Li Snap Pack anomaly

[pianotuna]

Hi All,

I brought my li snap pack home from the RV storage--as I think freezing is not a great thing for that chemistry.

I happened to check the snap pack state of charge at the RV. The temperature was 0 C (32 f).

reading suggested 96% state of charge.

The next day at the Condo at 21 c (70 F), I checked again. It was reading 80%.

Anyone have an idea about what is going on?

[pianotuna]

3 tons they are definitely not LiFePo4.

[StirCrazy]

pianotuna wrote:
Hi All,

I brought my li snap pack home from the RV storage--as I think freezing is not a great thing for that chemistry.

I happened to check the snap pack state of charge at the RV. The temperature was 0 C (32 f).

reading suggested 96% state of charge.

The next day at the Condo at 21 c (70 F), I checked again. It was reading 80%.

Anyone have an idea about what is going on?

yup, like any battery the capacity goes up with the temprature. Just trying to figure out how to explain it so it makes sence.

lets say you have a 100 AH battery and you have 80Ah in it. at room temp (what ever the standard is) ity will be 80% charged, as the temprature drops the capacity also drops so the battery will apear to be a higher state of charge, but it is realy just temprature compensation .

still probably didn't explain it very good. same thing happens with lead acid batteries but to a much larger degree.

how do ou like thoes Don, I have been thinking of getting them for every one for christmas this year?

Steve

[3_tons]

FWIW, my guess is that due to the higher power density required, it ‘may be’ of a ‘hotter’ cobalt based chemistry rather than LiFePO4…Just a guess…

3 tons

[Itinerant1]

I was thinking that might be what you were talking about. I have the NOCO boost GB150 but it lives a pampered life temperature wise, in the 5th wheel when not traveling in the truck.

[3_tons]

PT, Got it, I have one similar myself but did not know what it is called, Thanks for washing my windows 🙂

3 tons

[pianotuna]

A "snap pack" is a battery with cables intended to start vehicles when their own battery had died. I'm sorry that was confusing.

Here is a link: https://www.walmart.com/ip/GOOLOO-4000A-Peak-SuperSafe-Car-Jump-Starter-All-Gas-10-0L-Diesel-Engine-...



There is nothing in the manual about temperature vs capacity.

I don't wish to subject the pack to another low temperature excursion.

[3_tons]

“What is a Li snap pack though?”

It could be almost anything I suppose (??) the joy is in the guessing - :)…

I could only come up with this:

https://discount99.us/18%20volt%20snap%20on%20battery?p=bco&gclid=91f7fa4f90e0102426b29bdbbf2ef968&msclkid=91f7fa4f90e0102426b29bdbbf2ef968&utm_source=bing&utm_medium=cpc&utm_campaign=campaign+%5B023%5D&utm_term=18+volt+snap+on+battery&utm_content=adgroup+%5B23%7Cw5%7Cb%5D%3A+%7B2-18%7D

3 tons

[Itinerant1]

otrfun wrote:
We just went through a cold snap a few days ago. Our lifepo4's SOC and voltage was rock solid from 65f down to 25f. Zero fluctuation.

Could be a BMS/firmware issue/burp. A before/after voltage check with a VM that has at least .xx(v) resolution can confirm whether you've really lost any charge.

I have never seen deviations between SOC and cell temps at anytime over the years.

What is a Li snap pack though?

[otrfun]

We just went through a cold snap a few days ago. Our lifepo4's SOC and voltage was rock solid from 65f down to 25f. Zero fluctuation.

Could be a BMS/firmware issue/burp. A before/after voltage check with a VM that has at least .xx(v) resolution can confirm whether you've really lost any charge.

[time2roll]

Does it go back to 96% when left in the cold again?
What does the manual say on operating temperatures?

[Boon_Docker]

When you first checked, the little electrons were so cold they could not escape until it warmed up then a bunch of them left. :B