Battery thoughts

AaronC

I'm an electrical ignoramus, which is a problem. I have a Renogy LifePo4 100ah battery that seems sleepy! Charges up well on WFCO converter and my shore power battery charger/tender. Also charges on solar (with Renogy charge controller). I consulted with Renogy at length before using any of these to charge the battery. I wonder if I damaged the battery camping recently. I forgot that I was not plugged into shore power and let my Coleman 12v DC cooler run all night...and only noticed when it stopped running. It took the battery about 13 hrs. to drain all the way down. Dumb me! I wonder if I damaged the battery??? Again, it charges up nicely, but discharges FASTER than a NY second. Only parasitic draw in my 2016 TAB 320 CSS is the light in the 2-way fridge and the light on the Jensen radio.  Any ideas? We're leaving on a trip tomorrow and I'm thinking I should buy a group 27 AGM deep cycle.

jkjenn

Your Coleman draws about 4ah. Run that for 8 hours and you are down below 70ah, already. 

AaronC

I wonder if I damaged the battery by running it down to nada, rather than charging it before it was out of juice. My concern is that it seems to not hold a charge for long now. 

Marceline

AaronC said:

I wonder if I damaged the battery by running it down to nada, rather than charging it before it was out of juice. My concern is that it seems to not hold a charge for long now. 

Theoretically you shouldn't be able to damage a lithium battery by drawing down to zero. Except maybe if you left it that way for a long time. Assuming that your Coleman is thermoelectric, it's a power hog. I would only use one of those in a tow vehicle with the engine running or at a campsite with shore power. When you say, "[the battery] charges up nicely" how are you measuring that it has achieved a full charge? What are you charging it with? For example, if you are using a charging system that only puts out 4amps it would take at least 24 hours to fully recharge that 100ah battery with absolutely nothing drawing power from it. 

pthomas745

And:  what are you measuring the battery with?  Do you have a multimeter or any other device to measure?  You are saying the battery depletes faster than a "NY second". 

The whole point about having 90 amp hours of battery to use....is to use it.  Even if your Coleman used up 30 amp hours overnight, you still have 60-70 amp hours left......which is more power than I have available in my entire "stock" lead acid battery.  So.....use it! 

Tell us how you are monitoring your battery and coming up with your NY second statistic.  You are probably doing better than you think.

AaronC

Thanks, I probably exaggerated about the discharge. I'm using a 75 ah wall charger and alligator clips on the battery. Got me from 8% up to 100% and 12.7 V in five hours or so. I have a cheap BM2 bluetooth battery monitor that was well reviewed but I don't know how accurate it is. None of my chargers or this monitor are specifically for a LifePo4 battery, but Renogy tech wasn't concerned about that. I did get 13 hrs. of runtime on the coleman drawing 5.6 ah so that was pretty awesome, but now the battery seems to go to sleep, even with some charge left, and only "wakes up" when connected to a 110 v source. 

pthomas745

The BM2 is just a simple "multimeter" that just does battery voltage. It probably does a decent job on battery voltage.

The most important thing about taking a voltage reading from any battery:  if the battery is in use, either being charged or "discharged:......the reading is "false".  If you are binge watching your little monitor while that fridge is busy using those amp hours...it would be really "false", to the point where you might be seeing readings below 50 percent of the battery state of charge.  I've shown how the fan in my camper, running when I'm taking a reading with my Victron, will display 12.09 for voltage.  On a battery that I know is mostly fully charged.  Turn the fan off...and the voltage "number" changes dramatically.

So:  take your battery reading with the fridge running......and then take one with the fridge off.  Your voltage will increase.  Even better: turn the battery switch off, so the battery is completely isolated from any draw or charge at all.  Let it sit for a little while.  This "rested" battery reading will be the most accurate.  Try it yourself and see. I bet your million dollar battery is doing better than you think!

Marceline

AaronC said:

Thanks, I probably exaggerated about the discharge. I'm using a 75 ah wall charger and alligator clips on the battery. Got me from 8% up to 100% and 12.7 V in five hours or so. I have a cheap BM2 bluetooth battery monitor that was well reviewed but I don't know how accurate it is. None of my chargers or this monitor are specifically for a LifePo4 battery, but Renogy tech wasn't concerned about that. I did get 13 hrs. of runtime on the coleman drawing 5.6 ah so that was pretty awesome, but now the battery seems to go to sleep, even with some charge left, and only "wakes up" when connected to a 110 v source. 

