Skip to main content

Solar Powered SLA Battery Maintenance


This circuit was designed to ‘baby-sit’ SLA (sealed lead-acid or ‘gel’) batteries using freely available solar power. SLA batteries suffer from relatively high internal energy loss which is not normally a problem until you go on holidays and disconnect them from their trickle current charger. In some cases, the absence of trickle charging current may cause SLA batteries to go completely flat within a few weeks. The circuit shown here is intended to prevent this from happening. Two 3-volt solar panels, each shunted by a diode to bypass them when no electricity is generated, power a MAX762 step-up voltage converter IC. 

Circuit diagram:
Solar Powered SLA Battery-Maintenance-Circuit-Diagram
Solar Powered SLA Battery Maintenance Circuit Diagram

The ‘762 is the 15-volt-out version of the perhaps more familiar MAX761 (12 V out) and is used here to boost 6 V to 15 V.C1 and C2 are decoupling capacitors that suppress high and low frequency spurious components produced by the switch-mode regulator IC. Using Schottky diode D3, energy is stored in inductor L1 in the form of a magnetic field. When pin 7 of IC1 is open-circuited by the internal switching signal, the stored energy is diverted to the 15-volt output of the circuit. The V+ (sense) input of the MAX762, pin 8, is used to maintain the output voltage at 15 V. C4 and C5 serve to keep the ripple on the output voltage as small as possible. R1, LED D4 and pushbutton S1 allow you to check the presence of the 15-V output voltage.

D5 and D6 reduce the 15-volts to about 13.6 V which is a frequently quoted nominal standby trickle charging voltage for SLA batteries. This corresponds well with the IC’s maximum, internally limited, output current of about 120 mA. The value of inductor L1 is not critical — 22 µH or 47 µH will also work fine. The coil has to be rated at 1 A though in view of the peak current through it. The switching frequency is about 300 kHz. A suggestion for a practical coil is type M from the WEPD series supplied by Würth (www.we-online.com). Remarkably, Würth supply one-off inductors to individual customers. At the time of writing, it was possible, under certain conditions, to obtain samples, or order small quantities, of the MAX762 IC through the Maxim website at www.maxim-ic.com.
Streampowers

Labels:

Comments

Post a Comment

Popular posts from this blog

A basic Arduino Solar PV Monitor

I have just recently had solar pv installed, mainly to future proof my energy costs, I do not expect it to be like drilling for oil in my back garden, however the return looks to be encouraging. The install gives you another single unit meter, from this you will see the total amount the panels produce, but that is about it. I wanted to know how much the production was as it was happening, I discovered the light blinks on the front of the meter will flash 1000 times for each kWh of electricity which passes through. The rate of the flashing of the LED tells you how much power is currently passing through the meter. [ ]
Post a Comment
Read more

Apple releases TV spot for new iPods

Apple has just released a fun commercial to showcase its new line of iPod players and the various colours they come in. The TV spot titled ‘Bounce’, has a bunch of colourful iPod touch, iPod nano and iPod shuffles er…bouncing to music. With all that colour and dancing and bouncing, you may forget that Apple’s latest gen line of iPods has some other awesome features. For instance, the fifth gen iPod touch comes with Siri, 4-inch retina display and an A5 chipset. Maybe the next ad will showcase some of these features with less bouncing.link
Post a Comment
Read more

3 Channels Audio Splitter Amplifier Circuit Diagram using TL084

This is the schematic diagram of 3 channels audio splitter amplifier circuit which built using op-amp IC TL084. The 3 channels amplifier output distribution applies a single TL084.   3 Channels Audio Splitter Amplifier Circuit Diagram The very first step is to capacitive coupling having a p. 1.0 ~ electrolytic capacitor. The entries are railways Vee Y2 or 4.5 V. This enables working with an individual 9V power source. A voltage gain of 10 (1 M?/100 Kohm) is obtained in the first stage, as well as the other three floors are connected as a unity gain voltage followers. Every single output stage drives independently through an amplifier output 50 pF capacitor towards the resistance of 5.1 k ohm load. The response range is flat from 10 Hz to 30 kHz.
2 comments
Read more