House battery health

[Jerry Liebler]

There have been a few recent posts about house batteries and I've just 'rescued' my house bank so I'll share some things I've learned.  My house battery is 4 ea. L16's that I bought from another busnut when he upgraded to AGMs.  The company working on his bus had removed them and set them in a storage place and basically forgotten them.  I bought them about a year after they had been removed and they had all of about 5 AH of capacity.  I built a 'pulse desulphator', actually ended up building 3, and began the long process of resurrecting them.  After about 3 months I had some capacity measurements near the specifications and I put them into the bus.  In the bus my Trace SW2512 basically kept them charged as I kept it on & powered whenever the bus was idle.  Somehow I pretty much forgot about the batteries for over a year.  When I checked them this spring the water level was below the plates!  OH S@@@!  I refilled them using an awesome amount of distilled water (about 3 gallons).   I ran a quick capacity test, running my window AC off of them (it draws 9-10 amps @120) through the inverter.  In about 1/2 hr the inverter was indicating the temperature corrected voltage as 11.2.  I found one of my pulsers (we've moved and much of my stuff is packed somewhere).  I took a hydrometer reading of what I thought were fully charged batteries, they were drawing no current with a 13.2 v float charge.  It was 1.200 indicating about a half charged state, obvious sulphation.  I found this bulletin: http://www.rollsbattery.com/Bulletins/605.htm
and decided to forgo pulsing and just try the corrective equalization as I've never actually equalised these batteries so the electrolyte is surely stratified. I folowed their instructions, it took 12 hours but the specific gravity came back to the 1.275 I remembered from when I installed them in the bus.  It sure worked!!  I let them cool last night and this morning tried another load test.  Same air conditioner showing as a 9 amp load on the inverter panel ran for 2 hours before the specific gravity dropped to 1.235  which according to the bulletin is about a 75% state of charge. and the temperature compensated battery voltage, according to the inverter is still 11.7 volts under load.  I shut off the load and the reported battery voltage is back to 12.6 after 5 minutes.  No need for pulsing!  With allowance for inverter efficiency I was pulling about 100 amps, did it for 2 hours and used 1/4 of the charge which says I've got about 800 AH, not bad for what is specified as a 740 AH under a 37 amp load (20hr rate). 
The moral of the story is follow the bulletin and do an occasional equalization charge if you have flooded cell batteries.  I'm also ordering a set of hydrocaps.
Regards
Jerry 4107 1120 

[kyle4501]

Hey Jerry, Thanks for the link.

We used water miser caps on Dad's 4 T-105's instead of the hydrocaps.

My reasoning was that the water miser caps require less attention, & dad wants to minimize things on the 'don't forget this' list.

My understanding at the time was that the hydro caps reclaim & condense (by catalyic action ?) the escaping vapor. But they can overheat & ruin the catalyst if left on during periods of heavy charging or discharging. Where the water misers simply try to catch the mist & drain it back into the battery & aren't ruined by heavy charge/ discharge cycles. Is this close?

I think I found the water misers for ~$5 each.

[Jerry Liebler]

Kyle,
     Yes hydrocaps heat up as they recombine the hydrogen and oxygen so they must be removed for equalisation, but that's really the only time.  They are designed to easily survive routine charging and discharging.  In researching them I found that their temperature rise, when measured with an infrared thermometer, is actually a very useful tool for detecting any inequality among the cells.  I'm also aware of the watermisers, which to me is not as good a solution.
Regards
Jerry 4107 1120

[David Anderson]

Jerry,

When you did the 12 hr equalization were you plugged into a grid or running a genny?  I only have a 15 amp plug for my coach at my house and due to distance from my home's breaker panel if I set the shore cord setting in my SW2512 to more than 9 amps I get a voltage drop from 120 to about 110.  I won't every let my line input go below 110.

With that in mind how many AC amps are you drawing at that equalization setting?  Also, what setting did you use?  I think my batteries recommend 15.3 volts. 

