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FREQUENTLY ASKED QUESTIONS
Q The LFP1225(LV)/LFP1240(LV) turns ON at 13.2V(12V) and OFF at 12.7V(11.9V), but you say it
operates down to 9V, explain?
A The LFP1225(LV)/LFP1240(LV) will turn OFF for a split second every 100 seconds to measure the
unloaded voltage at the battery. When the LFP1225(LV)/LFP1240(LV) turns off it is not drawing any
load from the start battery, no load means that there is no voltage drop over the cable run. This
allows the LFP1225(LV)/LFP1240(LV) to measure the actual battery voltage, or the voltage at the
battery. If this actual battery voltage is below 12.7V(11.9V), the LFP1225(LV)/LFP1240(LV) will turn
OFF. At any other time during the charging process, if the voltage at the LFP1225(LV)/LFP1240(LV)
drops below 9V the LFP1225(LV)/LFP1240(LV) will turn OFF.
Q How does the LFP1225(LV)/LFP1240(LV) charge an Auxiliary battery at 14V when it only gets 9V in?
A The LFP1225(LV)/LFP1240(LV) can act as both a reducer and a booster, so it can operate from a
voltage of above, equal to or below the desired output voltage. The unit is also microprocessor
controlled allowing it to output a REDARC proprietary charging algorithm independent of the input.
This allows the unit to charge specific to the battery type even if the input voltage is low due to
voltage drop.
Q Where should I mount the LFP1225(LV)/LFP1240(LV) Unit?
A The LFP1225(LV)/LFP1240(LV) should be mounted as close as possible to the battery being charged
(generally called the Auxiliary or House battery). If the Auxiliary battery is located under the bonnet,
pick a location for the LFP1225(LV)/LFP1240(LV) that is close to the battery and away from any
direct engine heat. If the LFP1225(LV)/LFP1240(LV) is to be mounted into a Caravan or Camper,
near or in the battery compartment is generally the best position. It is also a good idea to mount the
LFP1225(LV)/LFP1240(LV) to a metal surface if possible to ensure optimal heat dissipation, though
this is not crucial.
Q What does the charger do if the temperature around it rises above its operating temperature?
A As the temperature of the LFP1225(LV)/LFP1240(LV) rises above a certain level the current capacity
of the output is decreased gradually in order protect both the battery and the LFP1225(LV)/
LFP1240(LV) unit.
Q If I use the LFP1225(LV)/LFP1240(LV) to charge my auxiliary battery do I still need to install a
battery isolator?
A The LFP1225(LV)/LFP1240(LV) incorporates the functionality of a battery isolator, it will turn ON and
start charging when it senses that the vehicle has started and similarly it will turn OFF when the
vehicle is turned OFF.
Q I’ve heard that you shouldn’t charge 2 batteries of different chemistries from the same source,
will I have any problems charging my LiFePO4 auxiliary battery from my Lead Acid start battery?
A The LFP1225(LV)/LFP1240(LV) does not ‘link’ the batteries together like a battery isolator does, it is a
DC-DC battery charger. The output from the unit is tailored specifically to the selected output battery
type, and therefore allows the optimal charging of the auxiliary battery, no matter what chemistry
your start battery is.
