Start battery

[Mrcoolabah1au]

What am I looking for on the Motorhome when the start battery has not got power to turn the motor over it only takes a day is so to go shit if I recharge the battery that ok but hell there’s a gremlin in the system some were

[jon_d]

Put your current clamp on the battery wire and measure the current.

Then start pulling fuses until it disappears. Then find the problem in that circuit.
It helps if the wiring is tidy. This makes it easier to follow.


A 1 amp draw will completely flatten a start battery in 2 - 3 days

[T1 Terry]

Is there an inverter wired to the start battery? Even if it isn't switched on, it will constantly draw some power to keep the circuits alive and capacitors charged so it will be ready to go when you flick the switch. The lithium battery can handle that load and the solar recharges it each day, but nothing is recharging the start battery. Gradually the capacity of the lead acid start battery will reduce, this happens much faster if it spends much time below 100% state of charge ... remember, just because it is charged to 14.4v doesn't mean it is at 100% state of charge, it will need to see that 14.4v for at least 5 hrs to get to the mid 98% SOC, then 13.8v for another 24hrs to 48hrs to reach 100% SOC. If that hasn't happened every time since they were new, they will have lost capacity, the longer they have suffered not getting back to 100% SOC, the greater the capacity loss. Start batteries don't have a lot of capacity when they are new, they are not designed to hold a lot of charge, they are designed to release that charge very quickly and get back to around 70% SOC very quickly.

T1 Terry

[Mrcoolabah1au]

Ok will try that this afternoon did buy a clamp 🗜 last year on Terry’s say thank you