Upgrading to LiTime 12V 230Ah from Harris AGM - How to? [2020 T@b400]

b407driver

Our second set of Harris AGM batteries recently died and started to bulge (got up to 90°C when on shore power!), so decided to upgrade to lithium. Have read many threads here and consulted Will Prowse's product suggestions, and thus went with the LiTime 230aH (with low-temp protection) for $578 shipped. I am not planning on updating the WFCO WF-8955PEC converter, as we are mostly off-grid when camping, and generally have ample sun here in the southwest to top off. 

Despite all the reading, I just want to make sure that I'm on the right track here. I assume hooking up the battery is simple, obviously eliminating the white jumper from the dual 6v setup (we do have a BMV-712/shunt/temp probe installed). I guess my main remaining question revolves around the Victron Solar Controller MPPT 75/15 settings that need to be changed for the battery we are installing. Has anyone here updated to this battery, and been able to find the recommended settings that need to be changed in the solar controller?

Also, I've read that people that have completed this install with no changes to the WFCO controller also suggest turning off the battery switch when hooked up to shore power, but the reasons seem unclear to me. Will it cause a problem if I forget to turn the battery switch to OFF? In reading about this, it seems that people thought it to be a 'best practice', but were a bit nebulous as to why, or whether it actually mattered or not. Any clarity appreciated.

I assume nothing needs to be done in regard to the AIMS Power inverter?

Anyway, I just want to have a clear understanding of what I'm getting myself into and the potential ramifications of the changeover to lithium, so feel free to toss out any relevant issues that I might have neglected to mention.

As always, thanks to all in this forum for providing us access to the wealth of knowledge you all have, it is very much appreciated!

-Jeff

Grumpy_G

Charging LiFePo batteries is much less "complicated" than charging different types of lead acid batteries. The BMS is pretty much a sophisticated charge (and discharge) controller. It will do charging, balancing of the cells etc. with constant 14.4V, no need for different voltages and timers. Standard RV converters will change voltages over time so the battery might not get fully charged but I did some experiment with my battery and I could draw 1200 Wh out of specced 1280Wh when charging with the converter only. Cell balancing will likely not happen with a standard converter but that's not an issue with frequent proper solar charging.

I don't own any Victron devices so I let others chime in on how to configure the solar charger. I don't see any reason to disconnect the battery when on shore power, in fact it will keep your trailer from going pitch black if shore power drops out. Nothing need to be done with regards to the inverter.

manyman297

@b407driver Curious what white jumper you’re referring to. Are you talking about the series wiring of the 6V?

I just installed two 100ah LiTime batteries. To make it a parallel set up I had to fabricate a few new 4awg wires with welding lugs. I could’ve bought premade ones but I wanted a clean install. You probably won’t even have to include any new wiring with a single battery setup.

The new batteries were slightly smaller in footprint so I had to use some foam (just used the shipping foam that came with the batteries) to fill some empty spaces.

You’ll need to update your smartshunt (if installed) and solar controller settings. LiTime is good about providing specs so setting both of these up wasn’t a big lift. If you have any questions let me know as it’s fresh on my mind.

b407driver

manyman297 said:

@b407driver Curious what white jumper you’re referring to. Are you talking about the series wiring of the 6V?

I was referring to the series wiring, and of course it does slightly simplify the hookup with only one battery. 

I have a BMV-712, so I'll look into changing the settings along with the solar controller (though not sure how much it would matter compared to solar charge settings), which LiTime did finally get back to me on.

In case anyone also needs the numbers, here is what LiTime provided:

Thanks for contacting LiTime. Here is Kandy from Customer Service Center. I am pleased to help! 
 
  -High Voltage Disconnect: 15V
  -Charge Limit Voltage: 14.6V
  -Equalize Charge Voltage: 14V
  -Boost Charge Voltage: 14.4V
  -Float Charge Voltage: 13.8V
  -Boost Charge Return Voltage:13.33V
  -Over Discharge Return Voltage:11.8V
  -Low Voltage Alarm:11.2V
  -Over Discharge Voltage: 10.4V
  -Discharge Limit Voltage: 10.4V
  -Over Discharge Delay Time (seconds): 10ｓ
  -Equalize Charge Time (minutes)：120mins
  -Boost Charge Time (Minutes)：270mins
  -Equalize Charge Interval：180mins
  -Temperature Compensation: 0
 
Could you please advise your battery order ID & SN code and share your battery application with me?  (How do you use your battery?)

I'd appreciate it if possible to send some battery application photos. I'd like to check the compatibility for you. After confirmation, I will assist you in registering your information and the battery warranty.
 
