Battery question

[tylerdmoore]

When I was up at the MH a couple days ago I noticed the the batteries (coach & House) looked a bit on the low side. House was reading 12.6 and the coach was reading 12.4. I have a single Solar panel that is currently adding about 1/2 to 1 1/2 amp during daylight hours....yea the weather sucks here ATM. No real charging had been done for about 2+ weeks. I didn't have the time to run the gen that day so I planned on going back later.

Today I went up to measure my bathroom Skylight (another story), and checked them again. They were about the same. I always turn everything off and flip off the "salesman" switch when leaving. The batteries are all new, replaced in Nov. I ran the genny today for 2 hours and shut down with them reading 14.9 volts and the inverter about to switch to float mode.

Could the drop in voltage be attributed to the cold weather (30s-40s)? Or do you think that maybe I have parasitic draw that the salesman switch is not addressing?

[srydve]

imho as long as you're over 12v. you're ok. They always seem to drop a bit just sitting.

[distaff]

On my Patriot Thunder I have to cut off both sets of batteries as the solar panel at this time of year (sun low in the sky at noon, short days) the panels don't get ahead of the myriad of draws from all the electronics on the coach and chassis batteries.

Summer is different, it does fine. Suggest you throw your isolation switches, if you don't have them, get some installed.

[Mike Canter]

Over 14 volts is your charging voltage. Once you remove the charging voltage the battery voltage will drop down to the 12's. True battery charge status can only be accurately read when they are not charging. I would say your batteries are charged OK. See the chart below.

[Freebird23]

After you charge your batterys they will have a surface charge and may read a little high(on mine it is about 13V)I turn on the inverter and run microwave for a few sec.and it will drop and even out at 12.6 or so.On my unit the salesman switch only switches house.If you go by Mikes chart you will be OK.
Bill

[tylerdmoore]

Thanks folks. After thinking about it for awhile...I'm pretty sure that dropping to 80% after sitting for 2+weeks in 30 degree weather is nothing to worry about. They've got a good charge on them now after running the gen for 2 hours. The inverter/charger pushes them to 14.9 volts with temp sensing before it goes into float mode. I shut down the genny right as it was switching to float.

[mr300ce]

The Chart.

[Freebird23]

Quote:

Originally Posted by tylerdmoore Thanks folks. After thinking about it for awhile...I'm pretty sure that dropping to 80% after sitting for 2+weeks in 30 degree weather is nothing to worry about. They've got a good charge on them now after running the gen for 2 hours. The inverter/charger pushes them to 14.9 volts with temp sensing before it goes into float mode. I shut down the genny right as it was switching to float.

Not sure what genny you have ,but are you putting a load on it beside the charger .On mine I load it up for 30 min or so by using a elec. heater and the roof unit on air only to move old air around.I let it rest a few min without load before cutting off.
Bill

[tylerdmoore]

Quote:

Originally Posted by Freebird23 Not sure what genny you have ,but are you putting a load on it beside the charger .On mine I load it up for 30 min or so by using a elec. heater and the roof unit on air only to move old air around.I let it rest a few min without load before cutting off. Bill

Yep, I fire up with no load and run for about 3 minutes. Then start the inverter up...then about 3-4 minutes later fire off a 1500 watt heater for the duration.

The gen is a Onan 7.5 I try to never run it for less than an hour. Want to burn out any moisture that may be in the crank case

[wa8yxm]

Double checked.. 12.6, resting, is normal.. And yes, temperature will affect the voltage slightly. Without doing some research I can't tell you how much.