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Voltage Of Your Battery
What voltage is your battery at when you start using your BIG BERTHA oven? Traditional 12v batteries at
full charge sit around the 12.6v mark indicating they are healthy and ‘full’. If it is less than 12.6 volts an hour
after charging you may need to get it checked. When under load the energy drains out of them, and their
voltage slowly drops until when they are really flat, they are sitting around the 10.5-11 volts – or lower! If you
are starting from a lower voltage point, then this will significantly affect the ability of the oven to get to its
top temperature as the battery is struggling to pump out enough energy to allow it to heat up.
A good analogy is if a dam is 100% full then when you lower the flood gates then the maximum amount
of water is flowing out when the gates are at a certain level. If the dam is only 80% full then when the
gates are at the same point less water will flow out even
though the gate is in the same place.
If your oven is not reaching full temperature use a multi meter or similar device to check the voltage be-
fore you start your cook, and then throughout the cook. If it is getting below 12-volts at any point during
the cook then then it will not be able to heat at its optimum and you will need to consider the batteries
health, size or charging options.
Ongoing charge of battery
Many people use the BIG BERTHA oven when they are driving, others use it while their engine is not
running, using solar panels. Others rely on the energy stored in a battery bank or something similar.
Whilst your battery is connected to a (traditional) running vehicle or appropriate solar panel in opti-
mum conditions it is being continuously recharged and will sit around 13.7-14.7 volts, while a battery
bank is not. When a battery is being recharged it is (usually) able to pass on the highest amount of ener-
gy to appliances like the BIG BERTHA so it can operate at its full potential. If the battery is not receiving
charge then its ability to continuously operate at its full potential decreases over time, especially if more
than one appliance is being used, like a fridge or lights, at the same time.
Size/type of battery
The ‘size’ or Amp hour and battery type or chemistry also influence the ability of the battery to store
energy and release it over an extended period. If you are going to use BOTH elements of the BIG BER-
THA, we suggest a minimum of two fully charged 120 Ah deep cell battery to ensure a consistent 2+
hour cook. If you use only ONE of the elements, then a single battery will be sufficient for 2+ hour cook
Age of battery
Like most things in life, the older something gets the harder it finds it to perform at its optimum. An
AGM glass battery will last anywhere from four to seven years, while a deep cycle gel cell battery can
last from two to five years.
Connection quality
The quality of connections is a much under rated element in the transfer of energy in a 12v system. The
optimum connection for a BIG BERTHA Oven is through the supplied Anderson Plug connection, how-
ever it can be removed and hard wired using appropriate connections without voiding the warranty.
Running multiple appliances
When you are running multiple appliances you again need to consider the cabling that you are using.
Using an analogy, if you have a 10cm pipe that can supply your pump 100l per minute you cannot then
go and add another pump that also requires 100l per minute. To do this you will need to increase the
size of the pipe or you will have 2 pumps only getting 50l per minute. So, if you want to run your phone,
a fridge, UHF, maybe a dashcam or GPS and then try and add the BIG BERTHA to it you will need to
increase the size of the wiring, or the pipe, from the battery.
