Battery Not Charging on Tender

oyarsa wrote:
They are 12 volt and hooked up separately.

I'm not in a hurry for it to charge. Just want to be sure it is working properly.

Sorry, I should have said:
What voltage reading are you getting from each battery on a multimeter when not hooked up to a charger?

“They are 12 volt and hooked up separately.”

Not what grandpa was asking...not even close. You need thirty minutes of basic RV battery education. At 12 volts a 12 volt RV battery is just about....30 to 40% full. Danger level for a wet cell. At 12.7...12.72...fully charged.

“I'm not in a hurry for it to charge.” You should be. A battery left for a couple days at 30 to 40% of a full charge is a damaged battery.

oyarsa wrote:
They are 12 volt and hooked up separately.

I'm not in a hurry for it to charge. Just want to be sure it is working properly.

Yes we KNOW that they are 12 Volt.

But those come in different sizes.....from tiny ones in UPS systems and alarms to HUGE ones in tractors and big trucks.

The Junior tenders that you got are called "junior" for a reason.

They are NOT intended for use with a large car, truck or tractor battery; mostly for motorcycle and garden tractor use.

"Large" refers to the physical size and current capacity......not to the voltage.

Leave it connected for a few more days. If the green light still doesn't come on, disconnect the tender and take the battery to have it tested.

eHoefler wrote:
Are the batteries disconnected from the coach?? There is parisitic draws from many things inside, radio, CO detector, thermostate, fridge, etc... These draws most likely exceed the output of the tenders. Since you have power to the rig, just plug it in and use the convertor to maintain the batteries, that is what it is designed to do.

If you do that, be sure to check the electrolyte levels in your battery periodically. Some converters will boil the battery if given a chance.

They are 12 volt and hooked up separately.

I'm not in a hurry for it to charge. Just want to be sure it is working properly.

Boon Docker wrote:
That battery tender is only going to put 18 ah max in a battery in 24 hours.
Give it a week or so and the batterys may be charged.

The Jr model is not really intended to be used with a LARGE battery.
And it is intended to only maintain a full charge, not necessarily to recover the battery if it is flat.

Give it some more time. But you may need to borrow a larger charger to use on it first.

That also often is a sign that the battery is worn out and will NEVER come up to full again no matter how much you charge it.

It is sad but true that batteries in units sitting on dealers lots are NOT properly taken care of most of the time. That means that sometimes the batteries in your "new" trailer are already shot. More likely if it is a "left over" last year's model.

What’s the voltage of each battery?

As said, the battery tenders are designed to just keep a battery topped off. They will charge the battery but very slowly. If you are looking for more of a charger with tender capabilities, check out ctek chargers. You want a 10 amp charger for a single battery.

Are the batteries disconnected from the coach?? There is parisitic draws from many things inside, radio, CO detector, thermostate, fridge, etc... These draws most likely exceed the output of the tenders. Since you have power to the rig, just plug it in and use the convertor to maintain the batteries, that is what it is designed to do.

Not unusual if the battery has lost a good amount of charge. The junior's are very slow chargers as they only supply 0.75A to the battery. If a battery is low it will take days for it to reach just 80%.