Batteries drained because lights left on...how bad is it?

[SJ-Chris]

I retrieved my RV from storage today where it had been for 14 days. When I entered the RV I immediately saw that the interior lights (LEDS) were on. Yikes! They were on for 14 days straight. I do not have solar. I have three 12v deep cycle batteries in the RV living quarters that were all purchased new about 6 months ago. These batteries were all fully charged prior to putting away in storage 14 days ago.

I checked the battery voltage on the battery terminals (I've got a bluetooth monitor on them) and it said 11.4v. On the short drive home (about 1 mile) the voltage went up to about 12.4v while the engine was running (as the chassis alternator was trying to give them some charge). When I got home I plugged the RV in to shore power so the converter can give it a charge overnight.

After about 5 hours of being plugged in, the voltage on the batteries is at 11.7v. Seems like it has been there a while. Is this common/expected?

I've got a WFCO 75amp converter that is only about 6 months old. Very often over those 6 months when I plug into shore power it was common to hear the converter fan kick on and it sometimes would stay on for a couple hours before finally shutting down. So far, being plugged into shore power for about 6 hours now trying to charge the dead batteries I have not heard the converter fan come on at all. I thought that when under a heavier load and trying to charge the batteries it was common for the converter fan to kick on...but so far it hasn't.

From your knowledge/experience, what sort of damage did I do to my batteries? Is it reasonable to expect that they will mostly recover if I charge them for a very long time? How long should I expect to recharge them?

Thanks!

[MEXICOWANDERER]

Fully Automatic Charger



Where do I stick in the wires?

[Harvey51]

When a battery is charging it’s voltage is the voltage of the charger. Disconnect the charger for at least a couple of hours to get an indication of state of charge from a voltage reading.

I have a smart charger with equalize mode but in this case I would use my little bench variable power supply because I can set it at 14.8 volts for a few hours. Dumb can be better than smart because the charger doesn’t know what happened to the battery.

[pianotuna]

If you wish to eliminate generator use, 400 watts of panels would be the minimum I would install. I did 256 watts--but that was went panels were $5.50 per watt, now the lowest price I've seen is 26 cents per watt.

The wfco is NOT going to finish charging the batteries. The voltage is too low. You need to equalize the jars and that requires at least 14.4 volts and 14.8 would be significantly faster and better.

SJ-Chris wrote:
Update: Yes, my RV does have a battery disconnect switch. This was the first time ever that I accidentally left it on, draining the batteries for 14 days down to 11.4v. The only thing on was about 6 LED bulbs.

I took off the stand-alone battery charger once the batteries were up to about 12.5v. I plugged back into shore power and the WFCO converter fan kicked on and started charging the batteries. I left it on overnight and when I went out this morning it was charging at 13.8v. Seems like they should be good and charged now (3 12v deep-cycle batteries in my bank).

One thing I'm thinking about doing is adding 100w (or 200w) solar. This seems like it would be a great way to keep the batteries charged when not camping, and when camping they would provide much less need for plugging in and/or generator usage.

Thanks all for your suggestions!
-Chris

[MEXICOWANDERER]

Those batteries MUST SEE 14.4 to 14.8 volts. Or they are going to suffer a short lifespan. 13.8 is Tickle Me Elmo

[SJ-Chris]

Update: Yes, my RV does have a battery disconnect switch. This was the first time ever that I accidentally left it on, draining the batteries for 14 days down to 11.4v. The only thing on was about 6 LED bulbs.

I took off the stand-alone battery charger once the batteries were up to about 12.5v. I plugged back into shore power and the WFCO converter fan kicked on and started charging the batteries. I left it on overnight and when I went out this morning it was charging at 13.8v. Seems like they should be good and charged now (3 12v deep-cycle batteries in my bank).

One thing I'm thinking about doing is adding 100w (or 200w) solar. This seems like it would be a great way to keep the batteries charged when not camping, and when camping they would provide much less need for plugging in and/or generator usage.

Thanks all for your suggestions!
-Chris

[MEXICOWANDERER]

The batteries will be damaged unless they charge until they bubble. Hopefully your little charger has an equalize setting. BTW this is not guesswork you must revert as much of the material on the positive plates as is reasonable.

WFCO maintainers are only useful when connected full time in a permanent RV park.

[MEXICOWANDERER]

The batteries will be damaged unless they charge until they bubble. Hopefully your little charger has an equalize setting. BTW this is not guesswork you must revert as much of the material on the positive plates as is reasonable.

WFCO maintainers are only useful when connected full time in a permanent RV park.

[red31]

put the portable charger back on to charge.

[Wild_Card]

Its possible the converter went into fail safe or something. Diconect and reconect reset the converter. Most would have stopped diagnosis at failed converter and spent some wasted money. Good job.

As stated above get a disconect for when its in storage. Surprised there isnt 1 already.

[westend]

It may be a good time to install a battery disconnect switch. Even if you turn all the lights off, there are parasitic draws that will draw down the batteries while in storage.

[SJ-Chris]

Here's an update....let me know what you think!

So in the morning I went to check on the batteries. I was connected to shore power overnight (about 10 hours). The voltage had not changed...it was still at 11.7V.

So...I disconnected shore power and I decided to put a battery charger directly onto the batteries. The battery charger I have has a 15amp output. Immediately the voltage started climbing...11.9, 12.0, 12.1... After about 5 hours the voltage was up to 12.6v.

Once it got to 12.7v I decided to try something... I disconnected the battery charger and I plugged back in to shore power. Immediately the converter fan kicked on and the voltage at the batteries climbed up to 13.0, 13.1, 13.2 volts. So it seems like the converter is now doing its job. Note: I didn't change anything else. I didn't see any tripped breakers/etc.

Has anyone else experienced something like this? Is it just the case that the batteries were too low for the converter to activate/etc? Is this by design for some strange reason I'm not aware of?

Hopefully my batteries are almost back to normal. I understand that an event that drains the batteries will affect the overall life of these batteries but hopefully they last a good while still (they are only 6 months old).

[wa8yxm]

Be glad they were LED 14 days of LED is about 1 day of Regular, or less.

Now if you have GC-2 Golf Car DEEP CYCLE batteries. You likely have lost a month more or less of battery life.. They will recover

If you have MARINE/deep cycle.. they MAY recover.. or not. can't be sure.

Reason number I've long since lost count why I favor GC-2 DEEP CYCLE batteries.

[MEXICOWANDERER]

You should have heard the cooling fan and the battery voltage should have gone up substantially after several hours of charging. It is possible your charger has died, but that seems too coincidental. I bet your batteries have died and your charger will work just fine with new batteries. You can go to a battery shop and have them tested.

Troubleshooting error

Converter online and functioning would be heavily loaded by rationale of the voltage reading.

It is quite likely power to or from the converter has faulted

[azrving]

I always said "I'm not interested in friendship I'm interested in charging batteries". I had one for a minute and returned it to best and got a PD 4650.

I had texplained to him what I was doing and what batteries I had I don't know why he ever sold me that junk. I still buy stuff from them, it's a good place.