On Mon, Apr 27, 2009 at 03:24:49PM -0400, Gene Heskett wrote:
> IIRC there are 4 6 volt gel cell packs in it, 24 volts. This one is a
> big old honk and 6 years old at least. I have replaced the batteries
> and blown the dirt out of the fans & case several times, but it just
> plain runs too darned hot for gel cells and they expire in about a
> year, at $225 a set.
1500 VA is plenty to pull out of 24v. With four times the losses of a
48v inverter, it has to run hotter. But I don't think I'm delivering any
news there. :-) It won't take long to pay for a new one, just on the
battery savings.
> >[1] I'll heed your admonition about catastrophic capacitor failure. :-)
>
> Its not the caps that fail, its all the other stuff that can't take
> the surges when the esr on them goes to hell.
Ah, oh, hmmm ..., I'd better put together that little esr meter then,
because I found a bank of 2700 µF 80v capacitors in a retired SMPS. I
thought that if the esr is OK, I'll use them in the supply to drive at
least one axis.
I spent several hours last night, hunting the web for low esr
electrolytics here in Australia, but found nothing over 470µF in 80v.
There's 15,000 µF 63v, but using them at 50v seems cutting it too fine.
(At Siemens we weren't allowed to use electrolytics above half their
rated voltage, and 2/3 of rated temperature, IIRC.)
Maybe I can find some in the US. (I don't think they're a good item to
buy on ebay, though.)
Erik
--
The Heineken Uncertainty Principle:
You can never be sure how many beers you had last night.
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