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Tom Lopez · 09-22-2015, 11:53 AM

Before my recent trip I checked my two Interstate GC2 6 Volt batteries. They looked low on water so I filled them up (to the bottom of the fill holes) with distilled water. A couple of hours later I saw overflow drippings on the ground under the battery compartment. The coach was plugged in to shore power. I have a Progressive PD9260 converter. I just thought I put a little too much in so a little came out. Didn't give it any thought after that. Left on my trip from Madison, WI to Rapid City, SD, then to Bismarck, ND to Fargo, ND then back to Madison, WI. Trip went fine until I got to about 90 miles from Madison, WI. I noticed a battery smell so I stopped and checked the coach batteries. I found them EXTREMELY HOT and the water inside of each one was BOILING real good. I disconnected the cable that connects them together (to make the 12V) so that they would stop charging as well as be disconnected. Drove the rest of the way home watching my scan gauge at the volts the alternator was putting out. It was reading from a low 14.2 up to 15.0 at the high point but averaging 14.4-14.8. I felt my chassis battery and it felt cool, no heat, it seemed fine. So I assume the alternator did not over charge the chassis battery.

This morning at 9:30 AM I put a meter on the GC2's and each read 6.2V and each was still a little warm from when we stopped at 1:30 AM.

Took the batteries to Batteries Plus to have them check the batteries. The guy said they were showing OK but have a little voltage lost. This was at 11:00 AM and they still showed over 6V each. He said the boiling over was probably because I had too much water in them and system was getting rid of excess water. Rather than fill them up to the bottom of the fill holes there should only be enough to cover the plates and that is it.

Could what the Battery Plus person be saying be true and the system just boiled off the excess water??? Can the alternator over charge the coach batteries and not the chassis battery ??? What could have happened if I would have left them connected and drove home ??? Would they have exploded ??? I am at a lost.

I have reinstalled the batteries and will see if it happens again.

Mr_D · 09-22-2015, 12:03 PM

I always filled to the bottom of the filler hole. Never had any boiling problems like you describe and our Interstate U-2200's lasted 10 years in the '02 Dutch Star.

Tony Lee · 09-22-2015, 12:35 PM

If the level is way down (below the top of the plates), correct procedure is to fill enough to cover the plates, fully charge and THEN top up to the bottom of the split ring.

zman-az · 09-22-2015, 12:42 PM

Quote:

Originally Posted by Tony Lee

If the level is way down (below the top of the plates), correct procedure is to fill enough to cover the plates, fully charge and THEN top up to the bottom of the split ring.

Bingo,

The water/acid level changes. Low when discharged and high when charged. If you topped them off discharged it certainly could happen. Also when the batteries are discharged they can freeze easier than fully charged batteries.

Another issue could be your charging systems or a bad cell in a battery. Being they were both at 6.2V they should be fine. I would pull them and put them on a 12v charger overnight and watch them, obviously place them in a spot where if they discharge more the acid wont damage anything.

Tom Lopez · 09-22-2015, 01:55 PM

I did not reinstall batteries into MH. My meter says 6.2v on each one. I put water at just enough to cover the plates and put on a 12v charger. The meter on the two combined to make 12v reads 12.8v. My charger says they are at 77 percent so will leave on charger until it says full charge. What I don't understand is how can they get to a boil and the chassis battery be fine. The alternator was charging both systems.

**pasdad1** · 09-22-2015, 02:13 PM

The batteries should never get EXTREMELY HOT like you said you found them.....so something is amiss.

Tom Lopez · 09-22-2015, 02:25 PM

I agree, but what is it that could be amiss?

Gary RVRoamer · 09-22-2015, 04:27 PM

A weak cell, or a short between cells, will cause the PD charger to work overtime trying to bring the bats up to 100%. A less capable (typical portable car charger) probably doesn't have enough charge rate to do that, but the PD 9260 can.

I suggest checking each cell with a hydrometer, or (better yet) have them load tested.

mrt_1111 · 09-22-2015, 04:41 PM

"Drove the rest of the way home watching my scan gauge at the volts the alternator was putting out. It was reading from a low 14.2 up to 15.0 at the high point but averaging 14.4-14.8."

I believe 15 volts is to high. Should be 13-14 volts. I would be checking the output of the alternate/voltage regulator with a volt meter.

Gary RVRoamer · 09-23-2015, 11:36 AM

The normal engine alternator output will be right around 14.4v It should not reach 15v for more than a few minutes, but 14.0-14.4 is quite normal.

mel s · 09-23-2015, 12:01 PM

Quote:

