Battery monitor sensor 2nd battery?

[glenandemm]

I’ve fitted two batterys and ran a battery feed from the original to the 2nd battery but I noticed there’s a spare set of plugs for a 2nd battery monitor sensor on the newly fitted 2nd battery, do I need to have this fitted or will just the one do on the original battery next to it?

[loot]

Second power cables and all? Seems strange for ford to do that

I'm limited with custom stuff but I would expect you need to configure it to have all the second battery stuff and then connect it all, I think you'll need the right starter and bcm for stop start. Etc.

I'd it possible someone changed it to single and took the battery?
Have you checked the spec to see if the van originated as a single battery?

Bloody Ford again ignoring the trends

[BHM]

Mmm
I have twin battery as oem upgrade from new.
I shall be changing both batts tomorrow and can take pics if you want?
Bhm

[glenandemm]

All fitted and running ok, both batts charging at 14.8v
I just basically extended the battery feeds from the 1st battery to the second battery, still interested to know if I’d really need to connect the 2ns battery monitoring sensor up or not?

[Frag]

No,
Not with that layout,as you've basically just made one larger capacity single battery.
On a twin battery setup they are separated with ignition off.

Your method may 'confuse' the battery monitoring / charging as it's expecting state of charge and voltages for a specific AH capacity of battery.
I'm sure in the past I've had battery warning light issues with non standard batteries,
Where bigger is better in most cases,this may be an issue.

Customs as I've seen,can be single battery no monitoring
Single battery with monitor
Twin with monitors.

Ones with single and monitor,have the wiring for a 2nd monitor (but not the motor itself)
Also if you have the inverter under handbrake,only avail with 2 batteries for obvious reasons.

[Kardaani]

Frag is right. On twin battery system both batteries negative terminals are connected with same wire, but from positive+ terminals are independent. Both goes to Fords "Surestart" relay so they are separated when engine off. Also im guessing the charging system needs both battery monitor sensors attached, to know if one or both are empty or fully loaded etc.

BEMM manual (for 2012 custom) page 84-> has some basic info about the wirings. There i noticed this, yours prewired battery cables might also be for third party needs. Meaning those are not for auxially battery at all, but for some special needs. You can maybe check this from Etis service, where listed what accessories has your car choosen when buying (if you are not the first owner?).

[glenandemm]

Thanks guys, frag Mines the one with single battery single sensor then but wiring there for the second battery, I’ll see how it goes been so far been fine last few hours driving.
If I need the second monitor it just looks like I need the earth sensor as the live fused side just bolts to the terminal.
I wonder if I wanted too could I run the separate live too so it isolates the batteries but if it works and the battery holds charge longer than a week I’ll be happy!

[loot]

Looking at the diagram I see that the battery monitor sensors are wired in parallel. Which suggests that it makes no odds.

[glenandemm]

Thanks pal so does that mean one battery monitor fitted to the first battery should be ok for both then?
I’d have thought so if both batts are linked together as all I’m doing is just making the battery last longer by having more power, I wouldn’t have thought it would be loading up the alternator any more as that would be just topping them up too?
I need a test now if leaving it for a week or so and seeing if it drains dead again but the vans gonna be getting used with work every day until I go away end of March for a month so I may disconnect one when I go and then if I come back to a flat one I can reconnect the other, that’s the only downside I can see to doing it this way unlike the factory option that separates them!

[loot]

I don't know the complete strategy to be honest, the diagram shows lin, which is spliced to both sensors which then go to both batteries.

Also on the mk7 relay setup there is a bridge plate on single batteries so it links the twin battery permanently so it's a big battery if you see. But if you removed that plate then it wouldn't work because it is not programmed as double battery.

So let's say that you have 1 battery and the monitor senses the state of charge and turns on and off when it decides that the battery is full.
Now you have 2 batteries which in this connection is basically 1 big ass battery, this means that the alternator needs to work more to get them full, it may not even see a state that will turn it off??
Or the second battery might draw power in a way that it is never full or cause a load on the first battery or cause it to over charge?

I know on the old iveco 7.5t lorries with dual batteries if you had a no start it was always just 1 of the batteries that was flat not the other

Another thought /idea is have you seen those 140A durite voltage sending relays? You can link it to the first battery and to the second battery and negative to first battery ground, it then only switches on with the 14.4v from engine run. Maybe got maybe shite.

Personally if so it factory, 2 separate batteries and sensors and configured as dual battery setup.

[glenandemm]

Cheers mate, I wouldn’t mind putting a separate live in and then the battery earth monitor sensor bit and then configuring it but do you have a pic possibly of where the 2nd battery live wire heads off to in the loom?

[loot]

No idea how it is setup, mk7 the wire just stays on the battery fuse panel area and connects to the relay.

[glenandemm]

Cheers pal sorry I meant can you see it on the wiring diagram!

[loot]

I see the 2 sensors, I also see the aux battery relay, it appears to have 2 switch coils so it isn't spring return, it has aux relay on circuit and aux relay off circuit.

All at the seat fusebox.

You'll need to have a look at your battery setup to see if the relay etc is all fitted on the fuse panel.

Your extra red cable should go to the relay, it may have a bridge plate like on the mk7.

Pictures will help, you have the second red wire and the second sensor, how did you hook up the red? I'm still confused how you had it fitted and it worked? Did you add the red wire or just plugged it in to the battery?
If it isn't activated in configured then it must have some kind of link to the main battery.?

[glenandemm]

Hi mate I’ve just bridged off the other battery.
Here’s a pic of one I copied but I have exactly the same set up