Searching a solar charger

Hardware
1

Hello everybody :slight_smile:

I recently spent some time searching for a fitting solar charger board but still could not figure out which solar charge controller would fit my project the best.

I want to build a light in my backyard, but all solar charge controller I found don't have enough ouput.
For example the waveshare solar charge manager (d) looks really well designed, but the output is max. 3A 5V, which is too low.

An alternative would be a bq24650 module, but this module is too expensive (like 20€).

I really would appriciate any recommendations :slight_smile:
(i have laying around 4x lifepo4 3000mah batteries)

2

To 'size' a solar charger, you need to know the size and characteristics of the battery bank which is governed by the load, LiFePO4 is generally the best choice. Now goto this Link to determine your solar power by month for a given sized panel. If you need 100% reliability, assume 3 days of NO solar so size the battery accordingly. Once you know how many solar panels of a given voltage and current, I recommend Victron Energy for an MPPT solar charger. Also don;t forget you will need a battery monitor, your choice of a controller and eventually cables, connectors, breakers (I ALWAYS use marine grade so NO corrosion)

3

Thank you for your reply, i have laying around some lifepo4 batteries. I will buy a small solar module then.

4

Um, do you not understand what I explained, did I do a bad job explaining it.
FYI I built a 7,200 Watt Hr battery bank, 1,080 Watt solar array, 3,000 Watt inverter, 120 Amp charger. AFAICR $10,000+ CDN.
So you can see I have some experience and I am happy to share it.

5

Maybe you should tell your specs, numbers, what you need to accomplish...

6

What sort of light? What power requirements?

7

Sorry, I should have written that in my first post.
I need 30W of ouput, the voltage is not important, since i can use a step up converter.
It is just a light out of leds i build myself.

8

Sorry, but since Power = VOLTS * Amps, how is voltage NOT important.

9

The first module Waveshare is ok only for one li-ion 3.7V battery and has regulator for 5V usb out. Bq24650 doesn't have output, so you output directly from batteries.
You could put your four lifepo4 cells in series, get 18V solar panel and use module similar to that Bq24650:
https://www.aliexpress.com/item/1005006334087146.html?spm=a2g0o.detail.pcDetailTopMoreOtherSeller.2.58b2SfiZSfiZL9&gps-id=pcDetailTopMoreOtherSeller&scm=1007.40050.354490.0&scm_id=1007.40050.354490.0&scm-url=1007.40050.354490.0&pvid=f34d0425-0b51-45c6-95c8-c738716178e9&_t=gps-id%3ApcDetailTopMoreOtherSeller%2Cscm-url%3A1007.40050.354490.0%2Cpvid%3Af34d0425-0b51-45c6-95c8-c738716178e9%2Ctpp_buckets%3A668%232846%238114%231999&pdp_npi=4%40dis!EUR!3.12!2.93!!!24.10!22.61!%402103835e17241584957994063e829b!12000036796626805!rec!IT!103797544!XZ&utparam-url=scene%3ApcDetailTopMoreOtherSeller|query_from%3A

Be aware that it doesn't have battery over discharge protection or "load shearing" circuit.

10

Example math:

For a 30W light, you will need a battery of at least 30 Watt-hours to run for 1 hour. 4x3Ah Li batteries will be sufficient for that 1 hour.

A solar panel with a minimum of 5W, running for 8 hours is needed to recharge the battery for that 1 hour of use.

How many hours should the lamp be on?