Charging leisure battery via engine running query

[sciac2001]

Can anyone give me a rough idea on how many amps my engine will charge into my leisure battery in an hour?
(The engine would only be idling when parked up.)
I have a 110A leisure and my engine is a Fiat 3.0 160hp diesel.
Thanks.

 

[maxi77]

I would think you woud be lucky to get more than 10 AH in. The trouble is alternator controllers are simple minded and as soon as the battery voltage rises they back the charge right off hence the fitting of BtoB chargers which fool the controllers

 

[tonyidle]

I would think you woud be lucky to get more than 10 AH in. The trouble is alternator controllers are simple minded and as soon as the battery voltage rises they back the charge right off hence the fitting of BtoB chargers which fool the controllers

Exactly what he says.

 

[f6c]

Ditto

 

[Lenny HB]

Depends on the size of the wiring to the split charge relay and battery in my Hymer I can get 20 amps in an hour if the battery is fairly flat as said once the battery starts to come up it drops to about 10 amps. If the wiring is not up to scratch could only be 5 amps.
You shouldn't leave diesel engines idling quickest way to wreck the CAT & DPF.

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[sciac2001]

Thanks for the info. I will only be boosting the battery charge rather than charging from zero so even 10amps will help.

 

[pappajohn]

Very inefficient and unreliable method of topping up or charging.
As an example, it can take several HUNDRED driven miles to top up a battery from 50% discharged via the split charge system.
B2B charger is the way to go and, depending how much you want to pay for the device (there are various outputs), can bang out 50 or more amps per hour.

 

[Deanobeano]

I tried mine, as I wanted to see what my new NASA monitor would report.

20 amp max that quickly dropped down to 10 ish

So, in conclusion, not the best way to top up your battery.

 

[Richard n Ann]

When I switch our fridge to 12v the leisure battery charge drops to about 2.5 amps. I blame the thin wiring letting the voltage drop.

 

[f6c]

BtoB is best

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[Boringfrog]

Hope I'm not hijacking the thread, but I have been looking at B2B today and there seem a lot of different choices. What would be the best for a 300AH battery bank and electrobloc ebl 99 fitted.

 

[Allanm]

Funny isn’t it, if the word “engine” had been changed to “generator” in the title of the post, the replies would have been totally different, but the noise the same.....

 

[Lenny HB]

When I switch our fridge to 12v the leisure battery charge drops to about 2.5 amps. I blame the thin wiring letting the voltage drop.

That is due to undersize wiring. Coming back last week 2 separate ¾ hr drive,s I put a total of 30a/h Back into my batteries and the fridge was taking around 14 amps.

 

[nicholsong]

Another vote for BtoB. As long as we are on the road for 1/2+ hour every 2-3 days that keeps our leisure batteries up.

Geoff

 

[sallylillian]

Sorry to raise the chestnut of smart alternator again, but if your engine is recent, 2-3 years then this may be enabled in the ECU which makes a complete hash of leisure battery charging.

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[Lenny HB]

Sorry to raise the chestnut of smart alternator again, but if your engine is recent, 2-3 years then this may be enabled in the ECU which makes a complete hash of leisure battery charging.

Mainly on Mercs I know Hymer fit a bit of Schaudt kit to overcome this, Fiat base vehicles for Motorhomes don't have a smart alternator providing the convertor specified it correctly.

 

[Bart]

Our sterling 60amp B2B charger puts around 40amps into the discharged batteries when we drive , but this drops to like 15-20 when they have not had much discharge.

 

[nicholsong]

Our sterling 60amp B2B charger puts around 40amps into the discharged batteries when we drive , but this drops to like 15-20 when they have not had much discharge.

As he says - this is how it is meant to work; giving the battery what it needs without cooking it. It is quite a smart system, as one would expect from Sterling.