[RE-wrenches] Surrette Battery Question

[Todd Cory]

Did this customer check the voltage of the individual batteries/cells? 
Maybe there is a weak cell developing. Sometimes EQing can take a long 
time. I do not "buy" that batteries need to be cycled to stay healthy.

Todd

jay peltz wrote:

> Hi Robert,
>
> When you mention cycling batteries, are you saying that batteries in a 
> offgrid system that are being cycled 15-25% a day should be cycled 
> even deeper than that?
>
> Thanks,
>
> jay 
> peltz power
> On Aug 1, 2008, at 8:36 PM, robert ellison wrote:
>
>> A couple things that I haver noticed in the past, sometimes batteries 
>> like to be cycled, shut off the controllers and run them down, then 
>> charge them up fully and then give them an eq charge till it comes up 
>> the peak voltage and hold it there as it (sometimes) slowly rises. 
>> Any of these thoughts are superseded by Jamie if he has any thoughts. 
>>  
>> Also, if you have not given them an eq in a while it might take 
>> longer than the available solar time has to get them to the top and 
>> hold them there..
>> Have the controllers settings changed?
>>  
>> Bob
>> On Fri, Aug 1, 2008 at 10:18 PM, Allan Sindelar 
>> <allan at positiveenergysolar.com 
>> <mailto:allan at positiveenergysolar.com>> wrote:
>>
>>     Wrenches,
>>     In late 2003 we installed a 24V set of Rolls-Surrette 4-KS-21PS
>>     6V 1104 A/hr batteries in the off-grid system of a long-time
>>     client. The client's system had a democracy array of around 800
>>     watts of tracked PV. In early 2005 we added 1,280 watts of
>>     additional PV, and the client hasn't run the generator since; the
>>     system rarely drops below 80% and fills to 100% most days in
>>     sunny New Mexico. Batteries are located in a basement, so
>>     temperatures stay relatively constant, although it will vary
>>     slightly seasonally. MX60 controller is temperature compensated,
>>     with 29.6 VDC bulk and 31.4 VDC EQ set points.
>>
>>     The problem is that the client reports being unable to achieve
>>     previous EQ voltages, and this inability appears to be a new
>>     development. The system is otherwise performing well. As the
>>     client is sharp and pays close attention to the system's
>>     operation, I'm not ready to blame user ignorance (with one
>>     possible exception; read on). This may be an issue of seasonally
>>     warm temperatures, but I'm not sure this would explain the full
>>     0.4 VDC reduction in voltage. I told him that I would post his
>>     problem to this list, and also request advice from Surrette Battery.
>>
>>     Here is the client's description of the symptoms:
>>     I'm concerned that I am unable to equalize batteries at this
>>     time.  Up
>>     until June of this year the Tri-Metric readings during equalizing
>>     indicated
>>     holding voltage at 31.1, with maximum amps gain of around 52.  
>>     Three weeks
>>     ago, when set on equalize, the maximum voltage reading was 30.7,
>>     with
>>     maximum amps of 46; this was reached around noon, and by around
>>     1:30 pm
>>     voltage/amps began its typical afternoon drop-off.  I attempted
>>     equalizing
>>     on two other occasions since then--the last time this past
>>     Saturday, with
>>     clear skies up until mid-afternoon--but having the same results. 
>>     So, the
>>     question is: are my batteries beginning their decline? We've had
>>     this set
>>     for 4 1/2 years, so it would seem a bit too early for this, given
>>     that these
>>     batteries are expected to last 7-10 years.
>>