Originally Posted by troutstalker
A quick follow up question -- Is there a simple answer to how long it will take to bring the battery back up to charge when plugged into shore power at the house -- understanding that it not the best way to recharge. I will get a trickle charger to use when I return from maiden voyage, but for now am wondering how much of a charge I will get by hooking the TT to shore power at home?
thanks again for all the great help everyone
Troutstalker...it is quite diffficult to say without you telling us either the model number or the amp rating of your built in converter charger.
Let's assume though that you have a single 12V battery and it is rated at 100 amp hours, (Chances are that you actually have something smaller but the principles hold.)
Deep cycle batteries should be used ONLY until they are "half full" if you want them to last. So you really should only use about 50 amp hours. There are other threads here that tell you how many amps various products typically use so you have some guidance. A true battery monitor costs about $150 bucks and can let you know exactly where you stand at all times. Now...
If you use 1/2 the battery or 50 amp hours...then you need to put 50 back in. If you have a 50 amp charger then it would seen you could just charge for an hour and be done...but unfortunately...batteries will accept fewer and fewer amps as they approach being full. So...you can bulk charge getting full acceptance up to about 80% full. (Your first 30 amp hours in this case.) That will take about 45 minutes with a 50 amp charger. The next 20 amps will take around 2 hours! ...So...I'd guess around 3 hours with a 50 amp charger to refill a 100 amp battery from a 50% discharge.
If you have a 75 amp hour battery (group 24) or a 90 amp hour battery (group 27) which is more likely...you have around 40-45 amps hours till you hit 50% discharged...and therefore LESS to put back into the batteries...so it will take a little less time with that 50 amp charger...maybe 15 minutes less...but you'll be charging more often with the same electrical use.
Obviously...adding another battery of the same size...gives you twice the capacity to use between charging.
If you have a true deep cycle wet cell battery and you're camping for a few days in the boonies and don't like the sound of a generator... adding more batteries is the first step. You can also cycle between a 50% and an 80% charge instead of spending the time to get that last 20% in. You DO need to bring the batteries up fully to 100% at least a couple of times a week to avoid shortening the battery life cycles.
One big mistake a lot of people make is assuming their battery can power things for quite a while. They end up murdering their batteries quickly.
Most people understand Watts...so lets say all you wanted to do is run a 100 watt bulb (off your battery with an inverter). Well Watts = Volts x Amps. So in this case... we have 100Watts = 12V x 8 amps (roughtly)
Now lets go back to that large 100amp hour battery we started talking about. You could have NOTHING else on but a 100 watt bulb and 6 hours later it would be time to recharge. 12 hours later and you'd have a dead battery. My computer uses 65 watts... that will give me about 10 hours on a big battery...less on the ones that come with most trailers.
Hopefully that will give you a point of reference about what a single battery will do for you.
Good luck with it all!!