Can I charge lithium batteries with lead acid solar charge controller ?

Thread Starter

M3D0

Joined Oct 8, 2020
49
I bought this solar charge controller (CMP12 Solar Charge Controller 10 AMP 12V/24V auto switch), which I was going to use to charge (lithium-ion super rechargeable battery pack (12V, 3A). I know this will harm the battery, my question here is how much damage will the solar charger will cause to the battery over time, is it a long duration damage process or a short one (instantly damaged)? I will be using this for a small project which I will be using for a few times for only demonstration purposes. I would like to know if there is any way to slow down the damaging process of the battery.

More Detailed information about the mentioned components:
Battery: https://ram-e-shop.com/product/battery-li-12v-3000mah/
Solar charge controller: http://www.gadgetpower.co.uk/12V_24V_10A_charge_controller_CMP12.pdf

Thanks in advance!
 

SgtWookie

Joined Jul 17, 2007
22,220
You are wanting to use a charge controller that is capable of supplying more current than the battery is rated for, and the battery chemistry is different than than the charge controller was designed for.

Rather than just damage to the battery, I'm wondering how long until you have a blazing fire.

If you still try to use these woefully mismatched battery and charge controller together, I suggest you place them in an outdoor brick barbeque pit or a large gravel, sand or concrete surface away from anything combustible. Have a pair of welding gloves handy for when you panic and try to pull the flaming battery wires from the controller, and have protective face mask and flame retardant clothing on. Keep an ABC class fire extinguisher handy.

It would be a whole lot safer and far cheaper to just buy the proper battery charger for your battery chemistry, mAh capacity and voltage. Unintended fires tend to be not only inconvenient and dangerous, but very expensive.
 

Audioguru again

Joined Oct 21, 2019
2,048
The battery says it is 100% safe but it has absolutely no detailed spec's.
Today on another website forum a battery protection circuit burned out with smoke because a charger that is too powerful was used.
 

Bernard

Joined Aug 7, 2008
5,680
It looks like you are caught between a rock and a hard place. Did battery come with any information? Lacking any better information, I would measure V of the battery , multiply reading by 1.14 for estimated charge cut off V and multiply by .85 for cut off V. I would connect SP thru a diode to battery. Monitor battery V. I made a solar charger for 2 LiFePO4 batteries in series which lasted for 2 years when during Winter one cell went squirlley. On close inspection in fine print cells were LiPO4-lost the Fe. Some day will convert to NiMH.
 

OBW0549

Joined Mar 2, 2015
3,566
I know this will harm the battery, my question here is how much damage will the solar charger will cause to the battery over time, is it a long duration damage process or a short one (instantly damaged)?
I would expect drama within the first few minutes.
 

Thread Starter

M3D0

Joined Oct 8, 2020
49
It looks like you are caught between a rock and a hard place. Did battery come with any information? Lacking any better information, I would measure V of the battery , multiply reading by 1.14 for estimated charge cut off V and multiply by .85 for cut off V. I would connect SP thru a diode to battery. Monitor battery V. I made a solar charger for 2 LiFePO4 batteries in series which lasted for 2 years when during Winter one cell went squirlley. On close inspection in fine print cells were LiPO4-lost the Fe. Some day will convert to NiMH.
Can you please show me the schematic of the circuit you made or the connection? This will help me a lot! Thanks in advance.
 

Irving

Joined Jan 30, 2016
1,056
As I see two (insurmountable?) problems....

1) Its not clear what actual charge voltage is needed. If 3S LiPo (11.1v out, 12.6v charge) might be OK. 4S LiPo with regulator (12v out, 16.4v charge) would potentially be difficult.

2) need to limit supply current to cells to say 1.5-2A, with constant current output- that's pretty easy, except there's not enough voltage headroom, a CC chargecontroller needs 1 - 1.5v headroom over output.

That charger could potentially ruin lead-acid cells over time as it doesn't provide enough volts at 13.7 to fully charge a good SLA (need typically 14.4 - 14.8 depending on brand) so cells would never be fully charged, but would be safe as the are voltage basd charge not CC charging.

4S LiFePO4 cells (12.8 out, 14.6 charge) would have similar 'not fully charged' issues, but at least would be safe.
 

Bernard

Joined Aug 7, 2008
5,680
This circuit from 9-19-2015, includes a dusk to dawn control & comes with no guarantees.
A short video is still on YouTube, Jack Bernard 202259.
LH Battery Manage. 00000.jpg
 
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Thread Starter

M3D0

Joined Oct 8, 2020
49
This circuit from 9-19-2015, includes a dusk to dawn control & comes with no guarantees.
A short video is still on YouTube, Jack Bernard 202259.
View attachment 219528
Thank you so much for providing the circuit schematic, I have watched the miniature lighthouse demonstration, interesting light intensity control I have to say. There are a few things that are not clear to me I hope you could help me with.

1- There are three components that are not connected to anything like ( LM3362, LM339N, and FDS9435A), can you please where should these components be connected to? (I have attached the same schematic with these components circled to make things more clear).