David

[Jerry Liebler]

David
  I was plugged in to my 40 amp shore cord outlet (50 amp setup but with a 40 amp breaker cause that's what I had).  I'd initially set the max charge current to 3 AC amps, the voltage to 16, on the inverter but the voltage never got above 15.  The bulletin says charge current should be limited to 5Amps /100AH of battery rating but that's at 12 volts so to be on the safe side I chose the 3 AC amps figuring it would equate to about 30amps at the battery and I knew my batteries had reduced capacity.  The bulletin also advises checking battery temperature every hour and avoid going over 115 f.  On my 4th hourly check I was seeing 110 degrees f so I cut the charge current back to 2 amps AC.  The temperature fell back to 105 and never went higher after.  It took 9 hours for the specific gravity to get to the 1.265 then, as the bulletin instructs I continued for another 3 hrs.  You should have no problem doing a corrective equalisation on a 15 amp shore cord because of the 5 amp/100AH limit.  This means 1 amp AC for each 200 AH of battery.  BTW it's not in the Trace manual but you can end an equalisation charge from the inverter panel by selecting the inverter mode 'off' then back to 'on" or whatever.
Regards
Jerry 4107 1120 

[TomC]

In reading and experiencing all the time and effort in maintaining normal wet batteries, both my starting and deep cycle batteries are sealed.  The 2-Interstate 950cca size 31 batteries that are used to crank the big engine are sealed wet type batteries.  My two 8D Lifeline AGM (Absorbed Glass Mat) deep cycle batteries are also sealed.  The advantage to AGM is that the batteries can be operated in any position (they prefer you not to run them up side down, but they will), they don't gas, can sit for a year and still have power left, only need to be equalized when capacity is down, don't need any servicing-since they don't gas the terminals never get corrosion, can charge them twice as fast as wet batteries-I could only charge my wet batteries at about 50 amps-now have the inverter set at 90 amps.  Disadvantages-their about twice the cost of a quality wet battery, have a 5 year prorated warranty, and have to be very careful of not over volting them to boil the electrolyte off (no way to replace it-can boil it off since they do have pressure vents).  Good Luck, TomC

[David Anderson]

Thanks, Jerry.

The last time I did this I did 4 batts at a time for 3 hours each.  I have 8 batteries in my bank.  I laid a sacrificial terry towel over the fill holes to catch the bubbling gas and liquid.  It kept the fumes in check.  I guess I need to do it much longer, but you have to babysit them the whole time, like watching cookies in the oven.   I remember seeing stuff floating around in the cells.  Lots of muck falls to the bottom of those batteries over time. 

David

[Jerry Liebler]

Tom,
     AGM's suffer from the same problem of sulphation that flooded cells do, perhaps somewhat less because of different plate materials. The under lying cause of the sulphate build up is not fully charging battery.  With an AGM you can't tell the actual state of charge by measuring the specific gravity so the undercharge is less likely to be discovered. But the different plate materials do lower the self discharge rate. Equalisation of AGM's involves much more risk of damaging the battery.  With flooded batteries, restoring capacity lost to sulphation by prolonged equalisation is much less likely to damage a battery as water can be added as needed.  Also with flooded cells a much more accurate assessment of 'health' and need for equalisation, can be made because one can measure the specific gravity of the electrolyte.  I'm not sure I'd go to AGMs even if the cost were the same.
Regards
Jerry 4107 1120

[Dallas]

As for the Lead acid Group 31 'sealed' batteries, I just got rid of all my old ones!
They quit working well after only 9 years of use. I just don't understand why!

Oh, I do have to mention that I cut the glue on vinyl 'seal' over the top of the batteries and filled them with distilled water every so often.

I also used EDTA twice in them to desulphate them. Once in 2003 and again in 2006. It must not have hurt them since they did last a bit beyond their projected lifespan.

If you buy those so called, sealed lead acid batteries, go ahead and cut the seal, they will love you for it.

Dallas