My starter battery was getting rather low - down to about 30% or so. At this level, I’d expect the alternator to be practically constantly on and charging it back up relatively quickly. However, after about a half hour drive, during which the alternator certainly wasn’t constantly on (judging by voltage), it’s only put in 10% or so. Does this seem right? I’ve also got a factory fit leisure battery, which generally lives at close to 100% from a solar panel - any chance this could be confusing the starter battery charging logic.
Alternator/battery Issue
- Thread starter t0mb0
- Start date
How Was you getting your voltage readings to make your assumptions.?
And no.... your solar charger/charge to your leisure battery shouldn't affect your starter battery "State of charge"
What's the Spec of your starter and Aux batteries? Both AGM?
Also how long was your drive after? I'd expect you would need a drive of 2hours or so to replenish a 90% loss of charge on your starter battery.
And no.... your solar charger/charge to your leisure battery shouldn't affect your starter battery "State of charge"
What's the Spec of your starter and Aux batteries? Both AGM?
Also how long was your drive after? I'd expect you would need a drive of 2hours or so to replenish a 90% loss of charge on your starter battery.
Battery charge level is from ctek bluetooth gizmo. Instantaneous voltage from plug in voltage gizmo. Both measurement methods have been completely reliable in the past.
Both batteries are factory 75ah AGM.
Given the drive was only half an hour, maybe it’s ok. I’ll keep monitoring. Given the state of charge though, I was expecting the voltage to be constantly high from the alternator and it certainly wasn’t. Regenerative braking was definitely working though, spikes up to 14.8v on braking.
Both batteries are factory 75ah AGM.
Given the drive was only half an hour, maybe it’s ok. I’ll keep monitoring. Given the state of charge though, I was expecting the voltage to be constantly high from the alternator and it certainly wasn’t. Regenerative braking was definitely working though, spikes up to 14.8v on braking.
All sounds good.
The ECU determines the alternator output depending on the starter battery SOC. So providing all is well the ECU will top up the starter as it sees fit with regen braking Etc. Unless the load is high in which case you will see a 13.8v/14.2v constant charge.
But even so a 75ah AGM battery will still take a few hours to charge back up of its flat.....
A 30 min drive would not be enough.
Just keep an eye on things for now and see how it replenishes it's self.
The ECU determines the alternator output depending on the starter battery SOC. So providing all is well the ECU will top up the starter as it sees fit with regen braking Etc. Unless the load is high in which case you will see a 13.8v/14.2v constant charge.
But even so a 75ah AGM battery will still take a few hours to charge back up of its flat.....
A 30 min drive would not be enough.
Just keep an eye on things for now and see how it replenishes it's self.
Are you sure that it's 30% soc and not 30% discharged? I wouldn't expect the van to start from a battery at only 30% soc. As Dell says, a 30 minute drive will do very little to alter things much. What is the resting voltage of the battery?
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