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Bat Buss

R

rwarre

Well Known Member
I am not planning on having a battery bus in my wiring plan. If I do not have any electrical items on without the engine running is this ok. I plan on using flashlights or the battery powered light that is on my headset at night before start up. My EFIS is connected to the master switch and comes on at the same time as everything else. The EFIS has a two hour rechargeable back up battery. Am I missing something? Thanks, I really appreciate suggestions.
 
Just wondering how you're going to start the engine? The Pitt's M12 that I hangar with, uses a high pressure scuba tank for air starts. Of course that takes a system to send air to each cylinder in succession.

Other than that, if you have an alternator, then you need a battery to act as a reservoir.

L.Adamson --- RV6A

edit: Never mind, now that PCHunt has probably explained the correct situation... :)
 
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Maybe "rwarre" meant he wasn't planning to have a HOT battery bus???? i.e.: everything goes off with the master switch off. :confused:
 
Correct

Thanks for correcting my ignorance. You're right in that everything will go on and off with the master switch. Thanks
 
Technically speaking, you DO have a "Battery Buss" - it's just that short length of "hot" wire that goes from the battery to the Master Solenoid. If you ever need to have something in the "Always On" category, you just connect it there (through circuit protection, of course), and you can claim to have one of those fancy "Battery busses"....

Paul
 
So the question is, are you forgetting anything?

rwarre said:
I am not planning on having a battery bus in my wiring plan. If I do not have any electrical items on without the engine running is this ok. I plan on using flashlights or the battery powered light that is on my headset at night before start up. My EFIS is connected to the master switch and comes on at the same time as everything else. The EFIS has a two hour rechargeable back up battery. Am I missing something? Thanks, I really appreciate suggestions.
Click to expand...

That depends. Do you have anything that needs a hot "memory" wire? If so, than just run that to the hot side of the main relay with an inline fuse for circuit protection, as Paul suggested. If you have an endurance bus, the supply wire for that will need circuit protection (breaker or fuse) I just checked my main wiring schematic. Both my MicroEncoder and MicroMonitor have memory wires. My battery bus only has 6 items on it.
I'll bet your EFIS needs a battery hot wire to keep it's internal battery charged. ;)
Charlie Kuss
 
Radios???

rwarre said:
snipped Am I missing something? Thanks, I really appreciate suggestions.
Click to expand...

What about your radios? Most modern radios use digital tuning and have a feature to allow you to program radio stations into memory. I'm sure they have a "battery hot" wire to retain that memory.
Charlie Kuss
 
...and a related question

What type of local circuit protection would be used on the hot wire coming from the battery? This of course would be on the forward side of firewall.
As mentioned before, items on my batt buss list would be keep alive, cabin light, cig. lighter power port, etc.
Would these from B&C be robust enough?
http://www.bandc.biz/index.asp?PageAction=VIEWPROD&ProdID=9
http://www.bandc.biz/index.asp?PageAction=VIEWPROD&ProdID=10

I would like to avoid the ANL type if possible.

Note:
I "may" also hook my Lightspeed EI power to the buss also so I don't have to go directly to the battery. Still trying to decide if that is wise or not.

Thanks for thoughts / experience on this.
 
More Info please

7A_@ABI said:
What type of local circuit protection would be used on the hot wire coming from the battery? This of course would be on the forward side of firewall.
As mentioned before, items on my batt buss list would be keep alive, cabin light, cig. lighter power port, etc.
Would these from B&C be robust enough?
http://www.bandc.biz/index.asp?PageAction=VIEWPROD&ProdID=9
http://www.bandc.biz/index.asp?PageAction=VIEWPROD&ProdID=10

I would like to avoid the ANL type if possible.

Note:
I "may" also hook my Lightspeed EI power to the buss also so I don't have to go directly to the battery. Still trying to decide if that is wise or not.

Thanks for thoughts / experience on this.
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What size wire are you bringing through the firewall? That will determine your options for circuit protection. For smaller gauge wires (22AWG to 16AWG), your first link would work. The second like would also work, but has the downside of having molded in PVC insulated wire. Common, commercial grade PVC insulation does not have the abrasion resistance or resistance to heat that Tefzel insulation gives you.
If you plan to bring more than one small wire through the firewall, installing a 6 fuse, fuse block like the one shown in the link below might be a better idea. See

http://www.steinair.com/fuseblocks.htm

ANL fuses are a "fast acting" type. They are only for use on the charging system. The idea is for the fuse to blow quickly (in an over voltage event) to prevent damage to the avionics in the instrument panel. In all other situations, the fuse or circuit breaker protects the wire, not the appliance down circuit.
For the feed wire going from the battery to my main fuse blocks, (6AWG) I selected Littelfuse's MidiFuse series fuse holder and corresponding fuse. See

http://www.littelfuse.com/part/498900.html

This holder uses a slow acting fuse, so it won't easily be blown by transient voltage spikes. There are plenty of other methods to protect larger wires, including self resetting circuit breakers.

Charlie Kuss
PS I got my holder and fuse for free. LittelFuse has a place on their site to request free samples. ;)
 
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Hey, thanks Charlie.

I'll probably put the fuse within a few inches of the bat terminal and then a wire to the 6-place holder, as you mentioned, on aft side of firewall. I still need to add-up my amps to determine the wire & fuse size. I really like the Little brand fuse you linked to...especially the slow-blow and the physical size. I had planned for another ANL for the wire (6AWG) going to the main buss. But the Little fuse does look like the better choice.

Also thanks for the heads-up on the PVC stuff. I just shake my head when I already know things like that, but just don't always think about them when I need to. :confused:

gittin' there....slowly

Sam
 
LittelFuse

Sam,
I prefer the LittelFuse brand over Amp for another reason. The fuse holder that Amp has for those ANL fuses is open. If something metal were to come in contact with the terminals, you would get a short circuit. The LittelFuse holders come with a cover. The cover has Punch Outs, to allow the wires to go in and out with the cover on. The base and cover are made from glass re-enforced plastic.
I use an ANL fuse for my alternator. However, I installed it into LittelFuse MagaFuse holders. I had to notch the ANL fuse slightly, as the center to center distance on the MagaFuse holder is slightly shorter than Amp's ANL fuse holder. MagaFuses are used in some late model Fords. I know they are used in 1998 and later Expeditions to protect the main power wires. MegaFuses come in 60 amp to 250 amp ratings. See

http://www.littelfuse.com/searchresults.html?Ntt=fuse+holder+for+Mega+series

Charlie
 
Thanks.

chaskuss said:
For the feed wire going from the battery to my main fuse blocks, (6AWG) I selected Littelfuse's MidiFuse series fuse holder and corresponding fuse. See

http://www.littelfuse.com/part/498900.html

This holder uses a slow acting fuse, so it won't easily be blown by transient voltage spikes. There are plenty of other methods to protect larger wires, including self resetting circuit breakers.

Charlie Kuss
PS I got my holder and fuse for free. LittelFuse has a place on their site to request free samples. ;)
Click to expand...

Charlie, this is exactly what I have been looking for, although I did not even know it until I saw your post.

I am setting up a fuse block for the seat heaters, power outlets, and ANR power for my RV 10. Due to the battery being behind the baggage bulkhead, I did not want to put the fuse block back there, but I didnt want to run an always hot lead under the baggage floor, forward to the fuse holder, which is going to go by the back seat.

All of the inline fuse setups I had looked at just didnt pass the TLAR test, but this one is just perfect for my needs.

Thanks a bunch
 
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