Originally Posted by Kanusport
Iíve been using a 100 ah lifepo4 Renogy since spring. I utilize a Renogy 200 watt solar suitcase to charge the battery. Itís been a great upgrade, the battery has a fast charge time. The only problem Iíve run into was the battery ended up at 0v and was locked. My solar suitcase with pwm charge controller would not unlock the battery from 0v. So be prepared for that eventuality. I tried my noco 1100 charger but it wouldnít do it , nor is it designed too in retrospect. I ended up buying a Renogy mppt charge controller and that did the trick. Iíll use that when I add some solar to the roof.
A lot of chargers have a lockout that shuts them down if the load pulls the output below some magic voltage. It may be 10V, it also could be 6V or .... The idea is to protect the system by not sourcing power into t shorted load. It also makes the design of the charger a bit easier. ( = lower cost).
If you are stuck out in the middle of nowhere and need the battery back up and running, a jumper cable to your tow vehicle battery likely will bring it back to life. Unless the BMS in the Renology batteries is unusual, the internal "battery" is sitting at around 10V. The BMS has shut things off to protect it.
It does not take a lot of amp hours into the system to get it back up to around 11V (or maybe 12V). That will get the BMS back into active mode. Once it's in active mode, you can hook it into the normal charging system to get it the rest of the way.
The only caution might be to shut off the engine in the tow vehicle when you do the jump. Lithium's can pull a lot of current. Lots of current is not what your vehicle alternator likes to supply. With the engine off, it's not doing anything so there is no concern. As long as you don't leave things hooked up for long (10 minutes should be plenty), there is little risk of the TV battery discharging to a crazy level.
As always, this is guesswork based on generic BMS behavior. The Renology's have not been out long enough for there to be a lot of information on their BMS.