Originally Posted by Tom Lopez

Before my recent trip I checked my two Interstate GC2 6 Volt batteries. They looked low on water so I filled them up (to the bottom of the fill holes) with distilled water. A couple of hours later I saw overflow drippings on the ground under the battery compartment. The coach was plugged in to shore power. I have a Progressive PD9260 converter. I just thought I put a little too much in so a little came out. Didn't give it any thought after that. Left on my trip from Madison, WI to Rapid City, SD, then to Bismarck, ND to Fargo, ND then back to Madison, WI. Trip went fine until I got to about 90 miles from Madison, WI. I noticed a battery smell so I stopped and checked the coach batteries. I found them EXTREMELY HOT and the water inside of each one was BOILING real good. I disconnected the cable that connects them together (to make the 12V) so that they would stop charging as well as be disconnected. Drove the rest of the way home watching my scan gauge at the volts the alternator was putting out. It was reading from a low 14.2 up to 15.0 at the high point but averaging 14.4-14.8. I felt my chassis battery and it felt cool, no heat, it seemed fine. So I assume the alternator did not over charge the chassis battery.
This morning at 9:30 AM I put a meter on the GC2's and each read 6.2V and each was still a little warm from when we stopped at 1:30 AM.
Took the batteries to Batteries Plus to have them check the batteries. The guy said they were showing OK but have a little voltage lost. This was at 11:00 AM and they still showed over 6V each. He said the boiling over was probably because I had too much water in them and system was getting rid of excess water. Rather than fill them up to the bottom of the fill holes there should only be enough to cover the plates and that is it.
Could what the Battery Plus person be saying be true and the system just boiled off the excess water??? Can the alternator over charge the coach batteries and not the chassis battery ??? What could have happened if I would have left them connected and drove home ??? Would they have exploded ??? I am at a lost.

I have reinstalled the batteries and will see if it happens again.

Tom Lopez
If/when I fill my house batteries (to the bottom of the fill holes) with distilled water when they are NOT fully charged they WILL "boil out" the excess.

However, if I fill them to a level "just over the plates" when they are discharged...(or "to the bottom of the fill holes" when they are fully charged)....they DO NOT "boil out/over".

(Me thinks maybe the electrolyte in lead acid batteries expands as the batteries charge)?

Mel
'96 Safari. mine since '01.
(for 117k miles of the total 144k)

RIDER FAN · 09-23-2015, 12:34 PM

Tom , you might want to get one of those good "Acid Viewers " [ hydrometer ] where you take a a few drops of battery water [acid] from EACH cell , dab it on the plate then look thru the viewer to see if the cell registers good , or fair...........or worse.
It is the truth about the condition of EACH individual cell. Bad cells do bad stuff to rest of battery.Cheers

530ktm · 09-23-2015, 01:30 PM

Quote:

Originally Posted by RIDER FAN

Tom , you might want to get one of those good "Acid Viewers " [ hydrometer ] where you take a a few drops of battery water [acid] from EACH cell , dab it on the plate then look thru the viewer to see if the cell registers good , or fair...........or worse.
It is the truth about the condition of EACH individual cell. Bad cells do bad stuff to rest of battery.Cheers

I have never heard of dabbing a few drops on a plate to see how good a cell in a battery is but testing the cells with a hydrometer where you suck up the water in each battery cell is a true test to see how good they are. (Called a gravity test) Also, you may want to put a load test on the batteries as well to see if that shows anything wrong with them.

TeJay · 09-23-2015, 01:38 PM

Man what a mix match of advice. Some is OK and some is not. Been around batteries and teaching about them for a long time.

Battery chargers if working correctly and not overfilled should not boil the EL (electrolyte) out of the battery at any time. When the battery operates correctly the only thing that is ever added is water. The battery works because the sulfuric acid breaks down as it discharges and recombines to make sulfuric acid when it is charged. The acid breaks down and is deposited onto the plates. When a battery is dead it is filled with water. The acid broke down and is on the plates. When it is charged it breaks off the plates and recombines to become a 64% water 36% acid mix which we refer to as the battery EL.

When a battery is very weak a good charger will increase the charging voltage early on and as it recharges the charging voltage will reduce more toward the 13.6 volts. A charged battery should read 12.6 volts. Most chargers will charge at a rate of 1-volt above or at 13.6 -V. Fifteen volts is to high for any extended period.

This part I'm kind of guessing. Over the years the way it id done has changed. The alternator will charge both the engine (chassis) battery and going through your converter will charge the coach batteries. The chassis battery was fine but the coach batteries were being overcharged. It's my guess that something is amiss with the converter and it's output to the coach batteries is to high.

That's easy to check. Check all batteries with nothing plugged in or running. They should be around 12.6 volts. Plug it in and read all batteries again. Should read 13.6 volts or higher. If the engine batteries read 12.6 then they are not being charged while plugged in. That's OK i don't know if they are supposed to charge the engine battery or not.

Redo the same tests with the engine running but not plugged in. You have to test electrical issues to determine what's going on. You can't just guess. If the voltage is above 13.6-V for the coach batteries that's OK but if after 10-20 minutes it's still that high or higher that's not OK. The voltage should drop after some time.

The alternator and the converter are smart chargers. They should reduce the charging voltage soon after they have had time to recharge the initial loss from cranking or coach usage.

One more item. Today's chargers are electronic not mechanical as they were years ago. If your control circuit either in the alternator or the converter failed to control the charge rate once it will do it again. It's not usually an intermittent thing.

The guy who told you they were overfilled and it was just getting rid of the extra water is crazy. You told him that you only filled it to the bottom of the hole which is correct. I've overfilled a few batteries and seldom did I have EL spilling out on the ground. I did have one boil the EL because it was overcharging.

Do keep us posted on the outcome.

TeJay