118F outside and battery maintainers

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Sep 4, 2021
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Truck is rarely driven and sits often. It's too hot for me to drive it(no A/C) so I take another car with A/C to work daily. It's been over 115 everyday this week here in Vegas. Is it too hot outside to leave tender on overnight/next day?
Will tender and or batteries get damaged?
 
Truck is rarely driven and sits often. It's too hot for me to drive it(no A/C) so I take another car with A/C to work daily. It's been over 115 everyday this week here in Vegas. Is it too hot outside to leave tender on overnight/next day?
Will tender and or batteries get damaged?
Disconnect and take inside to charge.
 
I would give it a break-- heat increases chemical reactions and charging is one of those reactions. Maybe put it on a timer for the coldest two hours of the day, at dawn?

Lenzee's idea has merit, too, just put the battery in a cold corner of your air conditioned house. It can go a month without charging.
 
You can google safe charge temps for flooded batteries.

My Ctek and Solar chargers have temp sensors built-in...
 
I have all 3 of my vehicles on battery maintainers. I have zero trouble with them, hot or cold. It won't hurt keeping your battery on a maintainer in hot weather.

As long as it has, "smart technology", it won't overcharge it. Mine are all Noco Genius 1's. They only put out 1 amp maximum. Most of the time they're only putting out milliamps.

And if the light is solid green, they are in, "maintenance mode", and they are just monitoring, and not charging at all. They're made to be connected all the time.
 
Unless your charging your battery in your basement with a battery maintainer, then your battery maintainer should have high and low temperature compensation. Not all do. I would guess the HF ones don't.
 
I think the short answer is yes, 118F is beyond the operating temperature that these devices were designed for.
 
I run mine once a month. I do it inside a garage. It has a built-in fan and battery sensor, so even though it’s 115, I haven’t had any issues in the eight years I’ve been using it.
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I run mine once a month. I do it inside a garage. It has a built-in fan, so even though it’s 115, I haven’t had any issues in the eight years I’ve been using it.
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It's not whether it's too hot for the maintainer to work properly, rather it's the voltage the maintainer needs to bring the battery to. And that voltage is different at 0F than 113F. The maintainer needs to understand the temperature of the batter in order for it to maintain it properly. Unless it's in the basement at 65F or 70F with those temps being what a battery maintainer would be designed for if no temperature compensation. And in the basement the battery maintainer would err on slightly under charging which is preferable over overcharging at high temperatures.
 
Which Tender? What float voltage does it keep? If you feel it (or have an IR heat gun) is it running hot?

Is the battery maintenance free or has caps so you can check fluid level? If you can, is fluid level low?

Can you measure /log charge rate as a daily average? How old is the battery and state of health to get an idea how lossy it *should* be? What battery? ;)

Essentially I'm stating, look at everything. If all your ducks are in a row, it can work fine to do that. If one duck is out of line, it is no longer a line.

Oops, I forgot a few ducks. That truck? What is the normal parasitic draw, say after it has sat long enough to go into its deepest low power state (which may take an hour or more undisturbed including no hood or battery disconnect, etc)? You may not need the tender hooked up 24/7, if the charging strategy isn't the kindest or it is just more advantageous to put it on a timer box where it runs during cooler night hours and off in the daytime. Next the question is, is it good for a timer box to be at 115F every day.

If this is going to be a long term situation, and it's outside where it can get some sun, or even if not, if it is practical to mount a solar panel and string some cheap low voltage wire (even leftover CAT5 network cable, doorbell wire, etc, would work for this...) then I'd wonder about getting a solar panel array to maintain the battery, need not even be one with a proper battery charger circuit on it, just measure it during peak sun hours, and put a resistor in series to the battery so it gets around 80mA at peak sun. Check battery voltage after a week or two and adjust resistor value if needed. They are only a few cents a piece.

I don't really like *smart* chargers in high heat, as they tend to have electronics more prone to fail from heat, then are more difficult to repair if not something obvious like a blown capacitor. Blown transistor on the other hand, can let the battery go flat or if shorted closed circuit, cook the battery.
 
Thx guys. I just decided to bring the battery inside garage and charge it there. Appreciate all the advice
 
Assuming it charged, it’s not going to be charging…

Some may float the battery which is a balanced charge,
Only replacing what is lost through internal self discharge (natural phenomena plus parasitics). Others just turn off and monitor for the battery voltage to drop past a point.

A hot battery will have lower impedance and won’t need as much charge, but the bad side reactions do accelerate.

So… “it depends”. If you have a true float
Charger with temperature compensation, then make sure it gets to float before the heat of the day, and then don’t worry about it.

If it doesn’t float, it could go into a bulk charge at any time. So I’d be more careful. Maybe keep them on a timer to only operate between 2-7am or something.
 
All this worry about high outside or garage ambient temperature when using a battery maintainer, is really quite meaningless when compared to the massive heat soak your battery endures by being baked under your hood, everytime you shut it off and allow it to sit.

You might just as well bake your battery in a oven. Especially with these large plastic hood bonnets all these newer vehicles have. That accomplish nothing except allowing for even greater heat soak.

So unless you're opening your hood when you park in your garage, and allow a fan to blow cool air under it, you are killing your battery far more, than by having a little 1 amp battery maintainer hooked up to it.
 
Is your battery lead/acid or other?
Define “other”. If you mean VRLA/AGM, it’s still lead acid.

All this worry about high outside or garage ambient temperature when using a battery maintainer, is really quite meaningless when compared to the massive heat soak your battery endures by being baked under your hood, everytime you shut it off and allow it to sit.

You might just as well bake your battery in a oven. Especially with these large plastic hood bonnets all these newer vehicles have. That accomplish nothing except allowing for even greater heat soak.

So unless you're opening your hood when you park in your garage, and allow a fan to blow cool air under it, you are killing your battery far more, than by having a little 1 amp battery maintainer hooked up to it.
Time at temperature matters too. Heat soak, sure, but that’s temporary versus day after day, hours after hours. Remember, degrading side reactions double in rate every eight degrees or so.
 
Define “other”.
Word omission on my part.
I should've said "flooded lead/acid" or AGM.
And I was thinking of the problems regarding over charging + killing and AGM.
I've read that if you clamp grandpa's old style charger to an AGM and leave it too long, it can kill the AGM battery.
 
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