Storage Bay Weight limits

[solardude]

Hello everyone, I am yet another over ambitious Bus Nut who has taken on a conversion. I have a 1993 MCI 102C3.
I'm hip deep into this project now, I am in-process of building the Battery Bank Storage, I am planning for six 8D sized 220AH batteries (24V System). Total weight of the batteries will be just short of 1000lbs. I have torn out all the over-the-road AC components and turned most of the space into a generator bay and the box where the heater core was is now where the inverters and transfer switch along with some busbars and wiring. My goal is to weld up a rectangle frame with a bottom and a drain hole that I will place along the centerline of the bus in the forward most bay close to the inverters and generator. I have installed 1/2" foam and 3/4in ply on the floor and walls to distribute the load and insulate/sound deaden. Im concerned that 1000lbs of batteries is too high of a load in such a small area. I have seen some conversions with crazy amounts of weight without any problem but I have also witnessed a conversion that was sagging from being overloaded. I have googled for several weeks now trying to dig up some weight specification limit on these buses but have come up empty. In my mind the bays were designed for storage and luggage. A rough guess would be 20 bags at 50lbs each that's 1000lbs distributed in a bay max.

So the question is: Does anyone know of a weight distribution spec?

Second: What is everyone else doing with similar battery banks?

Third: Does anyone think this is simply too much weight in one small area?

Thanks in advance for any information or sage words of wisdom you may have to share.

SolarDude.

[eagle19952]

Don't know specs. but, i am told that the center bay was the one that many interstate carriers used to send long blocks to disabled buses.

[lostagain]

I think you will be fine with it in the center. I would be careful to distribute your conversion weight (water tanks, other heavy items) so you don't overload one axle front or back, or side to side. There is a lot of margin with a real bus, versus a store bought S and S.

JC

[TomC]

If you have the height for a 16" tall battery, I highly recommend you stay away from 8D batteries. Mainly because they are so heavy (160lbs). 6-8D at 220 AH each is 1320 AH total. Lifeline makes the L16 which is a 400 AH 6v battery. At 119lbs each, these batteries are much easier to handle. Lifeline also makes a 2v version at 1200ah. AGM batteries are expensive, but are totally maintenance free. Any battery can fail, I have had good luck with my AGM batteries to the point, they are the only battery I will use. Good Luck, TomC

[luvrbus]

I have no idea about a MCI but do know a 40 ft Eagle is 1500# for the front bay,1200# for middle bay and 1800# for the rear bay.

I asked a old GreyHound driver and shop foreman in Dallas about carrying a engine and he told me it only happen with the 4501 in the bays and the MCI 7 freighter inside  

[Boomer]

He must not have been around in the Silverside days.  If it fit in the bay it went, regardless of how much it weighed.

[luvrbus]

True but I bet a 8v71 won't fit in a Silver sides bay either unless it's in pieces

[RJ]

I wouldn't put the batteries and the inverter in the same space together.  I prefer to have a wall of some type separating the two, "just in case."

The idea of having the battery bank in the old heater core area is a good one, but access for maintenance will be a PITA unless you leave the front bay open.

Also, all the weight of the batteries will now be on the front axle, which, at a rated 13K, can easily handle it, but it might affect tire wear.

Hope you're also planning on having some type of ventilation for the battery compartment.  Doesn't have to be much, maybe a couple of 3" screened holes on either side of the box near the top, with computer muffin fans on a thermostat to come on when the compartment temp reaches 75-80 or so.  Have the muffin fans pressurize the compartment, with exhaust thru the floor under the batteries.

FWIW & HTH. . .

[luvrbus]

.

Hope you're also planning on having some type of ventilation for the battery compartment.  Doesn't have to be much, maybe a couple of 3" screened holes on either side of the box near the top, with computer muffin fans on a thermostat to come on when the compartment temp reaches 75-80 or so.  Have the muffin fans pressurize the compartment, with exhaust thru the floor under the batteries.

FWIW & HTH. . .


Lol I can vouch for that heat,charging,batteries with no ventilation don't do well even the with AGM's 
   

[Iceni John]

I wouldn't put the batteries and the inverter in the same space together.  I prefer to have a wall of some type separating the two, "just in case."

The idea of having the battery bank in the old heater core area is a good one, but access for maintenance will be a PITA unless you leave the front bay open.


Hope you're also planning on having some type of ventilation for the battery compartment.  Doesn't have to be much, maybe a couple of 3" screened holes on either side of the box near the top, with computer muffin fans on a thermostat to come on when the compartment temp reaches 75-80 or so.  Have the muffin fans pressurize the compartment, with exhaust thru the floor under the batteries.

FWIW & HTH. . .

