jimbo409

I have a 2012 e350 and hooked up a new battery tender junior,the red light is on solid but it has been on for 2 days and still solid red.
my other battery tender plus never did this,should I just buy another battery tender plus and send this junior back
thanks again

S70Houston

What do the directions say? Is the light supposed to go off? How long for the battery to charge until the light goes off (If it is intended to go off?)

I would think that the directions of the battery tender will explain how it should work, what should happen when. Based on that information you should be able to determine if the tender is bad.

Chevota

My guess is the car sucks more power than the charger can provide so it'll never stop charging. That charger is pretty weak so I'd imagine it would only work if the batt was disconnected?
If you're curious enough, I'd check actual power draw without the charger and see what it is. Just note that the power draw may vary over time. Since my power draw varies too drastically to get an average, I read the avg on my charger, which is this guy:
It's made in china so it doesn't really work right, and not exactly accurate, and being made in china it'll be dead in a year, but it was on sale for $20. Fyi if it does manage to think the batt is full, it'll stop charging, period. Since it does that now and then, I had to plug it into a switch I have programmed to cycle power every hour to reset it.

rgf1999

FWIW, newbie here but I put a CTEK MXS 5.0 Battery Charger and Maintainer on my 2011 E350 Cabriolet last night and it worked like a charm. I put it in the mode for the AGM type battery and hooked it up to the battery under the front hood. It went over night to get to Step 7, but it sounds really strong. On another thread someone suggested a quick double-click on the fob lock button. This might cutdown on all the electrical scavengers running around, or so they said.

What I still can't figure out is where my alternate battery is. I can see the spare tire and fuse box under the floor of the trunk but maybe I just haven't looked hard enough.

Good luck to you.

I'm assuming I bought on Amazon.

pl626

Accessory battery should be under the bonnet/hood, passenger/right side near bulkhead/firewall.