1 Amp Smart Battery Charger

Read reviews of our chargers at: eHam.net1 or eHam.net2 or eHam.net3

Proudly made in the U S A


All versions of our 1A Smart Charger have been DISCONTINUED
1A Smart Charger data shown here for information purposes only
We will continue to support our products for at least the next 5 years
A & A Engineering is now a part time business
***** We are easing into retirement *****
After 41 years, no more 12 hour work days

Please allow extra time to process all orders
We have moved
Our new address is: 7970 Orchid Drive, Buena Park CA 90620-1930

Effective NOV 2014, company phone and FAX lines have been discontinued

The best way to contact us is via EMAIL to:



The A & A SMART BATTERY CHARGER is for use with any GEL-CELL or LEAD ACID battery. Sometimes these batteries are refered to as DEEP CYCLE, VRLA, VRSLA or AGM batteries. The design is based on the Unitrode UC3906 battery charging chip. It has three distinct operating states. Initially the charging current is limited to a pre-set bulk value and when the battery voltage reaches a specific level the charger enters the absorption mode and tops off the battery with an elevated voltage. After top off, it enters the maintenance mode where it maintains the battery at a precision float level value.

1 Amp Smart Battery Charger Operation/Notes download (1AChargerOperation.pdf)

A very important feature of this charger is a precision temperature tracking voltage reference. This reference is specifically temperature compensated to track the temperature characteristics of lead-acid cells.

If a load is applied to the battery while the charger is connected, the charger will contribute its bulk current to the load. If the load discharges the battery sufficiently, the charger will repeat the three state process described above when the load is removed. This charger can be connected to the battery indefinitely, it will not overcharge the battery.

This Smart Battery Charger circuit presents a DC load of only 175 µA when the AC is off or not present. A very important feature which prevents the discharge of the battery by the charger if the AC input is interrupted for long periods of time.

Great for a large variety of everyday uses with 5-15 Ampere-Hour batteries. Excellent for larger batteries (automobile/marine type 80 - 120 Amper-Hour) which are not used very often.

The Trailer Boater (Bass Boaters) or Sunday Sailor, who usually only use their boats on the weekends, can be assured of a fully charged battery if they have a SMART BATTERY CHARGER working 24 hours a day.

Repeater sites, burglar alarms, etc. can use this charger to maintain back-up battery systems. For items in long term storage such as trailer boats, travel trailers, 5th wheels, RV Trailers or RV Motorhomes, motorcycles, wave riders, motorhomes, etc. all benefit by using this Smart Charger as a BATTERY TENDER. For Battery Tender applications, custom cables are available, please call or email with your requirements.

HF mobile and fixed station operators, QRP and backpackers have applied this Smart Charger in a number of different applications. SEE LINKS BELOW FOR A FEW EXAMPLES.

Elecraft K2 QRP operators have requested a charger that would work well with the 2.9 A-hr gel cell option that Elecraft offers. We responded with our Switchable QRP Version.

Many Ham Radio Operators maintain an Emergency Battery Backup System for use during power outages. Quite often Ham Radio is the only source of communication following a disaster. To be prepared, HAMs practice for these events during RACES exercises or the annual ARRL Field Day. Many HAMs depend on our 5 Amp or 1 Amp Smart Battery Chargers to maintain their Emergency Battery Backup System. See the SHORT TAKES review by Joel R. Hallas, W1ZR, ARRL Assistant Technical Editor in the MAR 2004 QST. For full details click here: (QST Article.pdf)

Our standard KIT is 115 VAC input, 12V @ 1 Amp Maximum output. If you build the KIT, you can set the BULK current to either 1/2 or 1 Amp output. Our standard assembly is 12V @ 1 Amp. The BULK current can be set it to 1/2 Amp if requested, at no additional charge. KIT or assembled 6V @ 1 Amp or 1/2 Amp units are also available, at no additional charge, see Charger Price List

Although we commonly refer to a battery as a 12V battery, meaning a battery having 6 cells at 2.0V per cell (12.0V). The actual Lead-Acid battery voltage is closer to 2.3V per cell (13.8V).

Outdoor Model Railroaders (G-Gauge mostly) use our 18 V units to recharger their 18 V Gel Cell powered Electric Trains. Remote Control (RC) Airplane, Car and Boating Modelers mostly use our 6V @ 1A version to recharger their 6V Gel Cell.

Other voltages available are: 4V, 8V, 14V, 18V, or 24V. See table below for price adder.

The complete charger weighs 3 pounds and measures 4" W x 6 1/2"D X 3"H. Input is a six foot BLACK zip cord with molded AC plug. Output is a five foot WHITE zip cord with mini RED/BLACK alligator clips (shown below with Anderson OPTION). Both input and output are rear panel fused.

Output cable options include - Output cord with larger alligator clips (150-ALL) or with .187 QuickConnects (150-187) or with .250 QuickConnects (150-250), see price chart below or Charger Price List

This kit is 100% complete, there is nothing else to buy! The kit includes a prepunched, painted and silk-screened metal enclosure. All hardware, wire, cables, electronic components, and the circuit board are included.

SOLAR PANEL USE: Both our 1A and 5A Smart Battery Chargers have Auxiliary DC input capability via pads on the circuit board. This auxiliary input can be used with a solar panel. For details see Solar Panel Notes

We have quite a few satisfied customer worldwide, here are a few unsolicited comments; TESTIMONIALS

For the standard KIT, Order #150-KIT

For assembled unit, Order #150-ASY

KIT with Anderson Pigtail Option
specify AND-KIT, add $3

ASY with Anderson Pigtail Option
specify AND-ASY, add $5

Build your own version with blank circuit board, 150-PCB, $15.95 (click for details)

Build your own version with assembled circuit board, 150-PCA, $31.95 (click for details)

Need a cable with .187 QuickConnects, Order #150-187, $9.95 (click for details)

Need a cable with .250 QuickConnects, Order #150-250, $9.95 (click for details)

Need a cable with larger Alligator Clips, Order #150-ALL, $12.95 (click for details)

Need an Anderson Extension cable, Order #150-AND, $10.95 (click for details)

Shipping cost for KIT or Assembly via UPS insured to US 48 is $11.50

Shipping cost for KIT or Assembly to Alaska or Hawaii is $14.50

California Residents please add 7.75 % sales tax

Shipping cost for KIT or Assembly via mail to CANADA is $18.75

12V @ 1A or 6V @ 1A KIT or assembly is standard
For other output voltage (4, 8, 14, 18 or 24) Add $ 5.00 per KIT or $ 10.00 per ASY

Foreign orders require special treatment, please contact us for details

For options, blank boards, cables and parts, see Charger Price List

For 230V 50/60 Hz options, see Charger Price List

We NO LONGER accept checks, money orders, Visa or MasterCard directly (see ordering information)

We now only accept PayPal

PayPal, American Express, Discover, MasterCard or Visa through (see PayPal information)

If you would like to see the Smart Charger being used with the Elecraft K2 internal battery,
see the write up by Don Wihelm, W3FPR

Since Don wrote this article, we have devised a way to make a switchable charger without having to cut any etch, see our Switchable QRP version of this Smart Battery Charger
Click Here: W3FPR WebPage

If you would like to see a review of the Smart Charger,
see the write up by David Farris, K5NT
Click Here: eHam.net Reviews - A&A Engineering Smart Charger

A & A Engineering 7970 Orchid Drive, Buena Park, CA 90620
Phone (714) 952-2114 FAX (714) 994-1104

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