Since I'm retired, my truck may sit for sometimes up to 10 days without use. Recently, when starting, I could tell that the battery was loosing its charge. The crank speed was a little slower than normal, but it did start. I ran it for about an hour prior to shutting it down. So I decided to buy a Noco Genius 1 to keep the battery up. After a day on the Noco battery float charger, it was down to just a little over 11 volts. And the charger indicated that it was not charging and that I had a fault with the battery. I decided that this wasn't good, so I connected a "Battery Tender Jr" from my hot rod Mustang, to the truck's battery, let it charge overnight and this morning it showed a solid green indicating that it was charged. The Noco charger was set correctly to AGM to match the battery in the truck. Is the Noco charger bad, or did I do something incorrectly? I also connected the charger to the battery positive post and the negative to a nearby ground.

 

? I've generally heard good thinks about Noco, but it sure seems you have a bad one. What year battery is yours? Maybe the Noco was being safe, and the Battery Tender jr was simply throwing juice at it. Is the Jr for agm batteries?

 

The Battery Tender Jr is for both types, but there is no switch on it. The battery is a Sears replacement AGM battery. It's unknown as to how old it is, it was in the truck when I bought it.

 

Take a look at the Noco Genius2D. Its a permanent installed battery tender (2amp).
Make sure when you connect it. You connect to the positive terminal but the negative go to a chassis ground and not the battery itself.

 

Check this one out--Noco is a great brand and you can mount this under your hood too!!

https://no.co/genius2d

 

I have a 2020 F150 that I also drive infrequently and for short trips. It makes me uncomfortable to leave a battery maintainer hooked up 24/7 as I have read of them failing and frying a battery. I found hooking up a battery tender weekly is enough to keep the battery charged. It normally takes about an hour to fully charge the battery with a 4 amp battery tender. I used the harness that came with the maintainer with the positive connected to a terminal on the battery cable, and the negative to a bolt on the fender that another wire from the battery is connected.
This is the maintainer I use:

https://www.walmart.com/ip/Battery-T...sRedirect=true

 

I have the Noco Genius 5 and it works great on AGM mode. A couple months ago, I thought I was having a problem with it, but it turned out the battery was discharged more than I thought, and it just took longer to get it charged up than I'm used to.

I have the pigtail permanently mounted to the battery terminals. On the negative side, I have it connected on top of the negative ground cable, which is on top of the BMS sensor.

 

I have about 7 chargers..... including Battery Minder, and Battery Tender Jr I gave to my daughter. I'm impressed with the Noco Genius 1. I even bought a second one. They say you can do a force charge with the Noco genius 1 down to 1 volt. That is impressive.

Might have been you did not get a good connection. Call tech support, and or try it on a couple other batterys. The alligator clips on the Genius 1 can be taken off to use them as ring terminals. Taggart looks like his has the same ring terminal as mine. He also makes a good point that a 1 amp charger can take a very long time to charge. Like days in fact, depending on size.

 

I feel like on these trucks a one amp charger when used on a battery still installed is only good as a maintainer on a fully charged battery. To charge I'd disconnect the battery. I have one vehicle that a 1.3A Battery MINDer will not go to float mode if the battery is installed and at less than full charge.

 

For maintenance charging, (above the maintainer level), advise a Charger not less than 4-amp Capacity be purchased.
If it has an AGM setting, its program it will still act as a Maintainer plus do shorter charge times like overnight providing the Battery is in decent condition at start of charge time.
.
Charge Current is dependent on the >difference< between the Battery State of Charge and the Charger Voltage forcing the current into the Battery.
At the Maintainer level, the charger does not have the capacity for large currents, therefore will take a lot of time to get full charge recovery, at the lower rates.
Therefore, is time dependent to full charge recovery.
Remember, you're reversing a >chemical reaction< in the cells, that take time to accomplish.
Good luck.