How often to plug in to keep battery charged?

sbhtennis

 I lie in Seattle.  How frequently should I be plugging the T@B in to my house electric to keep batteries charged? Does it vary depending on weather etc. Should I monitor it on a regular basis? 

wizard1880

You can leave it plugged in indefinitely, as the built-in converter will maintain the battery OK.  You'll need to check the battery water level every couple months in the winter, and monthly in the summer.  Unfortunately the converter is notorious for keeping the voltage on the high side and it can boil your battery out over time.

I would recommend disconnecting the battery from the T@B entirely, and connect a smart battery maintainer, like the DelTran Battery Tender. 

Note that if you leave the battery connected to the T@B without plugging it in, the battery will be fully drained by the parasitic loads over a few weeks or months time.  Draining the battery entirely causes permanent damage.

If you go the battery tender route, you only need to check the water levels every 6 months or so.

Just a side note, if you're using an AGM style battery like an Optima Spiracell, avoid leaving it connected to the T@B for charging (by the converter) for too long as the high voltage from it will cause damage too, since the water cannot be replaced.

wizard1880

If you choose to leave the battery disconnected, give it a good overnight (if possible) charge with any smart charger every month.  Even though your charger might say it is done in an hour or less, it still slowly absorbs power over a few hours.  A complete charge is critical for longevity with lead acid batteries.

Personally, this is the method I choose to use.

seajeeper

I am in the Seattle area as well.  I leave the trailer plugged in all the time to keep it 55 degrees and have lights/radio when I go in it. I leave the battery disconnected (I have a battery disconnect) most of the time, and connect it for a day or two every month to top it off as the DC still works with the battery disconnected.

irvingj

+1 on an Optima battery. After I installed a shut-off switch, I could leave that Optima alone for weeks at a time and it would still register 12.6 or very nearly so. Amazingly able to hold its charge. Before a trip, I'd hit it with the charger and it would only take an hour or so before registering "complete." Prior to that, it was once a month, at least.... and then crossed fingers!

sbhtennis

What is considered a full charge?  I have 2   6 volt deep cycle type batteries connected in series.  When it gets hooked up to  shore power does that fully charge the battery?

Sharon_is_SAM

At one point I think there was debate about whether or not the battery is fully charged - even though it reads as charged.  I think the issue, at least with some batteries, is that it only maintains the bulk charge for 4 hours which may not be long enough to completely fill the battery if very depleted, hence some suggest to use a smart charger.  The other issue is wear and tear on the converter if it is continuously plugged into power.  A fully charged 12 volt battery AT REST should read at least 12.6 V.

ColoradoJon

@sbhtennis - In my experience, with two 6 volt batteries, you really need a good external smart charger (Deltran Battery Tender Plus, Pro-Logix, Noco Genius, etc.).  The onboard converter just would not charge my dual 6 volt batteries well at all - it's voltage output is on the low side.

Measuring charge by voltage is not very accurate but if you follow SAM's advice you should be pretty darned close