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DaanC
Lifetime VIP Member
Hello everyone,
We have just bought a new 2026 GC680 4m Dune, here in the Netherlands.
It has no factory Solar fitted and the 2 standard AGM batteries (leisure and starter).
I am currently fitting a lithium battery and inverter setup in the back cabinet. The inverter obviously will provide the 230V which is easily connected to the current 230v breaker box. My intention is to use the feed in the original 12v breaker switch fitted in the back cabinet to feed the 12v system in the camper from the new lithium setup. I will be charger the lithium with external mobile solar and a victron DCDC 50A charger connected to the starter battery or through the inverter charger when connected to wall power.
I don't intend to remove the original leisure battery or change any wiring to it, other than removing the connection in the back from the switch. With no detailed schematic drawings for the GC680 to go off, I have found that disconnecting the switch results in only some front led lights and the Aux cabine diesel heater (not the main diesel heater) still working of the original AGM leisure battery. Whilst all the rest (lights, sockets, waterpump, fridge, etc) all will work form the new Lithium leisure batteries in the back. So this setup should be fine as I assume the original AGM can easily maintain those lights and the AUX heater just from being charged whilst we drive.
Ultimately I would be charging the Lithium leisure batteries from the mobile solar, the DCDC charger when driving, or when plugged into the wall power as the inverter has a 125a charger.
The Starter battery would be charged during driving by the OEM setup (Alternator) and as a backup can be charged by the Victron DCDC charger in the reverse charge mode.
This leaves me with the AGM leisure battery, which I believe will then only be charged by the alternator when driving and unless I add solar or a dedicated second charger option from the Lithium setup, I don't see how I would be able to charge it in the existing setup.
What I am struggling to understand is the internal OEM battery charging setup.
When plugged into wall power I can see on the screen that both the AGM batteries get charged, I assume this is coming from the charger under the driver seat. However if I turn off the original 12v breaker switch in the back, this charge stops on both batteries. This surprised me as I don't understand why the starter battery would also stop charging. I would assume that the 230V wall power goes to the charger and this in turn would feed both batteries separately, but that doesn't look to be the case. So this would mean that the OEM underseat charger becomes obsolete in my new setup or am I missing something?
Can anyone explain or show how the OEM underseat charger is connected in the system? Ideally I would keep it in place and be able to use it to charge the AGM batteries.
Thanks!
Also the charger under the driver seat is a LifePo charger, not sure if this is standard??
We have just bought a new 2026 GC680 4m Dune, here in the Netherlands.
It has no factory Solar fitted and the 2 standard AGM batteries (leisure and starter).
I am currently fitting a lithium battery and inverter setup in the back cabinet. The inverter obviously will provide the 230V which is easily connected to the current 230v breaker box. My intention is to use the feed in the original 12v breaker switch fitted in the back cabinet to feed the 12v system in the camper from the new lithium setup. I will be charger the lithium with external mobile solar and a victron DCDC 50A charger connected to the starter battery or through the inverter charger when connected to wall power.
I don't intend to remove the original leisure battery or change any wiring to it, other than removing the connection in the back from the switch. With no detailed schematic drawings for the GC680 to go off, I have found that disconnecting the switch results in only some front led lights and the Aux cabine diesel heater (not the main diesel heater) still working of the original AGM leisure battery. Whilst all the rest (lights, sockets, waterpump, fridge, etc) all will work form the new Lithium leisure batteries in the back. So this setup should be fine as I assume the original AGM can easily maintain those lights and the AUX heater just from being charged whilst we drive.
Ultimately I would be charging the Lithium leisure batteries from the mobile solar, the DCDC charger when driving, or when plugged into the wall power as the inverter has a 125a charger.
The Starter battery would be charged during driving by the OEM setup (Alternator) and as a backup can be charged by the Victron DCDC charger in the reverse charge mode.
This leaves me with the AGM leisure battery, which I believe will then only be charged by the alternator when driving and unless I add solar or a dedicated second charger option from the Lithium setup, I don't see how I would be able to charge it in the existing setup.
What I am struggling to understand is the internal OEM battery charging setup.
When plugged into wall power I can see on the screen that both the AGM batteries get charged, I assume this is coming from the charger under the driver seat. However if I turn off the original 12v breaker switch in the back, this charge stops on both batteries. This surprised me as I don't understand why the starter battery would also stop charging. I would assume that the 230V wall power goes to the charger and this in turn would feed both batteries separately, but that doesn't look to be the case. So this would mean that the OEM underseat charger becomes obsolete in my new setup or am I missing something?
Can anyone explain or show how the OEM underseat charger is connected in the system? Ideally I would keep it in place and be able to use it to charge the AGM batteries.
Thanks!
Also the charger under the driver seat is a LifePo charger, not sure if this is standard??
