# [EVDL] Fan for venting battery boxes



## EVDL List (Jul 27, 2007)

Check the drain pipe section of Lowe's or Home Depot and look at the plastic 
drain caps. They have square ones that may work for you. You may have to 
whittle some plastic away with a Dremmel .

Stub





> Nathan Stowe wrote:
> > Hi All,
> >
> > I am trying to implement the venting for my battery boxes and would
> ...


----------



## EVDL List (Jul 27, 2007)

Hello Nathan,

Here is what I did.

It is most important to use a negative pressure or exhausting air flow in 
your battery boxes. You need a air input side on one end of the box and a 
exhaust air outlet at the other end of the box.

Only use PVC plumbing fittings and the heavy flexible PVC tubing. I use 2 
inch PVC fittings for pressure because the air flow though these fittings 
are smoother.

To connect to my boxes, I use a 90 degree chase nipple that is place on the 
outside of the box against a 2 inch entry hole. I use a 2 inch to 1 inch 
adapter bushing that has a flange and push it through the box hole from the 
inside and into the chase 90 degree elbow.

I did not have to glue the fitting together, these pressure fitting fit very 
tight. The reason I use 90 degree elbows coming off the box, is that I have 
one point down and connected to a 2 inch pipe going to the outside and under 
the car. This air entry point is stuff with that 3M green filter material 
that is use in swamp coolers.

On the exhaust side, I connected a 2 inch diameter PVC flexible pipe that 
ran a lone side the box and connected to a box fan that is about 4 inch 
square and about 1.5 inch deep. The most important thin about using these 
box fans, is that it should be a all plastic construction and no expose wire 
connections or holes in the motor housing.

My fan has it wires in closed in a small plastic tubing that spans the air 
flow passage. The four inch square box fan has four mounting holes in each 
corner. This is where I bolted on a 4 inch square by 1/4 inch plastic sheet 
that I drill a hole in the center to fit a piece of 1.5 inch PVC pipe that 
is about 2 inches long.

The 1.5 pipe dimension is the inside ID and will be about 2 inch OD. This 
allows for the 2 inch flexible PVC pipe to slip over it.

To fasten the 1.5 pipe to this plastic sheet, I vee out the hole on the pipe 
nipple side and rough up the end of the pipe that is going to insert into 
this plastic.

Take a piece of wax paper and lay it flat on a surface. Lay the plastic 
piece with the hole cut in it and lay it on the plastic. Then insert the 
pipe nipple into the hole.

Now mix up some JB Weld (the long setting type) and apply to this Vee and 
pipe joint. Let set for 12 to 24 hours. The standard PVC pipe cement does 
not have the filling capacity and some epoxy may not attach to some plastic.

The fan I use is a 120 vac at about 80 cfm. Fuse this fan for 1.25 percent 
of the running amps. Use the next size fuse if the numbers are not even.

I use a toggle switch that first turns on the fan, before I turn on the 
charger. A indicator light comes on showing that I have 120 vac going to 
the fan.

To feed a 120 vac fan, you need a neutral wire. That's why I have a four 
wire input plug for a 240 volt charger and a neutral for a 120 vac circuits. 
If you only have a 3 wire 240 volt input circuit, than you could use a small 
machine tool transformer which have a 240 vac primary and a secondary 
voltage to match you fan voltage.

To calculated the size of transformer, take the running ampere of the fan 
and the voltage and multiple it together. Lets say the fan reads 0.2 amps 
at 120 volts. Therefore 0.2 x 120 = 24 watts. Calculated a demand factor at 
1.25 x 24 watts = 30. A 30 va transformer is the correct size.

Use a 2 element or a fuse call a Fusetron that is design for motor circuits. 
The correct size fuse is the running amps of the motor times 1.25 or the 
next closes fuse.

Optional safety circuits:

There is no guarantee that the fan may quit working while the charger is on 
which could be filling up the battery box with vent gas. This happen to me 
one time, and when I turn off the charger, I had a hydrogen vent explosion 
out of the exhaust fan outlet.

