So did I ruin my batteries?

[Durango1]

OK, kinda embarrassing on two levels:

1) Preparing for our (starting out this Thursday) 3 week Oregon/ Idaho/ Montana/ Wyoming road trip I went to buy gas Saturday. Came back home and re-plugged the shore connection in. (I thought)

But today two days later I noticed my primitive cigarette lighter volt meter was reading 11.83 volts. Uh-oh! Even a electrical ignoramus like me knows that ain't right. And yep- the plug on the cord to the truck wasn't plugged into the outlet when connected it two days ago!

2) The second "embarrassment"? I'm so clueless on RV electrical theory I don't know if (or even how to find out if) my two year old FWC factory battery set-up is shot or not.

What do you electrical wizards think? I immediately plugged the batteries in and they are charging off 110 volt. In our road trip we'll be changing camp most days so can charge from the alternator. (I only have the 100 Watt folding Renogy solar panel- no rooftop solar)

Have I ruined the batteries? If so, it would be easier to change them out here at home instead of on the road. Many thanks in advance for your collective advice!

Steve

 

[Vic Harder]

short answer - no

Longer answer, is similar to what Paul says below. And it had been -10* outside they might have frozen, and then -- Yes -- they would be toast.

As is, you stressed them. Not a big deal if it only happens once a year. In fact, the only way to really test a battery is to run it completely flat. "Flat" meaning 10.5 V.

http://www.oceannavigator.com/May-June-2013/Testing-and-equalizing-batteries/

 

[PaulT]

+1 on no

(Longer answer)

My first camping trip (2014) in my Hawk, the batteries hit 11.8v also and I could not recharge much in the three remaining days camping due to shadows from trees at campground. Only had factory 100 watt panel, no access to shore power, batteries too low for alternator to do anything useful. Was seriously sweating it. Full sun with 5+ Amps on three hour drive home. Plugged in shore power & left connected for several days until Iota and Zamp both indicated fully charged. Batteries still working fine after three years.

I just knew I had ruined the batteries. Apparently, they forgave me for the poor treatment. Just make sure you fully charge the batteries as soon as you can. Go ahead on your trip but pay closer attention to avoid discharging so low.

Paul

 

[Beach]

Unless you leave them in that discharged state for an extended period of time they should be fine.

 

[Durango1]

THANKS to all concerned. And yes, I will be more careful and watch my $7.99 volt meter like a hawk! (I really want to add roof solar going forward.)

 

[Durango1]

So one more question from the Electrically Uninitiated: "Just how low can I let my batteries fall overnight before starting the truck to recharge them to keep them from danger?"

Life can be so complicated...

 

[Vic Harder]

The simple answer might be 50%.

The complicated bit starts when you find out that you can't tell what 50% is with just a volt meter. You need something like a Trimetric or Victron battery monitor.

Get one of those and life gets easier again.

 

[Durango1]

So help me out here, Vic.

I totally plan to get a Trimetric battery monitor. But just for this three week road trip what is an approximate and general voltage level I should try and keep my batteries above? 12.50, 12.30, 12.10, 11.90, etc?

Many thanks from a CED (Certified Electrical Dummy)

 

[Vic Harder]

Many thanks from a CED (Certified Electrical Dummy)

LOL! I'm no expert, but given what little I know about your batteries and usage...

If you can turn off the load for an hour and observe the voltage at that point, you will have something resembling a "settled" voltage.

12.2V would be about 50% discharged, which you don't want to go below on a regular basis. Long term battery life shortens if you do.

http://www.energymatters.com.au/components/battery-voltage-discharge/

 

[rando]

To second and agree with what Vic has said - 12.2V would be a good number to try and stay above, but I wouldn't begin to worry until things go below 12.0V (particularly if anything is running). As others have said - get your self a good battery monitor, and solar panels and sleep easy at night.

 

[Durango1]

My thanks to you both!

Will print this out and I promise (on this camper and if not my next build) to include roof solar and a good battery monitor! (Of course then I would have to actually learn how to read/interpret it!)

 

[Chadx]

Most folks seem to quote regular non-AGM flooded lead acid charts and say 12.2v (50%). Seems to me most generic AGM charts are higher and show an AGM 50% state of charge (SOC) is 12.6v.

If you are running the Exide flat plate AGM that FWC currently puts into the campers, then it gets easier to answer as the Exide website has the charging and storage spec sheets (linked below). For this particular battery, the chart shows 50% SOC is 12.4v. The same chart shows 60% SOC is 12.5v and Exide recommends recharging at or before 60% SOC. So, if you are using these batteries, keep it above 12.5v. That is probably a good target for any AGM.

I also used this table to program my Bogart SC2030 solar controller and trimetric 2030 (to ensure the various stages charge as the appropriate voltage for the appropriate time, etc.) I also verified numbers with a helpful senior engineer at Exide and so my Trimetric and Controller parameters were all confirmed. Very helpful folks over there.

Link to Exide table is here. Note that the Flat Plate AGM are the last/bottom row:
http://www2.exide.com/Media/files/Location%20Data/Battery%20Charging%20%26%20Storage%20Specs%20%2011_13_15.pdf