "what was that?" when a screen reboots.

I have a G5, but given the reported issues with the G5 battery, I'm struggling with why I'd want the battery. If you already have an IBBS or two to power displays, doesn't that mean the G5 battery is unnecessary? I'm probably missing something, but with the poorly rated G5 battery at $235, I think I'd rather install another 3ah IBBS ($249) if backing up the G5 is critical. Yes...extra work, wires and a switch, but more utility too.
 
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