Charge controller rec for LiFePO4 Deep Cycle Battery

[Jas]

Help please! I just bought a new Lithium ion battery Ampere Time 12V 200Ah Lithium Iron LiFePO4 Deep Cycle Battery, Built-in 100A BMS

but realized that my charge controller that came with this solar panel setup is only fitted for AMG/lead acid batteries.

So, I have two questions:

1. Can I use the same solar panels IF i link them up to a new charge controller and

2. what charge controller would you suggest I use to charge this specific battery?

Thanks a million. Can't believe I flubbed this one a week out.

Jas

(P.s. question 3. would this Renogy charge controller work?

[Elorrum]

You have the set of connector to bare end wires you need in this kit to attach to a charge controller with screw in fittings, yep.

Renogy site says that charge controller would work for lithium battery. Read the manual. There will be a setup menu to select chemistry and possibly voltage which you’ll need to have correct.

https://www.renogy.com/new-edition-voya ... ontroller/

[Elorrum]

I’ve read that A 120W solar panel can supply between 6 and 7.5 Amps on a sunny day, for most of the sunlight hours of the day. It’s possible you won’t need a 20 amp controller. The wanderer ten amp has 2 usb 5v 2A charge outlets built in which are kind of a neat thing (and can also work with a lithium battery.) at about half the price of the voyager model, though not waterproof. https://www.renogy.com/wanderer-10a-pwm ... =googlecsv

[Jas]

I’ve read that A 120W solar panel can supply between 6 and 7.5 Amps on a sunny day, for most of the sunlight hours of the day. It’s possible you won’t need a 20 amp controller. The wanderer ten amp has 2 usb 5v 2A charge outlets built in which are kind of a neat thing (and can also work with a lithium battery.) at about half the price of the voyager model, though not waterproof. https://www.renogy.com/wanderer-10a-pwm ... =googlecsv

Tysm . Yeah I love having the USB ports but I might expand my solar setup in the future and want the controller to be able to handle it.

[Token]

Look at the battery specifications. It will tell you the voltage needed to charge it correctly.

Usually it’s higher than Lead-Acid batteries by a few Volts plus a different charge cycle.

Then download the user manual for the charge controller you’re considering and see if they have a setting for the voltage you need and a charge program for the Lithium type of battery you have. INR vs FePO lithium’s will have different charge requirements.

[some seeing eye]

Batteries are delicate. They like a specific time-varying voltage and current, charging and discharging, and have temperature limits.

The common charge controller vendors are R*n*gy and V*ctr*n. The latter is more expensive and more long lived. Another variable is monitoring. Each vendor will have different monitoring including Bluetooth apps on your mobile device.

Different specific models have settings for different battery chemistry charging curves.

There are many forums discussing van, playa, and off grid solar charge controller buyer advice.

[HarryN]

Those R controllers are pretty much junk.

Get a bogart SC 2030 - will be much more reliable for what you are trying to do.

I have no affiliation other than I have used them.

The built in AGM setting on that controller is sufficient for your LiFe batteries.

[Jas]

Look at the battery specifications. It will tell you the voltage needed to charge it correctly.

Usually it’s higher than Lead-Acid batteries by a few Volts plus a different charge cycle.

Then download the user manual for the charge controller you’re considering and see if they have a setting for the voltage you need and a charge program for the Lithium type of battery you have. INR vs FePO lithium’s will have different charge requirements.

That’s really helpful. I’ve now set it all up and have another question. My LiFePo battery states in the manual that it ideally needs a charging voltage of 14.4V +\- 0.2V coming in from my 120W 12v solar array, so I set it to exactly that on my charge controller. But, my charge controller is displaying only about 13.6~13.7V incoming from the Panel.

Is this bad for my battery, and if so, how might I rectify it?

[HarryN]

The voyager is a PWM controller.

In actual operation, it will pull the Vmp of the panel down to the voltage of the battery charging side on a small wattage panel arrangement like that.

You are sort of using it all like a trickle charger and that is ok as long as it can keep up with your loads. In other words, I am not seeing a problem with how it is behaving based on what you have so far.

Let it charge the battery for a few days and see if the voltage rises.

Do you have a way to look at the current flow from the panel into the battery?

[some seeing eye]

Do not use a AGM charge controller settings on LiFePO4, or vice versa. Period.

Modern controllers have settings for multiple battery types at a button push.

[Token]

OK, your LiFePO4 battery is a 4-cell type with:

Nominal Voltage: 12.8V
Charging Voltage: 14.4V
Cell Nominal Voltage: 3.2V
Cell charging voltage: 3.6V

Please double-check the controller again and select the Lithium battery option (this sets the charging method) and set the correct voltage to 14.4.

What the unit is showing - 13.6V is not correct for your battery.

13.6V is the ‘float’ voltage for maintaining charge levels on an AGM battery and it is very likely that your charge controller is set in AGM mode.

