Genset shore charging.

richguess · 12-04-2021, 07:55 PM

Picked up my 27.2 ACE from storage today. It has 200w Renogy solar panels, and 2 series 27 Interstate Costco DC marine/RV batteries. Weather here has been cloudy, a d my storage site is quite tight, so I think the solar charging has been somewhat limited. The Renogy battery monitor showed about 35% capacity.

I needed to run my monthly genset time, which I did under load for an hour. The battery monitor showed 13.6v and +3.3 amps while running the genset. I then shut it off, and plugged into 120v in my garage. The battery monitor shows 12.5-12.6v and +.76Amps. Should it be higher, or is this just the difference between genset output and 120v (either 15 or 20) amp power?

These batteries did get run down once to 11.7V, but seemed to have survived. When I replace them, I think I will go to AGM’s.

m1noel · 12-05-2021, 03:56 AM

You are exactly right in that the batteries are being charged at 13.6V and after showing 12.6 which is normal for a fully charged battery.

Chateau_Nomad · 12-05-2021, 04:01 AM

Quote:

Originally Posted by m1noel

You are exactly right in that the batteries are being charged at 13.6V and after showing 12.6 which is normal for a fully charged battery.

I second that motion!!

dkoldman · 12-05-2021, 04:10 AM

I would try to keep those batteries over 12.2 vdc

If you do get AGM; 12.8 - 12.9vdc will be the normal for fully charged AGM House battery when charging is off.

12.4vdc is 50% SOC for AGM. My Chassis are FLA 12.6 or 12.7 vdc is normal after a full charge and disco9nnect from charging system

richguess · 12-05-2021, 05:02 AM

Thx everybody. My problem was that when on shore power, with the batteries charged to less than 50% capacity, they were barely charging. Turns out the Salesmen’s switch, which was lighted as the shore power was on, was switched off. Switching it on then showed charging at 13.2v, +18.5 amps. They’lll be 100% in the morning.

**16ACE27** · 12-05-2021, 05:22 AM

Quote:

Originally Posted by richguess

Thx everybody. My problem was that when on shore power, with the batteries charged to less than 50% capacity, they were barely charging. Turns out the Salesmen’s switch, which was lighted as the shore power was on, was switched off. Switching it on then showed charging at 13.2v, +18.5 amps. They’lll be 100% in the morning.

Ooops. Not the first to make that mistake.

And FYI, the batteries are charged by the same device whether you are on SP or generator. The SP and generator just supply the 120 VAC to the converter/charger.

sportcoupe · 12-05-2021, 12:47 PM

That's not the salemans switch anymore. That is your the owners battery disconnect switch.

dkoldman · 12-05-2021, 02:58 PM

You may think of it is as to cut OFF your DC items in USE. Distinction being there may be some DC items the RV Mfg has decided that should still be in USE even if you flip the Switch to OFF. Each coach is different; in my case it really is a battery disconnect. I am gonna learn to start using it more.

richguess · 12-05-2021, 04:46 PM

Yes, thanks to all. I get that the genset (which preferably is used when on and Shore power plugged in) sends it’s 120v to the converter/charger, as does the shore power. The”DC disconnect switch,” a name I like and think is more accurate, unfortunately lights up when plugged in, regardless if it’s switched on or off. My parasitic drain always seems high to me, varying between .3 and .7 amps. My solar usually just charges the batteries when sitting, but if not sunny they begin to run down. I may just put a disconnect switch directly on them, but allow for solar to continue to charge.

DavidEM · 12-05-2021, 05:08 PM

If your 200 watt solar panels wouldn't keep the batteries well charged, even in cloudy weather, then it is likely that they are wired on the opposite side of the "salesman switch" than the batteries. This is wrong IMO. They should be wired directly to the batteries with an appropriate size fuse to protect the wire.

I would make that wiring change and you will never have this problem again.

David

richguess · 12-06-2021, 05:29 AM

They’re wired from the panels to the controller, then directly to the batteries.

petef · 12-11-2021, 08:36 PM

I put a knife disconnect on my coach batteries, they can go a month in storage and only drop slightly.. the Store/use switch does not shut everything off...constantly charging and draining battery can not be good for it

Quote:

Originally Posted by richguess

Yes, thanks to all. I get that the genset (which preferably is used when on and Shore power plugged in) sends it’s 120v to the converter/charger, as does the shore power. The”DC disconnect switch,” a name I like and think is more accurate, unfortunately lights up when plugged in, regardless if it’s switched on or off. My parasitic drain always seems high to me, varying between .3 and .7 amps. My solar usually just charges the batteries when sitting, but if not sunny they begin to run down. I may just put a disconnect switch directly on them, but allow for solar to continue to charge.
..

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