I therefore added a very sensitive pressure switch sensor just behind the 
exhaust fan outlet. I went to a plumbing and heating supplier and pick up a 
adjustable pressure switch than can pick up air pressures down to 0.1 in.hg. 
This pressure switch controls a AC contactor that turns on the AC to the 
charger.

Now to turn on my charger, I first must turn on the exhaust fan which will 
show a indicator light that its on. A second indicator light comes on 
showing that the air flow is on.

I then turn on a 2nd optional toggle switch to turn on the AC contactor and 
another indicator comes on.

Next I turn on a 3rd optional toggle switch to turn on a 2 pole DC contactor 
connecting my PFC-50 charger to the batteries. If this circuit is complete 
it will show another indicator.

Then finally I can turn on my charger.

The batteries at this time are disconnected from the main contactor and 
motor control circuit use two safety battery contactors. At one time, I did 
not have these safety contactors, and the charger voltage of over 230 volts 
was suppress on to the DC motor and a DC-DC converter and cause arcing 
across the commentators.

Also what I found with the PFC chargers, is that when connected to the 
batteries at all times, the capacitors may be charge. One time I 
disconnected a battery link and it spark!!! So these contactors now prevent 
this arcing and sparking.

On board circuit breaker option.

Between my AC main plug and my battery charger, I have a chassis mounted 
Square D plug in 50 amp GFI circuit breaker. There is also optional GFI 
control modules you can add to existing circuits. One is that I may add, is 
one that will detect the leakage current flow of the main battery to the 
chassis of the vehicle. We normally use these type of circuits in explosive 
proof units.

Roland


----- Original Message ----- 
From: "Nathan Stowe" <[email protected]>
To: <[email protected]>
Sent: Friday, January 02, 2009 6:42 AM
Subject: [EVDL] Fan for venting battery boxes


> Hi All,
>
> I am trying to implement the venting for my battery boxes and would like
> to find the easiest way to add the fans. I have "crammed" my batteries
> in the car ( no other EV has this right?  ) so I have two large boxes
> and two additional single battery boxes. They are sheet steel with 1
> 1/2" pink foam insulation and resistance heaters. I plan to use a fan
> for the front boxes and another for the rears, both creating negative
> pressure in the boxes. It looks like flexible PVC will be sufficient
> for the plumbing. The question I have is what is the easiest and low
> cost method to connect a plastic brushless fan to the plumbing. I could
> use an old computer fan, but I do not see how to easily mount it. I can
> use either 12vdc or 110vac. I would have to run new wires for one of
> them no matter which I choose.
>
> Thanks.
>
> Nathan.
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
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>
> 

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## EVDL List (Jul 27, 2007)

There are many ways, dependent on the thickness of the PVC.
One way is when you mount the fan against its support
(using 2 L-brackets) to add 4 more L-brackets at the back
(inlet side) so that the PVC tube fits exactly between
them. Then you can choose whether to use sheet metal
screws to attach the tube if it has enough volume, or to
use a large hose-clamp around the 4 brackets and the hose
to clamp it into place (you can still add screws to keep
the clamp from sliding off the brackets)
But there are many other ways, even dedicated convertors
from round hose to square mounts as used in hood vents
and other air exhaust solutions.

Success,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Nathan Stowe
Sent: Friday, January 02, 2009 8:12 PM
To: [email protected]
Subject: [EVDL] Fan for venting battery boxes

Hi All,

I am trying to implement the venting for my battery boxes and would like
to find the easiest way to add the fans. I have "crammed" my batteries
in the car ( no other EV has this right?  ) so I have two large boxes
and two additional single battery boxes. They are sheet steel with 1
1/2" pink foam insulation and resistance heaters. I plan to use a fan
for the front boxes and another for the rears, both creating negative
pressure in the boxes. It looks like flexible PVC will be sufficient
for the plumbing. The question I have is what is the easiest and low
cost method to connect a plastic brushless fan to the plumbing. I could
use an old computer fan, but I do not see how to easily mount it. I can
use either 12vdc or 110vac. I would have to run new wires for one of
them no matter which I choose.

