VMAXTANKS 12V Smart AGM, Gel Cell and Flooded Lead-Acid Battery Chargers

VMAXTANKS 12V Smart AGM, Gel Cell and Flooded Lead-Acid Battery Chargers is series of microprocessor controlled smart battery chargers. They charge, maintain and if required, recondition lead-acid battery using several charging stages. They include several safety features to prevent overcharging, short circuits and other possible errors and problems.

vmaxtanks bc1220a 1

Features and technical details of these 12V chargers are given in the following table:

Charger BC1204 BC1205 BC1207 BC1215 BC1220
Photo vmaxtanks bc1204 t   vmaxtanks bc1205 t vmaxtanks bc1207 t  vmaxtanks bc1215 t  vmaxtanks bc1220 t 
 Input Voltage 110V 110V 110V 110V 110V
Input Current 1.1A 1.6A  1.9A 3.8A 4.8A
Max Bulk Charge Voltage  14.7V  14.7V  14.7V 14.7V   14.7V
Bulk Charge Current  3.3A  5A  7A 15A  20A
 Connector  Insulated Alligator Clamps Insulated Alligator Clamps  Insulated Alligator Clamps  Insulated Alligator Clamps   Insulated Alligator Clamps
Size (LxWxH)  4.75"x2.6"x0.63" 6.7"x2.8"x2" 7.68"x4.5"x2.5"  8.5"x4.5"x2.5" 8.5"x4.5"x2.5" 
Weight  0.6 lbs 14.5 oz 2.3 lbs  2.6 lbs 3 lbs
Number of Charging Stages  4  4  7  7  7
Recommended Batteries  15-80 Ah  20-100 Ah  30-140 Ah  60-300 Ah 80-400 Ah
Cooling Natural convection Natural convection   Cooling Fan Cooling Fan  Cooling Fan
Amazon Link: VMAX BC1204 VMAX BC1205 VMAX BC1207 VMAX BC1215 VMAX BC1220

Amazon links open in the new windows, feel free to check them for more comments and opinions.

Note - input voltages are actually 110-240V and 50-60 Hz, according to the manuals. However, if you go to the Europe, be sure to have proper mains outlet adapters and check twice if your model support 240V input voltage BEFORE connecting it to the 240V. Recommended operating temperature is between -5°F and 120°F (-20°C and 49°C), although this data varies even on the VMAXTANKS official page.

Although recommended batteries overlap, when considering chargers, have in mind charging time of the batteries, which is roughly:

charging time (h) = battery capacity (Ah) / bulk charging current (A)

Don't, but really don't charge lead acid batteries with extra large currents - this will shorten number of their charging cycles. Charging time, of course, depends on the battery discharge level, its age, condition and other factors that may influence battery charging and charging time. Hence, having 'smart' battery controller is so vital for battery health and prolonged operating life.

Also, note that BC1205 charger comes in several versions. They all have same electrical characteristics, except that they have different connectors:

vmaxtanks bc1205 versions

BC1205 charger/maintainer connector types are:

- BC1205A: Insulated Alligator Clamps
- BC1205RT: Ring Terminals
- BC1205XF: Insulated XLR 3 Pin Female Connector
- BC1205XM: Insulated XLR 3 Pin Male Connector

 So, if you need 5 Amps charger, check required connector. In most cases, alligator clamps are the best way to go.

4 vs. 7 Charging Stages

If you check the table, you will notice that BC1204 and BC1205 charge batteries using 4 charging stages, while BC1207, BC1215 and BC1220 charge batteries using 7 charging stages. So, which is better?

The BC1204 and BC1205 are four stage chargers:

Stage 1: Charger enters this stage if it detects battery sulfation or severe discharge and starts desulfating the battery through 18V pulses. Once the battery is rejuvenated, charger moves to next stage - Bulk charging.

Stage 2: Bulk charging - battery is charged using charger highest rated voltage and current for the type of battery in use, until it reaches 80% capacity.

