LM317 Battery Charger Circuit

LM317 Battery Charger Circuit

There are abounding circuits accessible for charging batteries, but abounding are for NiCd or NiMH batteries. They will not assignment for lead/acide batteries, so don’t use these!!! The best way to allegation a array is with a accepted bound voltage regulator. This sets a best accepted (say 1A) that will breeze to allegation the battery. If the accepted rises over this set current, the regulator will be affected to put out a lower voltage. Since voltage drops, so will the current; appropriately accepted limited. While the array is charging, the accepted should abatement boring while voltage starts to increase. In the end the accepted will be abutting to aught and the voltage will be according to the set voltage.

Use the afterward to architecture a charger:

1) The charging accepted should be kept to about 0.1 times the accommodation of the battery. So a 10Ah array should be answerable with 1A of accepted (10 x 0.1 = 1). The array will not be affected (quick charged) this way and assures a best lifetime.

2) The charging voltage should be set to 2.3 - 2.4V per 2V cell. So a 12V array (6 beef of 2V) is answerable at 6 x 2.3 = 13.8V.

3) The agent ambagious for the charger accumulation is called at the charging voltage additional 3V regulator bead additional 1.4V rectifier bead (two diodes) additional 10% safety. So for a 2V battery, the ambagious (AC) is 2V + 3V + 0.7V + 0.7V = 6.4V + 10% = 7V.

4) The charging accepted is bound by the baby resistor in the accepted leg of the charger. The amount for this resistor can be affected with: R = 0.6V / max current. So if I appetite a best accepted of 0.5A, I will charge 0.6V / 0.5A = 1.2 ohms. The 0.6V is the voltage appropriate for the transistor to go absolutely into conduction. Between 0V and 0.6V the transistor will acclimatize the regulator to access or abatement voltage depending on the accepted it is passing.

5) The charging voltage can be set application the potentiometer. Just angle up a volt-meter to the charger (without the array attached) and acclimatize the achievement voltage until it macthes the charging voltage. Use a 1K pot for 2V batteries, use 5K for 6V and 12V batteries.

6) Use an added agglutinate on the charger, about two times the best accepted you are charging with. Fusing is analytical for assurance reasons. A array can bear 100+ amperes during a short, so it can account austere accident or alike fires back article goes amiss with the charger. Put the agglutinate abaft the regulator in the advance activity to the battery. This agglutinate is not to assure the accumulation from a abbreviate in the charger, but to assure aggregate abroad from the array in case of a abbreviate anywhere. Don’t balloon to agglutinate the primary ambagious of the charger as well…

7) You’re set up to charger