[RE-wrenches] Outback FXR: Battery voltage exceeds settings

Sat Jul 23 08:55:19 PDT 2022

Outback controllers have a tendency to be a bit slow. 

So they can definitely get higher than the set points but only for a second or two which is not going do damage anything. I’ve seen them do this. 

Especially if it’s a larger array, sealed batteries and when the batteries are full and a load turns on and then off. 

At the load off the CC is dumping watts, and the sudden loss means a short voltage spike. 

Jay

> On Jul 23, 2022, at 9:43 AM, Jerry Shafer via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
> 
> 
> Most AGM's don't like voltage that high and it swells the battery and destroys its storage capability alot of the time
> Jerry
> 
>> On Fri, Jul 22, 2022, 7:50 PM Steve Higgins via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>> William, 
>> 
>> If the battery cases swelled, they saw over 52 degrees C temps for quite some time.   
>> 
>> While the swelling is usually only cosmetic, what's happening inside is the negative plates are starting to burn. This is where you will start to lose capacity and life cycle...  Extended temps of just 35C will half the overall battery life. 
>> 
>> One of the issues with the Outback gear is they only temp compensate at 5mv/Degree/cell. For all the AGM batteries I know of, you need to temp compensate at 4mv.   In hot temps, this should help, but cold temps could result in an overcharge.   Did you check the BTS and make sure it was operating properly? 
>> 
>> Another issue is that BTSs are often placed on the top or lug of the battery,   The top of the battery is about 5-10 deg C cooler than 1/2 way down the side of the battery, Which will also cause problems with proper temperature compensation, especially with warmer/colder extremes.  
>> 
>> Any kind of sulfation will cause an imbalance when you mix old and new batteries.   I'm not a fan of mixing any age AGM batteries as there is no way to tell what the SOC of the old bank vs. the new bank is.   They are not like flooded batteries; you can check SGs and dissipate heat much better than AGM or GEL batteries.   I discourage doing this if you can.   I probably wouldn't have mixed the old and new in the same strings. This way, you keep the higher resistance batteries in a single string,  
>> 
>> Lastly, bunching them together with no spacing between them is very bad. Batteries should be in a cool, dry environment.  Most battery companies want to see 1-3 inches in between each battery to allow for effective cooling. When they are all bunched up together, that is a lot of thermal mass that doesn't have much chance of cooling.   I have seen two parallel strings of AGMs take 24-36 hours with no charging or load to drop from 45c to 25C! 
>> 
>> Hope this helps!  Have a good weekend. 
>> 
>> 
>> 
>>  
>> 
>> Steve Higgins ⋅ Technical Services Manager
>> t +1.902.597.4020  m +1.206.790.5840
>> f +1.902.597.8447  e steve at surrette.com
>>      
>> 
>> 
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>> 
>> 
>>> On Fri, Jul 22, 2022 at 6:48 PM William Miller via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
>>> Friends:
>>> 
>>>  
>>> 
>>> I maintain a system with 16 AGM L-16 batteries.  Eight were installed in September of 2021 and 8 were added in March of 2022.  This is 5 months apart.  I have understood that when you install a string of batteries you have one year in which to add another string before the first string ages to the point it is contraindicated.  When I added the second 8 I put 4 new batteries and 4 old batteries in each string.
>>> 
>>>  
>>> 
>>> About a third of the batteries are discovered to bulging on top.  I assume this means the batteries are damaged.  I checked the FXR and Outback Extreme Charge controller settings and all were set to absorb at 58.8, and float at 55.2, as the manufacturer recommends. 
>>> 
>>>  
>>> 
>>> I downloaded the charge controller log and got 129 days of data.  In that log I see 68 days where the batteries exceeded 60 VDC. This is over half the days.
>>> 
>>>  
>>> 
>>> I wonder this:
>>> 
>>>  
>>> 
>>> 1.   Why did the voltage go up above 58.8 on so many days even though it was set at 58.8. (I set the EQ voltage at 58.8 just in case, but EQ was never engaged.)
>>> 
>>> 2.   Did the excess voltage damage the batteries?
>>> 
>>> Any input is appreciated.
>>> 
>>>  
>>> 
>>> Sincerely,
>>> 
>>>  
>>> 
>>> William Miller
>>> 
>>>  
>>> 
>>> Miller Solar
>>> 
>>> 17395 Oak Road, Atascadero, CA 93422
>>> 
>>> 805-438-5600
>>> 
>>> www.millersolar.com
>>> 
>>> CA Lic. 773985
>>> 
>>>  
>>> 
>>>  
>>> 
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