Hi everyone, first time here. I have a 2022 Fiesta titanium ecoboost 1.0 125ps Mhev with stop/start and regenerative braking. Can anyone tell me what size battery will fit in the battery box. Want to order a new one without removing the old. I imagine it's the original battery (not even 4 years old, a Varta 60Ah with the Ford logo on it). Would like to fit a 65Ah one in it's place, but not sure about the increased length 242 to 278mm. With stop/start i guess it will be an EFB battery. My confusion got worse when i realized that SLI in the battery photo means Starting Lighting Ignition. Googling that says it's a standard lead/acid battery not at all suitable for stop/start vehicles as the plates are thinner and will suffer premature failure. Just about what i've got. Have Ford fitted the wrong battery from day 1 ? Many thanks to anyone who can help. Mike Confused.

Hi,

This is quite a controversial question for your first post.

Technically Ford have not fitted the wrong battery.  Stop start is powered by the hybrid battery on the MHEV, so the 12v battery only does one start per journey, same as non-SS cars.  Therefore SLI is perfectly acceptable by design.

However, in the real world, we aren't sure whether an EFB would cope better and last longer on the MHEVs.  It seems that both SLI and EFB are failing around 3-4 years now. 

My personal view at the moment is that it will only make negligible difference in the real world, not enough to make either battery a definite choice.  However, if I was buying a battery for this car, I would go for the EFB as a test.

The Fiesta 1.0 Ecoboost battery tray is the same on all models.

Usually recommended on here is the Yuasa YBX7100

https://www.tayna.co.uk/car-batteries/yuasa/ybx7100/

Many thanks to Unofix for pointing me in the right direction for dialogue and for making clear the battery tray issue. Also thanks to TomsFocus for the battery recommendation. I was thinking of Yuasa, from long gone biking days. Now i know which one. My problems solved in a couple of hours, instead of scouring the internet and getting nowhere. Thanks again all round.

Interesting that this one has come up again, soon after the previous thread here:

It does seem that Ford have fitted SLI to MHEV Fiestas (Cologne plant) and Focuses (Saarlouis), but EFB to Puma (Craiova). Pumas seem to have had Rombat batteries which were thought to be an issue but it seems Ford have replaced them with Varta but these don't appear to last any better. 

It would be interesting to hear what recent Puma purchasers have in their cars.

My previous Fiesta (non MHEV, Varta EFB) was still ok when I traded it at 5 years, but I had got into the routine of using a smart charger every 5/6 weeks, my mileage being pretty low these days.

Whichever is the cheapest and fits is what Ford will use.

(TVM would've dug a lot deeper into Fiesta as it was the oldest model in the range)

Whichever works best is for you to decide after the warranty expires

Ford cares about quality

On 1/18/2026 at 11:44 PM, Mike Confused said:

Many thanks to Unofix for pointing me in the right direction for dialogue and for making clear the battery tray issue. Also thanks to TomsFocus for the battery recommendation. I was thinking of Yuasa, from long gone biking days. Now i know which one. My problems solved in a couple of hours, instead of scouring the internet and getting nowhere. Thanks again all round.

Remember also that the BMS will have to be reset after you change the battery.

Also I have seen elsewhere that the type can be changed from SLI to EFB but that requires Forscan. I am not sure how crucial that is but perhaps someone else could inform.

And by the way, I have a 2021 car with the same SLI battery and I'm interested in the Yuasa as well, so please let me know if it fits well in place.

Just to update and hopefully conclude, my Fiesta is a 2022 125 MHEV ecoboost with stop/start and regen. braking, and I wasn't sure what replacement battery to fit. The original was a Varta 60 Ah SLI , but was told I needed an EFB because it was stop/start. Recommended on this forum was a Yuasa YBX 7100 65 Ah. I was about to order one when I noticed that this battery was only 175mm high as opposed to 190mm on the original Varta. As such the battery strap that bolts across the top of the battery would not be holding it down securely. I'm sure the Yuasa would have sat well enough in the pan, but I figured it would be better if the strap touched the battery, and not allowed 15mm of up and down movement. So in the end I bought a Bosch S4 E08 70Ah EFB. It was one of several models recommended for my car and was fitted by the AA. It gives a useful extra 10 Ah over the original, and fits perfectly. Also because of my low mileage I bought a trickle charger to keep the battery in good condition. There are plenty to choose from, but the CTEK range seem well respected, and customer service are good to deal with. I needed to ask what setting to use for EFB batteries and was told it was the "car" symbol. I ended up with the CTEK MXS 5.0. Not cheap, but well made and a nice bit of kit. Just remember positive lead to battery positive terminal, but negative lead to a grounded earth and not the battery negative terminal.

Original Varta 60Ah L. 242mm W. 175mm H. 190mm

Yuasa YBX 7100 65Ah L.278mm W. 175mm H. 175mm

Bosch S4 E08 70Ah L.278mm W. 175mm H. 190mm

All is running well again, and I hope this is useful to somebody out there. Many thanks to all who have been of help on this forum. It's good such things exist, because main dealers are useless.