Engine battery State of Charge after driving with the not-so-smart alternator. (21 Viewers)

[LithiumConvert]

After driving for a couple of hours in our nice new Fiat based motorhome, the starter battery is in a state of discharge. This is by design as the regenerative braking does not work if the battery is charged.

The B2B has ensured that the leisure battery is fully charged, but the engine battery is well down, needing about 30Ah to bring it up to full charge.

So the question is:- Should I be charging it properly after every trip, if not going to used for a while and not on EHU.

Surely, lead acid batteries like to be fully charged? (even AGM starter batteries)

 

[Richard n Ann]

Sounds like you need a B2B for the engine battery. Definitely needs charging then maintaining.

 

[DBK]

If you had to put 30Ah in to fully charge it then this means it had probably "used" about 25Ah. Depending on the size of the battery this means it was at about 75% charged at the end of the journey. This is perhaps a bit low but I'm not sure this means it needs charging every time you stop.

However, my suggestion would be to fit a Battery Master and assuming you have solar this will keep the cab battery topped up.

 

[AdrianChen]

I always thought the idea of a smart alternator was to reduce the amount of energy used running the alternator at full chat by using "wasted" energy when the car is on the overrun to re-charge the battery. To allow this the ECU monitors the battery and only turns the alternator output up to a charging voltage when the battery is below around 60-70% or so. The voltage output thus idles at low levels, pretty sure my merc went down to 12.?v, so the alt uses little power from the engine, then when needed the ECU increases the voltage again on my merc I'm sure it went over 15v.

The B2B will boost this output back up to a useful charge and maintain the leisure battery, but the starter battery will remain as designed at a lower state of charge. I guess this level is chosen to be sufficient to maintain the battery from sulphation, and restart the engine when required. Personally I think it is a horrible system! AGM's do need to get a full charge regularly from my experience, and Lead Carbon seems to have replaced them in a lot of manufacturers vehicles. Our Mercs lasted 1 year, but I don't know how it was maintained during the build/shipping showroom time, so may have been left flat etc.

When we used that van, the CBE system linked the Hab and Cab batteries whenever there was a charge source so up to 6amps could flow into the start battery, and when in storage we had a BM type device to maintain the Cab battery. So for the majority of the time the battery was kept pretty full, and perhaps it was only on longer journeys it dropped to the "working charge level" when the BM thingy wouldn't keep up.

But in theory your battery is operating as designed by the manufacturer, so should be fine in regular use. Personally though I would use something to keep it topped up while there is Solar/EHU available, but then I'm no expert and it's OCD that drives that decision!

Our 2022 Iveco happily doesn't have a smart alternator.......

 

[andyman]

After driving for a couple of hours in our nice new Fiat based motorhome, the starter battery is in a state of discharge. This is by design as the regenerative braking does not work if the battery is charged.

The B2B has ensured that the leisure battery is fully charged, but the engine battery is well down, needing about 30Ah to bring it up to full charge.

So the question is:- Should I be charging it properly after every trip, if not going to used for a while and not on EHU.

Surely, lead acid batteries like to be fully charged? (even AGM starter batteries)

What voltage is the engine battery showing on the dash display.

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[funflair]

I always thought the idea of a smart alternator was to reduce the amount of energy used running the alternator at full chat by using "wasted" energy when the car is on the overrun to re-charge the battery. To allow this the ECU monitors the battery and only turns the alternator output up to a charging voltage when the battery is below around 60-70% or so. The voltage output thus idles at low levels, pretty sure my merc went down to 12.?v, so the alt uses little power from the engine, then when needed the ECU increases the voltage again on my merc I'm sure it went over 15v.

The B2B will boost this output back up to a useful charge and maintain the leisure battery, but the starter battery will remain as designed at a lower state of charge. I guess this level is chosen to be sufficient to maintain the battery from sulphation, and restart the engine when required. Personally I think it is a horrible system! AGM's do need to get a full charge regularly from my experience, and Lead Carbon seems to have replaced them in a lot of manufacturers vehicles. Our Mercs lasted 1 year, but I don't know how it was maintained during the build/shipping showroom time, so may have been left flat etc.

When we used that van, the CBE system linked the Hab and Cab batteries whenever there was a charge source so up to 6amps could flow into the start battery, and when in storage we had a BM type device to maintain the Cab battery. So for the majority of the time the battery was kept pretty full, and perhaps it was only on longer journeys it dropped to the "working charge level" when the BM thingy wouldn't keep up.

But in theory your battery is operating as designed by the manufacturer, so should be fine in regular use. Personally though I would use something to keep it topped up while there is Solar/EHU available, but then I'm no expert and it's OCD that drives that decision!

Our 2022 Iveco happily doesn't have a smart alternator.......

Thought a 2022 IVECO would be "smart" I am pretty sure ours is.

 

[Tigger-Tim]

In the summer months, when my solar panel keeps the starter battery well charged, the alternator runs at 12.2v unless I'm braking (when it goes to 14.9v)

In the winter months, the alternator runs at 14.9v until it thinks the starter battery is reasonably charged. For at least the first 2-3 hours of the journey.

Both seem to be normal behaviour for my van. It prefers to leave the starter battery at about 75% charged. Doesn't seem to cause any issues.

 

[Richard n Ann]

Great for the environment, 10 million AGM batteries in a skip somewhere

 

[AdrianChen]

Thought a 2022 IVECO would be "smart" I am pretty sure ours is.

Yes I was surprised! Especialy after spending half a day looking for a non existent B2B!