Your understanding will be so much appreciated.  Have a good day!
 
Wish you all the best，
Kandy 

Thank y'all for the help!

manyman297

Thanks for posting those settings. Not sure how much the 230ah settings differ from the 100ah battery settings but I'll check these against what I have. 

b407driver

manyman297 said:

Thanks for posting those settings. Not sure how much the 230ah settings differ from the 100ah battery settings but I'll check these against what I have. 

I'd be curious to know if they are the same or not.

b407driver

So I got the battery hooked up, and both the Victron MPPT 75/15 and BMV-712 settings sorted... I think.

Yesterday I never really saw a voltage above 13.35 or so, but today it has gone above 13.55. It has been disconnected from shore power since yesterday morning (stock non-lithium WFCO). Today I reset the BMV-712 100% SOC setting when the battery was in the mid-13.5s. 

I'd be forever appreciative if someone could look over the settings below just to confirm they are correct. I used LiTime's settings, though their terminology is a bit different, and the email they sent is slightly different than other references (both printed and their website). 

In going through this conversion, I am puzzled by one thing. Although I understand the 'flat' discharge rate of Li batteries (and the consequent ambiguity of the State-of-Charge % indication), I am confused by LiTime's following statement in regard to controller settings:

"1) Based on theCharacteristics of LiFePO4 batteries, the voltage measured by all LiFePO4 batteries during charging/discharging is not the real voltage of the battery. Therefore after charging/discharging and disconnecting the battery from the power source, the voltage of the battery will gradually drop/increase to its real voltage.

2) After this battery is protected from overcharge, the tested battery voltage (not the real voltage) will be lower than the real voltage. To calculate the SOC(%) add 0.5 to 0.7v to the tested battery voltage."

I get that the voltage needs to stabilize (or whatever), but it would seem that the charge controller settings are thus based upon numbers that are not necessarily accurate, and in fact may be either lower (or higher) than recommended. In regard to the last bolded sentence, is this something that I would take into consideration when programming the BMV-712?

Also, I assume I should do a load test, i.e. fully charge and then run the battery down (solar charge of) until the BMS shuts it off, to confirm that all the cells are relatively OK (i.e. that it gives roughly 230aH)?

Thanks for any clarity on all this, I just want to make sure the system is working before I take it to storage.

-Jeff

manyman297

Yeah, I'm not sure what they mean by "real voltage" either. Your settings look similar to mine (I don't have them in front of me at the moment). I think my float voltage is 13.5. I haven't messed with expert mode at all. 

I honestly haven't even run the battery down to test it. It's something I need to do though. 

pthomas745

The idea of a "battery at rest" is the only decent way to get a fairly accurate readout of voltage is true of lead acid batteries and lithium batteries.  It seems that physics and chemistry cannot measure things accurately when the atoms are flying around making electricity.  So, if you want a clearer picture of your voltage, have the battery switch off, and no charging coming in.  Maybe a lab tech in a white coat testing with a huge voltmeter that goes out to 7 digits would have a problem with a difference of .05 to .07 of a volt...but a RV'er in a campground wouldn't be able to make out any appreciable difference at all.

b407driver

pthomas745 said:

The idea of a "battery at rest" is the only decent way to get a fairly accurate readout of voltage is true of lead acid batteries and lithium batteries.  It seems that physics and chemistry cannot measure things accurately when the atoms are flying around making electricity.  So, if you want a clearer picture of your voltage, have the battery switch off, and no charging coming in.  Maybe a lab tech in a white coat testing with a huge voltmeter that goes out to 7 digits would have a problem with a difference of .05 to .07 of a volt...but a RV'er in a campground wouldn't be able to make out any appreciable difference at all.

I think it was 0.5 to 0.7v, which for lithium batteries can be significant, yes? Per the SOC table in the battery manual, 25% to 100% SOC is a difference of only 0.33+ volts, thus my lack of clarity. 

Will get the rested battery number in the AM.

pthomas745

Sorry, my math skills fail again.  I was thinking of .07 in my head.

What is confusing is trying to sort out what they are trying to describe in this sentence:

"After this battery is protected from overcharge, the tested battery voltage (not the real voltage) will be lower than the real voltage. To calculate the SOC(%) add 0.5 to 0.7v to the tested battery voltage."

They don't describe "protected from overcharge" or is the "tested" battery at rest.

Sorry about adding to the confusion.

rh5555

@b407driver - You might want to check out this discussion where the (weird) behavior of these LiTime batteries gets discussed.