Battery temperature specs

garynappi · August 2017

I read about how lead acid batteries do not like high temperatures. OK, I get it, but why or how then to car and truck batteries stand the scalding temperatures under the hood of my car easily for 4 and 5 years in Florida heat that barely gets a break below the 80's in winter outside, but under hood temps are still very high?

What is it I miss in all of this specsmanship?

mcgivor · August 2017

The car battery is generally lightly discharged and immediately recharged and maintained by the alternator, it loses capacity over time less noticeably than a deep cycle battery in cyclical use, so under the hood is hot which also increases the apparent capacity, until that cold day arrives and when you try to start, all you get is a click.

softdown · August 2017

Believe I have read of Florida drivers who usually don't get more than a few years from their battery. The color of the car and parking conditions are also important. Lots of shade in the sunny state. Lots of garages as well. A weakened battery may still start a small engine when it is 85 degrees.

Scalding temperatures tends towards hyperbole. Florida is just a few degrees warmer than many other states, actually cooler than cities like Phoenix, San Antonio, and El Paso.

Wish I could find my battery life vs. temperature chart....I tried. With six old laptops, I am frequently using the "wrong" computer. Sometimes the "nekkid ladies" act to shove aside "science"....now waiting for the "principals" to show up.

BB. · August 2017

Car batteries are, generally, discharged to a maximum of 85% state of charge (use a maximum of 15% of capacity).

A very common temperature vs life equation is for every 10C rise in temperature (25C/77F for batteries typically) there is a 1/2 reduction in life. 35C (95F) battery would have 1/2 the life of a 25C operated.

But remember, most vehicles are operated 1-2 hours per day, and the batteries are not subjected to elevated engine temperatures 24 hours per day.

I have had cars that used an insulated box around batteries or directed outside air to batteries to help keep them cool(er).

-Bill

softdown · August 2017

How much insulation? If it is the common ~5/16" of bubble wrap, they may have ulterior motives. Such as encouraging exact replacements at the dealership? I spent a *lot* of time in various econ and business classes. Maximizing profits was about the only thing frequently encouraged. Bit of a culture shock after spending a lot of time being immersed in the ethics of the Bible and the Boy Scout Handbook. Evolution of a trouble maker.......

BB. · August 2017

It was not bubble wrap--But probably equivalent insulation value/size (20 year old VW Jetta).

OEM battery long ago replaced with something that "fit" in the space available.

-Bill

Marc Kurth · August 2017

garynappi said:

I read about how lead acid batteries do not like high temperatures. OK, I get it, but why or how then to car and truck batteries stand the scalding temperatures under the hood of my car easily for 4 and 5 years in Florida heat that barely gets a break below the 80's in winter outside, but under hood temps are still very high?

What is it I miss in all of this specsmanship?

It is perspective. Yes, heat kills lead acid batteries. Yes, they can go 4-5 years under the hood - but that is not an acceptable lifespan for off grid batteries.

Hence, it is suggested that batteries be kept cool in order to get 10-15 years or more.

softdown · August 2017

Marc Kurth said:

garynappi said:

I read about how lead acid batteries do not like high temperatures. OK, I get it, but why or how then to car and truck batteries stand the scalding temperatures under the hood of my car easily for 4 and 5 years in Florida heat that barely gets a break below the 80's in winter outside, but under hood temps are still very high?

What is it I miss in all of this specsmanship?

It is perspective. Yes, heat kills lead acid batteries. Yes, they can go 4-5 years under the hood - but that is not an acceptable lifespan for off grid batteries.

Hence, it is suggested that batteries be kept cool in order to get 10-15 years or more.

Well established dogma. Yet I can't seem to recall methodology for keeping batteries cool in challenging environs such as Florida and Texas. Other than the extremely obvious of shade and, I think, burial has been mentioned.

I wonder if water mist and a small fan would pay off? Considering the fan and mist could be designed to operate only when the sun is shining...I think it may be possible.

*Also....for BB's reference. Here is more data on the Trojan Agent we discussed yesterday. It showed up but did not "takeover" my computer this morning. It did not "manifest" until I hunted it down. Paste: C:\Windows\hosts (Trojan.Agent.E.Generic) It only gets implanted into memory. It could only be found and removed with specialty malware removal such as mentioned yesterday. I'll be "keeping an eye on it".

Marc Kurth · August 2017

I am in Texas, but my battery applications include homes, industrial/commercial and military applications worldwide. (Never gets boring!)

Yes, dugouts, basements or root cellar type vaults of various depths have been commonly used in Southern desert areas for years. When PV module prices fell so precipitously, I saw a big increase in mechanical refrigeration being used for battery room/battery box cooling. I have posted pictures of some of applications in the past, including one under a garage floor slab. One customer used a concrete battery box with the lower half flooded with water, and used the flowing water to handle irrigation.

As with DOD planning, there are cost effective crossover points. Sometimes the economics work in favor of simply buying new batteries more often. There are no hard fast rules of the road.

Disclaimer: I backed away from flooded and gel batteries in 2010, and and have focused strictly on AGM since. So my experience is limited to AGM projects now, but I do a lot of projects.

Marc

jonr · June 2018

In a hot climate, I think it makes sense to put the batteries in a water bath and, during sun hours with excess capacity, use a chiller from a water cooler to cool the water. I can't prove this :-). Using ground water for cooling (in some climates) is an interesting idea. A pool of water with a large surface area will see some cooling due to evaporation (depends greatly on relative humidity).

Soil is also insulation - be careful that burying batteries doesn't cause them to over-heat.

softdown · June 2018

On the human body, water removes heat 17 times faster than air does. I would imagine a similar principal applies to other solid objects including batteries.

Heat kills batteries for sure.

Estragon · June 2018

> @softdown said:
> On the human body, water removes heat 17 times faster than air does. I would imagine a similar principal applies to other solid objects including batteries.
>
> Heat kills batteries for sure.

Obviously assuming the water (or air containing water) is colder than ~98°f. Above that, the opposite would apply.

Also, I'm not sure the same ratio would apply to static water vs moving air. A little wind at -40° makes a huge difference

Battery temperature specs

Comments

Categories