Is it ok to charge a hot battery after a long ride at 5 amps?

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Glens carzy ebike   1 mW

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Is it ok to charge a hot battery after a long ride at 5 amps?

Post by Glens carzy ebike » Aug 21 2019 6:28pm

Is it ok to charge a hot battery at 5 amps or is it better to let it cool down for an hour ?

markz   100 GW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by markz » Aug 21 2019 6:40pm

It depends on what the charge rate for the battery is.

Better to let it cool down, but it depends.


john61ct   1 MW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by john61ct » Aug 21 2019 6:55pm

Best to let it at least start cooling first, and at a rate slower than the max spec.

What exact battery?

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wturber   10 MW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by wturber » Aug 21 2019 7:02pm

Glens carzy ebike wrote:
Aug 21 2019 6:44pm
5 amps
I'm pretty sure he was wondering was the charge rate per cell and then would want to know what kind of cells. In other words compare what you are doing with the actual or typical cell specs.
Last edited by wturber on Aug 21 2019 8:23pm, edited 1 time in total.
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flat tire   1 MW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by flat tire » Aug 21 2019 7:26pm

When you're a noob and you give a one line post and someone asks for more information you should assume that you need to give information OTHER than that already provided. Worst post I've seen all day.

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by john61ct » Aug 21 2019 8:22pm

well he does put carzy right in his handle

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E-HP   10 kW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by E-HP » Aug 21 2019 8:46pm

Glens carzy ebike wrote:
Aug 21 2019 6:28pm
Is it ok to charge a hot battery at 5 amps or is it better to let it cool down for an hour ?
Nope. Too cold is bad as well. Depending on the battery chemistry, it could be hazardous.

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by amberwolf » Aug 22 2019 2:22am

If the battery is hot, you have the wrong battery for your application.

You should size the battery to provide the current your system needs without significant voltage sag, without creating significant heat. Both are indicators of insufficient batteyr capability.

And no, you shouldn't charge a hot battery at all.

If it's getting hot while in use, you've already created a fire risk while in use.

If it's getting hot while charging, you've created a fire risk while charging.

If it's already hot before charging, then the extra heat from charging increases the fire risk.

Your choice, but I hope I don't live near you if you do. ;)

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by Volt_Ampere » Aug 22 2019 10:23am

Let it cool down to ambient before charging. Too cold is below freezing so don't put it in the freezer. :D

markz   100 GW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by markz » Aug 22 2019 11:02pm

This is an interesting article, though its a123 you may find of use or not depending on your chemistry.
Lots of temperature related info with my quick search of "temp"
https://www.buya123products.com/uploads ... 4db60a.pdf

I was actually trying to find a NASA battery pdf file here on ES that I remember reading.

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dogman dan   100 GW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by dogman dan » Aug 24 2019 9:37am

Define hot. In my garage, room temp might be 110F. Not ideal to charge it in a place that hot, but one cant exactly wait till fall to charge it again.

But if you can't hold that thing in your hand, then no, don't charge it till it cools enough to hold it. For most folks, that's around 140F or so. And it might be an inconveniently long wait for a larger battery to cool to ambient temp, so if that is the case, charge it very warm, but not so hot you can't hold it in your hand.

And as said above, if its getting that hot discharging it, the problem will go away pretty soon when you kill the pack.

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by Ford Prefect » Aug 24 2019 1:52pm

I am rather unsure what the weather should be like in New Zealand in August. Maybe the battery got warm because he was riding outside, in the sun? :lowbatt:
The fundamental laws of thermodynamics will place fixed limits on technological innovation and human advancement.

How would you react if I said that I'm not from Guildford after all, but from a small planet somewhere in the vicinity of Betelgeuse?

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by john61ct » Aug 24 2019 2:01pm

middle of winter

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MadRhino   100 GW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by MadRhino » Aug 24 2019 2:22pm

Any batteries, any size, any chemistries...
None like being charged or discharged when hot.
Some you are just killing them slowly, some will leak gas and start a fire.

The best indicator of battery health is heat, although most EVs are only equipped to monitor voltage and Amps.
Make it fool-proof, and I will make a better fool.
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Ford Prefect   1 W

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by Ford Prefect » Aug 24 2019 2:40pm

Yes I know, it is middle of winter. basically a February of the northern hemisphere. We get anything between -20°C and +20°C in February. Even simultaneously in Germany. When I was in NZ as a teenager they were warning because of the hole in the Ozon layer.

But whatever. Not the point here. Sorry…
The fundamental laws of thermodynamics will place fixed limits on technological innovation and human advancement.

How would you react if I said that I'm not from Guildford after all, but from a small planet somewhere in the vicinity of Betelgeuse?

john61ct   1 MW

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Re: Is it ok to charge a hot battery after a long ride at 5 amps?

Post by john61ct » Aug 24 2019 3:18pm

There is a critical distinction between "hot batteries" due to thermal / chemical reactions caused by high discharge rates

and regular old hot weather, or high **ambient** temps for other reasons

It is the former cause where you need to wait, let things "settle down internally" before inflicting further stress by charging, especially if at a high C-rate.

The latter, ambient conditions, is not conducive to longevity whether in storage or in use cycling, but is not immediately damaging, and no problem for regular charging.


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