Use with Ham Gear
115 AC Input Currents
Charging Time Considerations
Batteries in Series
Loss of Input AC considerations
Will your charger work with an Absorbed Glass Mat (AGM) battery?
Can I connect a VOLTMETER across the output of the charger?
Can I connect an AMMETER in series with the output of the charger?
Can I connect a solar panel to the charger?
Use with Ham Gear
With the AC OFF. Connect the charger to your battery which may also be connected to your RIG. Initially with NO LOAD, let the charger cycle through the three states and reach the MAINTENANCE mode. You may leave the charger ON and connected indefinitely. It will not overcharge (or trickle charge) your battery. If you apply a load in excess of Imax, the charger will simply contribute Imax to the load. If the load is removed, the current will then flow into the battery. If the load draws the battery down sufficiently, the three mode charging sequence will repeat again. (Imax depends on the charger model )
EXAMPLE: 5 A Smart Charger connected to battery with typical HF transceiver drawing 1A in RX and 20A in TX. When you turn on the transceiver, the RX 1A will come from the charger. When you key the RIG drawing 20A, 5A will come from the charger (which will self limit) and 15A will come from the battery. When you un-key, if the battery has been drawn down enough, 4A will immediately flow into the battery initiating recharge while 1A will power the RX function.
Typically you do not want to discharge any battery past 1/2 of it's total AH rating. Drawing a battery down past this value will shorten it's useful life. Although we refer to a standard car/deep cycle battery as a 12 volt battery, the open circuit, at rest voltage will read about 12.60 - 12.85 volts when fully charged. The battery is considered discharged when the voltage is pulled down to 11.80 - 12.00 volts.
For long life, limit the maximum charging current to less than 20% of the AH rating. You may charge at a higher rate but then battery life is shortened. You may charge at a lower rate in which case you can expect to achieve full useful battery life.
Typically, when you charge a battery, you have to put back about 140% of what was taken out. When you use a battery, the chemical to electrical conversion is not 100% efficient. Likewise when you charge a battery, the electrical to chemical conversion is not 100% efficient. Example: for a 100 AH battery, discharged down to 50%, plan on putting back about 50 AH x 140% = 70AH. About 3 days to recharge at 1 Amp rate. Note that as any battery becomes charged, the current tapers and recharge time could extend past the 140% rule-of-thumb stated above.
You should parallel batteries only to create a battery bank with a higher capacity. We do not recommend paralleling batteries only for charging purposes. The weaker batteries can hog all of the charging current.
When you parallel batteries, do so with batteries that are the same voltage, same AH rating and with the same past history. We recommend using new (identical) batteries. Don't connect new batteries in parallel with old batteries. Don't connect 7 AH batteries in parallel with 100 AH batteries. You should charge each battery separately, let them rest at least 12 hours, and then connect in parallel to create a battery bank. No two batteries are the same. Once connected, the weaker batteries will draw down the stronger batteries and eventually all the batteries in the bank will equalize. Until then, the weaker batteries will hog all the charging current.
Batteries in Series
You should series connect batteries only to create a battery bank with higher voltage. We do not recommend connecting batteries in series only for charging purposes. The current flowing through all series connected batteries is the same, a weaker battery may force a larger than desired voltage across the better battery.
When you series batteries, do so with batteries that are the same voltage, same AH rating and with the same past history. We recommend using new (identical) batteries.
Don't connect new batteries in series with old batteries. Don't connect 7 AH batteries in series with 100 AH batteries. You should charge each battery separately, then let them rest at least 12 hours, and then connect in series to create a higher voltage battery bank.
Quite often two 6V golf cart batteries are connected in series to provide a 12 V battery bank.
Although not usually stated, it should be understood that the AH rating of most batteries is what you can expect to draw from that battery over a 20 hour period, pulling the terminal voltage down to 10.50 volts. This is well below the 12.00 volt lower limit we recommend.
As an example, if you have a 20 AH battery, the manufacturer guarantees that you can draw 1 ampere for 20 hours (1A x 20H = 20AH) before the battery is considered discharged. For a 50 AH battery, you can withdraw 2.5 ampere for 20 hours (2.5A x 20H = 50AH) before the battery is considered discharged. In normal use, we usually load a battery higher than it's 20 hour rated current.