The acid fumes given off by FLA batteries when they charge can damage electronics, even encapsulated or conformally-coated circuits, so that's why chargers and inverters must be in a separate enclosure, but still as close as possible to the batteries.   I use insulated cable pass-throughs made by VTE to take power through the wall.

Even if you were using "maintenance-free" batteries like AGMs, and definitely if you're using FLA batteries that need their electrolyte regularly checked, you should have the batteries on pull-out trays.   This way it's easy and safe to check every cell.   An owner of an expensive RV in the yard where I store my bus had to replace all his batteries recently, because the RV manufacturer had not made any way to access the rearmost batteries, and when one of them failed it dragged down the others to the tune of over a thousand dollars to replace them all.   All because they hadn't made a slide-out tray for them!

FLA batteries produce hydrogen when they charge, so any vents should be high to let it disperse.   This is the opposite of propane whose vents must be as low as possible.   It's also probably wise to use sealed or explosion-proof lighting enclosures in the battery compartment.

John

[RJ]

FLA batteries produce hydrogen when they charge, so any vents should be high to let it disperse.   This is the opposite of propane whose vents must be as low as possible. 

John -

Duh!  I must have been asleep at the wheel when I made the suggestion about the muffin fans.  Completely forgot about the hydrogen gas dynamics. . .

Thus:  Set them up so they suck air out of the battery box and to the exterior of the coach, not discharging inside somewhere.

Better?

FWIW & HTH. . .

[lvmci]

Hi solardude, one more time, side to side is as important as front to back weight, of course generator, refrigerator,  diesel fuel tank positions, and liquids tanks, should be considered in the balance also, lvmci...

[HB of CJ]

Would it be as easy for you to spread out the heavy stuff as it would be too concentrate the heavy loads into one small area?  Has all the stuff to be installed been weighed?

One might also consider static and dynamic weight shifts.  Fuel, fluids, passenger movement, future additions; it all should (must?) be calculated and allowed for.

In addition to that, road conditions must come into play.  Usually it is best to spread out the heavy stuff between the axles.  Side to side weight also must be very close.

Ideally when all things are considered and installed correctly your weight and balance should reflect closely the chassis capabilities.  Front, rear, side to side, top, bottom.

[solardude]

Thanks everyone for giving at least some indication of weight limits.

So, I'll try to briefly reply to some of the comments.

So the bus layout is planned to be as follows. The old condenser bay has been converted to a Gen bay with a Diesel 7.5KW. The old A Coil and Heater Core is where the Inverters, Autotransformer and Transfer switch are all mounted. This area works well for this as it will be easy to pull conditioned air from the coach to maintain a positive pressure as the bay still has its original door that separates it from bay 1. One thing I have not thought too much about yet is what to do with the conditioned air cooling the inverters. If I push it into the adjacent bay, it will pressurize that bay and mess with the battery air flow, and could push HHO into the surrounding area. I have not worked out how to separate the battery box completely yet. I don't really want to build an "air tight" box around the batteries. That will make servicing them a pain. If there is anything I know about myself and others is we all take the path of least resistance, so if servicing is not easy, it just simply will not happen as it should. Im hoping to build slides on either side of the battery box for storage, so I will have to keep an eye on the weight that gets loaded into the slides, but that should not be too difficult.

Bay 2:
Bay 2 will be storage, tools on one side and consumable goods on the other.

Bay 3:
Bay three will be where all the plumbing will be, so I'm happy to hear that bay 3 is rated for the most weight. 1800# is about 220 gallons total, so that will be the main constraint. Hopefully I will find a good balance for each tank. It is hard to predict what one will use without knowing exactly how the coach will be used, ie. boon docking, or sitting at a camp ground.

Our initial use will certainly be boon docking, as the plan is to find land and park/live and build a new home. After that the coach would be used for recreation.

I also wanted to touch on some points that some contributors made.

My batteries will be 12V Gel. Which hopefully never out gas, so I struggle with creating a bunch of work for myself creating battery enclosure built to hold and vent HHO. So stay tuned for an update on the direction I go on that.

TomC:
Yes, you are correct the the taller L16's are nice batteries, and would make great low cost batteries. However my experience tells me that heavier batteries most always out perform a lighter one. Battery performance is directly related to lead by volume, and surface area. I design and install commercial solar for a living, including large battery banks, as well as whore myself out as a corporate engineer, so I have some knowledge on these issues. I love the Trojan batteries, I am using the 8Ds to conserve space and make it easier to keep the batteries balanced as large inverters are REALLY hard on batteries.

Again, Thanks EVERYONE for your guidance and support, I appreciate the input.   


SolarDude

[kyle4501]

Have your coach weighed as soon as you can - cost me $10. I was able to get the weight of each axle. then you can do some simple math to estimate how the added weight will effect the axle weights.

Easier to move some stuff around on paper than to retrofit a heavier front axle.