I have a yuasa efb 75Ah battery fitted to my car 

just checked with my multimeter and it shows 12.58. 
 

would I be right using this chart to assume the SOC is near 100%?
 

 

1 hour ago, Andyr55 said:

would I be right using this chart to assume the SOC is near 100%?

Yes it is about 97 to 98% charged.

Over the next few weeks you can expect that to fall to around the 80% level as that is all the car charging system will maintain it at.

Shame….. thought it might have reset the SOC 

Have you done the reset BMS procedure, otherwise your battery will fail prematurely 

1 hour ago, Neb_engineer said:

Have you done the reset BMS procedure, otherwise your battery will fail prematurely 

Yep Halfords did the reset

16 hours ago, Neb_engineer said:

Have you done the reset BMS procedure, otherwise your battery will fail prematurely 

Why would not resetting cause premature failure? It won’t be able to take advantage of the new battery so much and cause battery saving techniques to come on earlier than they need to. But I can’t think how it could increase the wear rate?

Efb/AGM batteries differ from the standard wet batteries in that they accept a slightly higher charge over a short period to accommodate stop/start cycles.

They do age over time and the charging program takes this into account and adjusts to suit.

Not resetting or using the wrong type of battery will subject it to the wrong charging regime and reduce the life of the battery.

hope this helps to explain

7 minutes ago, RL123 said:

Efb/AGM batteries differ from the standard wet batteries in that they accept a slightly higher charge over a short period to accommodate stop/start cycles.

They do age over time and the charging program takes this into account and adjusts to suit.

Not resetting or using the wrong type of battery will subject it to the wrong charging regime and reduce the life of the battery.

hope this helps to explain

Yeah that’s the information I usually give for resetting the BMS when someone hasn’t changed the battery. But if the battery is new then not resetting it the car will be using an aged battery profile which should be gentler on the battery. I can’t see how it would shorten the life, if anything it may slightly lengthen it. You just won’t get the full benefit of a new battery. 

8 hours ago, alexp999 said:

Yeah that’s the information I usually give for resetting the BMS when someone hasn’t changed the battery. But if the battery is new then not resetting it the car will be using an aged battery profile which should be gentler on the battery. I can’t see how it would shorten the life, if anything it may slightly lengthen it. You just won’t get the full benefit of a new battery. 

Actually it's the opposite, as the battery ages, the car increases the charging rate in order to maintain a similar performance, if your replace the battery with a new one it will cook the new battery.

2 minutes ago, Neb_engineer said:

Actually it's the opposite, as the battery ages, the car increases the charging rate in order to maintain a similar performance, if your replace the battery with a new one it will cook the new battery.

Be interested in the source for that if you have one?

 I know on mine at least things like stop start were not working as the car still thought it had an old battery. I heard it from a mate of mine who is an automotive engineer.

4 hours ago, Neb_engineer said:

 I know on mine at least things like stop start were not working as the car still thought it had an old battery. I heard it from a mate of mine who is an automotive engineer.

Stop start not working by definition is being gentler on the battery. 

16 minutes ago, alexp999 said:

Stop start not working by definition is being gentler on the battery. 

That part is I suppose, but doesn't change the fact the alternator increases charging current as the battery ages to maintain same SOC, so when you out a new one on, the car doesn't know it has a new battery and so stays at high current demand from alterntor

4 minutes ago, Neb_engineer said:

That part is I suppose, but doesn't change the fact the alternator increases charging current as the battery ages to maintain same SOC, so when you out a new one on, the car doesn't know it has a new battery and so stays at high current demand from alterntor

The car bases the charge on the voltage and it also monitors the incoming and outgoing current. It can sense how much current has been used and how much is going in. The alternator will run at a higher voltage on older batteries to maintain the charge because the voltage drops slightly with age and it has to overcome the internal resistance which also increases with age. It can also sense how hot the battery is which will increase during charging due to heat loss from the internal resistance. A new battery has lower internal resistance and should be able to take higher current dumps. That’s what’s meant by working a new battery harder if it thinks the battery age is 0. It’s worse to reset the bms on an old battery as it will expect it to take those larger current charges with less turning to heat. 
A new battery will be at a higher voltage so it won’t need to charger it as hard as an older battery in any case. 

