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08-11-2020, 01:54 PM
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#1
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2 Rivet Member
2021 25' Flying Cloud
2014 Interstate Ext. Coach
Angier
, North Carolina
Join Date: Jun 2016
Posts: 32
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EMS changes with Lithium upgrade
I am completing upgrades on my Interstate 2014 including 400 Ahr lithium battery bank, 300 watts solar and a 2000 w Inverter/Charger. I now wonder if the BMS is necessary any longer. This of course is the current sensing addition that switches off a couple of circuits if too much current is being demanded. Any thoughts from those of you who have recently upgraded your systems?
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08-11-2020, 04:16 PM
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#2
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Contributing Member
2018 Interstate Grand Tour Ext
Austin (Hays County)
, Texas
Join Date: Jun 2002
Posts: 7,164
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You are apparently asking about the Power Control System, not the Battery Management System. They are two different things. BMS simple connects the batteries when appropriate.
I'll leave the answer to someone who has done the conversion, but the Power Control System is still critical when you are plugged into 30 amp service or running on generator.
__________________
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"
WBCCI #9632
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08-11-2020, 04:57 PM
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#3
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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And that is exactly why I believe lithium isn't ready for prime time in a trailer application. A "real" BMS does much more than that....like liquid heating and cooling of the battery, among other things.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
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08-11-2020, 06:11 PM
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#4
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Rivet Master
1972 23' Safari
Middletown
, Rhode Island
Join Date: Sep 2016
Posts: 546
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Doesn't the lithium batteries come with built in BMS? Mine did.
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08-11-2020, 06:28 PM
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#5
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3 Rivet Member
Currently Looking...
2016 Interstate Grand Tour Ext
Traverse City
, Michigan
Join Date: Mar 2018
Posts: 214
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Is the BMS aka the BIM? I removed the BIM and isolator running the alternator to a Sterling dc to dc charger.
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08-11-2020, 09:24 PM
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#6
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3 Rivet Member
2013 Interstate Coach
Indianola
, Iowa
Join Date: Jun 2019
Posts: 161
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The power management system is on shore power or generator side of the system, so lithium vs lead acid for the 12v side is neither here nor there for that component. You would keep this system in any event. Like Heckler56, I also removed the BIM which sometimes connects the chassis battery to the house batteries and put in a sterling dc to dc charger, in my lithium conversion.
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08-12-2020, 01:27 AM
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#7
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2 Rivet Member
2021 25' Flying Cloud
2014 Interstate Ext. Coach
Angier
, North Carolina
Join Date: Jun 2016
Posts: 32
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WOW, i blew that post. I meant to address the Power Control System as Pahaska pointed out! I regret the confusion that my post has caused. The BIM (Battery Isolation Manager) will be replaced as it appears not to be working anyway. My new batteries do have a BMS (Battery Management System) built in that reports the current SOC of the batteries. It is the Power Control System and its related current sensor that I mean to question. While making the other changes to the system I discovered that microwave circuit connection to this sensor was fried. The result of perhaps a loose connection. Appears that I may have to replace the sensor if that part of the system is still necessary.
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08-12-2020, 09:29 AM
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#8
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,674
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Quote:
Originally Posted by dznf0g
And that is exactly why I believe lithium isn't ready for prime time in a trailer application. A "real" BMS does much more than that....like liquid heating and cooling of the battery, among other things.
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Hi
If that is your standard for a BMS ( "liquid heating and cooling" ) then roughly 99.9999% of all systems out there are "doing it wrong" .....
Bob
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08-12-2020, 09:47 AM
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#9
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Contributing Member
2018 Interstate Grand Tour Ext
Austin (Hays County)
, Texas
Join Date: Jun 2002
Posts: 7,164
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Quote:
Originally Posted by uncle_bob
Hi
If that is your standard for a BMS ( "liquid heating and cooling" ) then roughly 99.9999% of all systems out there are "doing it wrong" .....
