Battery being over charged????

[fighterpilot]

1994 Calista Cove MH. Book says charging system will sense fully charged and not over charge the house battery. After being hooked to shore power the volt reading at the battery terminals is 14.2 volts which seems like too much. ???? 13.2 to 13.5 more appropriate. Being a 1994 I don't believe they made use of the smart chargers that are available today so should I unhook the house battery for a period of time until need to recharge again? Thanks

[No More Snow]

From what I've read, max charge for a house battery according the the battery manufacturer is actually supposed to be 14.8. A stop point of 14.2 sounds pretty normal.

Do you have the manual from the battery manufacturer to verify?

Karen

[fighterpilot]

Don't have any paper work. I googled battery charge and everything I read had the max charge down in the mid 13s for max charge on a ordinary wet cell battery. Plus my experience with the smart charger on the boat batteries also confirms that. Also, the charge versus % charge has the batteries full charged at about 12.75 or so, but even less than 13 volts. I would appreciate a link to the 14.8-14.2 sources that indicate it is alright to maintain a charge of 14.2 volts or more from the charger.

Also, does any one know if they were using smart chargers in 1994? Thanks

[Luckiest Dreamer]

I don't know what 1994 brought but you are probably reading the output of the charger rather than the charge of the battery. Recheck the batterys after the charger has been off for a while to get the actual readings. (a laymans understanding)

[TeJay]

A charge rate and actual battery charge would be different. The normal charge rate should be as stated around 13.3 - 13.6. It might be slightly higher if the battery is in a low rate of charge. A fully charged battery would be around 12.6 V's.

Your best bet would be to get some specifications for your charger to determine the type of charger used at that time. Chances are good that it's not as good as today's systems which can decrease the charge rate as the battery reaches a full charge. We leave our MH charged in most of the time. Think about it. If you go to a CG for 30 days you leave it in all the time. Yes you will used current and it is constantly being re-charged by your converter. The only difference is that when you are parked at home you are not draining the battery as much as if you were using it at a CG. However the charger should work in either case. The difference being that today's chargers will probably tailor the charge rate better than the older ones.

One other thing. If your charger you feel is charging to much check the water level frequently. Extra gassing would result from over-charging and a loss of water. Your charger while not as modern as today's may work OK but getting the specifications would help determine if it is charging in excess.

TeJay

[fighterpilot]

I haven't found the darn thing yet. Looked in every outside compartment and in all the interior spaces. Haven't crawled under it yet to trace back the wires that come into the house battery compartment. I believe, if a smart charger, the reading at the battery terminals would taper down as the battery reaches full charge and be in the 13.2-13.5 when the batteries are fully charged. Since that doesn't seem to be the case I conclude it is a dumb charger and the, next to useless manual that came with the coach is misleading. I say useless because compared to the Dolphin Manual that we had with previous motorhome, the Carriage manual is an embarrassment. But the Mh is very nice, so I can live with poor paper work.

[TeJay]

fighterpilot,
You are correct in your assessment of the charger. Usually if a charger goes bad the output control will put out a voltage way above the usual voltage. Like in the 15+ or 16 plus volt range. Yours is only in the 14's and that may be what it was designed to do. Your charger just may not be a smart charger. Maybe it's time to upgrade to a more modern converter system for the sake of the batteries.

Have you googled for a manual on the existing charger??? I have a Delta variable speed drill press that's probably 30-40 years old. I was able to find a complete manual for free on the net. I believe you can find a manual but maybe having the name of the charger would be necessary.

[MattC]

Ray,

The converter may be hidden behind the power distribution panel. There were more than a few made in that period that were nice package units, but they have been out designed.

Matt

[fighterpilot]

Well, I crawled underneath trying to trace wires, but no luck. Looked behind the power panel compartment but that panel only covered wires. Haven't pulled the power panel out yet. Really don't see a panel as such to bring out. Maybe will have to take the word of the manual writers that charger will not overcharge the batteries, but voltage still reads 14.02 volts, while just sitting there hooked up to shore power.

[camaraderie]

If you've been sitting on shore power for more than a few hours and not using anything big...the charger should have come down from the NORMAL bulk charging voltage of 14.2-14.8V range and be sitting in the mid 13V range while the charge is on.

Example: If you have a 100amp hour battery that you've discharged 60% then you have 40 amp hours left in the battery. Turning on a 20AMP charger will put back 20 amp hours per hour AT 14.5V for TWO hours or so...at which point you will be 80% charged with 80 amp hours of capacity. From that point, both your voltage and current will ramp down to around 13.8 volts and finally less than one amp of current when you are full charged. The last 20% of "filling your battery" generally takes about the same time it took you to get to 80%. BUT...you ALWAYS have to do it or you will kill your batteries life leaving them less than fully charged.

Obviously...the size of your battery bank and the amps your charger can put out will change this equation...but anything more than a few hours reading over 14.2V is cause for concern and likely means you need a new charger and/or new batteries.

[jamesrxx951]

My 12V inverter is under the cabinets in the kitchen. Might have to pull some drawers to find it.

[fighterpilot]

Thanks for the information. I'll start pulling drawers. Did look under the dinette but didn't see anything that looked like wires or inverter.

[clyon51]

If your charger is original, it's most likely a single stage. The output on these are in the 13.6v range and should not fluctuate.

When driving, your alternator will pump 14.0 to 14.6v to the house batts. So this voltage does not hurt them. What it does do however is 'boil' them, so you need to monitor water levels closely, just as you would need to do with a single stage plugged in 24/7.

Your average smart charger will put out 14.3v in Boost Mode until the batts reach 90% charged. Then will drop back to Normal Mode, 13.6v to fully charge. Then to Float 13.2v to maintain them. My PD9200 Series has an additional Desulf mode, which periodically runs itself in Boost Mode about 20 mins per day. This prevents or rids the batteries of any sulfation of the plates extending battery life.

If you discover you have an old single stage, I would recommend a Progressive Dynamics 9200 Series.

[fighterpilot]

Thanks Clyon51. Your analysis is the way I understand a good smart charger works. We have one for the boat. Now I have got to find the one on the MH.