Anyone explain how battery booster function works.

[G-A-R-Y]

After a overnight ferry battery was showing 12.4 so whilst in the off que I set the battery boost function. Light came on and rev's raised up.
Voltage dropped to 12.2 and -15 amps. I thought it's meant to charge quickly. I checked voltages through Victron app.

Once on the motorway voltage went to 13.2, I set boost function and it worked, voltage went up to 14.2v.

Stop start wouldn't work whilst in que so I guess engine battery was low.

 

[Eber123]

Hello,

The electric in a Grand California is a mystery to me. The more I read about it the more confused I get.

What I know is the following:

The "booster button (this is not the correct name, but I can't remember the correct one)" on the dashboard (that is what I believe you mean) does actually not "boost".

While driving the alternator charges the leisure battery, but only up to 90% (I thought it would be 80%, but the people from Car Electric Hamburg were adamant that the leisure battery will be charged to 90%).

The way I understand this is, if you have no solar panel, even after a 6 hour drive your leisure battery, should be charged only up to 90%.

Only if you use the "booster button" it will charge up to 100%. So if you need the full charge of the leisure battery it would make sense to press the "booster button" a short while before you reach your destination.

In short, the "booster button" does only switch the electric from standard (90%) to full charge (100%).

Have I all said that, pressing the "booster button" will increase the engine revs and the camper will use a tiny bit more of diesel.

Electrified Grand California
Eberhard

 

[secret lemonade drinker]

A battery booster in a caravan is a DC to DC converter that takes the output of the alternator suitable for a cold crank lead acid battery (13.8v nominally) and boosts it to the 14.4v suitable for charging a deep discharge cyclic leisure battery. Modern start stop alternators have a variable voltage output controlled by the ECU, but higher voltage at greater current would more rpm

 

[GordonH]

The button is described in the GC manual as a ‘maximum battery charge’ button and as per Eberhards post it ensures the leisure battery is charged to 100% state of charge, VW don’t mention if it charges things any faster. The manual doesn’t say if start-stop gets disabled but it may well do and even if it doesn’t you can always disable it with its own ‘disable’ button if needs be. VW don't specify exactly what the lower ‘normal’ charge would be and 80% has been an oft quote figure in the various forums/groups but I’ve no reason to doubt the 90% stated by the folks at Car Electric given their expert knowledge on GC electrics. If you have solar the leisure battery will always get charged to 100% when the sun shines enough

 

[G-A-R-Y]

Yes I understand, what I don't get is why it took power from my leisure battery when pressed. It definitely dropped from 12.4 to 12.2 and showed -15 amps. I checked through the Victron app. I assume by pressing the button it reverts to a dump alternator and charges at max amps until voltage is reached.

 

[GordonH]

How the smart alternator works is a mystery. It’s a simple split charge relay to the leisure battery rather than a dc:dc charger so I guess if the starter is very depleted you may get current flow from the leisure to the starter if the alternator is not providing sufficient support and the relay is closed, wild guess.

 

[G-A-R-Y]

Yes, I think that's how it works, I don't understand why it didn't start charging until I hit motorway speeds. Where is this dump relay located, it must be quite large.

 

[G-A-R-Y]

Anyone know where No5 is located.

 

[GordonH]

Yes, I think that's how it works, I don't understand why it didn't start charging until I hit motorway speeds. Where is this dump relay located, it must be quite large.

Like I said , the smart alternator is a mystery. Its
All about Euro 6 compliance so may need the engine to be warm before it loads things up …. another wild guess.

 

[secret lemonade drinker]

The number 5 on your drawing is the split charge relay, which connects the leisure battery to the vehicle alternator only when the engine is running and if intelligent enough when the vehicle battery has been charged enough to compensate for the loss due to starting, I have installed a votronic unit in place of a split charge relay which takes an input from a euro 5 alternator (start stop) and this unit can be set to charge specific leisure batteries in ways according to their charging characteristics. I did this on a caddy conversion