Changing out the 12V battery in a 2018 Leaf: any gotchas?

[ODgreen]

Has anyone tried the Ohmmu LFP battery yet? Currently $265.30 and says it's specifically for all Nissan Leafs. If not, I'm about to try it in my wife's 2018 Leaf.
https://www.ohmmu.com/product-page/12v-lithium-battery-for-nissan-leaf

I know I'm 2 years late to this party. We were really lucky with our OEM battery and got additional life out of it by using a battery maintainer on it ever couple of months. This forum is still the top search engine result

 

[gmcjetpilot]

I bought a Walmart Everstart Group Size 51r battery. This was 5 yrs ago, $109. No regrets. The original OEM battery kept dying. More on that later. But the replacement has never died. If you have OEM battery over 3yrs and it dies on you repace it. Life will be good.

A couple of things, the load or demand on the 12v Battery in a LEAF is light; it does not have to start an ICE engine.

The car was designed for FLA Battery. AGM and LiFePO4 have different chemistry and different ideal charging voltages. Not saying bad but more expensive and not needed. It is likely the non FLA batteries will not be optimally charged in LEAF. That "work" since it has low demand, no need to start engines. It's necessary. FLA works well. If you go with AGM get a dedicated AMG charger and throw it on from time to time. AMG does have lower disuse discharge rate. Same for a LiFePO4. You will pay x2 to x4 for these batteries over FLA.

If you look at post on 1st Gen LEAFs, including my 2015 SV the 12v battery's going dead was infamous. There was great discussions how to prevent it and why it happened (some of them guesses w/ no proof). After 7 yrs of ownership (bought used 3yo LEAF now 9yo) the issue of battery going dead was the low quality OEM barrery. Yes mine went dead on occasion. I did all kind of things, including charging and checking it. Gor tired of tge sporadic dead battery. Bought a new battery. Problem solved.

After a few years, the already weak OEM batteries lost charge quickly. Also my EV is a 2nd car, can sit for days or weeks. Never an issue since, with replacement battery.

Some say that not loading the battery with high start drain causes sulfates to form in battery. I don't know, it could, but low charge causes sulfates to form. If you don't drive and charge your LEAF, throw a 5 amp battery charger on it from time to time. I don't do that unless going out of town and not driving it for weeks or months. I put a 2amp NOCO smart charger on the 12v battery. Safe for extended charging. Drive battery I store at 50% approx (charging cable not connected).

My $109 Walmart battery not one issue, never died. I check it's health and it has most of it's CCA, 95%. I am at my 5yr warranty and expect it to go another 5 yrs.

There is no secret to DIY repacement. Just good shop practices. Biggest mistake paying too much for a 12v battery.

 

[cornbinder89]

Actually there is one thing that is different. The service manual has a procedure to follow to minimize the chance of an erroneous code being stored. They still say after all is done to clear any codes set.
The procedure is key-on key-off then no draw (no doors being opened, etc) for 5 min minimum, one hour maximum. Remove and replace battery. If done in the 5-60 window, the manual suggest a minimum chance of a erroneous code setting. They still recommend clearing the codes via the OBD 2 port.

 

[hradek]

Has anyone tried the Ohmmu LFP battery yet? Currently $265.30 and says it's specifically for all Nissan Leafs. If not, I'm about to try it in my wife's 2018 Leaf.
https://www.ohmmu.com/product-page/12v-lithium-battery-for-nissan-leaf

I know I'm 2 years late to this party. We were really lucky with our OEM battery and got additional life out of it by using a battery maintainer on it ever couple of months. This forum is still the top search engine result

"self-heating technology inside warms battery during charging in extreme cold conditions as an extra layer of protection." Not something I would want. Just get the AGM and one of these bad boys instead. https://www.amazon.com/NOCO-GB40-Ul...nIiN7RefYfwS0UpMcBwRrCQYXVX5gc8hoCtT8QAvD_BwE

 

[knightmb]

You then price out the AGM and make another maintenance step when the linked battery takes of that all into one form factor that requires no further user effort. My 12V lithium never had a heater in it, but then I also don't see temperatures that get below 0F (-17.7 C) either for weeks, so if someone lived in such a climate, the Lithium with a heater would be much more convenient than having to pop the hood to hook on some plugs or clamps every-time. Lithium 12V with a heater are not new, just more affordable now it seems. Especially given the replacement cost now of SLA/AGM types for the Leaf.

[edit] This linked battery is much more expensive with the heater and bluetooth, which I would not really care about if my battery is blue-tooth compatible, I would just look for the battery with the heater only if needed.

 

[macgeeknz]

I just took my Leaf in for inspection/PM/brake fluid, and I'm told that the 12V battery is starting to go.

Are there any "gotchas" on changing out the 12V battery?

I recommend doing the swap with the vehicle in the 'Power ON' state (not just ACC, but full ON), as that way the car's DC-DC inverter will maintain the 12V rail from the traction battery energy store whilst the 12V battery is removed. This will avoid the Christmas-tree effect on your DTC list from all the ECUs receiving power 'transients'.