Thanks.

Nathan.

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http://evdl.org/help/index.html#conv
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## EVDL List (Jul 27, 2007)

I used a boat bilge exhaust blower and 3" dust collector hose and fittings.


Hi All,

I am trying to implement the venting for my battery boxes 

-----
2000 Ford Focus, 9" ADC, Zilla 1K, 18x Sam's Club 6V GC-2's 
-- 
View this message in context: http://www.nabble.com/Fan-for-venting-battery-boxes-tp21252222p21264872.html
Sent from the Electric Vehicle Discussion List mailing list archive at Nabble.com.

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## EVDL List (Jul 27, 2007)

You have to be care full in using that type of exhaust blower and duct. I 
at first use the marine exhaust fan and vinyl air duct. The vinyl duct had 
holes ate in it by the venting batteries and was exhausting hydrogen fumes 
inside the compartment.

Also, after a while the fan was making a racket. The metal blades were all 
corroded and half gone. I had to replace it with a all plastic totally 
enclosed fan unit.

Roland


----- Original Message ----- 
From: "Walter Guinon" <[email protected]>
To: <[email protected]>
Sent: Saturday, January 03, 2009 5:27 AM
Subject: Re: [EVDL] Fan for venting battery boxes


>
> I used a boat bilge exhaust blower and 3" dust collector hose and 
> fittings.
>
>
> Hi All,
>
> I am trying to implement the venting for my battery boxes
>
> -----
> 2000 Ford Focus, 9" ADC, Zilla 1K, 18x Sam's Club 6V GC-2's
> -- 
> View this message in context: 
> http://www.nabble.com/Fan-for-venting-battery-boxes-tp21252222p21264872.html
> Sent from the Electric Vehicle Discussion List mailing list archive at 
> Nabble.com.
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
> 

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Usage guidelines: http://evdl.org/help/index.html#conv
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## EVDL List (Jul 27, 2007)

If positive pressure is used wouldn't that save the equipment? I saw 
warier in this thread that negative pressure was recommended. Why is 
that? Sorry if that is a noob question, I am curious though.

Kelly Hales

Sent from my iPhone



> "Roland Wiench" <[email protected]> wrote:
> 
> > You have to be care full in using that type of exhaust blower and
> > duct. I
> ...


----------



## EVDL List (Jul 27, 2007)

Positive fan pressure (meaning a blower pushing air into a battery box) will 
not only exit out a ductwork, but will leak out every other hole and battery 
covers. This will then put the battery venting through out the into the 
equipment bay, which could ignite the hydrogen gas, which it did one time, 
when I was using a standard vinyl air hose instead of a pvc heavy wall hose.

Negative fan pressure is pulling the battery air out to the outside which my 
exits under and out like a engine exhaust system towards the rear of the EV. 
The fresh inputting air should be coming in on the far side of the battery 
box and as far away from the exit air, which is normally towards the front 
of the EV.

All the spark producing equipment such as the motor, controller, and 
equipment enclosures are normally at positive pressure bringing in filter 
clean air at a higher location in the EV. This cools and keeps the dust, 
dirt and water out of these units.

Roland

The incoming air should be also filter


----- Original Message ----- 
From: "Kelly Hales" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, January 03, 2009 11:43 AM
Subject: Re: [EVDL] Fan for venting battery boxes


> If positive pressure is used wouldn't that save the equipment? I saw
> warier in this thread that negative pressure was recommended. Why is
> that? Sorry if that is a noob question, I am curious though.
>
> Kelly Hales
>
> Sent from my iPhone
>
>


> "Roland Wiench" <[email protected]> wrote:
> >
> > > You have to be care full in using that type of exhaust blower and
> > > duct. I
> ...


