12V battery replacement poll

[bthanos]

Old post, I have the new one with Bluetooth and self heating.

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[RLXXI]

But the down side is cold. LFP can't be charged below freezing and has limited discharge below freezing.

Yeah, they now make them with built in heaters to eliminate that short coming. The one I use can safely discharge @ -4° with no heater.

Definitely need to be sure and use a heated lfp in Northern climates, I'm in the tropics which rarely sees below freezing temps.

 

[Lytning]

For every "Ohmmu is amazing" post there should be a mandatory warning post with this:


or - at a bare minimum a disclaimer mentioning that they're not suitable for vehicles being used in cooler climates (that see below freezing temperatures).


Ohmmu might be great for some, but it is definitely not a solution for everyone.

I expect mine is built like the one in the video at this link ...

 

[chl]

Wow! All this sounds so complicated. With a gas engine you replaced the battery when you needed a jump start. Apparently that strategy doesn’t work so well for an electric car

Since around 2011 Ford started putting a 12V battery management system in their F-150s and I assume other vehicles, because so much is now 12V battery powered and it is even more important that it used to be, according to reliable information from the Internet (is that an oxymoron? yes sometimes).

And it seems that even the ICE F-150s will have their batteries go low if not driven maybe 45 min to 1 hour every day.

The problem is the load on the 12V system doesn't leave 'room' for significant battery charging if you only drive short trips all the time whether it is recharged by an alternator in an ICE truck or the DC-DC converter in our Lightnings. Of course when off there are also small parasitic loads that add up over time.

Then funny things start to happen.

First you may get a warning message on the screen that loads are being shed to maintain the battery when you first turn off the truck. You may notice the lights don't stay on very long when you first unlock the truck as well. Before I put my Lightning 12V battery on a trickle charger I would see that happen. In ICE F-150 trucks the message may say "System off to save battery" and then the truck will go into a battery saving mode.

Later the truck may not boot up (or start if ICE) without a jump.

In Lightnings another symptom is failed OTAs - some OTAs require at least an 80-85% or so 12V battery SOC so they can fully install. I saw that happen as well.

I just learned recently that some people are reporting high 12V battery charging currents - if true, that is a sign of a deeply discharged battery (50% or lower), and it is not a good thing.

That would also indicate that the battery management system for the Lightning (maybe ICE F-150s also) does not control the charge current so that it stays at or below an optimum level when the battery is deeply discharged. High currents are not good for AGM batteries and will shorten their lifespan. Neither is a deep discharge level.

So, if you are like me, and don't drive 45 min to 1 hour every day, putting the 12V battery on a trickle charger with an AGM mode seems like the best way avoid those issues and make the 12V AGM battery last.

Keeping the battery topped off is always a good idea with any lead-acid battery anyway.

There are other ways to cause the DC-DC converter to charge the 12V battery without a trickle charger and get your OTAs to install (see link):

https://www.macheforum.com/site/threads/how-to-get-failed-otas-to-install.29749/

So to simplify it all: Keep the battery topped off - if you don't drive at least 45 minutes every day, get a trickle charger with an AGM mode and connect it when the truck is not being used.

 

[bthanos]

All these problems solved with Ohmmu Lion Battery.

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