[RE-wrenches] discharging Rolls batteries

[Darryl Thayer]

Hugh
I find your insite to be correct.  If you take any battery, and it is most noticable on slow charge batteries(such as RE and Rolls Solar batteries) if you discharge rapidly the voltage will drop much lower than SOC would indicate, if you let the battry stand the voltage will recover.  So yes you should be able to discharge to a lower voltage and still not be below the safe SOC.  

AS to weather anyone has this possibility Outback should be able to with there FnDC, I have discussed this with them, but ...the future.  

A new company Silent Power has also looked at this discharging parameter, and ... the future.   They say if I can come up with the algorhythm then maybe.  

Thanks for raising this important issue, it is a problem almost every time.  
Darryl

--- On Thu, 1/14/10, Hugh <hugh at scoraigwind.co.uk> wrote:

> From: Hugh <hugh at scoraigwind.co.uk>
> Subject: Re: [RE-wrenches] discharging Rolls batteries
> To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
> Date: Thursday, January 14, 2010, 4:35 PM
> 
> Re: [RE-wrenches] discharging Rolls
> batteries 
> Hi Jamie and Dan,
> 
> 
> Thanks for keeping up this thread!  And sorry for
> being
> impatient.
> 
> 
> Now, if the capacity 'loss' is simply due to
> reduced performance,
> is it logical to say that one can push the battery to lower
> voltages
> under low temperature conditions without actually cycling
> it harder or
> reducign its life that way?
> 
> 
> On the question of inverter temperature compensation
> for
> discharge set points, these would surely be adjusted
> downward in low
> temperatures whereas the charging setpoints are adjusted
> upwards. 
> I had never heard of such adjustment to discharge setpoints
> (low
> battery disconnect, genstart, etc).  I would be
> interested to
> know if this type of temperature compensation exists and
> indeed
> whether it is legitimate in terms of sustainable battery
> management.
> 
> 
> Hugh
> 
> 
> 
> 
> Hugh,
> 
> 
> 
> 
> Sorry if you
> found my response limited but have been traveling since
> early this am
> and don't have all information at hand, at the
> moment.
> 
> 
> 
> 
> Regarding
> temperature effects on capacity, earlier responses are spot
> on as the
> lower capacity is totally as a result of slower reaction
> times as a
> result of lower temperatures.  
> 
> 
> 
> 
> Approximate
> Temp effects;
> 
> 
> 
> 
> 40C
> =
> 104%
> 
> 
> 25C
> =
> 100%
> 
> 
> 5
> to 10C =
> 90%
> 
> 
> -5C
> =
> 80%
> 
> 
> -22C =
> 60%
> 
> 
> -- 
>  
> Hugh Piggott
> 
> 
> 
> Scoraig Wind Electric
> 
> Scotland
> 
> http://www.scoraigwind.co.uk
>  
> 
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