Planning a small device charge setup, input so welcome.

[gmcoates]

Hi

I am very new to the Solar world and have been learning what I can to get started. I am on a budget and don't want to get initial spending in the wrong place and have that put me off learning so I am hoping to find help from a community so I get off to the best start possible.

I have been looking to use a battery I already have. Its a Celestron Powertank Lithium LT, typically used for powering a telescope but it also has USB out so can be used to charge small devices. As I have this battery I wanted to create my first setup using that so I keep initial costs down.

I have been looking for a relatively inexpensive first panel, I would spend around £100 but can be flexible to get a decent panel that in the future has other uses, I think the panels I have looked at so far would all be a decent fit.

I think the area I need help with the the Charge Controller, I need to make sure I get the correct one so I don't harm the battery I have and I am a little confused about this. Again I would spend around £100 as I am sure that would give me flexibility in the future for, new batteries and panels.

So I guess the question is which charge controller do I start with. The battery has an input of 16VDC@2000ma (that still doesn't mean loads to me but I'm learning). From what I can tell most change controllers will determine this about the battery and set the correct charge for the battery to get the best from the panel without harming the battery.

Is that a correct assumption? Would most controllers work in this situation.

Any help would be really appreciated for this newbie.

Thanks in advance.

 

[sunshine_eggo]

This?

https://celestron-site-support-files.s3.amazonaws.com/support_files/18763_PowerTank_Lithium__Li_Manual.pdf

Manual indicates 12V input. Specs repeat the 16V/2A input.

Take a look at the AC charger. It should list its DC output, voltage and current.

Other consideration:

Charge controllers work by being POWERED by the battery (since the sun doesn't shine at night). If this unit's INPUT doesn't also provide output, typical charge controllers won't work. If that's the case, you'll need something different - like a DC-DC converter that doesn't need to pull current from the battery.

 

[gmcoates]

Hi

Thanks for your reply, all information I get is helpful at this stage.

The AC/DC charger shows an output of DC 16V/2A.

The units input (what I use to charge it) is the same as used to connect to the telescope I normally use it with the input is also output so that should provide the charge controller power.

As I would like to remove the Powertank to use around the house I guess I would need another battery or load from the charge controller to prevent it being damaged from a solar panel providing charge.

That leads me to other ideas, maybe I just buy a full but small solar system to start, Jackery or similar. I could then charge the Powertank from the Jackery. That would give me a very simple start and additional battery.

 

[Rednecktek]

That leads me to other ideas, maybe I just buy a full but small solar system to start, Jackery or similar. I could then charge the Powertank from the Jackery. That would give me a very simple start and additional battery.

That is definitely the simplest way to go. Get yourself the right adapter (MC4 -> 8mm?) for the Jackery's input and just go panel -> Jackery -> Powertank. You'll lose a little efficiency but it's pretty small and VERY simple.

If you haven't bought a panel yet, any of the Mono or Poly crystalline 100w panels would be a good start. They're pretty universal so easy to build on in the future. AVOID any flexible panels or Amorphous as they're WAY overpriced for the performance and it doesn't sound like you need it to be flexible. When looking at panels, you'll find cheap "100w" kits/panels that aren't actually what they say. In the specs there should be listings for VoC (voltage, open circuit) and Imp (amperage). Multiply VoC by Imp and that'll give you the real watts of the panel. It's a buyer beware situation out there. If you stick to the name brands like HQST, Renology, etc you should be OK. If the picture shows a small panel, maybe with holes in the corners, run away.

 

[gmcoates]

That is definitely the simplest way to go. Get yourself the right adapter (MC4 -> 8mm?) for the Jackery's input and just go panel -> Jackery -> Powertank. You'll lose a little efficiency but it's pretty small and VERY simple.

If you haven't bought a panel yet, any of the Mono or Poly crystalline 100w panels would be a good start. They're pretty universal so easy to build on in the future. AVOID any flexible panels or Amorphous as they're WAY overpriced for the performance and it doesn't sound like you need it to be flexible. When looking at panels, you'll find cheap "100w" kits/panels that aren't actually what they say. In the specs there should be listings for VoC (voltage, open circuit) and Imp (amperage). Multiply VoC by Imp and that'll give you the real watts of the panel. It's a buyer beware situation out there. If you stick to the name brands like HQST, Renology, etc you should be OK. If the picture shows a small panel, maybe with holes in the corners, run away.

Brilliant, thats very useful. I was looking at a Jackery 240, start cheap. I also had my eye on a Renogy 100 Watt 12 Volt Monocrystalline Panel on amazon at £77. Its a solid panel which is what I would want as its a start point and as you suggest could be used in a bigger system in the future. The specs below suggest 100w as you have mentioned with the calculations. Plus an adapter for the panel to get to the 8mm for the Jackery.

The panel specs:

• Maximum Power: 100W
• Maximum System Voltage: 600V DC (UL)
• Optimum Operating Voltage (Vmp): 18.6V
• Open-Circuit Voltage (Voc): 22.3V
• Optimum Operating Current (Imp): 5.38A
• Short-Circuit Current (Isc): 5.86A
• Weight: 14.3 lbs (6.5 kg)
• Dimensions: 42.4 X 20.0 X 1.38 In(1076 x 509 x 35mm)

 

[Rednecktek]

Yup, that's a good starter setup!