# Holding Down Your Batteries



## PatricioIN (Jun 13, 2008)

as you know, I used the same indoor/outdoor ties like the black ones in your picture. I had to remove all four batteries that sit over the motor when I had to send the motor back for repair. I had to cut them all off and they showed no sign of wear on them after 1000 miles of driving.


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## etischer (Jun 16, 2008)

rfengineers said:


> I've been experimenting with different methods for securing my flooded lead acid batteries.
> 
> Steel bars and rods lasted about six weeks, no surprise there.


Why did the steel bars and rods only last 6 weeks?


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## speculawyer (Feb 10, 2009)

etischer said:


> Why did the steel bars and rods only last 6 weeks?


Yeah, that was my reaction as well. That is basically what holds batteries in nearly every car.


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## Guest (Mar 23, 2009)

Why do yours look melted? Either you have them where they can get so hot they melt or you have leaking batteries that are melting that plastic. Either way it seems like you have a problem other than the hold downs. If steel hold downs only lasted 6 weeks you for sure have a leak problem and you are not fixing that and you have not protected your hold downs with anything. Seems like you are then using bare steel in an acid environment. Not good. How is the rest of the vehicle holding up? Got some pictures of your batteries? Are your batteries clean and dry? Caps holding tight? No cracks in the cases? Electrolyte level OK? 

Pete : )


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## DIYguy (Sep 18, 2008)

I've been thinking about this issue a bit lately also. Personally, I would be a bit worried about using "tie-wraps" (zip ties etc). They may hold your battery down ok....but in the event of accident or very sudden stop.. I just don't believe they would hold things in place well enough. I guess what I am saying is the safety factor is too low, particularly for my 100+ lb batteries. I'm sure that there are some battery box designs where they MAY be ok.... but for mine, I will use something more substantial like steel or nylon banding...or redi-rod...not sure yet. Just something to think about.....


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## rfengineers (Jun 2, 2008)

The steel corroded very quickly. The steel rods that held down the angle-iron lost more than 50% of their cross-section in about six weeks. The steel in the trunk is fine, but I did heavily coat them with automotive undercoating. I also regularly sprinkle a liberal amount of baking soda in the spare tire well.

Here are pictures of the batteries. The back seat of the car is folded down, so you can see through to the inside of the car from the trunk. Normally the seat is up.

The batteries were clean and dry when I serviced them this weekend. The electrolyte levels were fine, each cell took about 1-1/2 turkey basters of water each. (One turkey baster is, of course, the standard unit of electrolyte). 

The broken/melted ties were on the two most forward batteries in the trunk. Those are the ones up against the back of the rear seat and, I suspect, get the least air circulation from the exhaust fan.

The damage was not heat related. The damage occurred where the tie ran next to a vent cap. They were still soft/gooey even a day after I cut them out of the car.

PatricioIN: My front ties, which get a lot of air circulation, were fine. The damage was in the trunk, possibly where gas was accumulating.


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## Guest (Mar 23, 2009)

Interesting to see that plastic melt due to battery water. I know of no plastic that will melt in a solution of acidic water. I think I can assume it is not nylon. Usually nylon will live in that environment. Maybe something else got on the zip ties that caused that. Gooey seems more like some sort of solvent and not battery acid water. 

Pete : )

Nice and clean batteries. : )


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## DIYguy (Sep 18, 2008)

One other thought....many hardware stores sell stainless steel redi-rod (threaded rod). I'm not sure what grade...likely 18-8SS, so that should stand up better.

cheers. 
(oh yes, tie wraps are available in different material, additionally, some have a steel insert for the ratchet/lock mechanism...others are simply a piece of plastic/nylon etc....they are not all created equal. Oh ya, some get brittle in the presence of UV light also.)


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## rfengineers (Jun 2, 2008)

DIYguy said:


> One other thought....many hardware stores sell stainless steel redi-rod (threaded rod). I'm not sure what grade...likely 18-8SS, so that should stand up better.
> 
> cheers.
> (oh yes, tie wraps are available in different material, additionally, some have a steel insert for the ratchet/lock mechanism...others are simply a piece of plastic/nylon etc....they are not all created equal. Oh ya, some get brittle in the presence of UV light also.)


Yeah, My next step, if the nylon ties don't work, is to get fiberglass angle and stainless steel rods. A AISI-316 (316S33) steel is a common choice for acidic environments. Although any austinitic SS with a high silicon content will do. But that stuff sure is hard to work with, and it's $$.


