correct use of battery tender and....

I use the Battery MINDer 12117.
1. Do I leave shoreline always plugged when not using.
I leave the shoreline plugged in and turn the Converter breaker off. The CO and propane detectors are left on and I occasionally turn on a light (LED).

2. Do I turn aux battery switch on or off when using a battrrry tender.
I leave the battery switch on.

3. What size tender?
I believe the 12117 is rated at 1.3A.

4. When using tender should shorline be plugged in ?
I leave the shoreline plugged in and plug in the Battery MINDer inside the MH.

I am very happy with the Battery MINDer.

Several helpful replies...thank you
I am thinking I will go with a new charger similar to the battery tender. Any idea what amp I need or better yet a particular one. I only have twobhouse batteries and of course the one that starts the motorhome engine.

According to the documentation I could find online, the 7455 is a single stage converter set at 13.8V. A battery tender/float charger would certainly be preferable over it for long term storage (or replacement with a more modern multi-stage converter).

If it's a 7455T model, the converter has a simple time-driven two stage setup that will have a slightly more reasonable long-term float voltage (apparently 13.6V).

Mex knows of what he writes and gives sound advice. It may or may not be overkill for your particular needs.

An Echocharger is good for specific duty and maintaining all batteries during storage ain't it.

Example of what a bleed charger is good for

Regularly charged hotel batteries, maintaining a never started chassis battery.

I use a Xantrex echo charger to charge my engine battery off the coach batteries. The echo charger connects from the coach batteries to the engine battery. There is nothing to do or switch or worry about. As long as the coach batteries are charged to a certain level, the engine battery will be charged. It's pretty much set it and forget it. If the coach batteries drop below a certain level, it stops charging so all of your batteries don't run down. It's a no brainer.

When mounted in the same environment as the battery, a temperature compensated float charger is the preferred regimen except if you store the rig where the temperature is limited to say 50 - 80F and the OEM converter float is appropriate to begin with. See note at bottom

1000ma (one amp) per 100 amp hour 20/hr rate battery is enough capacity for a float charger. So 2.5 amperes float capacity is a good safety margin.

The batteries must be 100% fully charged verified via specific gravity before the float charger is enabled.

The batteries must be physically disconnected (electrically) from any possibility of having a ghost load overwhelm the float charger.


My Rolls batteries exist in an environment where the utter minimum temperature record is 67F and the maximum is 93F. I need no float voltage compensation.

Charger/converter is Series 7400 Model 7455 55 amp

What model of converter do you have? If it's the original equipment one, the tender might treat the batteries somewhat more gently. You should make sure the batteries are fully charged before using the tender, though; it doesn't have the guts to recharge the large batteries (or even smaller ones very well).

If using tender, converter should be off, which is easiest to do by disconnecting the shore power cord. It may be more convenient to turn the converter off with its breaker in the motorhome (or by unplugging it from its outlet or some other means), so that you can plug the tender into the RV electrical system.

If not using the tender, leaving the shore power cord connected or connecting it from time to time will help maintain battery charge.

What to do with the aux battery switch depends on what it actually does and how the RV is wired. If it's a typical house battery disconnect, you may need to leave it connected for the built-in converter to charge the battery. If it's to connect the house and chassis batteries together for starting purposes, it's best leave it disconnected. If it's simply to switch the radio from one battery to the other, I'm not sure it really matters much.

For winter storage, you can also charge the battery fully and disconnect the negative lead and just leave it alone.

If you have the original converter, I would be tempted to simply upgrade it to a modern multistage one rather than getting a tender. The PD 9200 series (deckmount) or equivalent 4600 series (mount into a power center chassis) are well regarded, though there are others that are also good.