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12 volt battery well rusted out- Houston, we've got a problem

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by priusrust, Feb 10, 2018.

  1. priusrust

    priusrust Member

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    A classic case study in acute procrastination. I've been living with the battery dangling over the road for quite a while (see pic). After drinking a couple beers to numb the procrastination inertia resistance, I finally finished fixing the rusted out battery hold. Pic shows the cardboard mock up and next to it - the corrective insert. Two thick bent steel bars, with attached sheet metal. What made this tough is access is a bit tricky, and everything is irregular shaped. Went in snug, then I used that spray foam insulation to fill cracks.

    ONE problem!! The battery now sits a bit higher which is a problem for the exit duct for the battery cooling fan- it is now blocked. QUESTION: Why is this air- that is sucked from cabin to cool hybrid battery- funnelled to the outside? I imagine it a bit warmed up. Is it funneled to the outside because there is a danger of vapors from battery ((?no idea) leaking into this air??

    If not, I won't worry about it and just let the warmer air (that has passed over batteries) exit back into the cabin. If there is a risk of toxic fumes from battery entering this air- I'll rig some sort of dryer duct replacement to funnel it outside. If anyone know- help appreciated. Thanks!
     

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  2. edthefox5

    edthefox5 Senior Member

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    Yes vapors from the battery. You must vent this outside.

    The battery fan is always on at a very low speed during normal operation. You cannot hear it. It removes heat and fume reduction and is designed for constant operation.

    IMHO it’s unsafe to vent it to the cabin. Sorry. Know it’s a lot of work but you don’t want to get sick over it.

    If it was me I would have just bolted a battery holding box and mount the battery to the floor of the hatch and leave the hatch bin out.
     
  3. dubit

    dubit Senior Member

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    Are you sure about this or is this an assumption. Because in a Prius C, this air is vented inside the cabin.

     
  4. edthefox5

    edthefox5 Senior Member

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    No assumption.

    On a G2 platform its vented to the outside right over the 12 volt battery well. Disconnected that vent to work on the battery many times.

    The Prius C uses different battery type so it may not be an issue but on a G2 the factory vented it out so I would too. But to each his own.
     
  5. Robert Holt

    Robert Holt Senior Member

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    Wish I had seen OP earlier.
    My suggestion is a formed-in-place layer of fiberglass that would curve up and adhere to the still intact metal sidewalls of the original battery compartment. My 1960s Valiants had floor pans that rusted out rather quickly, and I did this kind of form-in-place layers of fiberglass for the floor pan on both driver and passenger side, and that repair lasted about 5 years until I junked them. I would recommend a 2-3 layers of a mesh weave (NOT random chopped filaments) of fiberglass, and I used the resin + catalyst version rather than the epoxy version as that was much cheaper. You will have to support the bottom of the fiberglass layup in a flat position until it hardens as otherwise the layup in the mesh + liquid stage will sag due to gravity. For surface prep I wire brushed all the loose rust off and gave it a coat of primer, but that was it—the fiberglass adhered quite well to the rough, pitted edges of the metal. Once done, the fiberglass itself cannot rust, but you should keep an eye out for further rust around the edges of the fix, although that simply did not seem to happen to me on the cars I repaired this way (also used this method for rusted out fenders, etc.). This may sound dangerous, but we were dirt poor and the fiberglass floor pan was MUCH preferable to looking through the gaps in the metal floor pan and watching the pavement go by underneath me!
     
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  6. dubit

    dubit Senior Member

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    oh ok. didn't realize it vented the 12v.
     
  7. priusrust

    priusrust Member

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    Thanks for thoughts. I actually considered that solution (fiberglass). Part of the difficulty was the irregular size of the battery box....nothing uniform. So my solution was simply to create a cardboard mockup prototype to create the exact fit. Then replicate mockup (see pic above) using two bent thick steel bars (battery quite heavy) and then add attached sheet metal skin. I had planned on bolting the ends of the metal straps as they bent onto the horizontal lip of the vehicle.....but the fit was so snug (I had to stomp my fabricated battery well down into place) that I deemed any bolts to be unnecessary- snugness and battery weight held in place. I used that expanding spray foam insulation to fill cracks. I was considering Ed's ^ solution of just bolting a battery tray in rear hatch and not using the rusted well......however, the work to modify battery cable lengths...plus the loss of space.....made me decide to plod ahead with my creation. Anyway, I'm pleased....and it affords relative peace of mind (battery had been suspended by jury rigged slings over open road below). My steel strap + sheet metal is basically same shape idea as a molded fiberglass fitting would be. I like the idea of the thick straps for battery support better. I'd be afraid rust would weaken joining area of fiberglass/ prius and the weight of battery might cause future problems. Heavy battery.....bumpy roads....needed a good solid solution. Would have had to create the fiberglass molded battery well in place too.....not the most accessible area- and my ability to work on car location not ideal. The main difficulty was the non uniform shape....no right angles.....battery well walls curved. At one point, I was thinking of inserting a plastic trash bag......filling bag with that expanding foam insulation to make a 'mold' of battery well.....then having a sheet metal worker fabricate a battery well with added lip on circumference- so I could just set it in place. Obviously cost prohibitive.....but this highlighted problems I faced due to irregular shape .....appreciate suggestion!
     
