Frequently Asked Questions


Important safety and liability issues please read this first.


Battery chargers are safe and effective if used correctly and in accordance with the supplied instructions. However, repairs and adjustments should only be carried out by suitably trained technicians or engineers. If you are in any doubt, or if you are not suitably trained, you should not operate the unit with any covers or screws removed, or make any internal adjustments or modifications, or operate the unit in any way other than as set out in the instructions supplied with it. The safety aspects to consider when working on battery chargers include, but are not limited to, danger of electric shock from the AC input and primary circuits, danger of burns or fire from short circuits or poorly made connections in the high current DC output battery circuits, and danger of explosions due to spark ignition of hydrogen gas produced by the battery when charging.

Main FAQ

Should I switch off the charger when the green ready light comes on?

No, we recommend that you leave the charger plugged in and switched on with the battery connected. When the green battery light comes on, the charger is “trickle charging” the battery. This is the same method used in alarm panels and other applications which require constant charge. Trickle charging helps to reduce charge imbalance and extend battery life. The energy consumed is minimal, typically using only 10 Watts per 100 hours.

Your competitor sells a 12 volt, 10 Amp battery charger for a lower price. Why should I pay more?

The Interacter actually saves you money in the long-term. With precise voltage regulation, proportional timing, an overrun timer, low start voltage, and low parasitic loading, the Interacter keeps your batteries performing better, longer.

What’s the difference between a DC power supply and battery charger?

A battery charger is a type of DC power supply designed specifically for charging batteries. A typical DC power supply is not designed to reduce parasitic load, and doesn’t provide multiple stages of charging, reverse battery connection protection, or temperature compensation for the charge voltage. The Interacter Battery Charger does.

Do you sell any chargers that switch to standby mode when the current is low?

No, but we use an alternate, and more efficient, technique called proportional timing. This helps to reduce overcharging and extend battery life.

I can’t get any output from my charger when I measure it using a DC voltmeter. Should I send it back for repair?

Probably not. Our chargers feature short circuit and reverse polarity shutdown. They don’t produce any output voltage unless connected to a battery. By switching the AC supply to charger off and on, the LED indicators should show the power on the test sequence (Green-Yellow-Red). If there is no LED test indication, make sure that the charger is properly connected and try replacing the battery.

What is “Mains Zero Crossing Voltage Monitoring”, and why would I want it?

In SCR controlled chargers, the DC sends output to the battery as a pulse of current each half-cycle of AC supply. During the time when the AC is crossing zero, in between pulses of output, there is no current flowing from the charger to the battery. During this time, we use a sample-and-hold circuit to measure the battery voltage without errors that could be caused by drop on DC cables. This improves performance and eliminates the need for separate voltage sensing leads.

What is the override timer, and what is it’s purpose?

The override timer is a software timer which starts at the beginning of each charge and runs until the green ready light turns on. There is a fixed maximum time allowed for each charge, typically 18 hours. Should the time exceed that amount, the charger enters “fault mode”, indicated by a flashing green ready light. The purpose of this is to prevent overcharging due to fault conditions such as a shorted battery cell. Fault mode can be cleared either by switching the AC power supply on and off, or disconnecting the battery.

What is parasitic loading, and why is it important?

Parasitic loading is when DC current flows into the charger from the battery when there is no AC power supply to the charger. Over time, this can reduce AC power output and the battery’s ability to recharge. In our chargers, the parasitic load amount is 0.3 mA, low enough to be insignificant in most applications.

Why isn’t my battery getting fully charged?

This could be due to any number of things, as the battery, load, and charger must all work together as a system. Check the expected runtime of the load against the size/capacity of the battery. Then check the voltage settings on the charger and make sure they are correct. If the voltage settings are ok, leave the battery charging until it is fully charged. Also check the cables from the charger to the battery and make sure they are connected properly and aren’t damaged.

My battery is getting overcharged / It’s not switching to standby mode soon enough / Why doesn’t the green LED stay on?

If the battery has a faulty cell, it’s charge voltage will not reach the charger set point to reach constant voltage mode. This results in the remaining cells being overcharged until the overrun timer terminates the charge after 18 hours. The best solution is to measure the battery voltage when its in constant power stage and confirm it is correct for the battery type. To enter constant voltage mode, switch the charger on and off to reset it and wait for the charge light to flash, then use a digital volt meter. If the battery is supporting a higher load than the rate of charging, contact the factory for modification.

Can I run a DC load from the battery while it is charging?

Yes, but the load will be subjected to the on-charge voltage of the battery which is higher than the battery’s normal load voltage. Make sure your DC load is specified to be capable of handling the higher voltage with some allowance for voltage overshoot and charger adjustment tolerance. If you think it may be a problem, consider lowering the charger cyclic voltage adjustment setting or using a voltage regulator/reducer between the battery and load. This will lengthen recharge time but reduce the load. If using an SCR type charger, keep the charger cables and load cables separate or run them directly into the terminal separate from other wiring.

How should I connect one battery charger to charge multiple batteries?

Normally, this should be avoided as much as possible. It is more effective to use multiple smaller chargers to charge the batteries individually. If the batteries each support different loads, it is impossible to achieve optimal charge while charging them as a group. Also, our batteries are connected directly to the battery and will not operate correctly with a diode splitter. However, we do offer 5 bank chargers with individual charging circuits.

