# [EVDL] Battery Tray Material



## EVDL List (Jul 27, 2007)

Hello Mike,

The thickness of the metal is also going to depend on any welding you are 
going to do, like a full weld on the corners and additional supports.

Instead of having the corners of the box butt together and than full weld, 
it may be best to have the corners overlap with a 2 inch lip that the one 
side section laps over the other sides.

I find that welding any metal lighter than 18 gage, even with a mig welder 
with 20 gage wire, the metal will warp on you using full length welds. To 
keep the warping down, I stitch weld and even then you may get some warping.

Using 18 gage is a little better, but still must do stitch welded. It also 
depends on the hardness of the metal, the softer and easier to bend but is 
harder to keep the welding heat from warping the metal. You can use a 
harder grade metal, but you can only bend it once. Can make slight bending 
adjustments and must radius the 90 degrees bends a bit or it will crack at 
these bends.

The harder metal is also easier to weld too. At one time my first battery 
box was made out of 1/4 thick aluminum which is two times lighter than 
steel. The weight would be about equal to a little more than 1/8 thick 
steel or about 10 gage steel which is 0.1345 inch thick.

Even with a 1/4 inch thick aluminum plates welded together that measure 32 
inches by 32 inches and all the corners had another 1/4 inch 3 inch angle 
full welded on it, the flat bottom has a slight curve that developed which 
is about 1/16 inch which is not bad.

A soft 16 gage or 0.05 inch would be my choice if you are going to do a a 
lot of welding on it. A hard 18 gage or 0.04 inch would work too. You 
could use semi soft 80 thousands aluminum or .080 inch which I like to use 
for making cases and boxes. This is just little over 14 gage which is 0.074 
inch.

You can mig weld aluminum or even do aluminum soldering with a oxy/acetylene 
torch. I get my aluminum soldering sticks from a radiator shop that does a 
lot of this type of work. You can solder a thick 1 inch aluminum block to a 
thin aluminum sheets with this stuff.

Roland




----- Original Message ----- 
From: "MIKE WILLMON" <[email protected]>
To: <[email protected]>
Sent: Saturday, February 09, 2008 12:36 AM
Subject: [EVDL] Battery Tray Material


> If I were going to build a battery tray 19.5"L x 37"W x 8" deep to hold 30 
> Enersys 12V XE16 batteries (425# total weight) oriented in 6 rows of 5 
> batteries stacked length wise along the long side of the box......
>
> what thickness sheet metal should I use?
> I want to have the sheet metal guy build a plain old straight rectangular 
> box whose walls stick up 2" higher that the top of the box. Either I will 
> have him bend all the edges out to form a 2" lip or I will do it on site. 
> The lip will rest on top of a 2" Square tubular frame that is doubling as 
> the "back half" stiffners for the car.
>
> If the box can't be strong enough to handle the weight without bowing or 
> being too heavy, I'll add a couple small stiffner tubes across the bottom 
> side.
>
> ...anyway, not knowing material properties of sheet metal enough to talk 
> to the sheet metal guy, what do people recommend?
>
> Thanks for any info.
>
> Mike
> Anchorage, Ak.
>
> _______________________________________________
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> http://lists.sjsu.edu/mailman/listinfo/ev
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## EVDL List (Jul 27, 2007)

I would want to have a couple rows of thicker steel bar underneath that box regardless of the size sheet metal you use. The static weight is a consideration but dynamic loads (think potholes) can increase loading by several times. You could build the box as described then support it and perform dynamic testing (i.e. jump in it) to see how it reacts then stiffen accordingly. I would also plan to use bolted connections along the top.


----- Original Message ----
From: MIKE WILLMON <[email protected]>
To: [email protected]
Sent: Saturday, February 9, 2008 2:36:29 AM
Subject: [EVDL] Battery Tray Material


If 
I 
were 
going 
to 
build 
a 
battery 
tray 
19.5"L 
x 
37"W 
x 
8" 
deep 
to 
hold 
30 
Enersys 
12V 
XE16 
batteries 
(425# 
total 
weight) 
oriented 
in 
6 
rows 
of 
5 
batteries 
stacked 
length 
wise 
along 
the 
long 
side 
of 
the 
box......

