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I have the GM (C7 Corvette) US3300 battery tender and it seems to charge/keep the battery charged however get's very hot, at least hot enough that you don't want to hold on to it too long.
Is this normal?
I only use mine in the winter months, and keep it plugged in outside the car. Can't seem to remember anything extraordinary as far as it getting super hot, but if you're keeping it inside the car when plugged in during the summer heat, it may feel much warmer than normal
It will get hot if delivering a lot of current for a long time, especially in high ambient temperatures, but usually it isn't required to source near rated current for a long period of time.
I never use mine except in the winter. If you are having to use the battery tender a lot during the summer are you spending long intervals between drives (5 to 7 days at least) and/or doing mostly very short trips? If not there might be something in your C7 causing excessive current draw or your battery itself may have a problem causing high self discharge and you need to get things checked out.
I use mine year round. It hangs on the wall by the back and I just plug it in. Seems to stay pretty cool and i can see the light flickering to charge occasionally.
It will get hot if delivering a lot of current for a long time, especially in high ambient temperatures, but usually it isn't required to source near rated current for a long period of time.
I never use mine except in the winter. If you are having to use the battery tender a lot during the summer are you spending long intervals between drives (5 to 7 days at least) and/or doing mostly very short trips? If not there might be something in your C7 causing excessive current draw or your battery itself may have a problem causing high self discharge and you need to get things checked out.
Yes, only had it out the past two Saturday's on short trips. It hasn't shown any signs of weak battery over the near three weeks I've had it but thought I would hook up the tender to top the charge off. Evidently needed it. I checked it moments ago and noticed it's still charging but tender has cooled down a bit, so I assume everything's ok.
Short trips are the worst for batteries. Just starting the car consumes a lot of charge, and then the battery never gets fully re-charged on a short drive. That's why your 3300 is getting hot. It's charging all the time you have it plugged in.
St. Jude Donor '12-'13-'14-'15-'16-'17-'18-'19-'20-'21-'22-'23
If battery is below 'full charge', tender will run warmer until 'full charge' is reached and then it will run cooler as it maintains that level. From my observations the threshold is around 12.7 - 12.8 volts.
Noticed mine runs warm while charging so with it mounted to my work bench I attached it to stand off about 3/8" to allow air to circulate even behind it to help dissipate heat better. Overkill? Makes me happy.
Only used mine once to make sure it worked, mine too got pretty hot while in the charging mode but cooled somewhat after it switched modes. My initial charger was bad and got a replacement under warrenty.
I live in Las Vegas and mine gets really hot and seems to stay that way even though the battery is fully charged. My garage temp is extreme. It faces west so the sun really heats it up. I have a convertible so in the really hot months I don't drive it as much.
I live in Las Vegas and mine gets really hot and seems to stay that way even though the battery is fully charged. My garage temp is extreme. It faces west so the sun really heats it up. I have a convertible so in the really hot months I don't drive it as much.
I expect your environment is outside the expected normal operating environment of the battery tender. The active devices are silicon based and will operate at elevated temperature for a long period of time without significant degradation but some of the supporting passive components, electrolytic capacitors in particular, have a greatly accelerated aging rate when they are operated at elevated temperature.
Probably the most practical approach is to just expect to have to replace your unit about every time you get a new Corvette (or a 5 to 7 year cycle); alternatively a small fan to provide air circulation would make a big difference in its ability to reject internal heat to the abnormally hot external environment and will keep the temperature inside the battery maintainer quite a bit cooler.
It will run warmer when charging but will get cooler when battery is fully charged. Now my garage is very hot so obviously the charger will seem hotter then normal do to the high heat in Florida, But eventually will taper off.
I believe I made have a defective Tender as it continued to stay hot and in "charging" mode until I unplugged it from electrical after about 4-5 hours, then I immediately plugged it back in and it went directly to "charged" mode leaving me to believe that it's not automatically shutting off when proper battery voltage is reached.
Does that sound like a reasonable assumption?
I believe I made have a defective Tender as it continued to stay hot and in "charging" mode until I unplugged it from electrical after about 4-5 hours, then I immediately plugged it back in and it went directly to "charged" mode leaving me to believe that it's not automatically shutting off when proper battery voltage is reached.
Does that sound like a reasonable assumption?
It is going to behave differently to what it "sees" while charging is taking place vs initial connection to a nearly charged battery. While it was in charging mode it correctly sensed the battery wasn't fully charged so it was continuing in charging; even in charge mode these devices put out only a few amps so charging an even partially discharged battery takes a long time. But when you plugged it back in it sensed a battery that was only slightly depleted and rather than go to full charge mode it chose to do a slower charge to bring it up to where it should go. These chargers can fail but we have to realize they are programmed to respond to how the battery responds based upon its state of charge and that often doesn't correspond perfectly to our thought process.
It is going to behave differently to what it "sees" while charging is taking place vs initial connection to a nearly charged battery. While it was in charging mode it correctly sensed the battery wasn't fully charged so it was continuing in charging; even in charge mode these devices put out only a few amps so charging an even partially discharged battery takes a long time. But when you plugged it back in it sensed a battery that was only slightly depleted and rather than go to full charge mode it chose to do a slower charge to bring it up to where it should go. These chargers can fail but we have to realize they are programmed to respond to how the battery responds based upon its state of charge and that often doesn't correspond perfectly to our thought process.
Makes perfectly good sense, but then your posts always do.
I will wait and run it through several charging cycles and I'm sure it will be fine.
Thanks!
Last edited by Kevin A Jones; 07-20-2017 at 02:19 PM.
If you're not going to drive your car very often for 20+ miles at a time, the best thing to do is just leave the 3300 plugged in all the time. That will also allow you to make sure it's operating properly, which I suspect it is.
After reaching full charge, it will shut down and will only come on periodically to keep the battery topped off. That's why that and similar devices are properly referred to as "battery maintainers" as opposed to chargers. It may take 12-24 hours to reach a full charge depending upon how depleted it is, but once it does, it should be cool to the touch.
If you're not going to drive your car very often for 20+ miles at a time, the best thing to do is just leave the 3300 plugged in all the time. That will also allow you to make sure it's operating properly, which I suspect it is.
After reaching full charge, it will shut down and will only come on periodically to keep the battery topped off. That's why that and similar devices are properly referred to as "battery maintainers" as opposed to chargers. It may take 12-24 hours to reach a full charge depending upon how depleted it is, but once it does, it should be cool to the touch.
I'm considering leaving the tender connected full time, however that means leaving the trunk lid up and car cover off unless I create an access hole through the bottom of the trunk compartment to run the cord. The battery vent hole could be enlarged to accomplish this but I don't really want to cut anything.
07-19-2017, 09:49 PM
GM Battery Tender - Too hot?