Stage 3: Absorption phase - the output voltage is limited to 14.7V while current declines as the battery charges to its full capacity without overheating.

Stage 4: Float phase - at this stage, the battery is fully charged and the charger maintains the battery through pulse charging.

The BC1207, BC1215 and BC1220 are seven stage chargers:

Stage 1: Desulfation - charger enters this stage if it detects battery sulfation or severe discharge and starts desulfating the battery through 18V pulses. Once the battery is rejuvenated, charger moves to next stage - Soft Start.

Stage 2: Soft Start - charger starts gently to introduce the power to the battery

Stage 3: Bulk Charge - battery is charged using charger highest rated voltage and current for the type of battery in use, until it reaches 80% capacity.

Stage 4: Absorption - the output voltage is limited to 14.7V while current declines as the battery is charged to its full capacity.

Stage 5: Battery Test - battery test checks battery and its status. Battery test is automatically started right after the Absorption stage and it monitors battery voltage for 90 seconds to determine if the charging was successful. If the voltage drops below 13.2 volts, battery test has failed and charger will initiate Recondition charging stage. If the voltage stays above 13.2 V during the test, charger will initiate Float stage, skipping the Recondition stage.

Stage 6: Recondition - if the battery has failed the test, reconditioning stage will charge the battery with low constant current for period of 4 (four) hours. This helps with deeply discharged batteries by equalizing the cells. After 4 hours, charger will go into the Float charging mode.

Stage 7: Float - at this stage, the battery is fully charged and the charger maintains the battery through pulse charging.

This 7-stages charging cycle is fully automatic, and if terminal voltage drops below a lower limit, the charger will automatically switch to the beginning of the charging curve.

Which is better 4 or 7 stage charging? Well, good charger costs two to four times LESS than a good deep cycle or dual purpose marine/car battery. So, if you are not going cheap with your batteries, why would you go cheap with your charger?

Safety Features

vmaxtanks bc1220a 1mThe BC1204, BC1205, BC1207, BC1215 and BC1220 chargers come with numerous safety features that protects from accidental errors and other problems and they include polarity protection, output short protection, non-battery link protection, faulty battery, over voltage protection, over temperature protection and similar.

Note: Safety features are not there because they are 'cool', they sound 'great' or anything else - batteries and chargers can provide huge currents that can do serious damage, injuries or worse - if you are not sure what are you doing, stop, and ask for professional help!

Note that BC1207, BC1212 and BC1220 have thermostatically controlled cooling fans, while BC1204 and BC1205 are cooled passively.

Recommended VMAXTANKS Smart Battery Charger

If you have the need for regular charging of deep cycle or dual purpose batteries and those batteries are anywhere between 60 and 300 Ah, go for BC1215 smart battery charger. This charger is 'ideal' for batteries between 75 and 175 Ah and will test them and charge properly.

For batteries between 30 and 140 Ah, especially for batteries between 45 and 75 Ah, go for BC1207.

For batteries between 80 and 400 Ah, and especially for batteries between 110 and 225 Ah, go for BC1220.

If you like trolling using electric trolling motors, or have other reasons for use of such deep cycle or dual purpose batteries, smart battery charger is good investment - it will charge the batteries and prolong their operating life. 

Since most but the smallest electric trolling motors require 50 - 60 Amps for maximum thrust, it is good to dimension your trolling motor battery properly.

So, if you like this kind of fishing, be aware that good 120-130 Ah deep cycle battery can provide 50 Amps for at least 90 minutes - actually, it can provide 50 Amps little bit more, but for safety reasons, assume 90 minutes. However, if you don't push your electric trolling motor too hard, operating time on a single charge can be much longer.


Long story short - BC1215 smart battery charger is reliable and relatively cheap battery charger and can charge batteries between 60-300 Ah, and is excellent for batteries between 75 and 175 Ah. For more reviews and recommendations, feel free to check VMAXTANKS BC1215 Amazon link (link opens in the new window).

Whatever you do, stay safe!