LiFePO4 charging question

[triplethreat]

Get it down to about 13.0V and you'll be right at 50%. How do I know that .....I just ran the battery down on mine and finish up not 10 minutes ago. Cell voltage was 3.257, 3.260, 3.255, and 3.253......total voltage on the battery was 13.025 and SOC was reading 50.1%

 

[coglesby]

My battery is sitting on my workbench in my garage.

Sorry. I posted to the wrong thread.

 

[dryfly]

I've used those many, many times in my early career days as an Electrician....back in the late 70s and even into the 80s for a while. I had the roll up case for it also, the one that the front of it rolls up like an old roll up desk...LOL.

We had a new apprentice one time and we sent him back to our shop to get "the Simpson." Without telling us he didn't know what it was, off he went. After about a 15 minute wait for him to come back, the boss walked down to the shop and found him wondering around and ask him what he was doing. His reply was epic........"I'm looking for Mr. Simpson, but I don't know who he is." We all had a good belly laugh about that one and from there on out, the meter was referred to as.....yep.....Mr. Simpson.

I've still got two 260's and one has the roll up case. I also have a Simpson amp clamp attachment that is used with it. I'm sure they are worth very little, and only a few of us can really appreciate them.

And yes, they still look cool!

 

[Scott'n'Wendy]

No doubt Fluke makes excellent equipment, but you don't really need a Snap-On torque wrench to tighten the lug nuts on your trailer. Kind of the same thing with a clamp-on amp meter. I bought a Uni-T clamp-on meter several years back for around $30 and it works fine for what I use it.

In my case, after using them for years on the job, I don't want to use cheaper meters.
But you are right, there are lots of less expensive options out there that will do the job for rv troubleshooting

 

[reubenray]

Get it down to about 13.0V and you'll be right at 50%. How do I know that .....I just ran the battery down on mine and finish up not 10 minutes ago. Cell voltage was 3.257, 3.260, 3.255, and 3.253......total voltage on the battery was 13.025 and SOC was reading 50.1%

I am working on it. I have some 12v LED ceiling lights that I replaced that I will see what they do (when I find them). I know that it will take a while, but I will just leave them on. It will give me some lights in the garage also. I may still have a old trailer front jack that I could use. I never throw anything away, so I have a lot of stuff in my garage.

 

[Steven@147]

My antique Simpson 260 is cooler. LOL

View attachment 191160

OMG! I haven't seen one of those since I left the Navy back in 1979. We had a shockproof bag that surrounded the meter. We used it on the aircraft carrier working on our airplanes. When we were working on the flightdeck, Everytime the radar would sweep around the meter would peg. Had to time your readings and make adjustments before the radar came back around! Loved that meter!

 

[COGrandDes]

In my case, after using them for years on the job, I don't want to use cheaper meters.
But you are right, there are lots of less expensive options out there that will do the job for rv troubleshooting

I feel the same way after holding Snap On wrenches, sockets, ratchets, and torque wrenches in my hands for the last 35+ years. There is a difference.

 

[reubenray]

Get it down to about 13.0V and you'll be right at 50%. How do I know that .....I just ran the battery down on mine and finish up not 10 minutes ago. Cell voltage was 3.257, 3.260, 3.255, and 3.253......total voltage on the battery was 13.025 and SOC was reading 50.1%

I have two LED light on the battery and after a hour the SOC is down to 13.23.

 

[reubenray]

I have two LED light on the battery and after a hour the SOC is down to 13.23.

This is going very slow. I could not find the old trailer jack. I have been looking for cheap 12v heaters with alligator clips to use, but no luck yet.

 

[TimtheToolMan]

This is going very slow. I could not find the old trailer jack. I have been looking for cheap 12v heaters with alligator clips to use, but no luck yet.

@triplethreat uses something remotely like this but you need to deal with wiring. If I remember correctly, he hangs it and aims a fan at it. I really liked the idea. Cheap heater About 8Ah (100W/13V= 8A) per hour for one and double for two. Many more options look at 12V PTC heaters. 200W

Clamps--make sure you go with clamps that are rated many times what you need because claimed amp ratings for these items often are way too high. Physically larger clamp

Change: Corrected A to Ah and added 200W Clamps 30A

 

[triplethreat]

The one that I bought in late 2021 is currently (no pun intended...LOL)unavailable, but you get the idea of what I'm talking about....

