Triple 5mA battery trickle charger

This is a 5mA lead acid battery trickle charger along with its case. It works
with any battery up to 35V. You can maintain alarm system, motorcycle,
caravan, batteries. The input voltage of the device must be below 40V. The
input voltage must be 4 V above the battery voltage. This project will maintain the battery while in storage. It's not a battery charger. The battery must be fully charged before using this device.

This project should cost you less than $10. TO-220 LM317 are shown on the picture because I had them on hand. TO-92 LM317 can be used safely. You can increase the constant current by lowering the resistor. You may need to beef up the power capability of some of the components.

You will need the following to build this project:

* One 4 cm x 6 cm perforated prototyping board
* Four KF301-2P terminals
* One 330uF, 50V radial capacitor
* Three LM317 adjustable voltage regulators (TO-92 will work)
* Three 240 ohm resistors, 1/4 W
* Three 1N4001 diodes
* Basic electronic tools, including soldering iron and so on.
* Some glue to assemble the case.

Each charger should be plugged to one battery. Plug the positive pole of a battery to the positive pole of one of the charger. Plug the negative pole of the battery to the negative pole of the charger.

Support material is not required. An infill of 20% is recommended.

This object main web page is: http://www.ctheroux.com/triple-5ma-battery-trickle-charger/.

This object was designed using Solid Edge Community Edition.

You can request the source files on the page listed above.