Posted by RamRod Sword of Baal on June 21, 2010, 9:12 am
I find the flicker in incandescent lamps is caused by low frequency in my
I have a 28 Kw Diesel generator and when I load it quite a lot the frequency
(Hz) drops a bit, as the diesel engine governor lets the motor slow down a
bit on heavy current draw.
Now it is not all that much, here in Australia we have 50 cycle power and as
my 4 pole genny has to maintain 1500 RPM to hold that.
I have set up the speed slightly to try and keep it up, so lightly loaded it
runs at around 53 cycles per second, but under heavy load it may drop down
to 48 cycles, and although that is not much, I note there is a slight
flickering in the incandescent lamps when it is heavily loaded.
It does not worry me as the generator is simply an emergency standby unit.
There is no problem with the voltage and it remains quite steady, within a
couple of volts of the requires 415/240 volts.
If you have flicker in your lights while running on your genny, if you can
get hold of a frequency meter, it might pay to check and see if it is
holding at the requires frequency while loaded.
Maybe the inverter is not putting out the correct frequency. If you are in
the USA the frequency (cycles) should be 60 Hz.
Sorry, I have no idea what the effect of 'square sine wave' has on the
incandescent lamps, that is if your generator is supplying' square sine
I have been told some electric motors do not like square wave power supply,
especially refrigeration motors.
I do have a 2.5 Kw inverter (24/240 volt) and have had no problems running
the fridge and a small window air conditioning unit from it, but it is a
'true sine wave' inverter. My only problem is that I do not have enough
battery power with 4 x T 105 batteries (4 x 6V 225 Ah) , but that is
I have never checked the output frequency of the inverter, but I do not have
lights on the circuitry.
If I ever get around to installing that small transfer switch which I have
for the inverter, I will find out, I guess.
Posted by Jim Wilkins on June 21, 2010, 12:58 pm
How to you measure the Amp-Hour capacity of the batteries to know when
to replace them?
I know the laboratory methods but not a simple one I could suggest for
Posted by vaughn on June 21, 2010, 1:16 pm
I use a plain old automotive load tester (Around $0.00 from HF). Yes, it does
nothing to test the actual amp-hour capacity of the battery. What it is
actually doing is testing the internal resistance of the battery, which seems to
give me a usable reading on the battery's overall condition, especially if you
bothered to write down last year's reading. If gives me far more information
than a simple voltage reading!
Posted by Jim Wilkins on June 21, 2010, 3:23 pm
I think the capacity it shows is proportional to the remaining active
plate material, less means higher resistance, lower loaded voltage.
They do give a good quick check when buying used batteries swapped out
on a maintenance schedule but I've found that I could nurse one they
indicate as bad along for several years with equalizing charges, and
moving it to a lower draw inverter. When I trade one in it's DEAD.
As you say though the voltage means little, the quantity of charge
needed to reach that voltage is much more important.
When I repaired power wheelchairs I used a resistive load tester like
that to check the batteries. In that instance the tester approximated
the current demand from the traction motors. Swapping a questionable
battery was better than having the owner get stuck.
OTOH for [other] batteries the computer-controlled test stand
discharged and recharged the pack and recorded the current vs voltage
characteristic. This is necessary to reset the Fuel Gauge. It measured
the internal resistance by the slope between discharge pulses at low
and high current to cancel out other effects. An accurate measurement
required a programmable electronic load and a digital storage
If you have only the scope you could use a small steady load and a
larger one on a switch and record the step height, but you still
should have a current probe and not depend on E=IR; you probably can't
measure very low R well enough.
That's where I saw that the internal resistance a load tester actually
measures isn't always a good indication of remaining capacity.
Posted by RamRod Sword of Baal on June 21, 2010, 4:38 pm
No idea, sorry, I have this set up as a standby system, and it is hardly
ever used, I put it in before I installed my diesel generator.
The batteries have only been used a few times and I just keep them charged
up and occasionally use the system to run the computers in the house.