Took the battery out and looked at the battery leads. They look fine. I did a resistance check on both leads and they both measured 0.9 ohms. They appear to be fine.
I bought the battery tender junior just before leaving on this trip since it was compact and handy. Maybe, as stated before, it could have cause damage to the battery?
I forgot to check the model number of the battery, but found it in an e-receipt in my email from a few years ago when I bought it. Its: Shorai eXtreme rate LFX lithium battery - LFX18A1-BS12