Proper Battery Charging

[jleamont]

New coach (to us) to many gadgets on board, trying to put my head around the equipment on this coach. I have been going over our coach for the season and I checked the house batteries, they were low on water, so I unplugged the coach, disconnected them added distilled water, cleaned the tops and connections, reconnected the cables and shore power line.

Next I went into the coach and turned the Xantrex remote panel ( model RC7). The system went into a "battery equalization" mode, not knowing what this was I opened the manual and saw the batteries needed to be ventilated so I left the tray extended out and uncapped all 4 batteries (6 volt Interstate Workhorse batteries). In the next ten to twenty minutes they began to boil. According to the manual this is to take place for three hours, at about 1.5 hrs I checked them with a hydrometer my readings were in the normal range so I shut down the equalization mode.

My question is how often should this be done? How often should I check these? The last time I added water was in November when I parked the coach for the season.

Seems like it needs more maintenance than I gave it. This is the first coach we have had with lead acid batteries, the last coach had 1 AGM for a house battery.

[desertdeals69]

Typically once a year for equalizing, depending on usage. How old are the batteries? If they are over 4 or so years they may need replacing. You need to maintain the water level.

[dickandlois]

Joe,

I check the batteries on our coach every 3 months for the proper water level. Check them the first week in December before it gets cold up north. Then in February I sneak a quick peek at the water level(depending on the outside temperature range in this 3 month time frame) this is the point where highest evaporation a cures.

Then between February to May the batteries need about half as much water replaced. June to August time frame, add just a little water again. September to November a check and I'm back into the December(Check the levels before the cold settles in.

There would be a different evaporation rate for each area of the World and how often the load requirements necessitates recharging the batteries from there low point.

Battery life for us is about 6 years. I run a hydrometer reading every 6 months on average, unless the expected charge time drops and there is the possibility on one cell in the system adding an internal load to all the batteries.

This can degrade the entire bank of batteries in a short period of time.

NOTE! when this has happened to us I will Split the battery bank off / out of the bank. This drops to Amp Hrs. but prevents one bad cell from pulling everything down with it.

Had to replace one on a trip west, found a NAPA special application 6 volt battery(not the best solution)but we had 80% of the nominal Amp Hrs. to use-and we did not need to replace any other batteries on the trip.

Rich.

[jleamont]

Rich, thank you for the detailed explanation. I will have to monitor these more often, perhaps reposition the coach so I can access the battery compartment when it is parked for the season.

I am concerned about the "battery equalization" process the charger performs, if it is getting the batteries to boil how long can they take that before something catastrophic happens? The charger runs this cycle for three hours, seems a bit too long to me, could three hours do more damage than good?

On a good note each battery has a temperature sensor attached to them, so I am guessing the charger is monitoring this and will back off if they become overheated.

I would probably feel better if this was all taking place farther away from the coach.

desertdeals69; how long do you equalize yours once a year?

Thanks guys

[dickandlois]

Joe, the equalizer mode puts a high current and elevated voltage across the battery bank. I have never felt comfortable knowing the batteries are boiling. This condition can cause battery acid to be forced out of the cells, that needs to be addressed with some baking soda and water to wash the complete area and mount.

Like some other owners, when the system is in the equalizing mode - after around 30 min. I interrupt the cycle and run a hydrometer reading on all the cells. If they are not equal, I restart the cycle for around 30 more min. and repeat the hydrometer test.

Should there be a different reading after 90 min. in any of the cells, it is time to replace the battery(s) with a low reading-if it is 1225 or lower, is may cutoff point to replace.

The max reading is 1275 for most lead acid batteries.

Rich.

[jleamont]

Thanks Rich, I will take that approach with them, I just found it hard to walk away while that was going on for that extended period of time.

Thank you,

Joe

[wolfe10]

Equalization should/does only start with the batteries fully charged.

The voltage is driven up, but amperage (charge rate) is very low within a few minutes. The process desulfates the plates-- sulfates are deposited on the plates during discharge. In fact for years, I used an old 6 amp Sears charger to do this-- charge rate drops to 2-3 amps.

Like Rich, I monitor the equalization process with a hydrometer. When no rise in SG for 30 minutes, I quit the process. There is NO "here is how long it takes". Depends on the batteries-- as they age, it takes longer. It has taken from 30 minutes to 4 hours.

BIG CAUTION: A good idea to disconnect the batteries from the coach appliances with PC boards during this process. Many PC boards are not "happy campers" at 15+ VDC. Depending on your coach, may be easiest to turn off the salesman switch and then pull fuse to refrigerator or other circuits that the salesman switch does not disconnect.

[jleamont]

Brett, thank you for the input. once I install the nose protector i purchased tonight I am going to recheck the batteries and see where they are. Much easier to correct in my driveway than at the campground.

Thanks again

Joe

[jleamont]

I rechecked all 4 last night, only one cell on one battery was on the 1265 line, all of the others were on 1275 or above. That made me feel much better since these were on a float charge for the last day.

Thanks for all of the help.

Joe

[huffypuff]

This happen to me this winter at Desert Hot Springs, CA. I didn't know it was on and how to turn it off. Once I found out it already ran it course about 4 hours. Major clean up job of batteries, terminals and cables afterward. Then I finally found out on the net that holding the charging button a few seconds turns it on and same to turn it off.