Renogy 24v 200Ah Capacity Test Failed - Or I Did?

[discofunk]

I am hoping to get insight from you guys about an issue I am seeing on a recently purchased setup. I have been dreaming of the day I could replace my flooded batteries in our motorhome with LifePo4. Doing my research I understood that more than just the batteries need to be replaced (i.e. charge controller, alternator charging DC-DC).

I settled on doing a 24v system. Being in Canada our choices are a lot more limited for products we can get. Ultimately I decided to go with an Eco-Worthy 3000W 24v all-in-one paired with a Renogy 24v 200Ah self-heated LifePo4 (200A charge/discharge). I also had an existing Junctek KG140F 400A shunt.

All-in-one: https://ca.eco-worthy.com/products/...r-inverter-60a-controller-for-off-grid-system
Battery: https://ca.renogy.com/core-24v-200ah-deep-cycle-lithium-iron-phosphate-battery/
Shunt: https://www.aliexpress.com/item/1005005821745128.html

The all-in-one is similar to an SNRE HF2430U60-100 or PowMr

I received the battery and inverter on Feb. 8th 2024 and kept the battery inside my house. I proceeded to wire up a test rig before installing it in my RV to work out any bugs. From the positive battery terminal I go to a 200A T-Class fuse, into a disconnect switch and then into the inverter. From the negative terminal I go into the shunt and then into the all-in-one.



On Feb. 11th (4 days after receiving it) I hooked the battery up for the first time and powered on the inverter. I updated the all-in-one configuration from "GEL" to "L08" and set the Boost Charge Voltage to 29v as this was what was listed on the battery manual. I reduced the AC-DC charging to 30A as to not stress my 15A/120v main circuit. I plugged the all-in-one into mains and it began to charge the battery and eventually indicated the charging was complete.

The next day I (4 days since I had the battery) I proceeded to do a capacity test. I plugged a 1200W heat gun into the inverter and let it run. The shunt showed ~50A draw and I confirmed this with a clamp meter. During this test I watched the voltage and it seemed to be dropping quicker than expected. Eventually the BMS disconnected the battery. The shunt showed only ~100Ah was used. The elapsed time was ~2 hours so this lines up. This was odd to me as this was suppose to be a 200Ah battery so I only got 1/2 the capacity I was expecting.

Naturally, I decided to run the test again so I charged the battery until "full" then ran the test again and again only got 100Ah from it.

At this point I was worried the all-in-one may not be fully charging the battery (and this may still be an issue) so I ordered a AC-DC LifePo4 10A charger. This took several days to arrive but when I did I charged the battery again (took a while).

https://www.amazon.ca/dp/B09ZLDTRZ9

I ran another capacity test and found that I still only got ~100Ah (50A @ 2hrs).

During charging from the all-in-one I've observed the current steady at 30A and the voltage slowly increases. I have never observed it hitting 29v while charging but I did dump the shunt log at one point and see that it hit a max voltage of 29.4 at some point.

Some other things to note - as I did not want to burn my house down so I did my initial tests in my garage and the ambient temperature went as low as 4C (39F). This shouldn't be a problem though as this is a "cold weather" LifePo4 battery and the temp never went below 0C (32F). I have since moved it all into my house.

So question is - did I do something wrong? Could it be a bad battery? Is the all-in-one not working as expected?

Even if I am not achieving 100% SOC I should be getting more than 50%

I've opened a claim with Renogy about the battery and is currently in progress but I would like to know from your experience if anything jumps out as odd or wrong with what I have done so far?

 

[discofunk]

I logged the data from the shunt for charging from the all in one - here is the charge profile:


As well, I logged charging from the AC-DC LifePo4 charger:


And finally during one of the capacity tests:

 

[sunshine_eggo]

The voltage spike behavior indicates the battery isn't balanced. This is incredibly common across all brands.

recommend you hold the battery at 27.6V for 24 hours and re-test.

Alternatively, engage in small discharges and about 5A charges to peak voltage.

The BMS should bring the cells into balance.

Regular cycling and charging to > 27.6V should keep the battery balanced.

 

[NIFE]

I am hoping to get insight from you guys about an issue I am seeing on a recently purchased setup. I have been dreaming of the day I could replace my flooded batteries in our motorhome with LifePo4. Doing my research I understood that more than just the batteries need to be replaced (i.e. charge controller, alternator charging DC-DC).

I settled on doing a 24v system. Being in Canada our choices are a lot more limited for products we can get. Ultimately I decided to go with an Eco-Worthy 3000W 24v all-in-one paired with a Renogy 24v 200Ah self-heated LifePo4 (200A charge/discharge). I also had an existing Junctek KG140F 400A shunt.