How do I check and adjust the voltage settings of my battery charger?

To check the voltage settings, connect the charger to a fully charged battery, in good condition, with the correct number of cells. Connect a calibrated, accurate, digital volt meter or multi-meter to the battery terminals. Switch the charger on and observe the green-yellow-red LED indication. A Yellow LED light will then come on indicating that the battery is charging. After a few seconds, the charger should reach the voltage limit and enter the constant voltage stage (indicated with a flashing yellow light, or the 80% charged LED light coming on). When the battery is in constant voltage mode, observe the volt meter reading. The default setting should be 14.5 V, and if this is off it can be adjusted using the preset pot marked V-LIM1. Next, locate the test point link on the PCB and temporarily bridge the test point pins with a small flat-blade screwdriver. The green ready LED should turn on, and after a few seconds, check the reading. The default setting should be 13.8 V, and if this is off it can be adjusted using the preset pot market L-LIM 2 or STVY.

How do I check and adjust the Current Limit setting of my battery charger?

The current limit is set when the charger is made and doesn’t normally need to be adjusted. However, it can be adjusted using the preset pot marked I-LIM. Connect the charger to a recently discharged battery, or one that draws more current than the charger’s current rating. Then connect an amp meter to the charger output, switch the charger on, observe the current reading. The charger must be in current limit when adjusting the I-LIM or the adjustment will have no effect.

What is the battery type DIP switch for, and how should it be set?

On chargers that are fitted with a Battery Type DIP switch inside on the PC Board, the charger can be quickly configured for use with either gel cell, sealed lead acid, or liquid electrolyte battery types. The difference is the cyclic voltage limit setting (This is the first voltage limit, where the charger changes to constant voltage mode, which happens when the battery reaches about 80% level of charge). The DIP switch setting also has a small effect on the float/standby voltage. If in doubt, we suggest use of the default normal setting, as that will give satisfactory performance with most battery types, with a voltage limit of 14.5V (per 6 cells). The sealed lead acid or normal setting is appropriate for absorbed electrolyte or AGM batteries. The two switch levers are marked on the PCB next to the switch, as N for normal and G for gel. The default (factory) setting, unless otherwise specified, is the \\\”Normal\\\” or \\\”SLA\\\” (Sealed Lead Acid) setting, referred to as normal. To set this mode, the switch marked N should be on, and the switch marked G should be off. The gel cell setting lowers the cyclic limit voltage to 14.1V (per 6 cells) and to select this, the switch marked G is on, and the switch marked N is off. The Liquid electrolyte battery setting increases the cyclic voltage limit to 15.6V (per 6 cells) and to select this both switches should be off.

How long will my battery support my load, and how can I calculate the expected runtime?

To calculate how long the battery will run the load, just measure or calculate the current that the load will draw when running, and divide the battery Amp-Hour (Ah) capacity rating by the load current, to give runtime in hours. This will be the runtime to 100% depth of discharge (DOD) and should be de-rated by 20% to avoid over discharge. In a cyclic application, (meaning an application where the battery is charged and discharged on a regular basis) the battery depth of discharge should be limited to no more than about 80% of maximum, in order to get a cost effective battery cycle life. Typically, equipment batteries (like SLA or Gel batteries) are specified in Ah over a 20 Hour discharge. Large cyclic or traction batteries are often specified in Ah over a 5 Hour discharge.

How long will it take for a current rating charger to fully recharge?

The recharge time in hours equals the battery capacity in Ah, multiplied in the depth of discharge in %, multiplied by 0.8, multiplied by 1.5, divided by 100 times the charger current rating in Amps, plus one hour. For example, a 55Ah battery, discharged to 80%, on a 6-Amp charger, which would take about 9.8 hours. The battery should reach 80% recharge relatively quickly, while the last 20% is done in constant voltage mode, and will require more time. Our chargers indicate when a battery has reached 80% charge, with either an LED marked 80% charge or a flashing charge light. At the end of the charge cycle, a green ready LED will show that the battery is ready for use.

What’s the difference between a sealed lead acid battery, a gel cell battery, an absorbed electrolyte battery, and a valve regulated battery?

Sealed Lead Acid is a generic term for all lead acid batteries which have fixed tops. The electrolyte is supplied with the battery when it’s manufactured, and it\’s not intended that the battery ever be opened or topped up in the field. All lead acid batteries must have vents to allow any excess gas pressure to escape from the battery casing. Lead acid batteries should, in general, never be charged in a completely sealed cabinet or enclosure, for this reason. Valve regulated batteries release little to no gas during charge and discharge, as they are designed to operate with a small positive gas pressure inside the battery casing. Gel cell batteries have the acid electrolyte in the form of a gel. If the battery plastic casing is damaged in transit or in an accident, the electrolyte is not in liquid form and can’t run out the battery or cause further damage. However, gel batteries are more easily damaged by overcharging, because gas bubbles form in the gel and may push the electrolyte away from the plate surface, permanently reducing the capacity. Absorbed electrolyte type have the acid in liquid form, trapped in a glass fibre mat between the plates. There’s not much difference in discharge performance between batteries, but there is often a difference in recharge voltage limit. It is advisable to check the battery manufacturer’s spec for recommended constant voltage charging range before charging.