12 v battery change

[mtkkk45]

It shouldn't because its fully charged open circuit resting voltage, ~13.3V, is less than the DC-DC converter output voltage, so no 12V component experiences higher voltages than it was designed for.

When I took our former 2019 i3 to our dealer for a warranty integration level increase to enable voice over LTE so that emergency voice calls would work (this was overlooked during the 3G to 4G LTE migration), I swapped out the LFP battery for the OEM battery that it had replaced to avoid any dealer complaint.

I no longer have an OEM battery. The warranty on our 2021 i3 will effectively be expiring in about 2 months. I hope that our dealer won't deny warranty coverage should I need it. I wish that the original 12V battery had lasted until the car's warranty expired, but 3.5 years was the best it could do. I wouldn't replace a functional OEM battery with a LFP battery before the car's warranty expires, but I already had 2 LFP batteries and didn't want to buy another OEM battery. Keeping my fingers crossed…

I love your approach. Funny story. I was in a hit and run with my 2014 i3 in 2021 and used the payout to purchase a can't-pass-up certified pre owned 2018 i3s. The BMW financial loan was so favorable, I added extended warranty through 2026 - which I've never done, AND added tire replacement and key fob replacement coverage. I've had 7 tires replaced in 3 1/2 years for free and two fobs, easily paying for the warranty. I also had this odd drivetrain error fixed under warranty. The warranty has also paid for several flatbed tows and several Ubers back and forth from the dealer... And really hilarious but crazy said warranty win... I came back from a short trip to LAX late at night a few months ago and when got back to my car in long term parking to drive home NO KEY FOB. Locked out of my car in a sketchy parking lot. BMW paid for the 45 min Uber back home to pick up my backup FOB roundtrip back to the airport. I mean, I have made sure to get my money's worth. If I could only find a way for them to cover by mortgage and the 12v battery replacement - yes a bit scammy, but all legit.

 

[tob1as]

my bmw i3 group:
Two notes -
1. For anyone living in Southern California. I’ve replaced two i3 12v batteries myself and sourced oem batteries for cost, But I found a mobile certified mechanic who will replace the battery with the East Penn Deka OEM and register the battery for $350. Tell Harry that Marc sent you. The BMW dealership in Monrovia quoted $500 to install - and that beats other BMW dealerships in LA by $250.

https://h-autorepair.com/

2. If you want a backup OEM AUX 18L Deka / East Penn for by far the cheapest you can find delivered free You can get the OEM for $150 from:
https://www.batterywarehouseonline.com/cart.php

Your link under 2. Is just showing your empty cart

 

[i3m3fan]

I worked with Ohmmu to ensure that its LFP battery would work well with an i3. The i3 DC-DC converter's output voltage is ideal for an LFP battery. The 0.5V higher resting voltage of Ohmmu's LFP isn't a problem with an i3's 12V electronics because 12V components are designed work well with the 14.0+ output voltage of the DC-DC converter. The higher resting voltage and the much more flat voltage vs. charge level curve of a LFP battery means that the risk of all of the spurious DTC's being stored when the OEM battery's voltage drops too low when it fails isn't as great with a LFP battery. My Ohmmu LFP battery has been in our former 2019 and current 2021 i3's for about a year without any problems.

Do you by any chance have dimensions for this battery? L w h

 

[alohart]

Do you by any chance have dimensions for this battery? L w h

The OEM AGM AUX18L battery is 8.13" L x 3.56" W x 6.38" H without the screw-on SAE posts.

I have the 22 Ah deep cycle LFP battery model G1DC22-B which does not include a battery cell heater. Its dimensions are 7.125" L x 3" W x 6.65" H not including the screw-on SAE posts. Its 0.27" greater height compared with the OEM battery requires relocating the pad from the underside of the horizontal section of battery hold-down bracket to the inside of the vertical section so that the top bracket attachment screw aligns with its threaded hole. I also attached the included 0.25" thick spacer to the front of the battery which along with the 0.25" pad that I had relocated compensated for the 0.56" less width dimension.

The more expensive Rivian LFP battery model R1220R1-BH that includes a battery cell heater is 7.375" L x 3" W x 6.125" H. It is 0.25" shorter than the OEM battery which should make it easier to fit than the battery that I have.

The model G1DC22-B might be unsuitable where ambient temperatures could drop below 32 ºF unless one is willing to manually disable battery charging when the ambient temperature is below 32 ºF using the Ohmmu app connected to the battery via Bluetooth. The Ohmmu app displays the cell temperature, so that could be used as a guide. The DC-DC converter provides most 12V system power when an i3 is not off, so the battery would discharge only when the HV system turns on when unlocking or opening the doors, hatch, or frunk or beginning HV battery pack charging or preconditioning. The 12V parasitic load is quite small when an i3 is off, so the battery wouldn't discharge much then. I suppose that excessive battery discharge could eventually become a problem if the battery temperature remained below 32 ºF for a couple of weeks.

The Ohmmu battery BMS doesn't track charge level accurately when the current flow is low or high. The displayed charge level doesn't change while charging at 0.8 A with my CTEK battery charger until it suddenly jumps to 100% as a full charge is reached. It immediately jumps to a displayed 100% charge level when I enable charging with the DC-DC converter on at which point the initial charging current is ~50 A. This makes manually managing the charge level at less than 100% not possible using the BMS's displayed charge level. Instead, I manage the charge level using the displayed BMS internal and output voltages.