Even if the battery is at 12.7v, that’s not a full charge for a lithium battery. It should be in the mid 13v range when fully charged (check with Renogy). 

It’s not that your battery is draining quickly; it’s that you’re not fully charging it. 

Also, this is from the Renogy site:
“When the battery voltage drops to 0V, please reactivate the battery using an external charging device that has the lithium battery activation function.”

ScottG

I'm not very knowledgeable about lithium batteries, but what you describe is a symptom of dead or dying batteries in general (and I've seem a fair number of those).

However, as Marceline suggested, this assumes you are actually charging your battery fully before making an assessment. Batteries don't just "wake up" when connected to a 120V charger--it takes a long time to reverse the effects of the discharge and fully top the battery up.

You may get a high voltage reading when connected to the charger, but that is the output of the charger you are seeing, not the condition of the battery itself. Premature removal from the charger will also result in what appears to be the battery "draining" very quickly, but in reality it's just that it never got fully charged to begin with.

Horigan

AaronC said:

Thanks, I probably exaggerated about the discharge. I'm using a 75 ah wall charger and alligator clips on the battery. Got me from 8% up to 100% and 12.7 V in five hours or so. I have a cheap BM2 bluetooth battery monitor that was well reviewed but I don't know how accurate it is. None of my chargers or this monitor are specifically for a LifePo4 battery, but Renogy tech wasn't concerned about that. I did get 13 hrs. of runtime on the coleman drawing 5.6 ah so that was pretty awesome, but now the battery seems to go to sleep, even with some charge left, and only "wakes up" when connected to a 110 v source. 

You need a charger specific for a LifePo4 battery.

Mellow_Yellow

I would also like to learn more about the role of the older lead-acid converter with a lithium battery. The stock converter (in my 2014 T@B) only charges my 100aH lithium battery to about 13.3V on AC (house power). On DC (RV hookup) it charges to 13.6V. On solar, I can charge over 14V, but after connecting to the 7-pin on my TV, the charge reduces 13.3V.
Would upgrading the converter in the trailer improve the maximum AC and 7-pin charge levels? 13.3V is a 90% charge, so perhaps I will go with that and top up with solar when I get to the campsite.
I obtain my battery voltages from either the Renogy solar panel converter or a bluetooth app that connects to a battery monitor. Thankfully the readings from both devices match each other  
Here's the replacement converter, recommended by @dsfdogs
https://wfcoelectronics.com/product/wf-8735lis/

Denny16

Changing to a LiPo specific charger in the converter would increase the charging level whilst on AC, but the 7-pin is down to your TV system voltage output, which is designed for non lithium battery charging levels.  To increase the charging from the TV, you need a DC/DC charger designed for lithium batteries.  This increases the output from the TV to properly change the LiPO battery.  That said, your Solar will do the same thing while driving in daytime conditions.
cheers

Marceline

Mellow_Yellow said:

I would also like to learn more about the role of the older lead-acid converter with a lithium battery. The stock converter (in my 2014 T@B) only charges my 100aH lithium battery to about 13.3V on AC (house power). On DC (RV hookup) it charges to 13.6V. On solar, I can charge over 14V, but after connecting to the 7-pin on my TV, the charge reduces 13.3V.
Would upgrading the converter in the trailer improve the maximum AC and 7-pin charge levels? 13.3V is a 90% charge, so perhaps I will go with that and top up with solar when I get to the campsite.

If your solar controller is configured for lithium it will charge at a higher voltage (14v range) and get the battery closer to full capacity. If it's not configurable for lithium than it probably really doesn't get you up to a full charge.

In my experience the stock converter brings a lithium up to about 90% charge - that's the 13.3v number that you're seeing. Be sure to check the numbers with no load and no input. 

As Denny says, swapping the converter will get you to a higher charger on AC power. I went the lazy route, though. I have a battery charger with a lithium setting, so instead of swapping the converter I just use that. I'll swap the converter when it dies.