----------



## EVDL List (Jul 27, 2007)

OK I get that. Last question and I'll stop my edumacation on this. So if 
the battery enclosure is all in the bed or under the bed of a truck without 
any other equipment, would blow through be fine or is it just always a safer 
bet to pull through?
Kelly

----- Original Message ----- 
From: "Roland Wiench" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, January 03, 2009 1:32 PM
Subject: Re: [EVDL] Fan for venting battery boxes


> Positive fan pressure (meaning a blower pushing air into a battery box) 
> will not only exit out a ductwork, but will leak out every other hole and 
> battery covers. This will then put the battery venting through out the 
> into the equipment bay, which could ignite the hydrogen gas, which it did 
> one time, when I was using a standard vinyl air hose instead of a pvc 
> heavy wall hose.
>
> Negative fan pressure is pulling the battery air out to the outside which 
> my exits under and out like a engine exhaust system towards the rear of 
> the EV. The fresh inputting air should be coming in on the far side of the 
> battery box and as far away from the exit air, which is normally towards 
> the front of the EV.
>
> All the spark producing equipment such as the motor, controller, and 
> equipment enclosures are normally at positive pressure bringing in filter 
> clean air at a higher location in the EV. This cools and keeps the dust, 
> dirt and water out of these units.
>
> Roland
>
> The incoming air should be also filter

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Usage guidelines: http://evdl.org/help/index.html#conv
Archives: http://evdl.org/archive/
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## EVDL List (Jul 27, 2007)

In all cases, it is recommended to exhaust the battery box air. This flow 
of air allows the air flow to exit in one path, instead of pushing the 
venting fumes all over the inside surfaces.

It is best to have gaskets on the battery cover and have the cover about 3 
inches from the surface of the battery. The more air flow through out the 
top of the batteries will prevent condensation and the hydrogen in the 
battery caps will mix with the oxygen which will prevent more loss of water 
in the electrolyte.

I use to use a device made by the HydroCap Company that does this same 
reaction of a oxide to the hydrogen gas. You need a lot of space above the 
neck of the battery to install these units.

Roland




----- Original Message ----- 
From: "Kelly Hales" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Sunday, January 04, 2009 10:46 AM
Subject: Re: [EVDL] Fan for venting battery boxes


> OK I get that. Last question and I'll stop my edumacation on this. So if
> the battery enclosure is all in the bed or under the bed of a truck 
> without
> any other equipment, would blow through be fine or is it just always a 
> safer
> bet to pull through?
> Kelly
>
> ----- Original Message ----- 
> From: "Roland Wiench" <[email protected]>
> To: "Electric Vehicle Discussion List" <[email protected]>
> Sent: Saturday, January 03, 2009 1:32 PM
> Subject: Re: [EVDL] Fan for venting battery boxes
>
>
> > Positive fan pressure (meaning a blower pushing air into a battery box)
> > will not only exit out a ductwork, but will leak out every other hole 
> > and
> > battery covers. This will then put the battery venting through out the
> > into the equipment bay, which could ignite the hydrogen gas, which it 
> > did
> > one time, when I was using a standard vinyl air hose instead of a pvc
> > heavy wall hose.
> >
> > Negative fan pressure is pulling the battery air out to the outside 
> > which
> > my exits under and out like a engine exhaust system towards the rear of
> > the EV. The fresh inputting air should be coming in on the far side of 
> > the
> > battery box and as far away from the exit air, which is normally towards
> > the front of the EV.
> >
> > All the spark producing equipment such as the motor, controller, and
> > equipment enclosures are normally at positive pressure bringing in 
> > filter
> > clean air at a higher location in the EV. This cools and keeps the 
> > dust,
> > dirt and water out of these units.
> >
> > Roland
> >
> > The incoming air should be also filter
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
>
> 

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## EVDL List (Jul 27, 2007)

I don't know if it was on the evalbum or where but I remember seeing
the bed of a pickup that was damaged from a hydrogen explosion. I
don't know if the boxes were vented or not but it seems to me that
negative pressure in the box would do better at clearing out the H2
than positive pressure. Does any one know for sure? This is assuming
that for some reason it doesn't matter where the H2 goes, just so it
is out of the battery box.