 

[knightmb]

I recommend doing the swap with the vehicle in the 'Power ON' state (not just ACC, but full ON), as that way the car's DC-DC inverter will maintain the 12V rail from the traction battery energy store whilst the 12V battery is removed. This will avoid the Christmas-tree effect on your DTC list from all the ECUs receiving power 'transients'.

That also means that +2000 watts of power can flow if you touch the socket wrench to the wrong place while doing this. I wouldn't be comfortable doing this even if I had HV rubber coated tools because if the positive lead were to touch any part of ground on the Leaf it would short out and shutdown anyway; not to mention the nice big spark and miniature explosion to catch you by surprise.

 

[mrlithium]

Adding cost of battery tender puts the lead acid battery near price of a lithium - $250 with free shipping https://www.lithiummoto.com/12v-ev-lithium-battery and includes bluetooth
( other guys $265 + 19 ship ) = $284
No tender needed with lithium. I work at an auto parts store and the average time-out for replacements is 2 to 3 years. I always hear about the exceptional miracle batteries that cost a hundred dollars and last ten years. For that 1/2 of 1% that get that .. I'm happy for you.

 

[cornbinder89]

That also means that +2000 watts of power can flow if you touch the socket wrench to the wrong place while doing this. I wouldn't be comfortable doing this even if I had HV rubber coated tools because if the positive lead where to touch any part of ground on the Leaf it would short out and shutdown anyway; not to mention the nice big spark and miniature explosion to catch you by surprise.

And the service manual procedure for disconnection is done exactly to make sure the Dc to DC charger is not trying to charge the 12 volt when it is being disconnected. Doing while "on" is very likely to cause trouble code.

 

[macgeeknz]

That also means that +2000 watts of power can flow if you touch the socket wrench to the wrong place while doing this. I wouldn't be comfortable doing this even if I had HV rubber coated tools because if the positive lead were to touch any part of ground on the Leaf it would short out and shutdown anyway; not to mention the nice big spark and miniature explosion to catch you by surprise.

If you touch the 'socket wrench' to the wrong places even with the DC-DC turned off you'll still get sparks, so yes one always needs to take care when working on vehicles. That doesn't change the fact that I would absolutely make sure the vehicle is ON before disconnecting the terminals myself. Done it many times and recommend it to others. YMMV as always.

 

[macgeeknz]

And the service manual procedure for disconnection is done exactly to make sure the Dc to DC charger is not trying to charge the 12 volt when it is being disconnected. Doing while "on" is very likely to cause trouble code.

Done it multiple times on multiple cars. No trouble codes. Only codes I've got are when disconnecting the 12V battery without the DC-DC enabled.

 

[knightmb]

If you touch the 'socket wrench' to the wrong places even with the DC-DC turned off you'll still get sparks, so yes one always needs to take care when working on vehicles. That doesn't change the fact that I would absolutely make sure the vehicle is ON before disconnecting the terminals myself. Done it many times and recommend it to others. YMMV as always.

True, but the battery can not output 2000 watts of power, only about half that. For the same reason I wouldn't change out a 12V battery on a running ICE engine, it would not be safe to do this on an energized Leaf. You not only will have the 12V bus energized but you are also creating a possible electrical pathway from the HV battery. The issue that you are trying to solve by avoiding DTC or losing computer settings was solved long ago by simply using a small 12V battery which clips to the positive and negative leads with the vehicle off. You can change out the 12V battery in a much safer fashion and the vehicle computer won't know the difference.

Just because you can technically do a 12V change out while the Leaf is energized does not mean you should. It's not safe, not practical and not worth the risk.

 

[macgeeknz]

True, but the battery can not output 2000 watts of power, only about half that. For the same reason I wouldn't change out a 12V battery on a running ICE engine, it would not be safe to do this on an energized Leaf. You not only will have the 12V bus energized but you are also creating a possible electrical pathway from the HV battery. The issue that you are trying to solve by avoiding DTC or losing computer settings was solved long ago by simply using a small 12V battery which clips to the positive and negative leads when the vehicle off. You can change out the 12V battery in a much safer fashion and the vehicle computer won't know the difference.

Just because you can technically do a 12V change out while the Leaf is energized does not mean you should. It's not safe, not practical and not worth the risk.

Yep I agree that attaching an external 12V source is absolutely safer and a better approach for those who are unwilling to keep things clear. I think a current-limited power supply would be a better choice than another battery though.

I fully respect your opinion and your right to share it!

But I also disagree and will stick to doing what I do

 

[nlspace]

Trying to swap out the 12V while the system is energized is one of the most foolish ideas i've ever read on this forum.

To anyone reading this: What is the possible Benefit versus the Risk of expensive ECU damage?

Follow the manual and you won't go wrong; follow his bad advice and be prepared for an expensive education in the school of hard lessons learned the hard way...

 

[rrip]

I changed mine 3 times already in 12 years. Did mine with the car "Off" as it was already dead. Batteries were from autozone and wal-mart. You change it like you would any other car battery, just remove the negative first, and put the negative back on last. By doing so even if your wrench hits metal, it's still the negative side which is already electrically bonded to the frame of the car. When re-attaching the negative, do so in a single slam-down motion without letting it "dance" on the battery post. Also like any other car battery, buy the battery connector wire-brush tool from where you buy the battery and clean up the connectors.