RV 8 AFT Battery Cable Routing

[Lkitson]

Here are some photos of how I routed the cables in my 8. Note: I had to fabricate a spacer to move the contractor outboard to line the stud up with the cable.

[Lkitson]

Originally Posted by TimR

I'm going to jump in here. I'm at the same point in my -8 QB. Where did you all mount the master and starter relays? I need to get my hands on OP10 and 11, but looking to the brain trust right now. Right now, I have the master relay mounted to the battery tray, but I've been pondering placement of the starter relay. The master relay could be moved to the firewall and then place both relays under the hood. Thoughts?

If the master contactor is on the firewall the cable from the battery to the firewall will always be hot and you won't be able to cut power to it in the event of a short. That's why I put it on the battery tray. I put the starter relay on the firewall.

[TimR]

Originally Posted by Lkitson

If the master contactor is on the firewall the cable from the battery to the firewall will always be hot and you won't be able to cut power to it in the event of a short. That's why I put it on the battery tray. I put the starter relay on the firewall.

Excellent point! Thanks so much

[Vbug]

Grounds to lower longerons, power wires along mid longerons(armrest level). If you use welding cable getting around the flap actuator is a non issue. I had no room to run these cables on the floor.

[Carl Froehlich]

Rod,

No overboard vent on your batteries?

Carl

[Vbug]

I don't recall that being an option when I bought mine. When replacement time comes I will switch to vented.

[vomatic]

Carl, can you expand on your question? Does a sealed battery need to be vented (i.e. 680) or just lithium? Do you have any pics?

[Carl Froehlich]

Originally Posted by vomatic

Carl, can you expand on your question? Does a sealed battery need to be vented (i.e. 680) or just lithium? Do you have any pics?

Just lithium. For you Earthx battery people mounting the battery(s) anywhere aft of the firewall this would be the something like the EXT-900-VNT (VNT for vent).

Nothing to stop you from using a non-vented EarthX - but watching the EarthX videos it seems they recommend it. If I ever was to use an EarthX and mounted it aft of the firewall I would only use the vented version.

For my RV-8 I mount one PC-625 battery in the the forward baggage well, the second in the normal aft location. Both are mounted using modified stock Van’s RV-8 battery trays. I did this as my W&B calculations (IO-360-M1B, Hartzell BA prop, Grove gear) worked out best this way. 370 hours on the plane and I’m very happy with the W&B.

Carl

[dmn056]

I'm also planning on two aft batteries, with two power cables running forward. Because of the weight, I was thinking about using aluminium wire.

Does anyone have any experience with aluminium wire in this application? I'd welcome any information or advice.

Thanks for your help

[bob865]

Originally Posted by Carl Froehlich

Just lithium. For you Earthx battery people mounting the battery(s) anywhere aft of the firewall this would be the something like the EXT-900-VNT (VNT for vent).

Nothing to stop you from using a non-vented EarthX - but watching the EarthX videos it seems they recommend it. If I ever was to use an EarthX and mounted it aft of the firewall I would only use the vented version.

For my RV-8 I mount one PC-625 battery in the the forward baggage well, the second in the normal aft location. Both are mounted using modified stock Van’s RV-8 battery trays. I did this as my W&B calculations (IO-360-M1B, Hartzell BA prop, Grove gear) worked out best this way. 370 hours on the plane and I’m very happy with the W&B.

Carl

I'm a long way from working on electrical, but I'm curious why you're running two PC-625s. Is one not enough? I assume the 625 represents cranking amps. Do you need the power from two? Is 625 amps not sufficient for starting? Are you running them in parallel so you run higher current and lower voltage or series for higher voltage and lower current?