12V Battery Replacement

[nsartor]

Doesn't lithium ion phosphate have issues in cold temperature? I don't think they are a good idea for cars that have to go into the snow due to the low temperature cutoff. The car will insulate it somewhat, but not enough to go below I think 30F

The issue is LiFePO4 batteries will get roasted it you try to charge them at below freezing temps. Most have a BMS (battery management system) and the good ones will have a temp sensor and not let that happen. I don’t know if ohmmu batts have it but valid wuestion

 

[android04]

The issue is LiFePO4 batteries will get roasted it you try to charge them at below freezing temps. Most have a BMS (battery management system) and the good ones will have a temp sensor and not let that happen. I don’t know if ohmmu batts have it but valid wuestion

The Ohmmu batteries do not have a low temperature cutoff. They will still charge at below freezing temps. That will cause some damage over time and reduction in capacity over time because the Tesla does not reduce the charging current to the very low recommended values at below freezing temps (0.1C below 0°C, and 0.05C below -10°C).

 

[Flybyglass]

The Ohmmu batteries do not have a low temperature cutoff. They will still charge at below freezing temps. That will cause some damage over time and reduction in capacity over time because the Tesla does not reduce the charging current to the very low recommended values at below freezing temps (0.1C below 0°C, and 0.05C below -10°C).

Ohmmu batteries are tested from 365 F to -94 F.

 

[android04]

Ohmmu batteries are tested from 365 F to -94 F.

I know that, and they work. Doesn't mean that there's no damage caused when charging them in extremely cold temps. I even came across a forum post by the founder stating as much. It doesn't mean that they won't last a long time even in the cold (that depends on how they were designed based on their testing), but they won't last as long as in more temperate zones. OhmMu Batteries

 

[Birdsfan]

I'm considering buying the battery even though my car is only a few months old. Saw a post about updating software causing some issues on the 3?

 

[jjrandorin]

I'm considering buying the battery even though my car is only a few months old. Saw a post about updating software causing some issues on the 3?

Unless you are doing it for some reason other than cost, there isnt any point, as long as the OEM battery is $85. You can proactively replace your OEM battery every 2 years and still have it be cheaper than the Ohmmu. There is nothing wrong with the Ohmmu, I think its a great product for those who want a different battery type in their model 3, but at the same time, people should not be doing this because they think they are going to save some money.

 

[iwannam3]

I know that, and they work. Doesn't mean that there's no damage caused when charging them in extremely cold temps. I even came across a forum post by the founder stating as much. It doesn't mean that they won't last a long time even in the cold (that depends on how they were designed based on their testing), but they won't last as long as in more temperate zones. OhmMu Batteries

Much higer charging voltage delivered to lead acid as it gets colder.

Battery Temperature	Charge Voltage per cell	Charge Voltage for a 12 Volt battery
-10 °C *	2.51	15.66 to 16.2
0 ° C *	2.45	15.3 to 15.9
10 °C	2.41	14.94 to 15.54
20 °C	2.37	14.58 to 15.18

 

[android04]

Much higer charging voltage delivered to lead acid as it gets colder.

Battery Temperature	Charge Voltage per cell	Charge Voltage for a 12 Volt battery
-10 °C *	2.51	15.66 to 16.2
0 ° C *	2.45	15.3 to 15.9
10 °C	2.41	14.94 to 15.54
20 °C	2.37	14.58 to 15.18

Yes, Tesla also increases the charging (and float) voltage on the lead acid 12V battery as well. I noticed now that it's been very cold that the float voltage on my battery had increased from 13.45V to 13.85V. The charging currents haven't changed their patterns from what I can tell so far.