Problem Charging SOK's

[MsNomer]

I recently bought two 100Ah SOK batteries. I charged each with a NOCO g26,000. When the NOCO said they were charged, voltage was 13.3, which I understand To be somewhere in the 80-90% range of SOC.

I installed them in my van, which charges from the NOCO, a 40A Renogy B2B, and a Trimetric Solar Charger with 300W panels. Very quickly, voltage shot to 14.6 and the meter read 100%. Overnight, I applied a load I knew would consume 50A overnight, and, sure enough, this morning the meter read 75%.

Then I set about to charge them, and that's when the trouble began. Voltage of the batteries with 0.4A parasitic draw is 13.4-5. Solar would show 0 amps coming to the batteries with maybe 10A unused—the van is in the shade. The Renogy would act as if everything is hunky-dory, yet not send a single amp to the batteries. Green light on, red light off. IOW, everything acts as if the batteries are charged, yet I know they aren’t because I took 50Ah out and haven’t replaced them.

Renogy is set with S1,2,3,4 DOWN and S5 UP to charge lithium at 14.6V.

Temperature Sensor was removed from the Trimetric Solar Charger. Relevant Trimetric settings are as follows:

P1 (Absorb Volts): 13.8
P2 (Charged Set Amps): 2% of Capacity
P3 (Battery Capacity): 200
P8 (Max Allowed Voltage): 14.6
P10 (Assumed efficiency factor) 99
P12 (Auto Reset SOC): OFF
P14 (Max Absorb Time): 0.5 hr
P15 (Max volts finish charge): 13.1
P16 (Float Voltage): 13.1
P20 (Overcharge %): OFF
P21 (Finish Stage Current Limit) OFF

We were supposed to leave on an extended trip tomorrow. I guess that won’t happen, but any assistance would be greatly appreciated.

 

[Mcgivor]

Are these batteries pre assembled modules, like Battleborne?

 

[MsNomer]

Yes.

 

[Bud Martin]

The settings do not make sense:
P1 (Absorb Volts): 13.8
P15 (Max volts finish charge): 13.1

How can finish charge Voltage be lower than Absorb Voltage?
What does the user manual say about those settings?

 

[Mcgivor]

The reason I ask is because they may have a BMS which cuts charging when the voltage reaches a given value, a ballanced charging of 14.6V for example, to prevent damaging the cells by holding them at an unnecessarily high state of charge. The BMS will likely have a release voltage where it will allow recharge, I would suggest dischargeing them to a point where the voltage is somewhere in the 12.8V regon without PV input, then turn on the PV and see if charging resumes.

 

[Mcgivor]

The settings do not make sense:
P1 (Absorb Volts): 13.8
P15 (Max volts finish charge): 13.1

How can finish charge Voltage be lower than Absorb Voltage?
What does the user manual say about those settings?

Good point, assuming finish is the CV setting or bulk charging voltage, which may be as high as 14.6V or 3.65 volts per cell, though I would use a lower value of around 13.8V as there is little capacity above that.

 

[rmaddy]

I don't know anything about the Renogy but the SOK batteries should be setup like most LiFePO4 batteries. Set the absorption voltage to 14.3-14.4V. Float voltage should be 13.5-13.6V. If your two batteries are in parallel the recommended charge current would be 80A.

 

[MsNomer]

After sleeping on this overnight and reading your conversation this morning—thank you for caring—I’m wondering if part of the problem could be in my head. It's going to be a mental adjustment "livin'' in the middle" after so many years of trying to keep AGM's charged.

My understanding was that the P1 and P15 values keep lithium from going to float. SOK recommends charging at 14.2-14.6. I ignorantly thought lithiums would start charging at that instead of building up to that like AGMs do.

I have raised the P1 value and today I will run the batteries down.