If 
the 
box 
can't 
be 
strong 
enough 
to 
handle 
the 
weight 
without 
bowing 
or 
being 
too 
heavy, 
I'll 
add 
a 
couple 
small 
stiffner 
tubes 
across 
the 
bottom 
side.






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## EVDL List (Jul 27, 2007)

Hello Mike and All,



> MIKE WILLMON wrote:
> 
> >If I were going to build a battery tray...what thickness sheet metal should I use?
> >I want to have the sheet metal guy build a plain old straight rectangular box..
> ...


----------



## EVDL List (Jul 27, 2007)

From: MIKE WILLMON
> If I were going to build a battery tray 19.5"L x 37"W x 8" deep
> to hold 30 Enersys 12V XE16 batteries (425# total weight)...
> what thickness sheet metal should I use?

>From a simple strength of materials standpoint, even 24 gauge (0.025") steel (or 0.040" aluminum) should be sufficient. However, you would have to shape it appropriately to add stiffness. For example, corrugations in the sides and partitions between the batteries across the bottom to keep it from sagging. The 2" lip in the top would require special treatment.

> I want to have the sheet metal guy build a plain old straight
> rectangular box...

Then you would need somewhat thicker material just for stiffness. The bottom in particular would have to be very thick (and heavy) if you try to make it stiff enough with just thickness.

I'd suggest using the lighter sheet metal, but then adding thicker steel angle steel for the top 2" edge, and a few 1" square steel tubes as stiffeners for the bottom.

The only thing new is the history you don't know yet. -- Harry Truman
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart-at-earthlink.net

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## EVDL List (Jul 27, 2007)

Why not make the box the old fashioned way: hardwood
Nearly all the early 20th century EVs used HW battery boxes.
Weight is reasonable as is strength, plus the box is electrically insulated,
which has advantage in case of shorts to case.
A couple examples (for 1921 Milburn Light Electric):
http://www.milburn.us/docs/27_instr-08.jpg
http://www.milburn.us/pics/ron1918_02b.jpg

-Myles Twete

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Frank John
Sent: Saturday, February 09, 2008 4:49 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery Tray Material

I would want to have a couple rows of thicker steel bar underneath that box
regardless of the size sheet metal you use. The static weight is a
consideration but dynamic loads (think potholes) can increase loading by
several times. You could build the box as described then support it and
perform dynamic testing (i.e. jump in it) to see how it reacts then stiffen
accordingly. I would also plan to use bolted connections along the top.


----- Original Message ----
From: MIKE WILLMON <[email protected]>
To: [email protected]
Sent: Saturday, February 9, 2008 2:36:29 AM
Subject: [EVDL] Battery Tray Material


If 
I 
were 
going 
to 
build 
a 
battery 
tray 
19.5"L 
x 
37"W 
x 
8" 
deep 
to 
hold 
30 
Enersys 
12V 
XE16 
batteries 
(425# 
total 
weight) 
oriented 
in 
6 
rows 
of 
5 
batteries 
stacked 
length 
wise 
along 
the 
long 
side 
of 
the 
box......

If 
the 
box 
can't 
be 
strong 
enough 
to 
handle 
the 
weight 
without 
bowing 
or 
being 
too 
heavy, 
I'll 
add 
a 
couple 
small 
stiffner 
tubes 
across 
the 
bottom 
side.







____________________________________________________________________________
________
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----------



## EVDL List (Jul 27, 2007)

Maybe a good idea if I were back in 1921. For the racing vehicle 
aluminum would be best.

: )






> Myles Twete wrote:
> 
> > 1921 Milburn Light Electric
> 
> ...


----------



## EVDL List (Jul 27, 2007)

Yeah, context is everything...sorry I didn't catch that you were building a
racer.
Regardless, if it were me, I'd consider wood if space were available.

On aluminum, John Wayland's got good advice and experience in this.
I saw him pop a battery in 2006 in a race.
That same night 2 other batteries were popped including one in Otmar's
Orange "Poppy" Porsche and one in Dave Cloud's Geo, which unfortunately
caused a fire and caused a lot of fire damage.
The battery that Wayland popped was one of the ones near the dead center of
the aluminum battery housing.
And that is the spot you'd expect to get the hottest.
What struck me was the lack of any cooling at all other than thru the
thermal conduction of the aluminum shell.
The batteries were all jammed together.
This is not unusual.
Many or most of us simply cram batteries together.
And structurally, that's great.
However, for the drag racer, you need more.
John now has been air cooling his batteries between runs, and that's great.
Better would be to sandwich 1/4" aluminum honeycomb material between
batteries as well and to provide forced airflow between batteries. Maybe
John's doing this now. I believe Berube indicated he isolates and cools all
his batteries in a way similar.
Now would be the time to consider this as you're building and sizing your
box.

