0
\$\begingroup\$

I'm using solar panels + a micro wind turbine to charge a decent sized LiPo battery using this circuit - http://www.adafruit.com/products/390. The problem is that the solar/wind stuff will produce a highly variable voltage (anywhere from 0 to 30V+). To feed the ada module, should I be looking at just a switching regulator, or are there other considerations given the high variability of input voltage and current?

\$\endgroup\$
2
\$\begingroup\$

The adafruit module looks good but it's only really meant for input voltages below 6V. To maintain efficiency you should use a low drop-out switching buck regulator capable of withstanding the 30Vs you might apply.

I'd recommend the AD8610 (mainly because I've used it on two designs): -

enter image description here

It's maximum input voltage is 42V so be aware of this. On one design I put a switch-off-when-the-volts-gets-over-35V circuit with a couple of MOSFETs just to protect it.

When you under feed it with voltage it still pretty much acts as a voltage follower be be aware of the under-voltage lock-out it needs to be tied to Vin to get the most out of it.

\$\endgroup\$
  • \$\begingroup\$ Yes, sorry - I meant a regulator in front of the adafruit module.. \$\endgroup\$ – kolosy Feb 12 '14 at 16:33
  • \$\begingroup\$ Could I use a zener to siphon off anything about 40V or so, rather than just shutting the whole thing down? \$\endgroup\$ – kolosy Feb 12 '14 at 16:43
  • \$\begingroup\$ You can use a zener for sure but a better circuit is to use the zener on the base of a transistor with input to collector and output from emitter. It makes a decent voltage regulator but it all depends on load current and there's obviously series power lost in the transistor. There are not many circuits around for this but maybe there's a higher vintage version of the LT chip. \$\endgroup\$ – Andy aka Feb 12 '14 at 18:10
0
\$\begingroup\$

Yes one can use a rectifier-based DC converter to handle 0 - 30 volts input and rated current. The output voltage will be specified in tech specifications. Also check web for AC to DC or DC to DC step up/down converters as per your requirement.

\$\endgroup\$
0
\$\begingroup\$

You'll want a dedicated battery charging IC for this so you don't destroy your battery. There are a number available, and without knowing more about your specific setup (# of cells, charging current, etc) the best I can offer is this list of battery charging ICs. The LTC4000-1 looks like it will do what you want, but requires a number of supporting parts:

LTC4000-1
(source: linear.com)

The LT3650-4.1 has a smaller voltage input range, but looks to be much simpler:

LT3650
(source: linear.com)

\$\endgroup\$
  • \$\begingroup\$ The adafruit circuit is a dedicated battery charging IC (+some supporting parts), it just needs voltage that doesn't exceed 6V. My question is how to feed that specific circuit from a power source that can go to 30V or more. \$\endgroup\$ – kolosy Feb 12 '14 at 17:09
  • 1
    \$\begingroup\$ Ah, I see that you clarified your question as I was answering it. However, replacing the module with one of the ICs linked to above would be just as easy as adding your own regulator in front of the module. \$\endgroup\$ – sbell Feb 12 '14 at 17:47

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.