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Re: [EVDL] Solution to Melted battery posts - Post style - One more thing

One more thing.

If you do any torch work around the batteries, it is best to have them in a
discharge state to at least 80% SOC. Then loosen all the fill caps and let
the batteries set about a day.

When I do this type of work with batteries that have fill caps, I remove the
caps and roll up a paper towel to use as a plug in the fill cap. I immerse
the paper plug in distill water before I press it in. Make sure the paper
plug does not touch the acid. Some type of fill caps are too close to the
post, so I do it this way.

Then cover the entire top of the battery with 1 layer of wet wool cloth and
2 layers of wet paper towels on top.

Roland

----- Original Message -----
From: "Lee Hart" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, September 11, 2010 2:23 PM
Subject: Re: [EVDL] Solution to Melted battery posts - Post style


> Greg Tyler wrote:
> > ... I have the wrong post type for the cables I'm using. In Trojan's
> > terminology these are Low Profile Terminals as found at
> > http://www.trojanbattery.com/Products/terminal_types.aspx
> > I made the mistake of using cables that were designed for AP terminals.
>
> Aha. That is indeed a problem. There isn't enough contact area in the
> low profile posts to carry high current.
>
> > I did replace the first battery that had a melted post. The new posts
> > was the Universal Terminal type. This is a much better fit for the
> > cable connection, but was one of the first posts to melt after
> > replacement.
>
> But again, it has much less contact area than a real automotive post.
>
> > If I were to continue to use these style posts, I'd want to go with lug
> > terminal connectors that would bolt on. However, I'm not confident that
> > this would improve the situation if the posts are made of cast lead,
> > which I believe they are.
>
> That is correct, Going to a ring terminal on a 5/16" stud is a step in
> the wrong direction.
>
> > It may be worth a try if it didn't cost too much to have "a good battery
> > shop" fix the bad batteries. I just don't want to spend a lot of money
> > when
> > I'll be laying out over $20K on a Leaf in about a year.
>
> Understood. But recognize that an "old master" could cast a new
> automotive post onto your old batteries in just a few minutes each.
>
> What kind of terminals do you have on your wires? Are they also cast
> lead, or something better? Also, how are the wires attached to these
> terminals? Just bolted (the so-called "emergency" repair terminals sold
> for car starting batteries)? Or are they crimped and/or soldered?
>
> Best case: You have good cast copper terminals, with 1/0 or 2/0 wire
> properly crimped into them. They all test good when you measure the
> resistance between the terminal and the crimp. In this case, I would
> have automotive posts cast onto the batteries, and re-use your old
> terminals and wires.
>
> Worst case: You have junky cast lead terminals, and smaller gauge wire,
> which is poorly crimped or corroding. In this case, throw them away. Get
> some flat copper buss bar material, about 1/8" thick and 1.5" wide.
> Drill a hole in each end that lets it fit over your battery's stubby
> low-profile posts. (Positive and negative will be slightly different
> sizes). Clean 'em, flux 'em, and dunk these bars in molten solder or
> lead to coat them.
>
> Bend the bars into _/\_ shapes so they will fit between the batteries,
> and aren't flat (the bends allow the batteries to move slightly relative
> to each other, so it won't break the seals and make the batteries leak).
>
> Drop the bar over the batteries, and heat the end of the stubby post
> with an acetylene torch to melt it. The lead will melt, and "weld" the
> post to the buss bar. You have to use a hot acetylene torch for this,
> because it has to be done FAST -- just a few seconds at most, our you'll
> melt the entire post.
>
> You can't remove the batteries without cutting the buss bar, but I
> guarantee you won't have any more terminal failures! This is how
> industrial EV batteries are connected, because it is so reliable.
>
> --
> Lee A. Hart | Ring the bells that still can ring
> 814 8th Ave N | Forget the perfect offering
> Sartell MN 56377 | There is a crack in everything
> leeahart earthlink.net | That's how the light gets in -- Leonard Cohen
>
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