Are they really worth it?

[hilldweller]

But there's 345Ah of battery to absorb it! The batteries are now 7 yrs old and still have full capacity. It hasn't done them any harm, but 6 monthly topping up is required.

Can't argue with that. But can ad caution to Mr Ordinary with an ordinary leisure battery, 100A charge is not a good idea.

I can't remember are yours traction batteries ?

 

[yellabellyex]

Having just had our EGR valve replaced on an 08 Ducato, after 60K miles, ( it was well and truly caked up), and having read that excessive "idling" like trying to recharge the leisure batteries can help clog it up, I won't be using that method anymore. I might even look for a solar panel, even though we use hookup mostly. And I'll give it some wellie a bit more often,
regards
alan b

 

[tonyidle]

90 Ah of charge per hours run of the engine at tick over.....
But only with the right kit!

A standard split charge wouldn't put much more than 10-25 Ah back in that time.

It wouldn't put anything like that back in - more likely well under 10Ah. As you say - much more with the right kit.

 

[jonandshell]

Can't argue with that. But can ad caution to Mr Ordinary with an ordinary leisure battery, 100A charge is not a good idea.

I can't remember are yours traction batteries ?

Yep, traction monoblocs!

 

[mjltigger]

It wouldn't put anything like that back in - more likely well under 10Ah. As you say - much more with the right kit.

Why? My alternator is 100 amps. Surely in an hour it will give out 100ah. ok some of that will be used for lights and the stereo, ecu etc but I can't imagine they are pulling much over 20 amps leaving 80ah per hour to give to the battery.

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[Deleted member 29692]

Why? My alternator is 100 amps. Surely in an hour it will give out 100ah. ok some of that will be used for lights and the stereo, ecu etc but I can't imagine they are pulling much over 20 amps leaving 80ah per hour to give to the battery.

Because unless you have a b2b charger your leisure battery isn't connected to the alternator in a way that allows it to get the full whack. I'm sure someone will be along with a fully technical explanation soon but that's the gist of it.

 

[jonandshell]

Volt drop is the culprit. Unless your leisure battery is connected by thick, and I mean really thick, cable, the resultant voltage drop to the leisure battery causes significant current drop.
Our A2B charger amplifies the charging voltage from 14.4 to 14.8 volts, this .4 rise in voltage causes a massive rise in resultant current. When full charge is reached, the A2B charger drops the applied voltage to 13.6v to float the battery and not overcharge it, boiling off the electrolyte and damaging the battery.
On many split charge circuits, the cabling is so thin that sometimes only 13 volts is seen at the leisure battery. The current which results is tiny due to this drop and the battery charges very slowly and never completely.

 

[Reallyretired]

Why? My alternator is 100 amps. Surely in an hour it will give out 100ah. ok some of that will be used for lights and the stereo, ecu etc but I can't imagine they are pulling much over 20 amps leaving 80ah per hour to give to the battery.

Without a b2b charger the alternator output will drop to a very low level after a few minutes once the vehicle battery is charged. You might get 10 amps at best.
Remember a solar panel works all the time, not just for an hour. On a sunny day a single panel can produce up to 50ah. You would have to run your engine for 5 hours to get this.
We have four panels with inverter, and are completely independent of ehu, even using hairdryer, kettle, microwave, toaster etc.