-Myles

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of [email protected]
Sent: Saturday, February 09, 2008 9:40 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Battery Tray Material

Maybe a good idea if I were back in 1921. For the racing vehicle 
aluminum would be best.

: )






> Myles Twete wrote:
> 
> > 1921 Milburn Light Electric
> 
> ...


----------



## EVDL List (Jul 27, 2007)

I missed the fact that it was for the Pinto also (cool project BTW). 1/4" aluminum "diamond" plate is very stiff and might work well in this application.


----- Original Message ----
From: Myles Twete <[email protected]>
Subject: Re: [EVDL] Battery Tray Material


Yeah, 
context 
is 
everything...sorry 
I 
didn't 
catch 
that 
you 
were 
building 
a
racer.






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## EVDL List (Jul 27, 2007)

Is "diamond plate" aluminum cheaper or easier to find than smooth plate? =


If you want the most stiffness, all aluminum alloys have the same stiffness=
( within a couple of per cent). If it's strength you're looking for, I wo=
uld choose a high strength alloy like 6061-T6. It is generally pretty easy=
to find, especially as plate.

Also, 1/4 inch plate would be pretty expensive and heavy. Maybe 1/8 inch p=
late, with some stiffeners across the bottom (as Lee suggested) would work =
well also.

Phil Marino

> Date: Sat, 9 Feb 2008 13:27:33 -0800
> From: [email protected]
> To: [email protected]
> Subject: Re: [EVDL] Battery Tray Material
> =

> I missed the fact that it was for the Pinto also (cool project BTW). 1/4=
" aluminum "diamond" plate is very stiff and might work well in this applic=
ation.
> =

> =

> ----- Original Message ----
> From: Myles Twete <[email protected]>
> Subject: Re: [EVDL] Battery Tray Material
> =

> =

> Yeah, =

> context =

> is =

> everything...sorry =

> I =

> didn't =

> catch =

> that =

> you =

> were =

> building =

> a
> racer.
> =

> =

> =

> =

> =

> =

> ___________________________________________________________________=
_________________
> Be a better friend, newshound, and =

> know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_y=
lt=3DAhu06i62sR8HDtDypao8Wcj9tAcJ =

> _______________________________________________
> For subscription options, see
> http://lists.sjsu.edu/mailman/listinfo/ev

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## EVDL List (Jul 27, 2007)

Mike;

I fabricated mine out of 1/8" CS Plate. Continuous welds.
Welded 3 X 3 X 1/4" angle clips to the sides for bolting to the frame.
One straddles the drive shaft for 3 batteries on each side. Battery
weight 360 lbs.
The back box is designed to hold 7 batteries. 420#
I will send you some pictures.

Dennis
Elsberry, MO


-----Original Message-----
From: MIKE WILLMON [mailto:[email protected]] 
Sent: Saturday, February 09, 2008 1:36 AM
To: [email protected]
Subject: [EVDL] Battery Tray Material

If I were going to build a battery tray 19.5"L x 37"W x 8" deep to hold
30 Enersys 12V XE16 batteries (425# total weight) oriented in 6 rows
of 5 batteries stacked length wise along the long side of the box......

what thickness sheet metal should I use?
I want to have the sheet metal guy build a plain old straight
rectangular box whose walls stick up 2" higher that the top of the box.
Either I will have him bend all the edges out to form a 2" lip or I will
do it on site. The lip will rest on top of a 2" Square tubular frame
that is doubling as the "back half" stiffners for the car.

If the box can't be strong enough to handle the weight without bowing or
being too heavy, I'll add a couple small stiffner tubes across the
bottom side.

...anyway, not knowing material properties of sheet metal enough to talk
to the sheet metal guy, what do people recommend?

Thanks for any info.

Mike
Anchorage, Ak.



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