Battery Lighting Project

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watts-on

Member
Joined
May 27, 2017
Messages
188
I kinda accidentally volunteered myself for designing a lighting solution for an industrial service unit used on construction sites.

The unit has an onboard 240VAC generator that must be running when using hot water for hand washing, the kettle, microwave oven, etc, as well as when using the existing fluorescent overhead light.

The brief is, to create a battery solution for a new LED overhead light that will grab as much charge as possible into the batteries whilst the generator is running and at the same time power the light directly. Then run the light for at least a couple of hours from the batteries when the generator is off.

The lighting unit is this one:


image_dvvowr.jpg

http://www.ebay.co.uk/itm/36W-1200x...Panel-Light-Frame-Day-Cool-White/332336177734

The LED light requires 60VDC at 600mA 36W, and it came with its own 240VAC power adapter. I couldn't resist having a look inside. There is a single strip of 170 LEDs and no resistors, so the power must be accurately limited to drive them. There's no way they are all connected in series if it runs on 60V, but without irreversibly dismantling it further I couldn't tell what it's series/parallel configuration was.

If my maths is correct, I should need around 5 off 2000mAH 18650s per hour of run time.

There is no option for solar panels unfortunately.

I have come up with these two-possible configuration:


image_qnluzf.jpg


At first, I thought of buying an ebike battery, but they all seem to charge at just 5A which is way too slow for this application. I'm not sure if that limitation is the charger or the batteries themselves, but unless I buy a pack and rip it open to check, there is no way to know. So, I will probably just source some suitable cells and make up a custom pack. Maybe someone can advise on batteries with a very high charge rate capability. The discharge rate will obviously be relatively low. Pretty much the opposite of normal battery usage I guess.
Are 18650s a good fit for this or would I be better off using some of those RC type pouch packs?

I haven't shown any breakers or other safety stuff in the diagrams at this stage. Just thinking about the general idea. The relay automatically switches over to direct drive whenever the generator is running.

Anyway, if anyone has any advice or better ideas, it would be greatly appreciated.
 

jdeadman

Member
Joined
Mar 28, 2017
Messages
948
Personally speaking I'd run the setup as switching the power in AC and switching 60VDC is not something I would like to do with a normal switch. So for that application the generator would be doing most of the work and just a little backup power for after it's off. 600mA is not much of a draw but with losses in the inverter you might look at using 1A for any calculation for runtime.

I like the first option. but both work just fine
 

watts-on

Member
Joined
May 27, 2017
Messages
188
jdeadman said:
Personally speaking I'd run the setup as switching the power in AC and switching 60VDC is not something I would like to do with a normal switch. So for that application the generator would be doing most of the work and just a little backup power for after it's off. 600mA is not much of a draw but with losses in the inverter you might look at using 1A for any calculation for runtime.

I like the first option. but both work just fine

Yes, my gut feeling is that switching the mains is the way to go.

DanLim said:
Cannot confirm, but look like Solar Street light MPPT may able to fit your application... only need another AC>DC to fit the controller..
There's a timer control for the light as well..
http://www.epsolarpv.com/en/index.php/Product/pro_content/id/691/am_id/139

Thanks Dan, that looks quite interesting. I have emailed them some questions and about price and am awaiting a response.
 
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