2- I'm assuming that there are two terminals for the lithium battery the [Low Bat.] is being for the negative terminal for the battery and the [6-6.6V] is the positive terminal (correct me if I'm wrong). I still didn't get what is the [Hi Bat.] label is for.

3- I see that there is a battery is being used (beside the D1 1N 5817 diode, at the top of the circuit), what is the use of this battery and what is the voltage of this battery.

4- Is there another terminal for connecting the load? I couldn't recognize other terminals except the SP, and the battery terminals.

Thank you again for sharing this information and for your help, much appreciated.
 

Attachments

Audioguru again

Joined Oct 21, 2019
2,048
The charger circuit is for a two-cells LiFeP04 battery that you do not have.
Your battery has three cells for a higher voltage and I think (it does not say) it does not have Fe in it for a little lower voltage per cell.
This charger puts out a very high charging current for a big battery. It will explode your smaller battery.
This charger does not balance-charge.
 

Wolframore

Joined Jan 21, 2019
1,907
That battery is not designed for balance charge. Cheap Chinese garbage that’s not designed to last or even to be safe, also probably advertised as having higher capacity than they are. I have one I bought to use for a bicycle light and ended up getting a power bank system with a real charging system instead. More trouble than they’re worth.
 

Thread Starter

M3D0

Joined Oct 8, 2020
49
The charger circuit is for a two-cells LiFeP04 battery that you do not have.
Your battery has three cells for a higher voltage and I think (it does not say) it does not have Fe in it for a little lower voltage per cell.
This charger puts out a very high charging current for a big battery. It will explode your smaller battery.
This charger does not balance-charge.
Yeah, I did notice that, actually my second question was how to modify this circuit to be able to charge my Three cells lithium-ion battery.
 

Audioguru again

Joined Oct 21, 2019
2,048
Instead of modifying the very old circuit, why not buy a modern battery and charger made for it, or buy a Lithium-ion battery charger IC and make your own charger?

I have many Li-PO batteries and a few chargers made for them. They are inexpensive and safe. They are made by the same company. I buy them at my local hobby store.
 

Irving

Joined Jan 30, 2016
1,056
1- There are three components that are not connected to anything like ( LM3362, LM339N, and FDS9435A), can you please where should these components be connected to? (I have attached the same schematic with these components circled to make things more clear).
The LM336Z refers to the +2.5 reference above and the diagram below shows its pinout.
The rest are spares.
2- I'm assuming that there are two terminals for the lithium battery the [Low Bat.] is being for the negative terminal for the battery and the [6-6.6V] is the positive terminal (correct me if I'm wrong). I still didn't get what is the [Hi Bat.] label is for.
Wrong assumption.
Hi-BATT is a reference to R5 which sets the cutoff voltage for charging. The battery in the top centre of the diagram is the one being charged. Only the circuitry to the left-hand side of the battery is charge management. The arrow from the ground connection/battery -ve (bottom centre) labelled LH is the -ve connection to the Lighthouse. (LOAD)

The "LOW BATT LH" is confusing. As said above, the arrow & LH is the -ve connection to the LOAD. Most of the right-hand side of that diagram is discharge control and LOW BATT refers to the potentiometer R11 which sets the cut-off battery volts.
3- I see that there is a battery is being used (beside the D1 1N 5817 diode, at the top of the circuit), what is the use of this battery and what is the voltage of this battery.
That's the battery being charged.

4- Is there another terminal for connecting the load? I couldn't recognize other terminals except the SP, and the battery terminals.
No, see answer [2]

This is a really bad LiPo/LIFEPO4 charger, more like a lead-acid charger. It connects the solar panel (18v open circuit, 160mA short circuit) directly to the battery, as long as SP volts > battery volts and battery volts < 7.2v, relying on the SP's max current output to control charge rate until 7.2v is reached, then it stops charging (U3B/R5). U3C/R11 control discharge, turning the output off below 5.6v. U3A turns the output off if SP volts > 5v (e.g. Lighthouse only on at 'Night').

And it doesn't balance.... (though that's the least of your worries)

A charging circuit to charge LiPo directly from a solar panel isn't so hard, but need to know much more about your solar panel before contemplating that. Post a link to the panel.
 

Irving

Joined Jan 30, 2016
1,056
It is the Lithium battery that has no detailed spec's. Maybe it has a protection circuit in it.
Well the charge controller's specs are detailed enough to know its probably not great, but not enough to know how it works, limitations or even what solar panels it works with (other than '12v panel', which is meaningless....)
 

Bernard

Joined Aug 7, 2008
5,680
M3D0, have you measured the battery voltage ?
Measured solar panel V & I ?
For charging your Li-ion, it is desirable to charge at a constant current of about 2 A at a constant V of ?, as solar panel can not keep up, just run with what you have.
 
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Thread Starter

M3D0

Joined Oct 8, 2020
49
MD30, have you measured the battery voltage ?
Measured solar panel V & I ?
I didn't measure the actual battery voltage nor the solar panel voltage or current, I'm just working with the values provided in the specifications written for each part.
 
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