Using a generator

[MCBav42]

I use my 1kw Kipor to charge once in a while, I use it via a40amp smart charger and that is about the limit for 1kw. From low charge to full  ish takes an hour. Geoff

Hello all.
There's a 2015 post on this subject and Geoff mentioned it took an hour from low to full charge. I've bought a 2kw portable petrol generator and plugged it into the shore power socket but am getting nothing close to those speeds (it's been running for 2 hours and only lifted charge from 81.8% to 85.8%). Battery monitor varies but is currently showing input of 6.5A.  Am I doing something wrong?
I'd greatly appreciate any advice.

[SYJetzt]

To bring the batteries up is dependent on the state of your batteries (state of charge SOC), the maximum power of the battery charger and the chosen charging characteristic and at least the power rating of the genset.
Usually the battery charger reduces the charging energy if the battery voltage reaches higher voltage levels (and SOC), which seems to be the case on your boat. To rule out the effects of the genset try to charge the batteries from a shore power plug (with the same battery state ) and look for the resulting charging current, which should be pretty the same as using the genset.
To get full power over the charger you need a far lower SOC. Charging from 80 to 100% takes much more time than 50% to 80% due to the charging characteristic of your battery charger.
 
 

[diverphil]

when ours is on hard standing I use portable gen for power tools etc and have the other socket plugged into the boat shore power to charge up the batts, it would be on for 5 or 6hrs at a time, so how long it takes I couldn't answer, but as previously stated the last bit of charge takes quite a bit of time, I would think a lot more than 1 hr.  at work pair of truck battery's, which is the same as fitted to boats around 140ah each would be on charge overnight. so around 12hrs.

[MCBav42]

Thank you both for the very helpful advice.

I assume the battery charger (original Bavaria/SBC Quick) can't be adjusted to speed things up? 

[symphony2]

The speed is not dependent on the charger but the ability of the battery to accept the charge. As already explained while a deeply discharged battery will accept a high charge - but probably still not exceed your 40A mains charger - as it gets near to full as your batteries are (80%+) the acceptance rate declines and your 6.5 amps is quite normal for the last 15% or so. You cannot change this without changing to a different type of battery - AGMs have higher charge acceptance rates than normal lead acid, but will still be slow for the last bit. Lithium's big selling points are much higher charge acceptance rates and you can discharge to very low capacity without harm whereas lead acid does not like frequent discharges below 50% capacity.

However switching to lithium is expensive and for most peoples' patterns of usage difficult to justify. To get the best out of your current batteries you need to size the battery bank such that in normal use you don't go below 50% and have a means of charging that keeps the batteries close to 100% when not being used. The 2 main ways of doing this are to use the shorepower charger if you can after a sailing trip as 12-24 hours will bring even a well discharged battery up or fit solar panels which will charge whenever there is sun. You do of course need to have controls over the solar to prevent overcharging.