Battery Tenders

Sam Spade wrote:

beemerphile1 wrote:
Can't you just plug in the RV and let the converter do its job?

Maybe not if it is a cheap single stage model.

I have yet to see a mainstream RV as new as the OPs that doesn't have some kind of multistage charger. Mine is a bottom of the barrel 04 model and has a 3 stage WFCO charger which maintains the batteries nicely. But as already mentioned add a little solar, and forget about it. Or plug it in and forget about it.

beemerphile1 wrote:
Can't you just plug in the RV and let the converter do its job?

Maybe not if it is a cheap single stage model.

And to answer the original question:
A smart, automatic, tender type charger with a stated capacity of 2 amps should be plenty......IF the batteries are full or near to full to start with and you don't have a **** load of batteries. Cost should be around $30-40.

BUT.....it is important to know what voltage the batteries ARE and whether they are connected in series or parallel before you connect anything to them.

The advice of connect one lead to one battery and the other lead to the other battery only works in a parallel arrangement.

The advice that works regardless is to connect the red charging lead to the red battery cable leaving the battery pack and the negative charging lead to the negative cable leaving the pack.

Can't you just plug in the RV and let the converter do its job?

small solar panel and a charge controller set at 13.6V. No need to plug in. Keep the snow off it in the winter.

http://www.walmart.com/ip/Battery-Tender-Plus-021-0128-12V-Battery-Charger/15779498

This will work on 2 12 volt batteries wired in parallel. As bobbo already said connect the charging cables to positive of 1 battery and the negative of the other

As you can see -the market is flooded with gizmos giving you misleading description what they do.
Tender, minder, enhancer, restorer.
Those are all sale pitches not telling you what you are buying.
What you really need is batter MAINTAINER with FLOAT CIRCUIT, what will keep constant maintaninng voltage at about 13.5V.
Those usually give 0.5amp for single battery, although I had them on dual battery bank just fine.
Pull the clamp on battery to prevent accidental discharge.
Some advanced chargers also have so-called maintaining program, but that is on/off voltage control - not the best.

I prefer the BatteryMinders to prevent sulfation on all my batteries.

BatteryMinder website

I get 5 years out of the one year battery in my riding lawnmower with no problems leaving it over the winter in a storage shed out in the yard. I keep one on my chassis battery but let the 3 step charger in my inverter maintain the house batteries. I think about changing that arrangement so I can put the BatteryMinder on the house batteries too.

Depends on the draw. You need to get one big enough to cover all parasitic draws plus about 5 amps.

Hook the positive cable to one battery, and the negative cable to the other battery.