IMPORTANT NOTE: If you draw anything higher than the 20 Hour draw, do not expect to get the full AH rating from any battery. You will get a lot less, sometimes as low as 50% of full AH rating. As in the second example above, consider the 50 AH battery. If you put a 10 A load on this battery, you will most likely discharge that battery in less than 3 hours (10A x 3H = only 30AH).
If the load is intermittent, then duty cycle comes into play and the actual energy that can be drawn will vary from 50% up to the ideal 100%.
ACTUAL RATING OF A POPULAR 130 AH MARINE DEEP CYCLE BATTERY
130 AH @ 20 Hours
97 AH @ 5 Hours
225 minutes @ 25 Amps load
57 minutes @ 75 Amps load
At 25 Amp load, you only get 93.75 AH (72% of rated AH)
At 75 Amp load, you only get 71.25 AH (55% of rated AH)
Loss of Input AC
Both the 1 Amp and 5 Amp versions of the Smart Charger circuit presents a DC load of only 175 µ A when the AC is off or not present. In most applications, a load this small can be applied for long periods of time without damaging the battery.
For the 1 Amp Smart Charger only:
To lower the load on the battery even further below the standard 175 µA, J4 to J5 may be used in place of J5 to J6. When the DC input voltage to the chip is less than 8 volts, pin 7 is an open circuit and the sensing networks of RA, RB, RC and R1, R2 are disconnected from the battery. Under these conditions, the load on the battery is extremely small, usually non-measurable leakage. R1 and RA are typically in the 100K ohm range so the normal load produced by the sensing networks is already quite low, so use this option only if necessary. If you use this option, DO NOT use the DSp LED.
Will your charger
work with an Absorbed Glass Mat (AGM) battery?
VRLA & WET BATTERIES
For deep cycle batteries, there are two popular construction types. Flooded batteries (wet) and VRLA batteries (Valve Regulated Lead Acid). In the flooded types, the electrolyte is a solution of sulfuric acid and water that can spill out if the battery. In VRLA batteries, the solution of sulfuric acid and water electrolyte is suspended in a gel or a fiberglass-mat (AGM technology), allowing these batteries to be mounted in a variety of positions.
Charging information from various battery manufacturers recommend 13.8V to 15.0V BULK and 13.2V to 13.8V FLOAT.
Our 5 Amp charger is set to supply 14.1 volts BULK and 13.5 volts FLOAT.
Our 1 Amp charger is set to supply 14.4 volts BULK and 13.8 volts FLOAT.
We specifically set our chargers to service both types of batteries.
Can I connect a VOLTMETER
across the output of the charger?
Yes! You may connect a voltmeter directly across the battery or the output of the charger. If you wish to add a meter permanently, you will find extra pads on the circuit board for this purpose.
The 5 Amp charger has an internal ammeter.
For the 1 Amp Smart Charger only: If you wish to add an ammeter, you can lift one end of D1 and connect an ammeter in series with D1 and the pad that you lifted. This puts the ammeter in the circuit prior to the voltage sensing networks.
Both our 1 Amp and our 5 Amp Smart Battery Chargers have Auxiliary DC input capability via pads on the circuit board. This auxiliary input can be used with a solar panel. Pads are provided for an isolation diode on the board if your solar panel does not already include an isolation diode.
DC voltage input requirement is 16.5 volts at rated current. Note that both the 1 Amp and the 5 Amp circuits can be set to lower current values. The 1 Amp and 5 Amps are the maximum rating for the circuits. We suggest you add a fuse in the auxiliary DC input path.
Our enclosures DO NOT have provisions for the auxiliary inputs. We can customize a unit for auxiliary DC input, with or without the isolation diode and/or standard AC input components. Please contact us for details.
For the 5 Amp charger with AUX DC input, see 5 Amp AUX DC
The auxiliary DC input, along with the isolation diode, form a "OR" function with the existing AC input raw DC source. This means you can connect both the AC source and the auxiliary DC source, the battery would be fed by the higher voltage source.
EXAMPLE: We have some customers that use solar panel operation during daylight, and about 2 - 3 hours per evening during which a Diesel Generator supplies 110 VAC power to the campsite. Wired as described above, the AC and DC inputs are connect constantly, the "OR" function does the switching automatically.