Fluctuating voltage when in max charge

[$l@k!]

Anyone had this behavior before? On Max Charge.

Checked it with the multimeter and has the same values at the starter battery...

The amps keep going up and down sometimes goes up to 70 amps for a few seconds to drop back down to the values in the movies.

Is this some kind of battery protection or something? A couple of weeks ago I was wild camping int the UK and wanted to charge the leisure batteries by starting the engine for a while... They showed the same behavior. Even went for a drive... Same...

 

[dspuk]

Are you driving or static? Max charge is designed to take advantage of the engine alt when driving. I’d imagine if static you would just get the fast idle behaviour which isn’t enough to give you proper “max charge”.

 

[$l@k!]

I did it both... And I charged it once before when static...

 

[Webbah_in_Switzerland]

This is why I installed a Victron BuckBoost so I can then get max power when I want it most with a switch to enable or disable it. I don't have a Cali though but I know someone with a Cali that also installed it and is now pleased. In Winter my Solar is essentially worthless so this is essential as I work from my van occasionally!

 

[camper albert]

Hi,
A few seconds after the engine is started the starter battery and the two leisure batteries are connected together through a relay under the driver seat. (is that same in UK?)
The charger monitors all 3 batteries separately and charges them together. When all batteries are empty it charges at a maximum voltage of 14.8V. When one of the batteries nears it's maximum capacity (measured through a drop in current through the battery with a shunt resistor at the negative pole) it starts a pulse charging scheme. Few seconds on, few seconds off. That's what you see on the display.
Since your leisure batteries are still empty your starter battery will be full and triggering this behaviour. After a few hours the charge state of the batteries will get equal (because current flows from the full one(s) into the empty) and from that moment charging will be more efficient.
The basic cause of this is the fact that you cannot charge batteries with different charge state connected together in the optimal way because they are in a different phase of the charging curve.
The only good solution is to separate the charging of the leisure batteries and the starter battery. This happens for example when you hook on to electricity. That's the reason why VW tells you to hook up regularly. Without EHU your leisure batteries will degrade quickly because they are almost never charged fully by the car alternator.
Another option is to install a DC-DC battery charger. This will generate the optimal charging curve for the leisure batteries without interfering with the starter battery charging curve. The two leisure batteries can be charged together as they have the same charging state because they are permanently interconnected. I did chose for this one https://www.redarcelectronics.com/eu/dual-input-50a-in-vehicle-dc-battery-charger because it fits under the driver seat where the relay is for connecting the starter and leisure battery.
Because all necessary connection points are available under this seat installation is quite easy.

 

[$l@k!]

Hi,
A few seconds after the engine is started the starter battery and the two leisure batteries are connected together through a relay under the driver seat. (is that same in UK?)
The charger monitors all 3 batteries separately and charges them together. When all batteries are empty it charges at a maximum voltage of 14.8V. When one of the batteries nears it's maximum capacity (measured through a drop in current through the battery with a shunt resistor at the negative pole) it starts a pulse charging scheme. Few seconds on, few seconds off. That's what you see on the display.
Since your leisure batteries are still empty your starter battery will be full and triggering this behaviour. After a few hours the charge state of the batteries will get equal (because current flows from the full one(s) into the empty) and from that moment charging will be more efficient.
The basic cause of this is the fact that you cannot charge batteries with different charge state connected together in the optimal way because they are in a different phase of the charging curve.
The only good solution is to separate the charging of the leisure batteries and the starter battery. This happens for example when you hook on to electricity. That's the reason why VW tells you to hook up regularly. Without EHU your leisure batteries will degrade quickly because they are almost never charged fully by the car alternator.
Another option is to install a DC-DC battery charger. This will generate the optimal charging curve for the leisure batteries without interfering with the starter battery charging curve. The two leisure batteries can be charged together as they have the same charging state because they are permanently interconnected. I did chose for this one https://www.redarcelectronics.com/eu/dual-input-50a-in-vehicle-dc-battery-charger because it fits under the driver seat where the relay is for connecting the starter and leisure battery.
Because all necessary connection points are available under this seat installation is quite easy.

Wow... now thats an explanation! Thx 4 the time taken