Quote:
Originally Posted by TheSGC
How did the commute go?
I wonder how the Alum batteries handle under load compared to the lead acid ones.
I have been itching to drive my EV more, but it has been snowing for the past three days and I haven't finished my water heater yet.
|
My limited experience with alum batteries is that they are best as stationary batteries running light loads.
They droop in voltage much more almost down to 6v (but come back) and also bubble like an edison battery with probably the same charge efficiency, they also have a fast self discharge rate. They operate at much lower voltages because of the insolubility of the electrolite in solution, however you can run them flat without much issue it seems.
I have tested 3 batteries as alum, the first was junk to begin with and failed with a broken interconnect. The next ended up with a shorted cell (was before too) The 3rd a trojan T-1275 that only had about 30ahr left came back after some cycling 160ahr at 3 amp load, however the under load capacity was much lower and at much lower voltage (hard to guage going from 11.5v to 10.5v). Also I found you needed to use the battery straight after charge to have the best range.
Perhaps I am doing something different, looking at the "old" information it appears alum is to be added to water then mixed in the acid in most old recepies. Sometimes mixed in with cobalt and epsom salts. Perhaps the really good alum batteries have had the owners leave some acid in there, and sludge feeds the alum reaction but it also causes internal shorts which is how most of my batteries have ended up, shorted.
If anyone wants to test alum, go right ahead just make sure you do it on sulphated batteries, not ones with broken cells or broken interconnects. Alum doesn't really work on new batteries or ones that more or less are good.
Alum can potentially increase capacity beyond the original rating but it has the devistating side effect of offering that capacity at a linear discharge down to about half your original voltage. And in my experience only at lighter loads but perhaps my set of batteries were all failures. Some have claimed their alum batteries function at voltages higher than original, not sure how that would happen, would be nice if someone who was good at making sucessfull conversions would show how to do it correctly.
Also I would think EDTA or epsom salts work more reliably as Alum apparently needs a pretty specific situation to work ideally. Good though if the battery is a boat ancor, could at least use them to run lights and actually originally alum batteries were used to run lights, telegraphs and other long use light load applications prior to 1905. (one guy linked a book from 1899 describing an alum powered telegraph) So no we aren't crazy, there were alum batteries very early on but obviously had some problems or we would be using them now.
Cheers
Ryan