Sorry I meant voltage (I'm tired lol) but a battery being charged at a higher voltage tends to make it start venting, and the car can't sense battery temperature only voltage and current (the current through the current shunt on the negative terminal) so as I say you will cook the battery by boiling the acid off, it's a smart charging system but not smart enough for detecting a new battery.

7 minutes ago, Neb_engineer said:

Sorry I meant voltage (I'm tired lol) but a battery being charged at a higher voltage tends to make it start venting, and the car can't sense battery temperature only voltage and current (the current through the current shunt on the negative terminal) so as I say you will cook the battery by boiling the acid off, it's a smart charging system but not smart enough for detecting a new battery.

It measures temperature too. And it’s measuring the voltage and incoming current. It knows how not to boil a battery. The charging profiles just help with optimisation for the battery age.  And enable all feature if it knows the battery is new and at full capacity.  

https://www.bosch-mobility.com/en/solutions/sensors/electronic-battery-sensor/

I stand corrected

Well the new battery was measured at 12.58 after installing 

after two days of non use it measures 12.16

is this normal? 

Yes, as I said above the battery SOC will fall and can only ever be a maximum of 80% because that is all the cars Smart charging system will allow.

The hard facts are that modern cars can not maintain a good SOC unless they are used daily and driven at least 20 miles. The alternative is to connect a smart battery charger about once every 4 to 5 weeks and charge the battery overnight to get it's SOC back up.

You can adjust the SOC on the Focus Mk4 and probably the Mk4.5 to a more realistic 95% which will help prolong the time inbetween using a smart charger to 'top up' the battery.

2 minutes ago, unofix said:

Yes, as I said above the battery SOC will fall and can only ever be a maximum of 80% because that is all the cars Smart charging system will allow.

The hard facts are that modern cars can not maintain a good SOC unless they are used daily and driven at least 20 miles. The alternative is to connect a smart battery charger about once every 4 to 5 weeks and charge the battery overnight to get it's SOC back up.

You can adjust the SOC on the Focus Mk4 and probably the Mk4.5 to a more realistic 95% which will help prolong the time in between using a smart charger to 'top up' the battery.

Is this adjust to SOC something I have to pay £££ to Ford 

1 minute ago, Andyr55 said:

Is this adjust to SOC something I have to pay £££ to Ford 

I very much doubt if a Ford dealer will change the SOC (even if you pay them) as it would mean they have changed the setting from factory default, which Ford would most likely not give them permission to do.

You can change it by using FORScan, which many of us here have already done.

1 minute ago, unofix said:

I very much doubt if a Ford dealer will change the SOC (even if you pay them) as it would mean they have changed the setting from factory default, which Ford would most likely not give them permission to do.

You can change it by using FORScan, which many of us here have already done.

Thanks

i dont have FORScan ( probably wouldn’t know what to do if I did!! ) 

22 hours ago, unofix said:

The hard facts are that modern cars can not maintain a good SOC unless they are used daily and driven at least 20 miles.

I was going to say... I've done nearly 20k this year in my 2012 1.0 which I think has it's original battery (I'll have to check) - but *touch wood* I've not had any of the stereotypical low battery symptoms even in cold weather. I think I've noticed the keyless entry not working a couple of mornings last year - but rather incredibly I gather, my start-stop has functioned as expected all year round lol

I've been away for about 10 days, so my car hadn't moved in that time. I hadn't done a long journey before parking up, I had to defrost the car and used the heated seats and steering on my 20 min journey home last night at -1.

This morning, battery read 11.8V, but passenger keyless entry still worked, no battery saving messages and started with no hesitation. It then charged at 14.9V.

I'm pretty sure the car uses both the SoC and battery age to determine what it needs to shut off. It doesn't seem like it follows unofix's signature uniformly. It's a good guide, but I wonder if the cut off voltages change with battery age.

Morning all, had a few problems before xmas with the battery on my Mk4.5 Focus Vignale mild hybrid. Basically the battery went flat because I wasn't using it enough. On advice from Ford's I got myself a smart battery charger (Halfords). I was also advised to switch off stop/start which I did & also unplug the dashcam @ night. Anyhow with some snowy expected next week I thought I ought to charge the battery. So this morning I've connected the + lead to the positive terminal & the - lead to the chassis to charge the battery in situ. All seems to be going fine except the battery charger is showing the battery already @ 13.4 V after only 15mins? Is this normal?

Tks & Rgds

GrantLee