I have to replace the factory battery on my mk4 1.0 mhev. I know the recommended battery is the yuasa ybx7096 but for very few more I can get a ybx9096 which is AGM. Has anyone tried it and what do you guys think?

The charging system is not designed for AGM.

14 minutes ago, alexp999 said:

The charging system is not designed for AGM.

Supposedly I can change it through forscan but I have no evidence this actually works, that's why I'm asking.

FORScan had a lot of programming options for the the Batteries of the Mk4 Focus but most of them were wrong so FORScan has removed most of the options now, I'm not sure if the AGM option was one of them and has now been removed or not.

As Alex said, the mK4 was not designed for AGM Batteries.

4 hours ago, makois said:

I know the recommended battery is the yuasa ybx7096

There's your answer. Fit the YBX7096 and change the SOC level to 95% and live happily ever after as the story goes.

5 hours ago, alexp999 said:

The charging system is not designed for AGM.

Have you got any in-depth information on this, as looking at both the Varta and Yuasa websites suggest an EFB could be upgraded to AGM?

In addition, the following RAC website also suggests that an upgrade is feasible:

"If you have added any extra features, equipment or appliances to your vehicle which add a greater level of demand to your car battery, we would advise you to consider upgrading to an AGM battery. Similarly, if you usually drive short distances in which your battery is unable to sufficiently recharge such as in an urban environment or your battery is only used seasonally and needs to be recharged, we recommend that you fit an AGM battery to your vehicle for the best results."

https://www.racshop.co.uk/advice/agm-vs-efb-which-battery-do-i-need/

Thanks.

Are you sure the battery actually needs replacing?

I am surprised it hasn't lasted longer than that, or is it the case that you don't do enough mileage to keep it charged up?

There are lots of threads on here that indicate that the batteries need a top up charge every 6 to 8 weeks.

I would stick to the correct type of battery if you do decide to change it. My recommendation is also for a Yuasa battery, and I have had a few from Tayna batteries, good service, with next day delivery.

https://www.tayna.co.uk/ 

1 hour ago, Alan G H said:

and I have had a few from Tayna batteries, good service, with next day delivery.

The OP is not in the UK.

1 hour ago, Alan G H said:

Are you sure the battery actually needs replacing?

I am surprised it hasn't lasted longer than that, or is it the case that you don't do enough mileage to keep it charged up?

There are lots of threads on here that indicate that the batteries need a top up charge every 6 to 8 weeks.

I would stick to the correct type of battery if you do decide to change it. My recommendation is also for a Yuasa battery, and I have had a few from Tayna batteries, good service, with next day delivery.

https://www.tayna.co.uk/ 

It lasted me 4 years with no problems, so I can't complain much. Suddenly I couldn't use the ac and with forscan saw it was the battery. Charged it with a charger but the car is having difficulty to keep the battery charged so I guess changing the battery is the first thing I should try

6 hours ago, Tizer said:

FORScan had a lot of programming options for the the Batteries of the Mk4 Focus but most of them were wrong so FORScan has removed most of the options now, I'm not sure if the AGM option was one of them and has now been removed or not.

As Alex said, the mK4 was not designed for AGM Batteries.

This option is still active in the latest forscan. I have found some people who upgraded their batteries to AGM but none so far has measured if changing the setting made a difference in charging.

Hi Makois,

The charging system should have no problem handling the AGM since it can easily provide 14.4-15.0V which is well in range of the charging voltage for such a battery.

The problem might be in the estimation of the state of charge. EFB has a different voltage-state of charge characteristic than the AGM. I think in the beginning it wouldn't be much of a problem, but on the long run I don't know. If the change in FORscan does adjust the voltage profile, then everything should be fine.

However, as I read the recommended battery around here, I also installed the EFB Yuasa in May. I did not up the SOC to 95% and I decided to let the car do its thing. I just checked it this week with forscan and the SOC is kept between 77-80% (80% being the target), and I have had no deep sleep issues over these months.

I plan the next check in February or when the first deep sleep occurs (if that happens before February).

Therefore, at least from my point of view, an AGM does not really seem to be necessary, but let's see what happens over the winter.

22 hours ago, unofix said:

The OP is not in the UK.

Ah, I missed that!