  8. priusrust

    priusrust Member

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    btw.....my family car growing up was a 1964 Valiant wagon.....when I see pics of it, triggers great memories
     

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  9. priusrust

    priusrust Member

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    140030_20180211_165551.jpg IMG_20191127_150125 (1).jpg

    More obsessive thoughts: So these are before and after pics. Notice in the rusted well pic, the outside edge of the bottom of battery well (towards side of car) has a lip. I could have just set the fabrication down in well. The steel bars would have securely rested on this lip....however, in a moment of panicked redundancy, I decided to attach a couple links of cut chain and a tightening bracket (forget name) to both the end hole of one of the steel bars, and a screw hole above in the prius body. -added security for battery weight. I had originally planned to screw the ends of these steel bars into the prius itself.... but access was a problem- would have had to use some sort of molly bolt. I had also planned to rivet sheet metal tabs on fabrication onto prius. Two things happened that made me decide to do none of this: 1) I realized none of this was necessary with weight of battery anchoring everything in place 2) I got lazy. End result not pretty I know. Foam was messy. In pic you can see I attached round sticky foam pads to metal straps for battery to rest on. Also snaked a black strap under bars with clips that wraps around battery lengthwise to secure it in place. Not pretty- but I'm satisfied. (I haven't taken out a patent on this btw) :~)
     
  10. George W

    George W Senior Member

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    Not sure how bad your obstruction is, but in my 08 Prius, the HV ductwork didn't quite reach the chassis vent. I extended the last inch with aluminum foil, since it's easy to form around the plastic tube.

    I don't know why the duct tubing is an inch short as the pieces all align with their pre-cut holes in the car body. Anyway, the foil is easily wrapped/shaped to fit, until I can find a better solution.
     
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  11. priusrust

    priusrust Member

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    appreciate this advice.... the duct that exits the battery cooling air is rectangular.....I could simply attach some round round aluminum dryer tubing and duct tape it to the exit vent. Square plastic duct- to round vent tubing....where have I seen this before???
     
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  12. priusrust

    priusrust Member

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    So because of the new battery pan I fashioned, the 12 V battery sits a bit higher. This is generally no problem except that it prevents that piece of plastic duct (that you normally remove to work on battery) that vents the traction battery air from going in place. So this means I will just attach some of that round aluminum dryer venting duct to replace the plastic piece that will not fit. Hello duct tape.
     
  13. edthefox5

    edthefox5 Senior Member

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    Yes that will work. The stock connection itself is pretty poor the vent basically just sits in front of the rubber flap vent and counts on the fan air to push that thin rubber flap to open to vent whatever its venting heat or smell. Its not connected real well so maybe its not really critical to vent it out but as the battery gets older and starts to off gas from old age you really don't want to be smelling that so do whatever you can to present that vent tube to the face of the rubber vent flaps and you should be ok.

    Good Luck.
     
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  14. priusrust

    priusrust Member

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    ok.....response to an old issue: the venting of battery cooling air outside. My battery is propped up higher than norm, and blocks the plastic duct. So....began to work on bypassing battery obstruction with some dryer vet tubing / hose clamps/ etc. THEN.....I looked at the underside of the duct that carries battery cooling air up & over battery to outside:- seems to be a large opening on the underside!! Is this normal?? or did I accidentally punch some plastic panel out?? (see pic) If this is how it is supposed to look....the battery cooling air apparently vents both inside the cabin and out the vent.....which.....makes worry about venting battery cooling air inside cabin silly (seemingly). Don't get it. Why would you vent battery cooling air inside & outside the cabin?? Unless of course, I accidentally punched out some plastic panel creating this hole in plastic tube that is not supposed to be there. Do other gen 2 owners have this opening in the plastic vent? thanks
     

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  15. valde3

    valde3 Senior Member

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    That's normal. Some hybrid battery cooling air will come out from that hole and warm up the 12v battery.
     
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  16. priusrust

    priusrust Member

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    A-ha ! Never would have guessed that! Thanks. So.....since some of this air that warms the battery certainly will enter the cabin.....Toyota can't be too worried about the potential toxicity of the vented air (?). Yet, 1/2 of it is vented outside. HHmmm. This makes me think the main reason for venting the traction battery cooling air is because it is warm.....and not venting it would create a loop (assuming no a/c) of ever increasing warmer air. (?) Just guessing.
     
  17. valde3

    valde3 Senior Member

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    Hybrid battery cooling air is not toxic at all. If battery modules fail there are vents and hoses to push that toxic air out. Same kind of hose is attached to 12v battery too.
     
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  18. priusrust

    priusrust Member

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    IMG_20200627_143844.jpg So, long after fixing the rusted battery well, I happened to check the other side. Yikes. They say Prius are susceptible to mice problems....I could fall victim to possums or a litter of feral dogs living in my cargo area. I will address leaks soon. This issue: wire wheeled excessive rust. Painted with Ospho -chemically changing rust. Sprayed with Blaster. Nest fitted a piece of 'hardware cloth' screening and tacked it down with some fender washers and sheet metal screws. Next, sprayed with layer of 'Great Stuff' insulation foam. This anchored well as the wet foam penetrated the screen. This should do it. Rodents chewing through? -they will hit the screen. Obviously a bit of a mickey mouse solution- and would not use this method in many other areas....but here - I'm ok with it.
     

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  19. Tboy160

    Tboy160 Junior Member

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    I have the same problem, my battery well is rusted all to hell.
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    Never messed with fiberglass, but I may visit that option.
     
  20. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Time-honored method. I've 'glassed the battery floors of a bunch of old Volkswagens. Lets you squeeze a little more time out before they crumble.