C/5 - C/30 ? [RE-wrenches]

[Bob-O Schultze, Electron Connection]

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Dan,
Yes, all the C rates we are talking about are referenced against the  
20 hour discharge rate. for better or worse, that has become our  
industry's standard.
As Jay has pointed out, we rarely see those kind of rates in the  
"average" RE system and most inverter/chargers will taper off the  
charge rate based on voltage. IMO, if you somehow held a C/5 charge  
rate (say because you had a really small battery bank) with a  
constant current charger, you would start some serious and pretty  
violent gassing. Dangerous, especially with older batteries where the  
structures that hold the plates and separators have eroded over time.
On Oct 4, 2006, at 9:24 PM, Dan Rice wrote:

> Drake, Bob-O & other battery veterans,
> Two questions. When you refer to a charge rate of, say, C/5, is it  
> correct
> to assume that "C" refers to the amp-hour capacity of the battery  
> at the 20
> hour discharge rate? Which would mean that, for a single string of  
> Trojan
> T-105's with a 20 hour rate stated capacity of 225 AH, C/5 would be  
> 45 AH,
> and a C/5 charge rate would be 45 amps for this string? If that's  
> the case,
> what is your experience with such a high charge rate? Bob-O, your
> observation that this charge rate is applicable to heavily discharged
> batteries makes sense, as does your comment that the charge rate  
> must be
> tapered once the battery reaches 50-60% capacity. What I am  
> wondering is,
> can such a charge rate be maintained beyond 60% SOC plus or minus  
> in any
> case, or does charging voltage continue to rise beyond a reasonable  
> (safe)
> level? If a battery is not cycled below 50% DoD, is it even  
> possible to
> maintain a C/5 for more than a couple of minutes without the  
> battery voltage
> rising beyond a desirable level?
>
> I'd love to hear all 12 opinions...

Me too!
Cheers, Bob-O


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