E meter [RE-wrenches]

[John Blittersdorf, Cent. VT Solar & Wind]

Paul,
    I have just spent a month trying to figure out why the emeter gives such 
erroneous data.  I have found the cause but not the cure.  The emeter is 
correct ONLY IF the batteries are in good shape, ie not sulfated.  When the 
battery capacity is diminished due to sulfation, then the emeter is giving % 
of full based on a good battery and not the reduced capacity of a sulfated 
battery bank.  I have a customer with 16  NEW Trojan L16PF, who was seeing 
the same problem.  When I installed the batteries, they were used quite 
heavily and charged minimally (while the house was being buiilt).  Apparently 
the batteries sulfated due to poor recharge.  After checking everything else 
and talking with Trojan, we decided to start a program of multiple equalizing 
charges to see if the problem could be rectified.  It worked.  After each 
substantial charge cycle, the s.g. kept coming up and the apparent capacity 
of the batteries improved.  After 5 equalizing charges with the voltage 
allowed to go to 31v, the system is working normally.  My own system was 
showing a similar problem and I did the same thing and my batteries are now 
better.  I charged mine to 31.5v to get them to slow boil.  The Trojan 
contact said that the L16's need to slow boil to completely mix the 
electrolyte to eliminate stratification of the acid.  What happens is that 
when the acid stratifies (water on top, very concentrated acid on the 
bottom,), the plates start to sulfate where they are in contact with the weak 
acid effectively reducing the good plate area and reducing the battery 
capacity.  The emeter is assuming that you have all the battery capacity and 
therefore we see a lower voltage (ineffective plate area) .  When a system is 
charged only with solar and there is not enough PV capacity to do a good 
equalize charge, then this problem is most prevalent.  

If you have a generator, try hard equalizing charges and see if you can 
recover the batteries.  

Wrenches, has anyone had this problem with other meters?

John Blittersdorf
Central Vermont Solar and Wind

- - - - - - -
To send a message:
 RE-wrenches at topica.com

The archive of previous messages: 
 http://www.topica.com/lists/RE-wrenches/

To unsubscribe send a message to: 
 RE-wrenches-unsubscribe at topica.com

To check out the other RE-Wrench participants:
 www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine: 
 www.homepower.com

For info contact list moderator by email:
 michael.welch at homepower.com

___________________________________________________________
T O P I C A  http://www.topica.com/t/17
Newsletters, Tips and Discussions on Your Favorite Topics