> Kelly Hales <[email protected]> wrote:
> > OK I get that. Last question and I'll stop my edumacation on this. So if
> > the battery enclosure is all in the bed or under the bed of a truck without
> > any other equipment, would blow through be fine or is it just always a safer
> ...


----------



## EVDL List (Jul 27, 2007)

The topic is of interest to me as I will be building covers for my batteries
soon. My batteries currently just sit in metal frames and a bolt-down bar to
hold them in place. I'm waiting on a controller so I haven't yet driven the
car.

I live in Idaho and am very concerned about the batteries getting too cold
in the winter (I don't have enclosed parking at work and have no where to
plug it in there).

Isn't off gassing of hydrogen only really a concern during charging?

My plan is to put a layer of rigid insulation on the bottom underneath the
batteries and then build removable covers (essentally boxes without bottoms)
made of the same rigid foam. I'll then add a layer of radiant foil on the
outside of the covers (with a 1/2 inch airspace between the foil and the
foam). The foil is leftover from insulating my garage door. I can't put
the foil on the inside as the manufacturer tells me that it is not acid
resistant.

Anyway, asuming that gassing only happens during charging (which will happen
in my garage), I intend to have the engine compartment and the hatchback
left open and lift off the covers. Thus I was NOT planning on any active
venting of the batteries. In fact until this subject came up I wasn't even
planning any vent holes at all.

Am I assuming too much?

- Peter Flipsen jr

http://www.evalbum.com/1974





> Roland Wiench <[email protected]> wrote:
> 
> > In all cases, it is recommended to exhaust the battery box air. This flow
> > of air allows the air flow to exit in one path, instead of pushing the
> ...


----------



## EVDL List (Jul 27, 2007)

Hello Peter,

I did not put any foam in side my battery box. I cover the sides and bottom 
with 2 inch Dow blue foam that has a density of 25 lbs per sq in.

I than cover the foam with a glue on marine rug. The battery box slides in 
and bolts down in a pickup bed, that is also insulated with 1 inch of foam 
on the bottom and 2 inches of foam on the sides. All these surfaces are 
cover with a marine rug.

The cover which is a 1/4 thick fiberglass panel, is cover with 1/4 inch 
vinyl top foam and marine rug. The hinge hatch cover is cover inside and 
outside with the 1/4 inch vinyl top foam and felt back heavy vinyl top 
material.

My battery ventilation system as was explain has the exit outlet pipe 
extending out the back like a exhaust pipe on a engine does. Most of my 
trips are short which is 1 to 2.5 miles. I then do very lite charging of 5 
amperes when the batteries are still above 90% SOC in the winter with the 
garage door close.

In the summer, I may let the battery discharge more to about 80% before I 
will charge it. This time I will crank open the garage door.

If I want to do a equalization charge in a close building, I will slip one 
of those 2 inch rubber exhaust hoses that you see service garages uses. You 
can get this at a auto parts store and can get a through fitting that can go 
through a wall or garage door.

I have never had to use additional heat on my batteries. I park in a garage 
that maintains a temperature of 60 to 70 degrees. Is uses a 5 degree 
differential temperature setting.

I just came back from being gone for about 2.5 hours in a ambient 
temperature of 15 degrees this morning. My battery temperature is setting at 
66 degrees and will take about 24 hours for the battery temperature to drop 
to 62 degrees if the garage temperature is cycle back at that time.

My actual temperature above the battery box covers is 82 degrees, because it 
is a clear sunny day, and when I park the EV, I make sure that glass panel 
in the hatch back cover is pointed to the sun.

The batteries being cooler, I can add 0.028 x 2 = 0.056 volts per cell
for either a normal or equalization charge. When I equalize a battery that 
is setting at 60 degrees, it will warm up to about 70 degrees.

In the winter, about one hour before I leave, I will finish charge the 
batteries in a garage temperature of 70 degrees. This gives me a higher 
starting out voltage for the first mile, which could be about 20 volts 
higher, then if I only charge the batteries 12 hours before.

