House battery - Where are you pulling power for DC-DC charger

[Levi]

What’s problematic with factor dual battery? I’ve had this for 2.5 years and it’s been flawless. What’s the issue?

Hey mate, sorry for slow reply. I have been plagued with issues. We could not resolve, so now i have a fully independent system and just leave the 2 batteries for crank only, i do not use any auxiliary ports now.

Short summary-

• Secondary (factory-fitted) battery consistently healthy, holding ~13.3V and recharging normally.
• Primary battery began showing reduced SOC over time, no longer holding above ~80%, now capped at ~70% or below.
• Charge rate remains low (1–4A) even at low SOC, indicating the vehicle's charging system isn't recognising the deficit.
• Battery voltage drops immediately after external charging — surface charge only, not holding a true full charge.
• External smart charger (direct connection, 24hr+ cycles) provides the only meaningful improvement, temporarily lifting voltage to ~12.9V.
• After any normal use, battery returns to sub-70% SOC and will not recover through driving alone.
• Dealer swapped battery positions with temporary improvement — issue returned within weeks.
• Issue has been raised with dealer on multiple occasions but we cannot resolve.
• Functional impact is significant — reduced auxiliary power availability and roughly 50% reduction in useful off-road/away hours.

 

[TheDocAUS]

Hey mate, sorry for slow reply. I have been plagued with issues. We could not resolve, so now i have a fully independent system and just leave the 2 batteries for crank only, i do not use any auxiliary ports now.

Short summary-

• Secondary (factory-fitted) battery consistently healthy, holding ~13.3V and recharging normally.
• Primary battery began showing reduced SOC over time, no longer holding above ~80%, now capped at ~70% or below.
• Charge rate remains low (1–4A) even at low SOC, indicating the vehicle's charging system isn't recognising the deficit.
• Battery voltage drops immediately after external charging — surface charge only, not holding a true full charge.
• External smart charger (direct connection, 24hr+ cycles) provides the only meaningful improvement, temporarily lifting voltage to ~12.9V.
• After any normal use, battery returns to sub-70% SOC and will not recover through driving alone.
• Dealer swapped battery positions with temporary improvement — issue returned within weeks.
• Issue has been raised with dealer on multiple occasions but we cannot resolve.
• Functional impact is significant — reduced auxiliary power availability and roughly 50% reduction in useful off-road/away hours.

Did they check for a loose earth wire?

 

[Levi]

Did they check for a loose earth wire?

Not specifically noted on any of the numerous workshop sessions... hard to say what was and what not checked.

In the end, I gave up the battle, and installed a full stand alone system (except link to alternator) and run everything off this.

Car still behaves the same now, effectively i have 1.5 batteries, not 2 based on capacity.

Sometimes, if you want a job done right... you just do it yourself.