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Help with lithium external bms and battery voltage options
#1
Interesting debates going around regarding battery chemistries. Two complicate matters which I seem to be good at doing I have two oddball chemistries: Nickel manganese cobalt ( I think that’s what Nissan Leaf Generstion 2 batteries are) and lead calcium ( I think that’s what my ex-telecom ups batteries are). I’m going to a expensive battery university: Unfortunately the lead acid batteries weight broke the leaf springs and dented the frame of my cargo trailer. Actually that’s ad hominem red herring as I’m the one that drove the trailer through the two foot deep hole. Maybe the springs would have cracked without the lead in the trailer. 
 I have not tried the Leaf Lion batteries yet so cannot speak from direct experience. They are not installed yet as a frost free battery compartment is another complication. I did find a very interesting made-in-Europe external bms (battery management system) and ran it by a battery engineer. He said the connectors are not his favorite type but the electronics design and specs look good at a glance. It can be set up for around $500 rather than $1000-$1500 for the other domestically made external bms systems. I have not purchased it. Still sitting on the fence. 
 www.energus.com
 Now I’m looking for a 1000 lb heated safe to put the Lion batteries in. Just joking! I am trying to save weight and wear and tear. My point is I still have battery worries. I definitely see why the drop in replacement Lithium batteries are desired by many. They have internal bms and the voltage matches the inverter voltages and 12 volt, 24 volt, or 48 volt system. 
 So to the voltage question: Leaf Lion battery modules make a 12.8- 16 volt battery, a 26.6- 32 volt battery, or a 53.2- 64 volt Leaf Lion battery pack. The modules make a good 48 volt battery pack. But I have a 12 volt inverter or a 24 volt inverter I can use. And a 24 volt system all built in the cargo trailer with 1150 watts of solar connected to the lead acid UPS batteries. A good used Victron 48 volt inverter has eluded me. I could skip one cell at the end of each string of Leaf modules and leave the string end cells disconnected. That would make a 22.2- 28 volt battery which is a good voltage for a 24 volt inverter. But the end cells would be wasted. Separating these cells looks very tricky on these Leaf modules. If I could separate them I could use the extras for a starting battery or ?  I have not found much information yet about separating them. 
  Another complication: Can I place my lead acid batteries in parallel with the Lithium??? How is that done.  Id like to rebuild my trailer stronger than stock and taller for boondocking. Most cargo trailers are low and best for highway use. It could easily carry the extra weight as long as I dont drive through any more deep holes. 
 If anyone has any thoughts on the bms and voltage options Im all ears. I suppose selling the  Victron Energy 24 volt inverter and buying a new 48 volt inverter solves the voltage issue. But it’s $1800 for a new Victron Multiplus 48 volt inverter that would work with my Victron control panel. One advantage I’ve heard about these particular Multiplus inverters is they have a remote on off switch connector that a bms can connect to. The inverter and charger can be turned on and off by the external bms. That’s why I’ve been looking for this particular model but have not found a good used one. 
 If I can get this system working “properly” it would be great for running the tools I carry in the trailer and doing van builds. 
 Thanks. 

  
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#2
I can't answer with any confidence any of the issues you are presented with employing a Nissan Leaf lithium battery pack.

I would not however parallel lead acid to other chemistries charging discharging or floating. Perhaps discharging and charging if closely monitored and disconnected when either stops.

This ship might have sailed, but seek simplicity whenever you can, is all I can recommend as I have no experience cycling anything but individual 18650 and 14500 lithium cells.
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#3
Roadtripp, with all of that, it sounds like you will be on the 'bleeding edge' of mobile off-grid power. 

Good luck with it...let us know how it works out.
Wondering about Wandering.
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#4
Thanks. These Leaf Lion battery modules were for a 48 volt golf cart project that didn’t happen. So I’ve got them left over. The domestic made bms systems, Batrium, Orion, and REC, have a track record if one digs for it. But they are prohibitive in cost. I’ve read only a couple reviews of the Energus bms systems. The only N. America distributor is in Canada using them to build electric bikes. The 100 amp model is rated to 750 amp with the optional amperage sensor and a high amperage contact. 
 There are lots of people using these modules without active bms but I prefer not to. 
 Monitoring the battery temperature is another key feature.
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#5
My only comment from experience is not to mix chemistry. We mixed calcium and lipro in Russia. Calcium can perform sub zero lipro can't. We used calcium to provide light, and heating of lithium batteries containment box. Lithium went to inverters. Someone paralleled a calcium single and lithium single D6 size no BMS connection the BMS was external and not on the battery.

Lithium fire at -45

Not good
Beast Master,JunkyMonkey,Drinks with Wolves,Fup'd Duck,Sheriff Ricochet Cockroach 4B's 1 cluster,3 TFMS Tempory Weirdo Overlord replacement 
[-] The following 1 user says Thank You to Scott7022 for this post:
  • Roadtripp (08-23-2019)
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#6
Thanks, I’ll be extra careful, when I configure these Leaf modules to function safely I’ll post to this thread so there’s a another option for folks who need a lot off energy storage for whatever reason. This is only 21 modules which is less than half a whole Leaf pack. But I think it’s about 11KW which is a big pack for mobile solar.
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#7
How big is the Leaf battery?

I watched a video on how to rebuild the Nimh battery pack in a Prius, and was surprised that it was not a lot larger than it was. Looked to be about 1.5 feet wide, 3.5 feet long and 15 inches high, I was expecting something that could power a vehicle for any distance, even a hybrid, to be much much bigger.
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#8
I’ve been preoccupied working for a few days.  
 I took apart a 48 module Leaf battery pack once outside in the wet mud. I knew it was hazardous but I didn’t know just how extremely hazardous. 300+ volts DC! There’s a reason they are sealed up tight in a heated metal case. A lot of 10mm bolts to get it apart. 
 Some friends into custom EVs bought several Leafs that were damaged during shipping. 
 Anyhow my 48 volt packs are 14”tallx14”longx9.5”wide. Each pack weighs about 40lbs. There are 7 modules in each of these packs. There are 48 modules in a full Leaf Pack so thats 14”tallx96”longx9.5” wide. Fairly compact. 
  To create one enormously powerful 48 volt battery from an entire 48 module Leaf pack all that’s required is to purchase one extra module from Green Tech Direct or other EV wrecker for around $80. And then reconfigure it into a giant 48 volt battery with creative use of numerous busbars. If memory serves it’s somewhere around 26KW energy storage total for a new standard Leaf pack. And supposedly around 80% capacity in a used pack, so around 20KW . There’s a vlogger who documented his motorcoach build he did for his family including this type of 49 module pack. I have 21 modules so less than half a Leaf pack but still a very big solar storage potential especially for mobile use.
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