Roland




----- Original Message ----- 
From: "SLPinfo.org" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Sunday, January 04, 2009 12:03 PM
Subject: Re: [EVDL] Fan for venting battery boxes


> The topic is of interest to me as I will be building covers for my 
> batteries
> soon. My batteries currently just sit in metal frames and a bolt-down bar 
> to
> hold them in place. I'm waiting on a controller so I haven't yet driven 
> the
> car.
>
> I live in Idaho and am very concerned about the batteries getting too cold
> in the winter (I don't have enclosed parking at work and have no where to
> plug it in there).
>
> Isn't off gassing of hydrogen only really a concern during charging?
>
> My plan is to put a layer of rigid insulation on the bottom underneath the
> batteries and then build removable covers (essentally boxes without 
> bottoms)
> made of the same rigid foam. I'll then add a layer of radiant foil on the
> outside of the covers (with a 1/2 inch airspace between the foil and the
> foam). The foil is leftover from insulating my garage door. I can't put
> the foil on the inside as the manufacturer tells me that it is not acid
> resistant.
>
> Anyway, asuming that gassing only happens during charging (which will 
> happen
> in my garage), I intend to have the engine compartment and the hatchback
> left open and lift off the covers. Thus I was NOT planning on any active
> venting of the batteries. In fact until this subject came up I wasn't 
> even
> planning any vent holes at all.
>
> Am I assuming too much?
>
> - Peter Flipsen jr
>
> http://www.evalbum.com/1974
>
>
>
>


> Roland Wiench <[email protected]> wrote:
> >
> > > In all cases, it is recommended to exhaust the battery box air. This
> > > flow
> ...


----------



## EVDL List (Jul 27, 2007)

Roland,

Very interesting thoughts about venting and insulation! For my little car (
http://www.evalbum.com/1974) I'd have to run the pipe from the front
pack down underneath which might work if I used small fans. I guess I could
put it into the old exhaust pipe space (so it would be above the "belly pan"
I'm hoping to install). I coud then either tie it together with a pipe from
the back pack or have "dual exhaust". The idea of connecting to a hose like
in a service station is a good idea. I've been avoiding putting weather
stripping around the edges of the garage door because I didn't want to seal
in the venting gases. Yours seems like a better solution because I'd have a
more energy efficient garage as well! A single hole with a flap lke a dryer
vent would do the job.

In my case the intention is that the car will be for going back and forth to
work every day (about 3 miles each way). Don't know yet what kind of SOC
I'l be ending up with each day but it will be sitting outside in the cold at
work during the day so I'll be surprised if I don't have signifcant voltage
drop by the time I get home. I suspect that at least in the winter I'd have
to charge most nights. But then agan if I use heavier insulation like you
do it may not be that bad.

Lots of things to think about. Thanks.

- Peter



> Roland Wiench <[email protected]> wrote:
> 
> > Hello Peter,
> >
> ...


----------



## EVDL List (Jul 27, 2007)

> David Nelson wrote:
> > ... it seems to me that
> > negative pressure in the box would do better at clearing out the H2
> > than positive pressure.
> ...


----------



## EVDL List (Jul 27, 2007)

Let me ask a few
?questions about venting H2.
1. H2 rises, right?
2. charging batteries warm up, right?
3. warm air rises, correct?
4. most outgassing occurs at the end of the charge cycle when the batteries are warm, correct?
5. would a low intake vent and a high exhaust vent to the car's exterior be sufficient to vent the H2 using the lift generated by H2 and warm air?
6. would this not be simple, light, and foolproof?
7. is there anyone with experience with passive vents?
8. Am I nuts?
Bob Polgreen
1971 sonett project
















-----Original Message-----
From: Nathan Stowe <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Sun, 4 Jan 2009 8:52 pm
Subject: Re: [EVDL] Fan for venting battery boxes













> David Nelson wrote:
> > ... it seems to me that
> > negative pressure in the box would do better at clearing out the H2
> > than positive pressure.
> ...


