Lithium Battery Upgrade

Hello All
I know some of you are way ahead of me in getting your coach set up with all the proper equipment to install and use lithium batteries. Well I have finally decided to make the purchase of lithium batteries, my last step. I went and ordered 2ea of the SOK 206 AH lithium batteries. Well I just learned some interesting facts about using lithium batteries that I didn't previously grasp. I got this information from joining the SOK Facebook page where you can see comments from actual people who own these batteries. These operating characteristics however are applicable to most all lithium batteries like Battleborn, Renogy, Lion, Chins etc. What I am referring to is the BMS safeties and how they actual may affect how you use the battery.  Here is what I am getting at, the BMS has a max discharge capacity of 100 amps, that means if you are using 2ea batteries in parallel you have 200 amps discharge which is perfect for using a 2000w inverter.

Well here is a situation where these batteries leave a lot to be desired. Lets say its at night and you have pulled in for a stop at some spot just for the night without hook ups. You are using your inverter running the microwave or coffee pot etc. Then you decide to start the generator at the same time, and it didn't start right away, well this is where lithium has an issue. You unknowingly  just exceeded your maximum amperage discharge for the batteries. This has resulted in loosing all 12 V power as the BMS's tripped on over current. Now here comes the kick in the crotch, its night so no solar, you can't get the generator started because the BMS's tripped off the house batteries. In order to reset the BMS's on these batteries you need to apply a voltage of  around 14.4 to 14.6Volts. Most alternators aren't going to help as there usual voltage is less than that.  If you carry a jump box or a set of jumper cables you can probably jump the batteries and get the BMS's back on line and the batteries will come back to life if you get the voltage high enough.

Here is my answer to the issue, install a DC to DC charger, I prefer the Renogy 40 or 60 amp models. This will allow you to simply start the coach and supply the required voltage of 14.4 to 14.6 to get your batteries back on line. No messing around with jump boxes or battery cables, just turn the key and start the coach let the alternator do the work.

There is something else to consider when upgrading your coaches electrical system. Watch this video it does a good job of explaining what happens and what you need to think about when it comes to chargers for lithium batteries. https://www.youtube.com/watch?v=TJ_Klwp-JyM  Also this apllies to anytime the battery safeties kick in, overcurrent etc.

Very Respectfully
Lance

Thank you Lance for this very valuable information and the link to the Youtube.  Since installing our Battleborn and Victron Lithium system we have had no issues but I do monitor our voltage usage to ensure we don't run our batteries down to where the BMS goes into a sleep mode.   For those interested in what Lithium batteries are available and reviewing the quality here is a Youtube link that you may want to watch.  https://www.youtube.com/watch?v=KvCdo0cs99w

dave

Hello Dave
I was wondering if you ever had your Battleborn batteries trip off line for over current? Also are you using the Victron Mutli 2000W inverter charger? Regardless you have a very bullet proof set up, and unlimited upgrade options with Victron. I started this thread mostly because of the overload issues that you can induce by using your inverter and starting the generator at the same time. I have sometimes lost situational awareness and managed to overload the 30 amp house electrical system. I would imagine that if I didn't read the posts on Facebook I would have fond myself overloading the BMS's on the SOK batteries I am waiting to receive.

You also know I am in favor of the DC to DC charger, and I wanted to show that there is another reason to install one.  It will wake up your battery after it shuts down from a safety, either running it down to low voltage cutoff or overcurrent.

Very Respectfully
Lance

I have two 100 ah Battleborn in parallel. I have not reconfigured the wiring from the 2000 watt inverter to run the microwave so typically my current draw is much less than the 200 amp limit for the battery bank.  Thus I haven’t run into the referenced issue. 


Battleborn BMS appears to have given one an auto reset feature that doesn’t require a wakeup voltage to re-energize the battery to allow the converter charge to properly operate.