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## dimitri (May 16, 2008)

I used this type of ratcheting tie downs, just make sure that ratchet mechanism is further away from battery vents, in case some acid spills on them. They seemed to work well on my first EV and I am using same method on my new EV, although in this case cells are dry, so no acid issues.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47707

Hope this helps

EDIT: I didn't want to use the awkward hooks that come with it, so I cut them off and my wife sewed new loops on the ratchet piece, making it a single piece tie down. Make sure to use heavy duty nylon thread for sewing.


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## rfengineers (Jun 2, 2008)

dimitri said:


> I used this type of ratcheting tie downs, just make sure that ratchet mechanism is further away from battery vents, in case some acid spills on them. They seemed to work well on my first EV and I am using same method on my new EV, although in this case cells are dry, so no acid issues.
> 
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47707
> 
> ...


I looked at those straps yesterday while I was doing my weekly wish-list visit to our local Harbor Freight. I was concerned that the polyester webbing would suffer the same fate as the plastic zip ties. I did not see a similar strap with nylon webbing.


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## DIYguy (Sep 18, 2008)

dimitri said:


> I used this type of ratcheting tie downs, just make sure that ratchet mechanism is further away from battery vents, in case some acid spills on them. They seemed to work well on my first EV and I am using same method on my new EV, although in this case cells are dry, so no acid issues.
> 
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47707
> 
> ...


Ya, I like this option. I have AGM's so, no acid to deal with. This is more substantial for sure. I actually have some of these! 

thks.


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## Greenflight (Sep 13, 2007)

I'm just guessing here, but I have to say that you may have some ventilation issues if your old battery hold-downs corroded that fast. In my truck, I use an angle iron frame held down over the batteries by tie down straps. It's been in place for over a year and it has very light rust. It's not even painted.

My Tercel doesn't have a ventilation system yet (I open the trunk for charging) and the battery racks in the trunk are corroding significantly faster. This could be due to the batteries (much cheaper than those in my truck) gassing a lot more and what not, but I believe proper ventilation would probably help out.

You want something more durable than zip ties for holding down batteries. Even the high quality ones will wear out over time, especially in this kind of high-vibration environment. If one let loose while you were driving, bad things could happen.


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## racunniff (Jan 14, 2009)

dimitri said:


> I used this type of ratcheting tie downs, just make sure that ratchet mechanism is further away from battery vents, in case some acid spills on them. They seemed to work well on my first EV and I am using same method on my new EV, although in this case cells are dry, so no acid issues.
> 
> http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47707
> 
> ...


This seems like a dangerous, although frequently used, idea. What is the tensile strength of this strap? A 10-G crash is highly likely (that's a fairly low-speed crash - possibly as low as 35 MPH). Will this strap hold up 10 times the weight of the pack it is securing? If not - it is too weak. Even if it would hold that weight - how much will it stretch? Enough to let the batteries loose? You do *not* want batteries flying through the air.

FWIW, I try to design my racks and hold-downs for a 20-G crash.


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## tj4fa (May 25, 2008)

rfengineers said:


> ...each cell took about 1-1/2 turkey basters of water each. (One turkey baster is, of course, the standard unit of electrolyte).


 Would that be the scientific international micro-baster unit of measurement or were you just using the traditional master baster method? 

Whatever...1-1/2 turkey basters seems like a lot!

For the last 4 months, I only had to put in about 1/4"-1/2" of water above the plates to keep the water at that level.

Do you suppose your batteries are heating up really hot when you're charging them and boiling off the water and at the same time melting the straps from heat?


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## Greenflight (Sep 13, 2007)

Boiling water shouldn't melt zip ties... even the cheapest should be able to take that.

I wouldn't rule out overcharging causing excess gassing, which could melt them (acid melt, not heat melt ).


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## Coley (Jul 26, 2007)

It sounds much like overcharging.
I have aluminum straps across my LA with steel holddown bolts.
The aluminum bars are wrapped with plain old electrical tape. Not hardly any corrosion on anything is 3 years!!


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## rmay635703 (Oct 23, 2008)

You could always just make aluminum boxes, put on bedliner coating and put the batteries in, they can't go anywhere when in a box, although you would need to figure out how to make them accessable and removable.


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