If you have a multimeter handy, this is a good time to start measuring voltage at every component in your system.

[Jas]

OK, your LiFePO4 battery is a 4-cell type with:

Nominal Voltage: 12.8V
Charging Voltage: 14.4V
Cell Nominal Voltage: 3.2V
Cell charging voltage: 3.6V

Please double-check the controller again and select the Lithium battery option (this sets the charging method) and set the correct voltage to 14.4.

What the unit is showing - 13.6V is not correct for your battery.

13.6V is the ‘float’ voltage for maintaining charge levels on an AGM battery and it is very likely that your charge controller is set in AGM mode.

If you have a multimeter handy, this is a good time to start measuring voltage at every component in your system.

Thanks Token. I double checked everything.

“Battery type” on charge controller is set to LI [not SEAL/GEL/FLD], “battery voltage” is set for 12V (versus 24), and charging voltage is set to 14.4V. I even reset it now just to be sure. Same reading: 13.6 V coming in from my array (now getting down to 13.3 now that I’m getting even sun)

[Jas]

OK, your LiFePO4 battery is a 4-cell type with:

Nominal Voltage: 12.8V
Charging Voltage: 14.4V
Cell Nominal Voltage: 3.2V
Cell charging voltage: 3.6V

Please double-check the controller again and select the Lithium battery option (this sets the charging method) and set the correct voltage to 14.4.

What the unit is showing - 13.6V is not correct for your battery.

13.6V is the ‘float’ voltage for maintaining charge levels on an AGM battery and it is very likely that your charge controller is set in AGM mode.

If you have a multimeter handy, this is a good time to start measuring voltage at every component in your system.

Thanks Token. I double checked everything.

“Battery type” on charge controller is set to LI [not SEAL/GEL/FLD], “battery voltage” is set for 12V (versus 24), and charging voltage is set to 14.4V. I even reset it now just to be sure. Same reading: 13.6 V coming in from my array (now getting down to 13.3 now that I’m getting even sun)

Here’s the charge controller manual on setting it to Lithium

[Token]

Well that’s a pickle.

Your solar panel has these specs:

Voltage at nominal power [V] Vmp 20.8V

Current at nominal power [A] Imp 5.97A

Open-circuit voltage [V] Voc 24.6V

Short-circuit current [A] Isc 6.32A

So the panel voltage should be much higher.

Other than going to a multimeter and measuring, looks like you done things right.

You can try to continue troubleshooting or get a different part. Time is running out.

[Token]

This might be the problem:

Be careful of the your application. The listing has the DC input voltage is 15-55 volts. That is not accurate. When charging a 12 volt battery, the DC input rating is only 15-20 VDC. So match the solar array carefully. If you want to use a pair of panel to increase the charge rate, you'll likely need to wire them in parallel. Select panels carefully. A panel rated at 15.1 VDC at SCT is not going to make 15 VDC is the summer heat. So keep your VOC's towards the middle of the range. Start out too close to 20VDC, and winter time cold temperatures will push the VDC over 20. They stop charging in either situation. Its a very narrow window to play with, so do your VOC calculations based on expected high and low temperatures, and the temperature coefficients shown on the solar panel's label or specs.

Otherwise these are well built units I've used several times for the past 5 years in remote equipment 12V battery charging conditions.

Your panel likely has too high voltage for this controller.

[Jas]

This might be the problem:

Be careful of the your application. The listing has the DC input voltage is 15-55 volts. That is not accurate. When charging a 12 volt battery, the DC input rating is only 15-20 VDC. So match the solar array carefully. If you want to use a pair of panel to increase the charge rate, you'll likely need to wire them in parallel. Select panels carefully. A panel rated at 15.1 VDC at SCT is not going to make 15 VDC is the summer heat. So keep your VOC's towards the middle of the range. Start out too close to 20VDC, and winter time cold temperatures will push the VDC over 20. They stop charging in either situation. Its a very narrow window to play with, so do your VOC calculations based on expected high and low temperatures, and the temperature coefficients shown on the solar panel's label or specs.

Otherwise these are well built units I've used several times for the past 5 years in remote equipment 12V battery charging conditions.

Your panel likely has too high voltage for this controller.

You sure? These are the specs from the manual.

It just seems like it should handle it.

Worst comes to worse, will this low charging voltage damage my battery, or just charge it too slowly?

[Jas]

The voyager is a PWM controller.

In actual operation, it will pull the Vmp of the panel down to the voltage of the battery charging side on a small wattage panel arrangement like that.

You are sort of using it all like a trickle charger and that is ok as long as it can keep up with your loads. In other words, I am not seeing a problem with how it is behaving based on what you have so far.

Let it charge the battery for a few days and see if the voltage rises.

Do you have a way to look at the current flow from the panel into the battery?