----------



## EVDL List (Jul 27, 2007)

I used computer slot fans Like Ebay # 120164369879	. I drilled a 2"
hole in the battery box and bolted the fan to the outside of the box.
The exhaust blows down. It is very simple to do, requires no plumbing
and is inexpensive. Since I have 5 boxes to vent, cost was a
consideration.





-- 
http://www.austinev.org/evalbum/1059
http://stormselectric.blogspot.com/
Storm

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## EVDL List (Jul 27, 2007)

I purchased my battery box brushless fan from KTA Services 
http://www.kta-ev.com/ http://www.kta-ev.com/ at a cost of $22 plus
shipping. It is a 35cfm 120ACV that I wired into the AC feed to the charger.
So the fan only runs when the vehicle is charging and uses the house AC
voltage. When driving the batteries are cooled with a little ram effect off
the road through an inlet opening opposite and forward from the pulling fan.
See a journal entry on this site at 
http://www.saturn.lynnautorepair.com/?q=node/238 EV Battery Box Ventilation
& Test Video You can test the box afterwards for leaks with a smoke
machine.
Daniel Lynn



> Nathan Stowe wrote:
> >
> > Hi All,
> >
> ...


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## EVDL List (Jul 27, 2007)

One example I know about is Mike Philips' accident
after an equalization DIS-charge of his flooded NiCd 
cells (NiCds work opposite other batteries in many
aspects: including the electrolyte but also in their
preferred state of being completely discharged.)
After the first recharge Mike apparently had some kind of 
spark in his unvented box at the beginning of his first
trip and the lid blew off his box, warping the bed of
his pickup truck.
He has since installed venting on his battery box
to avoid another occurrence.

Regarding positive or negative - it really does not
matter if you do not care where the H2 is going, as
long as you design the flow properly, so that there
are no cases where you want it to vent, but the
design allows counter-acting forces to keep a
"bubble" unvented somewhere in the system, comparable
to some ICE designs where the cooling system is
impossible to fill without a lot of trouble to get
the airlocks out.
In venting you need to consider where the light
H2 gas wants to go all by itself, where any wind or
other pressure may build up and how the flow of the
fan is adding or (not!) subtracting from this - if
there is a change on a "zero" outcome then the air
stands still and H2 can build up....

Hope this clarifies,

Cor van de Water
Director HW & Systems Architecture Group
Proxim Wireless Corporation http://www.proxim.com
Email: [email protected] Private: http://www.cvandewater.com
Skype: cor_van_de_water IM: [email protected]
Tel: +1 408 383 7626 VoIP: +31 20 3987567 FWD# 25925
Tel: +91 (040)23117400 x203 XoIP: +31877841130

Please consider the environment before printing this e-mail.
-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of David Nelson
Sent: Monday, January 05, 2009 12:57 AM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] Fan for venting battery boxes

I don't know if it was on the evalbum or where but I remember seeing
the bed of a pickup that was damaged from a hydrogen explosion. I
don't know if the boxes were vented or not but it seems to me that
negative pressure in the box would do better at clearing out the H2
than positive pressure. Does any one know for sure? This is assuming
that for some reason it doesn't matter where the H2 goes, just so it
is out of the battery box.



> Kelly Hales <[email protected]> wrote:
> > OK I get that. Last question and I'll stop my edumacation on this.
> So if
> > the battery enclosure is all in the bed or under the bed of a truck
> ...


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## EVDL List (Jul 27, 2007)

Gotta get rid of that explosive gas...? Why not collect it? Maybe something
on this order? http://solarevolution.net/images/ng_vehicle_1930.jpg If not
while on the road, at least when charging. Natural gas from early oil wells
was vented into the air too. We know the ICE people want it (
www.google.com/search?rlz=1C1CHMP_enUS291US303&aq=f&sourceid=chrome&ie=UTF-8&q=hho)
and it's great for fuel cells.

Somebody out there invent a hydrogen reclaimer. Should be possible with the
right battery box.


Grant
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