Got to drill big hole... What might I hit?

[richard5933]

I'm installing a new battery box vent on my 4108. Battery box is in the rear driver side bay.

I need to drill a 2-3/8" hole through the floor of the bay for the exhaust.

I've checked under the intended location. Nothing there.

My concern is what might be hidden inside the floor of the bay. I'm guessing nothing, but I thought it best to ask in case someone knows of something that GM ran between the layers of the belly of the bus.

[Ed Hackenbruch]

I would suggest 2 things....  1. drill a small hole thru the upper layer and us a boroscope to look inside.  2. Drill your hole towards the outside wall as much as possible. If they ran anything thru the bottom of the bay it is probably running down the centerline of the bus.

[pabusnut]

Richard,

If your 4108 bays are like my 4905, which I am 98% sure they are---you will hit nothing.

My 4905 came with a retractable tag axle in the 3rd bay behind bay doors so I had to fabricate a floor there when I removed the tag(actually a bogie).  The structure is just corrugated aluminum decking that is in a 1-1/4" channel front and back, with rivets holding the tops and bottoms of the flats on the corrugation. 

All the piping and wiring runs through the channel in the bay ceiling.

Steve

[chessie4905]

Thats right. Till you get through the heavy corrugation, the hole will be about 2 1/2 deep till you are totally through. Try to center guide bit to go through centered between corrugations, otherwise hole cutter might catch unevenly. Or run center guide bit through center of one corrugation. Second option would be best of two choices, as guide bit would still provide centering clear the way through. Hang onto that drill or it may be a**hole and elbows. Since it is a custom conversion, double checkfor any wiring ot tubing entering or exiting in that area. Who knows what they did. I know GM didn't run anything there. When done, line the hole with some kind of pipe to keep fumes from following inside of channel.

[TomC]

Use AGM battery and you don't need a vent hole.

[richard5933]

Use AGM battery and you don't need a vent hole.

Looked into the AGM. Need more batteries to get the same capacity, especially, as well as more money. Just wasn't in the budget. With the Trojan Hydrolink it's not difficult to keep battery bank topped off, and the vent is on an automatic voltage controlled switch to only come on when charging.

[jcussen]

AGM's are a little more, but are generally better for deep discharges if using as your house batteries. The biggest wet cell 8d I have seen is 225 amp/hrs, but you can buy Lifeline AGM 8d"s, [same physical size] that are good for 255 amp/hrs.

[eagle19952]

Looked into the AGM. Need more batteries to get the same capacity, especially, as well as more money. Just wasn't in the budget. With the Trojan Hydrolink it's not difficult to keep battery bank topped off, and the vent is on an automatic voltage controlled switch to only come on when charging.

never ever trust an auto fill.
never ever trust an auto vent
never ever put a device that has the potential to ignite in an explosive atmoshere.
i built a few aircraft refuelers
and maintained more.
there are regs for these standards.
boat bilges come to mind.
DEKA sells AGM blems.
get to know your distributor
were i you i'd rethink.

[buswarrior]

Yes, please use an ignition-proof marine bilge pump or similar for your hydrogen gas exhaust.

Sparky cheapy fan go boom.

Some of that marine stuff is expensive for a good reason...!

Happy coaching!
Buswarrior

[richard5933]

Not my first trip to the rodeo hooking up a battery box. While I understand that AGM would be more ideal, for now I'm going with the flooded-cell L16 batteries.

The vent being used is: http://zephyrvent.com/

It's to be located outside the battery box, as will all its wiring. There are air intake vents at the bottom of the box, and the powered vent at the top.

The lid of the battery box will be acrylic so the physical condition can be monitored easily. The Hydrolink will fill the batteries easily, and it included an indicator to let me know that the water actually makes it to the cells. I used this system on our last coach and it worked well. I did open the battery covers periodically to confirm proper function.

I'll post photos when the battery setup is complete.

[buswarrior]

That's a lovely battery venting solution!

What other secrets are you keeping from the busnuts?

happy coaching!
buswarrior

[richard5933]

That's a lovely battery venting solution!

What other secrets are you keeping from the busnuts?

happy coaching!
buswarrior

You'll have to wait for the movie...

[TomC]

On my bus, I have 2-8D AGM Lifeline batteries (510amp/hrs). My first set went 7 years (they have 5 years warranty). I can tell you in that 7 years I did virtually nothing to the batteries-was as though they weren't even there-not even having to clean the terminals once. I now have my second set that have been in for 2 years and yet to do anything to them.
On my truck, I am going to use 4-L16 AGM Lifeline batteries for a total of 800amp/hrs @ 12v. Most starting batteries are sealed too now. Dealing with watering batteries, hydrogen out gassing, cleaning terminals, venting properly is just not my cup of tea when trying to be a tourist. Spend the extra money, you won't be disappointed. Good Luck, TomC

[chessie4905]

Unless they go into one of those thermal runaway meltdowns.

[eagle19952]

Unless they go into one of those thermal runaway meltdowns.

not if they aren't stuffed in the bowels of the bus and have adequate space and seperaytion...an inch or two is fine.

a trade off i am willing to make.