Latitude 7400 2-in-1 Battery Upgrade - 52whr to 78whr

Thanks for the update, do you know if a new back cover or palm rest plate is needed for it to close? Is it the same laptop after all just with different battery capacity fitted? Or there are two different chassis to accommodate the different battery size? Thanks 

It seems you need to change the palm rest . I'm guessing the palm rest dimensions may be different between the 52whr & 78whr compatible versions . With the leftover space in the 52whr palmrest, it would've been nice for Dell to just replace 52 whr with 60whr battery. my guess with the 52 whr battery is so Dell can market the starting weight of this device as under 3 lbs (2.99 lbs). 

Thanks so much for the confirmation. What a shame Dell does not make upgrades easier for options like Battery or WWAN/LTE cards. Thanks again for the reply!

I bought this spare part for exchanging the palmrest to get the WWAN module. Maybe they got something in stock that enables you to get the bigger battery too?

https://www.parts-people.com/index.php?action=item&id=31116

I know this is a late reply but the only way I got it to work was to remove the smart card reader and cut off the plastic supports for that smart card reader.  It was a Dell Refurbished and they gave me a $90 credit to replace the battery so i went for the 78whr only to see why it wouldn't fit.

Hi, I am also very late to this, but thanks for your insight @PoppinPinelli . I just purchased two of these machines and also wanted to upgrade the battery. Since I do not have the smart card reader, I hope the new battery will fit without too much hassle. I will keep you updated!

Actually the 78whr battery doesn't fit exactly on the other side as well.  Looks like there is a very specific top cover that says 4 cell or 6 cell cover.  I coun't find the 6 cell cover part available online.  It will look like your computer isn't booting and runs slow at first but it runs okay after a while. The 78whr battery runs on a higher voltage so it takes a while to adjust.  Then again it could be that my CMOS battery was dead because the BIOS was reset after I change the battery.  My battery came 90% full and my first charge showed full charge capacity at 77,680mWh with the design capacity at 78,010 mWh.  I'm still trying to do the power cycle of draining to 5% and charging to full 3x as recommended from the battery seller.  It's hard to drain a battery since I use this infrequently and the capacity is so high.  Windows has constant browsing at 14hrs life and streaming youtube has it at 20hrs.

The bottom cover bulges out a little bit but I'm not concerned about it. It's a good trade-off to get soo much more battery life.  The screws are in fully but the bottom cover is a little open on the bottom edges.

Thanks for your insight! I just received my two 78Wh batteries and tried to install them. Unfortunately, even though my laptops do not have the smart card reader, the plastic supports are still there and I will have to cut those off as well. However, other than that, the battery seems to fit well into the palmrest support.

May be you can share some photo please?

There are 3 locations I needed to cut down in order for the 78w battery to fit. The material is metal, not plastic, on mine so be very careful and have a good vacuum. I used a Tremel.

This worked perfectly thanks for the pic. I did the support lug cutting after removing the smart card slot and the RFID smart card device that it plugged into (on the left hand side). The 78w battery then fitted perfectly with no bulging on either side.

Tips when cutting: clingfilm the sections outside of the cutting area and masking tape down. Vacuum frequently to remove fine metal filings. Put a cloth in-between the keyboard and screen as fine metal filings will get through the keys on the keyboard.

Hi:

Thanks for the detailed picture (I can't believe this info isn't anywhere else on the Web but here, but it it appears it isn't. You'd think after several years, the people in this thread wouldn't be the only ones trying this).

Anyway, my question is: Are you saying that the ONLY thing you needed to do to get the 78w battery to fit in a 52w battery machine was to cut down those three metal lugs/spacers/whatever? Nothing else on the other side or anywhere else needs to be changed?

(And if that's all it takes, I can't believe Dell didn't make those screw-in parts. Oh wait, I guess I can believe it, but it is annoying).

Thanks!

Here's the picture of my Inspiron 7400 2-in-1 with the 54Wh battery removed. I see the three stand-offs on the right side, but nothin obviously a problem on the left side.

Yes, you just have to cut down those mounting points for the smart card reader.  If you look at the larger battery and how the extra packs go on, it fits into that section and on the other side as well.