All-in-one: https://ca.eco-worthy.com/products/...r-inverter-60a-controller-for-off-grid-system
Battery: https://ca.renogy.com/core-24v-200ah-deep-cycle-lithium-iron-phosphate-battery/
Shunt: https://www.aliexpress.com/item/1005005821745128.html

The all-in-one is similar to an SNRE HF2430U60-100 or PowMr

I received the battery and inverter on Feb. 8th 2024 and kept the battery inside my house. I proceeded to wire up a test rig before installing it in my RV to work out any bugs. From the positive battery terminal I go to a 200A T-Class fuse, into a disconnect switch and then into the inverter. From the negative terminal I go into the shunt and then into the all-in-one.

View attachment 198912

On Feb. 11th (4 days after receiving it) I hooked the battery up for the first time and powered on the inverter. I updated the all-in-one configuration from "GEL" to "L08" and set the Boost Charge Voltage to 29v as this was what was listed on the battery manual. I reduced the AC-DC charging to 30A as to not stress my 15A/120v main circuit. I plugged the all-in-one into mains and it began to charge the battery and eventually indicated the charging was complete.

The next day I (4 days since I had the battery) I proceeded to do a capacity test. I plugged a 1200W heat gun into the inverter and let it run. The shunt showed ~50A draw and I confirmed this with a clamp meter. During this test I watched the voltage and it seemed to be dropping quicker than expected. Eventually the BMS disconnected the battery. The shunt showed only ~100Ah was used. The elapsed time was ~2 hours so this lines up. This was odd to me as this was suppose to be a 200Ah battery so I only got 1/2 the capacity I was expecting.

Naturally, I decided to run the test again so I charged the battery until "full" then ran the test again and again only got 100Ah from it.

At this point I was worried the all-in-one may not be fully charging the battery (and this may still be an issue) so I ordered a AC-DC LifePo4 10A charger. This took several days to arrive but when I did I charged the battery again (took a while).

https://www.amazon.ca/dp/B09ZLDTRZ9

I ran another capacity test and found that I still only got ~100Ah (50A @ 2hrs).

During charging from the all-in-one I've observed the current steady at 30A and the voltage slowly increases. I have never observed it hitting 29v while charging but I did dump the shunt log at one point and see that it hit a max voltage of 29.4 at some point.

Some other things to note - as I did not want to burn my house down so I did my initial tests in my garage and the ambient temperature went as low as 4C (39F). This shouldn't be a problem though as this is a "cold weather" LifePo4 battery and the temp never went below 0C (32F). I have since moved it all into my house.

So question is - did I do something wrong? Could it be a bad battery? Is the all-in-one not working as expected?

Even if I am not achieving 100% SOC I should be getting more than 50%

I've opened a claim with Renogy about the battery and is currently in progress but I would like to know from your experience if anything jumps out as odd or wrong with what I have done so far?

Does your shunt have a voltage sense wire connected directly to a battery post? Useful for further troubleshooting would be measuring all voltages with a separate DVM directly off the battery posts. When completing the 24 hr charge, measure the voltage before disconnecting the charger. If time allows, let the battery set disconnected (one terminal) for 3+ hours, preferably overnight. Record that voltage before the next discharge test.

 

[discofunk]

The voltage spike behavior indicates the battery isn't balanced. This is incredibly common across all brands.

recommend you hold the battery at 27.6V for 24 hours and re-test.

Alternatively, engage in small discharges and about 5A charges to peak voltage.

The BMS should bring the cells into balance.

Regular cycling and charging to > 27.6V should keep the battery balanced.

Thanks for your reply. I could look at purchasing a power supply to see if this works but I am wondering if this possible imbalance could result in a capacity half of what the rated capacity is? This is a brand new battery from a reputable brand.... From my perspective, I haven't done anything to harm the battery from what I can see - it is getting close to 30 days since purchase and I guess what I'm hoping is that Renogy will replace this battery but I want to make sure I'm not doing anything wrong. This is frustrating for me as I paid more for a brand battery but it is falling short and I don't think consumer level batteries like this should require any special treatment - but maybe I'm wrong.

 

[discofunk]

Does your shunt have a voltage sense wire connected directly to a battery post? Useful for further troubleshooting would be measuring all voltages with a separate DVM directly off the battery posts. When completing the 24 hr charge, measure the voltage before disconnecting the charger. If time allows, let the battery set disconnected (one terminal) for 3+ hours, preferably overnight. Record that voltage before the next discharge test.

Currently I have the voltage sense wire connected to the input of the disconnect switch for convivence. There is only 3ft of 2 AWG cable from the battery to the fuse and then 6" to the disconnect. I suppose there could be a little loss in voltage but shouldn't be significant.

