by Bob
(Santa Fe New Mexico USA)
Look at how a golf cart battery are use in a golf cart.
Run down by day and recharged at night, a hard life.
In most off grid systems they have low power draw and slow recharge.
Not like the jump on it we have to find that ball.
Now my system is 12 6 volt batteries tied in series/parallel to make 6 banks at 12 volts at about 1200 amp hours with a 300 watt solar charging system,300 wind generator with a 2000 watt modified sign wave inverter.
Now the first set of 12 batteries were installed in 1996 and we got over 12 years on that set.That took us to 2008 and it is look like we are almost half way though the life cycle of or second set.
Now the secret to longevity is good water and keeping a close eye on making sure the
batteries are equalized on a regular basis when needed. Keeping all the cells preforming
at peak levels.
Now how do you determine if the batteries need to be equalized.
Now if you have a big big solar system the charge controller will do it for you.
The charge controller can also over do it for you and cook your batteries if you do not have all the fancy temp probes and stuff.
Example
The entire bank reads 12.5 volts looks good. Not so it is not charged up to the full 1200 amp hour rating.
Now if you read the voltage on each individual 6 volt battery in the series connection
you will find for example one will read 6.6 volts and the other will read 5.9 volts
give the series voltage of 12.5 volts.
The individual cells in the battery bank are not equalized causing the battery at 6.6 volts to over perform shortening his life cycle and the battery at 5.9 volts is under preforming.
Any battery in a series bank that is under preforming effects the entire parallel system ability to charge to it full potential.
Now how can you equalize a 1200 amp hour system. We have found that about 3 to 4 time a year we have to connect our 18 hp Hobart DC welder to the system.
Now many of you may say that’s crazy and your probably right. But, it works for me.
Well lets do the math 50 to 220 amps max output 6 banks that is 36 amps per bank max.
This is only true if all the connection on all the batteries in bank have been maintained and are in good working order.
You also have to consider what the golf cart battery charge is going to do to the
6 or so batteries every night charge, equalize and float.
Amperage is not the problem voltage is what your trying to achieve without over heating
the batteries. My batteries are in the ground and I have the ability to cool them with water if I have to.
Now I start at 220 amps and keep an eye on the voltage it will generally jump to
13+ volts when I start. It will slowly start to increase over the next hour or so.
The goal here is to get the voltage to achieve 14.7 volts max for one hour.
If my batteries start to warm up I shut every thing down and start up again when
the situation has returned to a more normal temperature. In the winter I have not had
any temperature issues with air cooling.
As the voltage increases you will find the amperage has to be turned down on the DC welder. This means shutting the welder off and turning the current select switch to the next lower setting start it up again.
I am luck that my Hobart has a fine tuner on the exciter field giving me good voltage control.
This entire process usually take me up to four hour at about a gallon of gas per hour.
Now a safer way to do this is you can buy a high power 220 amp commercial battery charger
with a charge, float and equalizer setting and a 10,000 watt generator to power it.
So in conclusion is.
Equalization help with the longevity of your battery bank.
CAUTION You will be make a hydrogen gas
Be in a well ventilated place.
Do not breath the fumes,
Do not smoke
Do not make sparks/open flame
Do not have your welder to close.
Remember the Hindenburg