Charging unit for protoype

Hello forum,

I've determined to power a mobile project (RFID reader with GPRS reporting system on a MEGA) with a 3.5Ah sealed gel battery. The unit will be powered with a solar panel, between 20 and 40W in size.

My question - is there a simple pcb unit available on the market that would charge the battery? I could use a conventional solar charge controller but these are relatively big and I'm tight on space on the project.

Tips would be much appreciated.

Here is a tip: tell us how much space is available! There are lead-acid battery charging chips available so you could make your own charging board with just a few other components.

Paul

The battery that'll fit snugly into my project box is 5.28 x 2.64 x 2.38 Inches. For the charger I can afford something the size of an UNO, give or take a bit. The box will have two tiny cpu fans to bring air in and hot air out, so the unit should not contribute to overheting the whole business.

But I need to come up with a number of these units, so ideally it would be an off the shelf product. When using a 20W panel it puts out around 1.2A at 18V.

I think I found what I need:

https://www.ebay.co.uk/itm/Solar-Pwm-Charge-Regulator-Controller-F2-3a-Auto-Working-Mini-12v-Battery-Kit/123030383603?_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D50428%26meid%3D5139ad1f87f94effbb76237e2762b06c%26pid%3D100675%26rk%3D4%26rkt%3D15%26sd%3D202136719442%26itm%3D123030383603&_trksid=p2481888.c100675.m4236&_trkparms=pageci%3A2f0d4721-3582-11e8-8ff4-74dbd1808523|parentrq%3A803522091620ab6ab66403fbfffa2836|iid%3A1