[T2] Run engine on idle to charge batteries

[John Anderson]

I think Sami is likely correct from my gut feeling, I know dad (an EE) always said you need to just bump off idle to get an alternator where it needs to be (though not so far like with a generator), I'd definitely say that cooling efficiency of the engine will be a bit better stationary at 1200-1400 rpm or so, but fuel efficiency will decrease a bit.  And running a 1600-2000cc engine to just power the alternator to charge batteries seems pretty fuelish.
 
Like everyone (and I know Daniel doesn't want to hear it) I'd go with solar, or I'd find one of the original old Honda generators from the 70s-80s as they are much, much smaller than the inverters, and will run indefinitely on miniscule amounts of fuel, with the same "can run em beside a tent while camping and not know they are on" sound output.  I know dad has one of the medium sized ones that has rectified direct 12V DC output built in (probably around a 750 watt generator) and it is 1/3 the physical size of one of the 1-2kW inverters, tucks under the back seat easily taking up hardly any room.  They do have issues with their permanent magnets failing over time, so one is always smart to load test one with a 500W worklight, or a heater or the like when purchasing.
 
My random thoughts anyway, you could do it without harm, but I wouldn't.
 
John
 

________________________________
 From: Sami Dakhlia <sami.dakhlia at gmail.com>
To: Daniel Martinelli <daniel.martinelli at gmx.ch> 
Cc: Type2 list <type2 at type2.com> 
Sent: Wednesday, October 2, 2013 3:33 AM
Subject: Re: [T2] Run engine on idle to charge batteries
  

I'm actually wondering if it would not make sense to run at sustained
rpm, maybe 1500 or 2000 rpm, charging perhaps being both faster and
more energy efficient?

On 2 oct. 2013, at 13:19, Daniel Martinelli <daniel.martinelli at gmx.ch> wrote:

Dear Martin

Thanks for your suggestions. I actually do have a small PV charger to keep
my starter battery nicely filled, if the bus is not used for a while, which
really works well.
Sure I could install solar panels on my poptop or get a generator. Having
already three batteries :) I think I am well equipped in that department.

But, I would really like to know if running the engine on idle for a couple
of hours would do any damage to it.

Cheers

Daniel