Yeah- that’s helpful thanks. I’m just trying not to damage my brand new battery. My loads are mostly pretty low. I can live with slow charging if it doesn’t cause long term damage to it

[Jas]

This might be the problem:

Be careful of the your application. The listing has the DC input voltage is 15-55 volts. That is not accurate. When charging a 12 volt battery, the DC input rating is only 15-20 VDC. So match the solar array carefully. If you want to use a pair of panel to increase the charge rate, you'll likely need to wire them in parallel. Select panels carefully. A panel rated at 15.1 VDC at SCT is not going to make 15 VDC is the summer heat. So keep your VOC's towards the middle of the range. Start out too close to 20VDC, and winter time cold temperatures will push the VDC over 20. They stop charging in either situation. Its a very narrow window to play with, so do your VOC calculations based on expected high and low temperatures, and the temperature coefficients shown on the solar panel's label or specs.

Otherwise these are well built units I've used several times for the past 5 years in remote equipment 12V battery charging conditions.

Your panel likely has too high voltage for this controller.

You sure? These are the specs from the manual.

It just seems like it should handle it.

Worst comes to worse, will this low charging voltage damage my battery, or just charge it too slowly?

I found some helpful information on this forum where OP is reporting the same problem with a different controller: https://forum.solar-electric.com/discu ... tery-maybe

Related to what Harry N said about, this comment from Raj174 seemed relevant, considering my own LiFePo (like the OP’s) arrived with a pretty high SoC:

“ Try to look at it as if the battery were a load on the charge controller. If the battery needs more amps than the charge controller can supply then the voltage will drop. The charge controller's actual output is still 14.4 volts, but the load that the battery is putting on it is dragging the voltage down.”

Thoughts?

[Token]

The quote I posted was from a user review, so take it for what it is. Similar to what you posted from the user forum. Could just be pseudo-science.

On the charge controller, toggle the display and report back the current it is reporting when the voltage shown is 13.8 - for Li batteries, charging is done via constant-current for bulk, then switched over to constant-voltage to finish off. It is possible that the bulk charging is done at 13.4 ~ 13.8 depending on input power from solar to maintain constant-current.

The only way you will know:

Get your hands on a digital multimeter of some kind that can measure DC voltage.

Start measuring voltage at the following points when the solar panel is in full sun:

Solar panel output voltage while connected to full system (charge controller + battery)

Charge controller battery terminal while connected to the battery.

Next: Remove fuse from battery circuit and repeat measurement of charge controller battery terminal voltage.

Next: Disconnect solar panel from charge controller and measure the no-load voltage from the solar panel.

This will give you all the data to figure it out.

[Jas]

The quote I posted was from a user review, so take it for what it is. Similar to what you posted from the user forum. Could just be pseudo-science.

On the charge controller, toggle the display and report back the current it is reporting when the voltage shown is 13.8 - for Li batteries, charging is done via constant-current for bulk, then switched over to constant-voltage to finish off. It is possible that the bulk charging is done at 13.4 ~ 13.8 depending on input power from solar to maintain constant-current.

The only way you will know:

Get your hands on a digital multimeter of some kind that can measure DC voltage.

Start measuring voltage at the following points when the solar panel is in full sun:

Solar panel output voltage while connected to full system (charge controller + battery)

Charge controller battery terminal while connected to the battery.

Next: Remove fuse from battery circuit and repeat measurement of charge controller battery terminal voltage.

Next: Disconnect solar panel from charge controller and measure the no-load voltage from the solar panel.

This will give you all the data to figure it out.

Just grabbed one this morning. Thank you

[Jas]

This might be the problem:



Your panel likely has too high voltage for this controller.

You sure? These are the specs from the manual.

It just seems like it should handle it.

Worst comes to worse, will this low charging voltage damage my battery, or just charge it too slowly?

I found some helpful information on this forum where OP is reporting the same problem with a different controller: https://forum.solar-electric.com/discu ... tery-maybe

Related to what Harry N said about, this comment from Raj174 seemed relevant, considering my own LiFePo (like the OP’s) arrived with a pretty high SoC:

“ Try to look at it as if the battery were a load on the charge controller. If the battery needs more amps than the charge controller can supply then the voltage will drop. The charge controller's actual output is still 14.4 volts, but the load that the battery is putting on it is dragging the voltage down.”

Thoughts?

Reporting back: I depleted my battery last night for an hour or so and started charging it again today in noon-time sunlight.

The charging voltage on the controller is now up to 14.0V, which lines up with the theory above.

Will continue to monitor the situation. Thanks again all!

[Token]

OK, that lines up with industry standard for Li batteries : Bulk charge at constant current, float at constant voltage.

Li batteries hate trickle charging, so all the curves and methods used in Pb batteries got thrown out the window.

See if it charges up to capacity and expected voltage once you leave it in the sun long enough.

Measure the battery voltage with the DMM after dark to get true reading. Should reach 14.4V once fully charged.

One of the earlier comments on Renogy being low-end : this is why. I wouldn’t call them garbage, but they just barely cover the specifications and are a bit removed from best-practice.