Unless I have misinterpreted the potential problem this video explains how BB BMS is configured.  [size=78%]https://www.youtube.com/watch?v=RufHMzaCmfY&t=11s[/size]

Hello FANDJ
Looks like Battleborn has did a better job at designing there BMS. I like that it will auto reset after a high current event. The Lithionics battery is also very robust and offers multiple ways to reset, you can do it through the app or with a extended press of the on/off button located on the case, but their 300 amp battery is now up to $4000.00. I went with the SOK for 2 reasons, It has a good warranty and you can access the inside of the battery. So if I do have an issue I can open the battery and check/repair the issue. Also I guess I thought it offered a better value so 3 reasons. Thanks for the video link, the more I learn the better I can make my next decision.

Very Respectfully
Lance

Lance,  I think you will certainly enjoy the benefits of the SOK Lithium batteries.  After about a year of use I much appreciate the benefits of Lithium technology.  When I had the OEM golf cart batteries I was anal about keeping check of the state of charge and if I was getting sufficient solar charging to get them back to full charge as quickly as practical in order to maximize their service life.  With the Lithium I pretty much trust them to do their job without any input from me.  I use what power I want and forget about it.  Even over the winter I left them in the PC outside and this spring found they stood very close to I where left them in terms of state of charge.


I have been out west dry camping for about a month and not needed any shore power for battery charging.  I have run my microwave once in the past month for about 6 minutes and did use the generator for that.  I expect with your much higher capacity system microwaving will be a non issue.  Do you intend to run your AC off the batteries and if so have you run any calculations as to how long could you reasonably expect to run the AC per day?

Hello FANDJ I didn't plan to run my AC, I can give it a try and see how long it operates. I would imagine not for more than a couple hours before it depletes the batteries. I was more wanting to be able to use the microwave and coffee pot etc. When I go to MacDill AFB in Tampa you get a spot for a couple weeks then you move into overflow camping with no hook ups for a week then you get a spot with hookups for a couple weeks. Its this shuffle some of us have to play.  There are some who get a spot for 6 months with hookups but I am not staying there that long so I play the shuffle.  I also being on the base it has some perks that you don't get everywhere. Plus it gets me close to friends in St.Petersburg where I use to live.

Very Respectfully
Lance

I have the original Xantrex Pro 1800 which is not connected to the microwave.  Most of what we use while on the inverter are the TV's and several of the AC outlets.   What we had an issue with prior to installing Lithium was using our furnace on those cold nights where it would come on frequently.  With the lithium's we feel comfortable that we still have sufficient power the next morning.  What we must be careful about using the lithium's is when we use our Keurig coffee maker or my wife's hair dryer.  But as you mentioned, it's nice that we can charge up the lithium's with the options of having a DC to DC charger, generator, solar, and shore power via the converter.

thanks again for your great contributions..

Dave

Hello Dave
I get way more out of this forum then I contribute. I have had the opportunity to share some thoughts and ideas. I have accepted ideas that were not mine but were a significant improvement to my original idea/thought. This forum has humbled me in many ways and forced me to look at my ideas more closely. I am truly grateful to people like you who have taken the time to explain how and why they did what they did. If people can keep an open mind this forum has everything they need to keep there PC in great working order. There are way more intelligent people here than at the factory or any RV repair facility. This is truly a wealth of knowledge.

Very Respectfully
Lance

This is quite an interesting discussion.

Like it was mentioned, PCs are not factory wired to run the microwave oven off the whole house inverter system, and running any 110V appliances are naturally limited by the capability of the inverter.

Utilizing the inverter to it's full capability of 1800w-2000w pending which inverter your PC has, while attempting to start the generator, seems like a common condition that PC owners generally wouldn't give a thought about.

The question comes into play concerning "significantly drained" house batteries under the same 2000w in-use condition.  Conventional battery technology under such a condition wouldn't provide enough power to turn over the generator's starter.  You would simply shut down the inverter and 12V activity and try starting the generator again.  But high tech smart lithium with over-load protection?  That is the question I think formulated here.

If your lithium batteries shut themselves down through a "self reset", your house operations are instantly off-line, maybe for a significant amount of time.  Can you jump them from the chassis battery to reset them?   Maybe there is an extended waiting period to let the lithium batteries cool down to "self reset" back to their operational state, before recharging from any external source can begin.