 

[MsNomer]

Another question: Renogy says 60A fuse before and 50A fuse after the unit “or close". Those specs would be generic for all types of batteries. Our very short (couple feet) 2-gauge wire from Renogy to battery could handle a very substantial amperage. The batteries could handle 100A within their spec. Would a larger fuse be OK there?

The reason I ask is that the 50A breaker appears to be defective. 100A is immediately available. 50A would have to be ordered.

 

[rmaddy]

Renogy says 60A fuse before and 50A fuse after the unit “or close". Those specs would be generic for all types of batteries. Our very short (couple feet) 2-gauge wire from Renogy to battery could handle a very substantial amperage. The batteries could handle 100A within their spec. Would a larger fuse be OK there?

The reason I ask is that the 50A breaker appears to be defective. 100A is immediately available. 50A would have to be ordered.

2AWG wire would be quite safe with a 100A breaker assuming it's high quality copper wire. And since the batteries could handle the 100A if needed, that won't be an issue.

But use a 50A as soon as you can get a replacement. Get a proper Bussman breaker. No cheap Amazon knockoffs.

 

[Mcgivor]

The purpose of over current protection devices is to protect the conductors, not the devices downstream, most conductor ratings are based on temperature, type of insulation and length of expected run, in other words they are conservative.

Often when thermal over current devices (OCD) are run close to their threshold, they suffer from thermal gain, in other words, notbeing unable to dissipate the heat gain, this may result in premature tripping, using a higher Amp rating may solve the problem, provided it safety protects the conductors, which is it's intended purpose.

The alternative is to utilize an electro mechanical circuit breaker, which more accurately measures the current without the influence of temperature, but in the given the stated situation, a 100A thermal breaker, would offer reasonable protection.

 

[MsNomer]

Thanks. You may have just saved us a day for traveling instead of sweltering at home.

 

[MsNomer]

All is well. Tomorrow, we leave this furnace for more favorable climes.

Solar was two bad parameter settings on the Trimetric. SOK had me change P1 to 14.6 and P16 to 13.5. It appears to work fine now.

Renogy had two issues. First, the bad breaker was replaced on the output wire. Second, Ummmmm, MsNomer discovered that MrNomer had not connected the Renogy to the shunt.

All's well that ends well. The Renogy charged the batteries in short order and we are good to go.

Thanks, everybody, for your support.

 

[Bud Martin]

So what do you set P15 (Max volts finish charge) to? I would think it will be higher than 13.10V.
I am still wondering what the 'Max volts finish charge' really mean.

 

[MsNomer]

Nope. SOK left that at at 13.1. My understand is that it is set so low so the batteries can’t float.

It was really curious to watch the amps during the charging cycle. Crept steadily up from 13.3 to 13.7, then jumped suddenly to 14.6. As soon as the Trimetric registered 100%, I turned the engine off. Now that the Trimetric is set, I may back some settings off to avoid 100% unless I need it.

 

[Mcgivor]

Turned the engine off would indicate alternator charging, Victron did some studies which may be if interest if not previously viewed.

 

[MsNomer]

There has been quite a bit of discussion about this on the Promaster forum. It appears that our alternator is quite capable of charging lithium directly without overheating. One guy beefed up his wiring and has charged 560Ah lithium directly from his 180A alternator for six years with no problem. We decided to add a B2B anyway.

Good Golly, this new system is nice.

 

[drumwood]

There has been quite a bit of discussion about this on the Promaster forum. It appears that our alternator is quite capable of charging lithium directly without overheating. One guy beefed up his wiring and has charged 560Ah lithium directly from his 180A alternator for six years with no problem. We decided to add a B2B anyway.

Good Golly, this new system is nice.

Could you please post the complete list of corrected Trimetric settings for the 100ah SOK battery?

I plan to upgrade to lithium this winter and the SOK seems the best option. But I really like my Trimetric controller and monitor and I hope I can continue to use them, if I can get the settings correct.

Are you still happy with the way the Trimetric is working with your SOK batteries?