Can starter Battery be set to fully charge?

I

iamrinswind

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Apologies if this has been covered before.

T6.1 2021

Is there a way to code the van so that the alternator charges the battery to a higher level?

The smart alternator seems to only get my battery to a (at a guess) 60% as the voltage on it is often only 12.0-12.2v when resting. If I am working in the van for a period of time then I get the low battery warning come up (below 12V). The battery is fairly new, so that should be ok.

I'm not bothered about loosing some of the benefit of the regenerative breaking. I would like to have the piece of mind that I'm not going to get a flat battery and not be able to start the engine.

Thanks
 
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how old is the battery ?

does it go flat often?

is there anything connected to the battery NEG terminal?

how often is the van driven - for how long?

post a pic or two of the starter battery
 
If you are opening and closing doors all of this causes various modules to switch on - and these can be surprisingly power hungry and may well drag down a decent battery to the voltages you describe. Our brand new TGE (aka a Crafter) exhibits this behaviour as well as the low voltage - but it never fails to start. If you are happy that the battery is indeed OK ( don't fall into the trap that just because it's new it's OK) I would be inclined to monitor and only act if you actually have a problem - sluggish starting esp on a cold morning. As for coding anything I haven't the foggiest but wouldn't be a route I'd rush into.
 
Thanks for the reply.

Battery is about 6 months old, fitted by main dealer just before I got the van.

It's a work van, so I'm often in it for short periods doing admin, so may have stereo on. My previous T5.1 never had issues with this type of use.

Nothing on the battery Neg

This happens more often when I do short journeys.

I genuinely think I just need this battery to charge more fully. It's likely to last longer as well.

20260422_152740.webp

20260422_152637.webp
 
what the big fat RED POS for ~?

Inverter? audio amp? DC_DC charger for leisure battery?

is it possible that your aftermarket stuff may be using power, and causing a low starter battery?
 
if you have a leisure battery setup - you can get a AMT1-12 starter trickle charger that we all use.

Dellmassive

Thread '[Guide] Battery Maintainer (for Starter battery) -- How I Done It --'

[Guide] Battery Maintainer (for Starter battery) -- How I Done It --

Right so its that time of year again . . . . . . . . Winter & (Lockdown 2020)

1606304364989.png


The van might be layed up not being used, which will lead to a flat battery in around 3 weeks.

The cold weather doesn't help the battery's either.



1606304290090.png


This Thread is about using "what you have" to "back charge" the starter battery...

lets look at some options. . . . . . . .

1# Connect a 240v/EHU charger to the starter battery and leave it connected, that's fine if you have a drive way etc, have a look for the...
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if you dont have a leisure battery . . .

you could try unplugging the battery NEG shunt sensor, that will (should) default the alternator to more traditional fixed voltage output.

but you will loose the stop start feature.

some people just remove the small POS cable , that apparently does the same.
 
Dellmassive said:
what the big fat RED POS for ~?

Inverter? audio amp? DC_DC charger for leisure battery?

is it possible that your aftermarket stuff may be using power, and causing a low starter battery?
Click to expand...
The red wire is feeding a leisure battery with a Victron Orion.

I am confident that it's not draining the starter battery. (I had this issue before fitting the leisure battery).

I can see from the Victron monitoring that the starter battery never charges above about 12.2V which equates to 60% ish. The alternator happily keeps enough voltage when needed to the Orion to keep the leisure battery full.

I was looking at getting a AMT1-12 after reading your other post, but was thinking it's working round the issue of charging the starter battery, when it makes more sense if I can change a setting to just make it fully charge.

I will look into unplugging the shunt. I don't use the start stop anyway.

Thanks for your help
 
keep us posted.

FYI, i dont use the Stop/Start and have the Auto-Button_press device.

but i do use the AMT2-12 on BOTH vans,

as the camper when we go away for long weekends the van lights and modules power up every time the doors are opened, - so that stops the starter running too low.

and in the VAN, i could be onsite all day with the doors open/close or having hazard lights on etc etc .

so the starter chargers works best option for me.

yes the Energy management system keeps the starter battery around 80% to allow headroom for the regen braking.


but,

to be honest they have fitted a crappy battery anyway.

those EFB+ batterys are nowhere near as good as a Proper AGM battery. and VW have cheaped out as they used to fit the AGM for the starter and EFB+ for the Leisure battery.


if it was me id swap ouit that EFB+ battery and put a larger 90A AGM battery in and go from there?




Dellmassive

Post in thread 'Dellmassive`s Camper Van Adventure'

Right - Starter Battery !!

i think this van has its original battery from 2017?

1755446334279.webp

the Staop-Start hasnt worked for like - ever?


The AMT2-12 does a grand job keeping it from going flat.

but after changing the SB on the VAN, and seeing what a massive difference it made - i just had to change the BUS battery as well.



not sure on the date code - but this battery is Original 2017 I'm sure.

1755446450254.webp


plugging in the VCDS, we can see the battery is shot..



1755446510038.webp



37% - 45% state of health - charge.

only 8ah available, resting around 12.2v.

its...
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and other van . .

Dellmassive

Post in thread '@Dellmassive`s T6 T32 Sportline 204 LWB DSG PV MY18 - Van Adventure'

After almost 7 years it's time to fit a new battery to the van.

It just goes to show that if you look after them they will last.

Anyway, decided to bump up the size to a AGM-115.

Went for the Halfords own brand (which is a Yuasa) - 5yr guaranty.

£209 down to £141 with the trade card.

That ll do.... I'll get the vcds out and swap over when I get a chance.


Screenshot_20250528_064627_Chrome.webp
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and the main thread. . .


Grim Reaper

Thread 'Upgrading Starter Battery - how to guide'

My van (April 2017 T28) is fitted with a Moll battery.
I am experiencing some issues with it not starting after a few days sitting on the drive. Now this could be due to the tracker I have fitted draining it but I doubt it, I'll do some drain current tests before taking the plunge.
If I were to change the battery myself, could I replace it with a larger capacity one (eg a 95Ah 850A G14 Varta AGM which should just fit in the battery tray) instead of the standard 70Ah 700A Moll?
Is there anything I need to do to let the van know it has a different battery fitted? (I have VCDS if needed)


.
 
All the above really.

However,
After a few months playing around with testers etc, I found that my battery was resting at around 12v as I don't do as many longer drives as the van would like. Probably the same sort of use as rinswind (Rincewind).
The van has (i assume) the original 70Ah battery in a 4 yr old van so prob might grab another year out of it or change it before winter.

If you have start/stop (after reading other threads on this encyclopedic forum) the battery will charge at most to 70% of full. Something to do with it being smarter than me and charging when slowing down in gear etc etc.
So - 70Ah battery @ 70% charge = 49Ah

With Carista (I assume VCDS/others) I told the van it was an 85Ah battery.
85Ah @ 70% charge = an ant's udder under 60Ah which gives it plenty of chance to be smart when it wants to be.
 
Last edited:
you can use a BM2 battery voltage monitor / logger for long term .

or the Victron Orion input voltage if you run it through a Cerbo etc. . .


take a look . . . . .


Dellmassive

Thread 'Battery Monitoring -- How I Done It --'

Battery Monitoring -- How I Done It --

Part #1

Battery monitoring is a very important part of your 12v system . . . . whether its just the vans starter battery or your leisure setup keeping an eye on the power in your battery bank will keep you from breaking down and make sure your weekends are not cut short from lack of power.

Battery monitoring is even more important with Lithium Lifepo4 batteries as the voltage stays fairly constant for 90% of the capacity.

first off lets look at a few basic 12v meters.

here a great little unit that I've been using for ages....

you can plug it...
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