Battery overcharging?

[Dee4j]

when we packed up at the campsite this weekend I noticed a weird smell and my DH thought it was from the stove since he'd just disconnected it. well today I smelt a sewer like rotten egg smell and I asked my neighbor and he said he smelled it too. He said it was the smell of a battery overcharging and when we took the battery cover off it was hot and had liquid on the top.  
the unusual thing that happened this weekend was I accidently turned on a second electric heater while the one inside was on and my breaker tripped. It tripped one more time the next morning but both heaters were not on.  so after the long story:
I look to the great all knowing  popuppers for the answer.

What did I blow up to cause this, and how do I fix it?  :confused:

oh yeah don't know if related but DH noticed the right break light & signal not working. I'm not sure if it was working before I left but it was the last trip for sure
Thanks

[mike4947]

Dee, the smell and the "water" on top of the battery are sure signs of overcharging. The battery was getting enough voltage to actually boil the fluid and by the way that's sulfuric acid and needs to be cleaned up with baking powder to keep it from eating whatever it dripped on.
Time to get out the trusty multimeter (don't have one? Radio shack or even Harbor Freight tools have them for just a few bucks w/instructions) and start checking voltages. Also to check for the running light problem.
Converters in PU's before 2003 are notorious for either not putting out enough voltage to fully charge a battery or not stopping when the battery is fully charged.
 
Here's a few links (I know it's a lot of info, but trust me it's saved me from ruining a whole bumch of batteies like I used to) to make you and yours 12 volt/battery experts.
http://bart.ccis.com/home/mnemeth/12volt/12volt.htm
http://bart.ccis.com/home/mnemeth/12volt/12volta.htm
http://www.dcbattery.com/faq.html#1
http://www.usbattery.com/care.htm
http://pweb.uunet.de/william.darden/index.htm

[Dee4j]

Thanks!!! I love this website...there is always great wisdom shared here. I have a volt meter (somewhere  :confused: ).. I'll put the baking soda cleaning on my to do list for tomorrow. I see a project for my dad :rolleyes:
hopefully it's straight forward and not an all day troubleshoot.
Thanks again  :p

[MommaMia]

Converters in PU's before 2003 are notorious for either not putting out enough voltage to fully charge a battery or not stopping when the battery is fully charged.
 

I was a bit confused by this statement.  I was under the impression that no converter should be used as a battery charger, only for converting 110 to 12v.
After reviewing the paperwork on our 688 electrical control center in our 84 Starcraft, I found that is says that a converter is "Not suitable for battery charging".  A seperate charger should be used. Yes? No?  How would a converter charge a battery anyway?

[MommaMia]

I'll put the baking soda cleaning on my to do list for tomorrow.

I'm sure you already know and excuse me if I am being offensive but take extra care not to get ANY baking soda inside the battery or it's dead for sure!

[mike4947]

I was a bit confused by this statement. I was under the impression that no converter should be used as a battery charger, only for converting 110 to 12v.
 How would a converter charge a battery anyway?

A few things for you Cindy.
Anytime the voltage from a source such as the converter is higher than the voltage of the battery it will transfer energy (amps) to the battery.
Problem is the normal output voltage from most converters used in PU's is exactly what a fully charged battery should be or just above, so there's no "push" to get the amps into the battery. If the voltage is high enough to "fully charge" a battery then you can either overcharge (boil it dry) or else have problems with other 12 volt items due to excessive voltage as there's no "control" over the voltage. What it's set at is what you get and the converter doesn't know when to stop.
 
Some of the newer converters for PU's and larger rigs have a seperate circuit in them for just charging the battery. When you plug into shore power, the converter disconnects the battery from rest of the trailer and connects it to the charging circuitry which is actually a 3 stage battery charger built into the converter. It "knows" how much and when to shut off, unlike the older converters that were just a transformer from 110 voltAC to 12 voltDC.
 
And you're right about the baking soda, My meaning was to use it to clean up anything that got battery acid on it from the battery boiling over, not the battery itself. I made that mistake one time cleaning off the posts on a battery and some must have gotten into a cell.....End of battery.

[MommaMia]

A few things for you Cindy.

Thanks... I get it now.

[Steve-o-bud]

Diedre,
The thing to keep in mind is, in most cases, the converter is simply wired "in parralel" to the battery. When you plug into shore power, the converter powers your 12 volt accessory items, (lights, pumps, etc.), and also is providing charging current to the batteries.

These 12 volt converters are not intelligent, that is, they don't control the ammount of charging current that will go to the battery. They just put out a constant output. So, you can overcharge the battery, and boil the electrolyte out of it.

A true battery charger senses the current being delivered to the battery, and adjusts its output accordingly. When the battery reaches full charge, it reduces it output to put a trickle charge on the battery, which keeps it at full charge.

However, long term trickle charging is bad for batteries, it will cause the electolyte to deplete, and will reduce the storage capacity. After reading the info on the web links previously posted, I went out and bought a battery charger. I take my battery out of the pop up, and then charge it occassionaly, particularly before an outing.

When you tripped the breaker on your pannel, that was on the shore power supply, it should not have affected the converter at all.

P.S. Hope all is well!