Solar Charger Enquiry

Dear Core Electronics,

I would appreciate your assistance in selecting suitable components for a small solar light project. I spoke to Clinton yesterday afternoon who suggested I post my enquiry on your forum.

Background: I recently purchased a Deelat “Solar PIR and Security LED Light” system that includes motion sensor electronics and remote control only to find out that it had no manual operating mode which is all that I really need (a simple On/Off operation using an external light switch). I would like to change this to simple On/Off operation.

The Existing System details are: (see also attached photos)
Solar Panel: 6V, 5W
LED Panel: 44 LED, 1,000 Lumen, 15W, 3.7V
Battery: 3x individual 18650 cylinders (pink – brand unknown), 3.7V, 8,000mAh (per Deelat spec sheet), soldered onto a single circuit board which includes the solar charger and daylight and motion sensor electronics.
LED Enclosure Internal Dimensions: 180mmL x 50mmW x 30mmD

The metallic LED enclosure and intensity of the LEDs are great and I plan to re-use them along with the existing solar panel (both with flying leads). However, I plan to replace all existing batteries and electronics with new ones (plus an external on/off switch – not part of this enquiry). This means purchasing new batteries (capacity around 8,000mAh) and a compatible solar charger. This is the subject of this enquiry.

On your website I found the following that might possibly do the job, and I would like your advice regarding suitability, fire safety (Li batteries), availability, cost and delivery of all required components, as well as any other recommendations or solutions you can suggest:

Battery Options
A. 2 x CE04380 LiPo batteries (3.7V 4,400mAh), protected – connected in parallel
B. 1x CE04381 Li Po battery Pack (3.7V 6,000mAh), protected – connected in parallel; retired product?
C. Any other suggestion from you

Solar Charger Options
A. 1x AF-390 USB / DC / Solar Lithium Ion/Polymer charger v2

(Adafruit website shows as out of stock)
B. Any other suggestion from you

Additional points which need to be addressed are:

  1. Confirm that any proposed batteries have min V, max V and max I protection as these chargers do not.

  2. Highlight any charge/discharge issues with connecting identical batteries or battery packs in parallel (in case of increasing difference between individual battery conditions though initially “identical”).

  3. What is the max charge current possible with the final proposed charger, and any special requirements for achieving this, e.g. the AF-390 has a 900mA option by soldering a 2K ohm resistor over the existing 2K resistor across the PROG pads (per the Adafruit manual). I am hoping to achieve something close to the max possible from the solar panel, around 800mA.

  4. The new batteries and charger PCB will be placed inside the existing fully enclosed metal casing behind the LED panel. Please advise whether a hi temperature cut-out thermistor should be installed; the AF-390 charger has this option including thermistor (10K Precision Epoxy Thermistor - 3950 NTC, Product Id: 372).

  5. What restraint options are available to protect the batteries from moving around inside the enclosure during installation.

  6. What connectors are required to attach the solar panel flying leads to the charger, e.g. AF-369 (Male DC Power Adapter - 2.1mm Plug To Screw Terminal Block).

  7. What connectors are required to attach the LED panel and series connected external On/Off switch (SPDT dry contact, flying leads) to the charger, e.g. PH plug or other spec.

  8. What mounting supports are available to avoid the charger PCB contacting any metal surface inside the enclosure, e.g. Adafruit AF-1116 “Board Edge Mounting Kit - Pack of 4” or other, also to stop it moving around.

  9. What options exist for adding remote status LEDs that can be mounted on the enclosure, as the charger PCB will be inside the enclosure, the charging status LEDs will not be visible from the outside. The AF-390 charger has this option.

Your early advice would be very much appreciated. Let me know if any you require any further information. Thank you.

George Prattos

1 Like

Hi George,

  1. I would go with the single 3.7 6000mAh (CEO4381) it does have Vmin, Vmax, and Max current protection.
  2. I don’t think there would be any problems with this though I personally would just use the one 6Ah
  3. I think the the 800mA is a good place to put it.
  4. Saftey is always a good idea though alternatively, you can reduce the charging current.
  5. I’d use some kind of tape or glue, though you could 3D print something nice
  6. something like this 2.1mm one
  7. They look like JST.
  8. Those look good(I’m an electrical engineer because I’m not great at mechanical )
  9. Standard LED’s should work you could add a microcontroller like the Adafruit HUZZAH32, and add all kinds of features!

Dear Core Electronics,

BACKGROUND: The order arrived in good time and the parts were assembled per the manual only to find that the LiPo battery would not charge via the USB port.

On 8-Aug-18 all parts were returned via Aust Post to you and an email to the effect sent to you. This was acknowledged same day (Graham), your technical people investigated it and confirmed the issue (Clinton), and a credit was given to be used in another order (Gordon).

On 20-Aug-18 after finding out online that the charger was out of stock I called Core Electronics seeking advice on how to best proceed (Gordon), my specific requirements being:
a) connecting a solar panel with flying leads and,
b) having a backup charging source (USB or other, even if a separate power supply).

Gordon mentioned that he would have the technical people consider the options next day and get back to me. I confirmed our telecon with an email same day (20-Aug-18) and received a reply next day (Graham Mitchell) that Core Electronics manages technical support via a forum.

As I have not heard back in four days I thought of giving this a go, hopefully the right approach.

NEXT STEP: I would very much appreciate your advice and recommendations on what solar chargers (with a USB or other backup charging source) and ancillary components are available that will enable me to connect my existing solar and LED light panels both with flying leads.

I look forward to your early reply.

George Prattos

Hi George,

Here are our Maker Favourites which are worth considering. All of the specs are listed on each product page; so you can assess them against the needs of your project. We don’t have much more than these 3 products, and if you are after something outside this flight envelope then some DIY might be needed (or shop around).