Amazon.com

 

[Butcher]

Fluke is a trusted brand in the automotive industry. I had the privilege working with John and his son's cars over the years. Good guys.

 

[reubenray]

I bought a cheap trailer tail light and the SOC is steady going down. It is about 13.15 right now after a few hours where it was around 13.21.

 

[TimtheToolMan]

I bought a cheap trailer tail light and the SOC is steady going down. It is about 13.15 right now after a few hours where it was around 13.21.

Good to hear that you found something that works for you. Anything will work and some ways take more or less time to drop SOC than others.

My apologies that my 200W heater link above does not work so here it is again (click on 200W to open link). 200-watt heater $13 would take 100Ah battery from 100% to 50% SOC in about 6.5 hours.

 

[triplethreat]

Good to hear that you found something that works for you. Anything will work and some ways take more or less time to drop SOC than others.

My apologies that my 200W heater link above does not work so here it is again (click on 200W to open link). 200-watt heater $13 would take 100Ah battery from 100% to 50% SOC in about 6.5 hours.

Mine is a PTC heater also, and the trick is to use a fan on it to dissipate the heat away from it. Doing that will increase the current flow through the heater....mine is constantly pulling 15 to 15 1/2 amps with a spike once in a while up to 16.xx amps. If you allow it to self regulate, the current will die down and it just takes longer to drain the battery down to where you want it. 15 amps at 4 hours is 60AH, so you could take a fully charged 100AH battery down to 40% SOC in that amount of time.

 

[TimtheToolMan]

Mine is a PTC heater also, and the trick is to use a fan on it to dissipate the heat away from it. Doing that will increase the current flow through the heater....mine is constantly pulling 15 to 15 1/2 amps with a spike once in a while up to 16.xx amps. If you allow it to self regulate, the current will die down and it just takes longer to drain the battery down to where you want it. 15 amps at 4 hours is 60AH, so you could take a fully charged 100AH battery down to 40% SOC in that amount of time.

Good to know about the fan and speed. My math for time to complete is way high on post #94 (factor of two--ish). Thanks for correcting me...

 

[reubenray]

The book that came with my LiTime 100ah battery says to bring it down to 50% SOC for storage. The range for 50% per the book is 13.15 to 13.2 I currently have my battery at 13.16, so I will stop bringing it down more. The book also says to recharge after 3 months of storage. This will bring me to the first of March. Will solar charge it back up from 50% SOC? At this time it will be warm enough to put the battery back in the trailer and let the solar do it's thing.

 

[triplethreat]

The book that came with my LiTime 100ah battery says to bring it down to 50% SOC for storage. The range for 50% per the book is 13.15 to 13.2 I currently have my battery at 13.16, so I will stop bringing it down more. The book also says to recharge after 3 months of storage. This will bring me to the first of March. Will solar charge it back up from 50% SOC? At this time it will be warm enough to put the battery back in the trailer and let the solar do it's thing.

Yes, if Solar charging it before....or even just topped it off, it will do it again. And depending on how much solar you have, how much light it receives to actually be charging at it's full capacity, will determine how long it takes to bring it back up to full SOC. The more current going in, the faster it will charge...and vice versa.

 

[dryfly]

I just got my LiTime 100ah battery in last week, and along with it I got the LiTime battery shunt monitor. To calibrate it, in order to monitor battery capacity, the manual states to discharge to the BMS cut off point 10.8v. I assume that's not an issue with the battery as long as it's not a routine procedure.

Also, I'm wondering if the shunt has any type of a memory on this reading so when it's taken out of the circuit it will remember this voltage calibration?

 

[triplethreat]

I just got my LiTime 100ah battery in last week, and along with it I got the LiTime battery shunt monitor. To calibrate it, in order to monitor battery capacity, the manual states to discharge to the BMS cut off point 10.8v. I assume that's not an issue with the battery as long as it's not a routine procedure.

Also, I'm wondering if the shunt has any type of a memory on this reading so when it's taken out of the circuit it will remember this voltage calibration?

Discharging to 10.8V should cause zero issues with the battery. That works out to be 2.7V per cell and the standard for never taking them lower than, is 2.5V per cell or 10V even for the battery. I've got my low cut off point in my BMS set at 2.55 or 2.6 volts. Sorry, I have no knowledge of the LiTime shunt and it's capabilities or lack thereof.