Battery Equilazation?????

[rv_safetyman]

The subject of battery equalization has been discussed before:  http://www.busconversions.com/bbs/index.php?topic=3346.0

As was noted in my CO detector thread, I think I have an issue with my battery bank/charging.  I filled them with distilled water a couple of months ago and found two of them were pretty dry and the rest were down quite a bit.  I refilled them and left them overnight.  I checked them with a hydrometer this morning and the cells showed in the red - not too concerned since I added water yesterday. 

I have not equalized the batteries in quite some time.  So, I am in the process of trying to do that.  My system is:

--Trace SW2512MC
-- 8 ea Exide golf cart batteries

I set the equalize voltage to 14.7 and the time to 1 hour just to play with the settings.  A couple of times the system returned to float.  Once was because the time was set for ten minutes.  The next time, I am pretty sure the 1 hour limit was not reached.  I have just started the process again, and after 20 minutes the battery voltage is only 14.0 as measured by the Bogart Trimetric and 14.1 volts on the Trace.

Am I doing something wrong? 

I have tried to find the correct settings for the Exide GC batteries, but their site is terrible.  Any thoughts on voltage and time?

Jim

[Utahclaimjumper]

If your hydrometer test was that low then you will need a 24 hrs. charge , then equalize.>>>Dan

[rv_safetyman]

Dan, thanks for the input.  I think the hydrometer was low because of the water I had added and had not had a chance to "mix".

What you say makes sense and the manual sort of touches on it.  However, the Trace thinks the batteries are charged and goes into float very quickly.  I added the water late yesterday afternoon and the inverter is always on.  I thought that it might be enough to get the water "converted" (sorry about the less than perfect descriptions).

I just went out and checked the voltage and it is still at 14.0 and the system is still in equalize after 45 minutes.  I checked the batteries and they are doing a fair amount of bubbling and the hydrometer readings are getting better. 

I think I will force the system into a few cycles of this one hour "equalization" today and see if I can get the batteries in a condition to accept a full equalization cycle tomorrow (cooler temperatures in the shop).  I will do the cycles today with some rest time (maybe an hour) in between.

Jim

[Sean]

Jim,

As I wrote in that  other thread (http://www.busconversions.com/bbs/index.php?topic=3346.msg30195#msg30195), the SW series will only go to equalize after completion of a bulk cycle.  And it will only go to bulk in the first place if the voltage indicates it is needed.

I recommend you charge completely at existing settings until you get two green lights.  Then disconnect the input AC and deplete the battery bank at lest 20%, and preferably closer to 40% discharge (i.e. between 60% and 80% SOC).

Set your equalization voltage and time as per manufacturer's recommendations, plug in your AC power, and immediately select "equalize".  The bulk LED should blink.

Scroll down to meters and monitor the voltage.  You may find that there is enough lag in the voltage due to absorption that you are not getting enough equalize time.  If that's the case, measure the time spent above the bulk setting, subtract it from whatever you set for equalize time, and add the difference to your equalize timer for the next time you equalize.  I would give it at least a week and three or four discharge cycles before trying another equalization.

HTH,

-Sean
http://OurOdyssey.BlogSpot.com

[rv_safetyman]

Sean, thanks for the continued support for these issues. 

I now have the bus on invert and will take it down to about 60% SOC.

I got a call from a person on this board that gave me a couple of good thoughts.  First, make sure that all 12V components are turned off when you equalize.  The 15 volts could hurt some LED lights and some control boards.  He also suggested that I turn off the inverter and disconnect the batteries.  I did that for about an hour.  The thought being that that would "reset" the inverter and force it to look at the battery voltage as it really exists.  Not sure I understand, but it can't hurt.

Jim

[rv_safetyman]

I have struggled to find time to update this thread.  But I need to detail the root cause of the problem.

Based on the input here, I took the batteries down to 69% SOC based on my Bogart Trimetric.  I then let the inverter do a bulk charge.

When I put the inverter into equalize (set voltage at 15.5 and time to one hour), the inverter kept "cutting out" of equalize and back to float.   Happened about every minute and then it would go back to equalize, then drop, etc.  Finally it stayed in equalize but would not get over something like 14.4 volts. 

I let the bank set for a few hours and then checked the batteries with a hydrometer and discovered one cell dead in one of the golf cart batteries.  I took that pair out of the wiring for the bank and all seems to be "normal" now.

Sean, in another thread, you mentioned temperature compensation:

That said, 13.4 is considered the upper limit for float on flooded batteries, and many manufacturers recommend 13.2.  More importantly:  All these ratings are for 70°F ambient -- you need to lower the voltage a little bit for every degree above that.  Generally above 85°, 12.6v is the highest float voltage you should use; above 100°F I would drop that even further to 12.1-12.2v.  If you don't already have it, I highly recommend you get the battery temperature sensor for your SW inverter, which will let the inverter automatically make these adjustments for you.  Find the hottest spot on your battery bank and affix the sensor there.

I have that option, but never explored how it functions.  Since I am down to 6 batteries, I need to change the Bogart to reflect the lower capacity.  I won't do that for a while, as I have hopes that I can salvage the battery with the dead cell.  In-the-meantime, I have been watching the voltage and it is really interesting.  I have float set at 13.2 volts, but it does not get there because of the temperature compensation.  Yesterday it was pretty hot where we were, and the voltage was 12.9.  This morning it is about 70* and the voltage is 13.0.  That is a bit misleading, since the batteries are in a fairly tight wood box and the batteries are at a higher temperature than ambient.

Jim