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Battery Charging

Yahoo Message Number: 11441
A friend gives classes on RV 12V electrical systems. I asked him to comment on the recent battery charging discussion and this is his response. And I'd like to add that the West Marine catalog has some great info on batteries, as well as other technical subjects of interest to motorhomers:

--------- Forwarded message ---------- From: (deleted)

To: campagna@... Date: Sun, 5 Sep 2004 18:06:47 -0400 Subject: Re: Fw: [Country-Coach-Owners] Digest Number 1236
"Ok! I assume that the batteries are AGM, not Gell Cell or Standard Wet Cell Design. If that is correct they have sealed or pressure caps vice covers that can be removed to add water. ONLY Wet Cells have removable caps, just like the old auto batteries. AGM and GELL Cell batteries are LOW maint batteries and should NEVER require the removal of their caps and they should NOT gas or spill electrolyte at ANY time during NORMAL use and/or during PROPER charging. That said, there are other parameters that SHOULD NORMALLY not be exceeded. 1. Keep the tops of the Batt clean. 2. Ensure the Elec leads are tight and the proper wire size. 3.
NEVER discharge below 12.2 Volts. depending on temp.
4. In normal room temp, Never charge above 14.6 Volts for AGM. Never above 14.1Volts for Gell Cells. Never above 14.4 Volts for Wet cells. Wet cells can accept an equalization charge on a routine basis based on their service and their condition. I will not dwell on this issue as it requires considerable preps and control during the equalization process.
5. NEVER use the equalization CHARGING PROCESS on Gell or AGM batt. The reason is that these cells must not GAS during the charging process or you will build up pressure and lift the pressure caps and release electrolyte, which is highly corrosive and skin burning, and lost of electrolyte means loss of overall battery capacity.
 With that said, any of the above or a combination of the above is killing the batteries early in their life time.

What can they do to increase Battery Life?
1. Determine their daily (24hrs) usage in Watts and convert that into AMPS, total battery capacity should be a minimum of 3 times their daily usage. This will provide adequate reserve power in time of excessive usage as well as during extremely cold periods.

2. Never discharge below the voltage stated above, (I like 12.5V) to do so once in a while is OK, but on a routine basis you are slowly killing the battery and reducing it's total capacity a little at a time.

3. Ensure your charging system, ALTERNATOR, SOLAR PANELS, INVERTER/CONVERTER combinations, BATTERY CHARGERS, output from the GENERATOR CHARGING SYSTEM are putting out the proper voltage AT THE BATTERY, after the ISOLATOR if one is installed.

4. Ensure that the wiring from all charging systems is of an adequate
size for the distance from the charging source to the battery and back to the source. Some systems use the chassis for negative return.
In your first msg Bill said they tried to equalize the batteries and checked the coolant level, I assume he means the electrolyte. He should not have been able to do that.

Most batteries fail because of DEEP DISCHARGING / improper CHARGING and or improper Maint ( lack of water).
Based on what Bill had to say and your 2d msg about Equalize bothers me.

Hope this will help Bill get his system back up to snuff. Bob
PS A fully charged in excellent condition AGM battery at REST should read between 12.88 - 12.90 Volts

A fully ' ' ' ' ' Gel Cell battery at REST should read between 12.85 - 12.95 Volts A fully ' ' ' ' ' Wet Cell battery at REST should read between 12.60 - 12.70 Volts "

Dick (& Geri) Campagna
CC Intrigue/NJ

Battery Charging

Reply #2 –
Yahoo Message Number: 13978
Eric,

I have not followed all of the posts, but when connected to shore power or with the generator running AND your coach engine running two things are happening. Your coach alternator is charging the chassis battery, and if the charger side of your inverter is "on", that is charging your house batteries. Shut the generator off or disconnect from shore power with the engine running and both battery banks are charging via the battery boost/charge solenoid.

Fred Sage '01 Magna #5983
 

Battery Charging

Reply #3 –
Yahoo Message Number: 13998
Hi Eric,

I cannot speak for CC, you will have to ask their engineers. But keeping AC out of the DC charging system is a good idea, or the possibility of mixing the two. I like the echo charger in my Magna I even added one to my '98 Intrigue when I had it. Simple.....works well.

Fred Sage '01 Magna