Renogy did ask me to do readings 2 hours after a "full" charge and the VOC was 26.85 and after 12 hours was 26.78. Does this seem correct in regard to a 24v LifePo4 battery?

I'm trying to determine if it is a bad battery or if both charges I tried are failing to charge it.

Here is a link to the battery manual if it helps - it calls for a 29v Bulk/Boot/Absorption voltage: https://store-fhnch.mybigcommerce.c...25.6V 200Ah Core LT Series Battery Manual.pdf.

 

[discofunk]

The other thing I should note - it seems like the BMS is disconnecting around 24.4 volts which seems really high - but maybe that is because one of the cells is a lot lower?

 

[NIFE]

The other thing I should note - it seems like the BMS is disconnecting around 24.4 volts which seems really high - but maybe that is because one of the cells is a lot lower?

Yes, disconnecting at 24.4 when discharging is a little soon. This indicates one or more cells is at a lower voltage than the rest which is a sign of battery imbalance. But... only getting 100 AH from a 200 AH battery is a huge miss. I am a little confused how a 50% charged battery can have a resting voltage of 27.8 Try what Sunshine recommended to see if there is any significant improvement. If time is not on your side, get the manufacturer to solve the problem fast before they begin the "stalling" process. I purchase one of these a while back (different brand).
It also had a battery imbalance problem, not nearly as bad as yours. I returned it, built my own, and am living happily ever-after. It is a bummer these pre-packaged battery manufacturers have such a bad track record of delivering a working product out of the box.

 

[mikefitz]

opened a claim with Renogy about the battery

If the cells are seriously out of balance this is not uncommon.

Problems with renogy 170ah batteries

Hi, new to this forum but have built a number of solar systems for motorhomes over the years. I installed 2 x renogy 170ah lifepo4 batteries in my van 18months ago, parallel 12v setup. They are acting very strange and I wonder if anyone has any idea how to fix them. I've asked renogy for...

diysolarforum.com

 

[discofunk]

I've come to resolution with Renogy and they are going to send out a replacement so good on them - hopefully I don't see the same issue with the replacement.

Thank you again members for all your help!

 

[NIFE]

I've come to resolution with Renogy and they are going to send out a replacement so good on them - hopefully I don't see the same issue with the replacement.

Thank you again members for all your help!

Sorry for being cynical, did they give you a ship date and a tracking number? I hope this has a happy ending.

 

[discofunk]

Sorry for being cynical, did they give you a ship date and a tracking number? I hope this has a happy ending.

No - just a message saying they have "requested a replacement" for my battery

 

[JRH]

The voltage spike behavior indicates the battery isn't balanced. This is incredibly common across all brands.

recommend you hold the battery at 27.6V for 24 hours and re-test.

Alternatively, engage in small discharges and about 5A charges to peak voltage.

The BMS should bring the cells into balance.

Regular cycling and charging to > 27.6V should keep the battery balanced.

Not being a big chart guy , I am assuming when you say voltage spikes on his referenced chart you speaking of the right side in the upper knee where it’s whipsawing back and forth from the top only.

Or are you also including the little blurbs across the entire charge profile…. Just wondering ….

Thx…J.

 

[sunshine_eggo]

Not being a big chart guy , I am assuming when you say voltage spikes on his referenced chart you speaking of the right side in the upper knee where it’s whipsawing back and forth from the top only.

Yes.

Or are you also including the little blurbs across the entire charge profile…. Just wondering ….

No. I would regard that as bad data, odd charger behavior or loads turning on/off.

 

[discofunk]

I thought I would provide an update in case anyone was interested:

Renogy agreed to send me a replacement battery as they considered the battery to be defective. However, that turned into delay after delay and I noticed on the website they were "Sold Out" of that battery so I eventually asked for a refund and received it. I must say I am very disappointed with my experience with Renogy's quality however the support staff were really accommodating and empathetic to my issue so good on them.

I was originally going to build a battery but bought the Renogy one as it should of just worked for a bit more of a premium. I guess the good news is I will now build my own which I can ensure works to my satisfaction (if I get good cells).

Further, I did grab a variable DC power supply and tried giving the battery a constant 28v voltage for 36 hours and ran a capacity test - no change, still had half the advertised capacity. I'm starting to think that this battery is mislabeled and priced and actually has smaller cells in it.

 

[Alkaline]

some of these shunts you have to set the amperage like 50,100, or 150 otherwise the measure incorrectly. I have a little shunt like this:

https://www.amazon.com/MELIFE-Multimeter-Impedance-Resistance-Voltmeter/dp/B09BQ1PLYT

in this one you have to tell the lcd screen if its a 100A, 200A, or 300A shunt if you don't it will give you the wrong readings. So make sure the shunt was setup properly.