I hope I understand this discussion accurately enough to even comment on it.  There was a time I considered going lithium, hence my curiosity.

As a bit of trivia,  I just used my instapot (electric pressure cooker) and was curious how much power was being drawn from the Lithium batteries.  It appears to be approximately 700-800 watts/60 amps.


I have measured my PC supplied microwave on high setting and it consumes about 17-19 amps at 120  Volts.  I would estimate if the power came from the 12 volt inverter the current would be on the order of 200 amps.  Thus I would be on the ragged edge of what my two 100 ah batteries could provide without tripping the overcurrent protection disconnect. Too close for comfort for me to try.  Lance with your much higher capacity battery bank and adequate wire and inverter size this certainly sounds doable.


I suspect though I haven’t researched it to confirm, the PC supplied microwave is a higher capacity unit than many of the other RV installed microwaves.  I suppose one could operate the microwave at a lower power setting if this was a problem but I will leave that to others to confirm.

Hello Ron
You are tracking correctly. Using the starting battery to reset the batteries may work but the voltage may not be enough to influence the BMS to come back online. For the SOK batteries I have read two things 1 is battery cells voltages added together plus 0.6 volts, should reset the BMS,  2 another states 14.4-14.6 Volts. The 2nd process will require more than the standard start battery with alternator configuration. That is where the DC to DC charger would work as it boosts voltage up to the 14.4 to 14.6 Volts. My general point was lithium is truly another ball game and you really need to realize very quickly that you are not dealing with the old lead acid ways, where you could load up the battery and just expect to draw the amperage down faster. I have seen in the Facebook SOK group that people have exceeded the BMS capacity and lost all 12volt power and were clueless on why and how to get it back. I also seen on that site where people have thought one SOK 206ah was sufficient for a 2000W inverter. The BMS shuts down at a 100amps.

 Hello FANDJ
I believe my Sharp Convection Microwave states its 1.60 KW so 1600 watts consumed and 850 watts output to the magnetron. So if total consumption is 1600 watts then divide by 12.5 Volts equals 128 Amps roughly consumed by the inverter not counting any losses in the inverter. I guess rounding up to 150 amps would be safe to say. I ran my microwave on shore power at 115volts and it was drawing 14.5 amps running which equals 1667.5 watts, that's pretty dead on. My 2000 watt inverter is capable of supplying about 160 amps. So I am close but not over it should work as long as I don't add more load to the 12 volt system. You are correct it would be tight. 

Even though these 206ah SOK's  have the ability to hold a larger charge, SOK still used that same BMS as the 100ah batteries. So maximum discharge is 100 amps before the BMS trips. So 200 amps for 2 batteries in parallel. Not ideal, wish SOK would have increased the BMS size, but then they would have to increase the wire size to the terminals inside the case. I guess they didn't want to do that,  they would have to raise the cost of the battery making them less competitive in the battery market.

Very Respectfully
Lance

Thanks for your explanation and what you are learning along the way.  Anyone going lithium and pushing them hard, needs to know what they "might" be in for.

Hello FANDJ I didn't plan to run my AC, I can give it a try and see how long it operates. I would imagine not for more than a couple hours before it depletes the batteries. I was more wanting to be able to use the microwave and coffee pot etc. When I go to MacDill AFB in Tampa you get a spot for a couple weeks then you move into overflow camping with no hook ups for a week then you get a spot with hookups for a couple weeks. Its this shuffle some of us have to play.  There are some who get a spot for 6 months with hookups but I am not staying there that long so I play the shuffle.  I also being on the base it has some perks that you don't get everywhere. Plus it gets me close to friends in St.Petersburg where I use to live.

Very Respectfully
Lance

We played the dance at Patrick for years. Only one time at MacDill for the big RV show. You are correct in saying that there are bennies staying behind a "gated" facility. Haven't been back since the big FamCamp addition project.

v/r
Rob