5v solar charger with over-volt protection.

Hey,

So I have managed to make a bluetooth repeater to increase my range from a greenhouse.

The only problem now is getting it powered in the field (essentially...my only option is solar).

The repeater draws between 60-100mA.

I have been browsing youtube for a bit now and can only find systems that are non-protected (simply putting a 5v regulator on a panel and connecting straight to 4AAs in series.)

Is this actually fine for long term use, or should I look at over-volt protection? Also what do I need in this case?

Thanks!

I’m quite happy with this one ans a 5v step-up, step-down https://www.adafruit.com/products/390

Well looks like it is not worth trying to build my own...2 of these in parallel will keep my 60-100mAh draw going I feel!

http://www.ebay.co.uk/itm/5000mAh-Dual-USB-Waterproof-SOLAR-power-Bank-Battery-Charger-for-Cell-Phone-UK-/131453180161?pt=LH_DefaultDomain_3&var=&hash=item1e9b385901

Even better :P.

http://www.ebay.co.uk/itm/30000mAh-Mobile-Phone-Solar-Panel-Charger-Charging-Battery-Dual-USB-Power-Bank/131465424618?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D30989%26meid%3Da074bb532b23440e8af775159b4a848c%26pid%3D100005%26rk%3D5%26rkt%3D6%26mehot%3Dpp%26sd%3D181514642194&rt=nc

Is the repeater required to be powered all the time , or just for a few hours a day? If you want 24/7 operation, then you need to determine the size of the Solar Panel needed.

mauried:
Is the repeater required to be powered all the time , or just for a few hours a day?
If you want 24/7 operation, then you need to determine the size of the Solar Panel needed.

24hour.

I have some USB power meters in my USB ports and they show between 0.05W @ 4.85 V (about 10mA) for what would be a lot of the time. Looking at any others experiences, they said between the two, around 100mA (I am assuming that is the unpaired/scanning states).

So with the 2 1.2W solar panels, giving even 10% efficiency (night time included), should be well more than enough.

How much repeating is going to be done. The high current draw will occur when the repeater is transmitting, so you need to know how often during the day this will be happening. If you dont know , then you will have to design the system based on the worst case scenerio which is 100ma draw all the time.

What is the distance between the original units. Did you try directional aerials. Leo..

Johnny010: I have been browsing youtube for a bit now and can only find systems that are non-protected (simply putting a 5v regulator on a panel and connecting straight to 4AAs in series.)

Is this actually fine for long term use, or should I look at over-volt protection? Also what do I need in this case?

Are you intending to use NiCd batteries? If so you can't protect them against overcharging with a voltage regulator. As they reach full charge the voltage actually starts to drop and it's that drop that you need to detect to stop the charging.

For long term un-attended use I would suggest using a sealed lead-acid battery. Nominally 6 V but can be charged with a 6.6 V regulator connected to your solar panel to limit charging. Followed by a 5 V LDO regulator to give you your 5 V supply.

Russell

5volt/100mA is quite demanding 24/7 for 4 NiCd or NiMH batteries.
One rainy day, and you’re dead in the water.
I would think 12volt/7Ah SLA (cheap) and a 12volt/~500mA charging system.
Dropped to 5volt with a Pololu 5volt/500mA micro buck converter.
That one will draw <50mA from the battery for 100mA out.
Enough power to bridge three or four rainy days, without draining the SLA more than 50%.
Leo…

Johnny010: Well looks like it is not worth trying to build my own...2 of these in parallel will keep my 60-100mAh draw going I feel!

http://www.ebay.co.uk/itm/5000mAh-Dual-USB-Waterproof-SOLAR-power-Bank-Battery-Charger-for-Cell-Phone-UK-/131453180161?pt=LH_DefaultDomain_3&var=&hash=item1e9b385901

How does this work? I mean LiPos have about 200 load cycles. Having your device connected to this charger would continuously switch between charge/discharge of the battery (depending on sunshine). Wouldn't that extremely shorten the lifetime of the battery?

Zealot: How does this work?

I wouldn't believe a word of the description for that product. It is so full of contradictions. Charging time 15 - 18 hours or 50 hours depending on which part of the description you read. Charging time on ac 3 hours or 6 hours? Charging current "no more than 100 mah (sic)".

Russell.