Can you safely use a motorbike 12V GEL battery in a PV system ?

Haglun · 12-09-18, 04:08 AM

Eventually, my goal is to build IoT functionalities on top of it, using micro controllers. This way I will be able to monitor the PV, battery and control loads from a web app. I can do a few things in IoT, but I am a complete beginner in PV systems.

For the moment, the cheapest parts I found are the following:
- 18v, 85 watts solar panel
- 12v GEL battery (Motorcycle GSYUASA GETX9-BS from Rakuten - can't post URLs yet)
- PWM charge controller (AP-OT-002 from amazon - can't post URLs yet)

I suspect that the system will be pretty inefficient. I also know that the battery is insufficient to store all the electricity i can get from the solar panel. It is ok, my goal is to get a first experience and and the focus is on implementing IoT.
But I have the following question:

Is it safe to use the GEL battery to charge home appliances (using a 12v-5v DC converter) ?
I read that the GEL batteries are safe because they do not reject Hydrogen. But the battery manual says that the battery may reject hydrogen, and advises not to use it for any other purpose than engine starting.

Please tell me about any potential risks of using such a battery to store the PV generated electricity and charge small appliances (I will connect it to a 12 to 5V DC converter). Also, I have a lot to learn about PV systems, so I'm interested in any other remark you have.

jjackstone · 12-09-18, 11:24 AM

Shouldn't be a problem. My company used to use small gel cells all the time as backup power for small electronic systems. If there was out gassing from the battery it would more likely come from being over-charged than discharged.

I assume by small appliances you are talking about things like cell phones, tablets...etc. Motorcycle batteries aren't made for long term discharge so I would only use it for something that doesn't bring the voltage down too much. Try it out and let us know how it works for you,
JJ

oil pan 4 · 12-09-18, 09:17 PM

It won't last very long.
It's a starting gel battery. Just about the worst battery you could pick.
If the charge controller ever tried to run an equalization cycle the battery would be toast.

Haglun · 04-08-19, 06:27 AM

Thank you for your replies !
A quick update, it has been working fine so far.
Indeed, i don't expect the battery to last very long. The point was to experiment whether i could recycle batteries from motorcycles, so the lifetime is not a big issue (the batteries wouldn't be used anyway).

philb · 04-10-19, 05:22 PM

You could easily feed two 6 volt golf cart batteries in series with an 85 watt module. I would buy a quality charge controller to turn off the panels and prevent overcharge.

My first batteries were small gel cells. They only lasted a few months. Some large UPS's have gel cells that are larger than automotive batteries. They last longer but also will fry from equalization.

12-09-18, 04:08 AM	#1
Haglun Lurking Renovator Join Date: Dec 2018 Location: Japan Posts: 2 Thanks: 2 Thanked 0 Times in 0 Posts	Can you safely use a motorbike 12V GEL battery in a PV system ? Eventually, my goal is to build IoT functionalities on top of it, using micro controllers. This way I will be able to monitor the PV, battery and control loads from a web app. I can do a few things in IoT, but I am a complete beginner in PV systems. For the moment, the cheapest parts I found are the following: - 18v, 85 watts solar panel - 12v GEL battery (Motorcycle GSYUASA GETX9-BS from Rakuten - can't post URLs yet) - PWM charge controller (AP-OT-002 from amazon - can't post URLs yet) I suspect that the system will be pretty inefficient. I also know that the battery is insufficient to store all the electricity i can get from the solar panel. It is ok, my goal is to get a first experience and and the focus is on implementing IoT. But I have the following question: Is it safe to use the GEL battery to charge home appliances (using a 12v-5v DC converter) ? I read that the GEL batteries are safe because they do not reject Hydrogen. But the battery manual says that the battery may reject hydrogen, and advises not to use it for any other purpose than engine starting. Please tell me about any potential risks of using such a battery to store the PV generated electricity and charge small appliances (I will connect it to a 12 to 5V DC converter). Also, I have a lot to learn about PV systems, so I'm interested in any other remark you have.

12-09-18, 11:24 AM	#2
jjackstone Helper EcoRenovator Join Date: Mar 2009 Location: Sacramento,Ca Posts: 88 Thanks: 5 Thanked 32 Times in 23 Posts	Shouldn't be a problem. My company used to use small gel cells all the time as backup power for small electronic systems. If there was out gassing from the battery it would more likely come from being over-charged than discharged. I assume by small appliances you are talking about things like cell phones, tablets...etc. Motorcycle batteries aren't made for long term discharge so I would only use it for something that doesn't bring the voltage down too much. Try it out and let us know how it works for you, JJ

12-09-18, 09:17 PM	#3
oil pan 4 Land owner Join Date: Nov 2012 Location: NM Posts: 1,026 Thanks: 12 Thanked 127 Times in 107 Posts	It won't last very long. It's a starting gel battery. Just about the worst battery you could pick. If the charge controller ever tried to run an equalization cycle the battery would be toast.

04-08-19, 06:27 AM	#4
Haglun Lurking Renovator Join Date: Dec 2018 Location: Japan Posts: 2 Thanks: 2 Thanked 0 Times in 0 Posts	Thank you for your replies ! A quick update, it has been working fine so far. Indeed, i don't expect the battery to last very long. The point was to experiment whether i could recycle batteries from motorcycles, so the lifetime is not a big issue (the batteries wouldn't be used anyway).

04-10-19, 05:22 PM	#5
philb Apprentice EcoRenovator Join Date: Nov 2010 Location: Oklahoma City Posts: 155 Thanks: 58 Thanked 17 Times in 14 Posts	You could easily feed two 6 volt golf cart batteries in series with an 85 watt module. I would buy a quality charge controller to turn off the panels and prevent overcharge. My first batteries were small gel cells. They only lasted a few months. Some large UPS's have gel cells that are larger than automotive batteries. They last longer but also will fry from equalization.