Bob
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Believe me, the BMS in my BMW I3 does exactly those things, not only when the HV battery is being charged, but when it is being used in hot or cold conditions. This is true of just about every EV on the road with the exception of the early Nissan Leaf and maybe the smart. Nissan tried to get away with no controls and failed miserably.
I charged in the hot garage yesterday afternoon and the cooling system automatically turned on to cool the HV battery. I normally automatically charge from 11:00 PM to 7:00 AM when the electric rates are the lowest and the temperature low enough that cooling is not needed.
__________________
John W. Irwin
2018 Interstate GT, "Sabre-Dog V"
WBCCI #9632
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08-12-2020, 10:37 AM
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#10
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by Pahaska
Believe me, the BMS in my BMW I3 does exactly those things, not only when the HV battery is being charged, but when it is being used in hot or cold conditions. This is true of just about every EV on the road with the exception of the early Nissan Leaf and maybe the smart. Nissan tried to get away with no controls and failed miserably.
I charged in the hot garage yesterday afternoon and the cooling system automatically turned on to cool the HV battery. I normally automatically charge from 11:00 PM to 7:00 AM when the electric rates are the lowest and the temperature low enough that cooling is not needed.
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Exactly. My training and experience comes from the automotive world. Those manufacturers who chose air heating and cooling and not providing for multiple temperature sensors per pack, among other things, experienced premature battery degradation. Those with liquid cooling plates between cell packs did not.
My problem with rv applications is not so much the battery itself, but the radically cyclic extreme (for a lithium) temperatures in which they live, and are used, with no provision for constantly maintaining an internally acceptable temperature window.
(I was trained on Volt and Bolt and am a Volt owner)
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
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08-12-2020, 11:04 AM
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#11
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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I, like Pahaska, have caught my Volt heating and cooling the battery of it's own volition. If the car has not been used for a time and the internal battery temperature is equalized to the ambient garage temp (a minimum or 24 hours is my observed SWAG), the heated water pump will come on at about 35* garage temp. The a/c compressor will run and chill the battery coolant at about 90* garage temp.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
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08-13-2020, 08:55 AM
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#12
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,674
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Hi
..... and .... the charge / discharge rates in an EV battery are nothing remotely similar to those in an RV setup. It's not the same thing at all ....
Bob
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08-13-2020, 09:58 AM
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#13
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by uncle_bob
Hi
..... and .... the charge / discharge rates in an EV battery are nothing remotely similar to those in an RV setup. It's not the same thing at all ....
Bob
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In proportion to overall capacity, they may not be as different as you may suspect. Especially if your use the inverter for some higher amperage items. Barring the level 3 and above charging rates of cars.
But internally generated heat from discharge rates and charge rates are only half the story. My trailer can easily be over 100* on any given summer day. So, depending on the length of the heat soak, the internal temp of the cell pack could be that high. As the above video mentions, even in the BattleBorn...only one temp sensor and it is on the top, outside of the cell pack.
Then to top things off, where do we put the batts in our trailers? Small enclosed compartments with little to no airflow.
Again, I love lithium technology, I am just not willing, yet, to spend the amount for a complete conversion into an environment which is detrimental to the battery's longevity.
BTW, while we are on the subject. Don't use or charge your charging bricks, vacuum batteries, e-bike batteries, etc. immediately after heat soaking all day in the RV or TV. Also, always try and park your e-bikes in the shade or remove the batt and take with you in a backpack or something. Those suckers get really hot in the sun.
I love the latest and greatest, but there are some valid decision points here.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
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08-14-2020, 07:32 AM
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#14
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Half a Rivet Short
2017 30' Classic
2022 Interstate 24X
Carlisle
, Pennsylvania
Join Date: May 2017
Posts: 15,674
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Quote:
Originally Posted by dznf0g
In proportion to overall capacity, they may not be as different as you may suspect. Especially if your use the inverter for some higher amperage items. Barring the level 3 and above charging rates of cars.
But internally generated heat from discharge rates and charge rates are only half the story. My trailer can easily be over 100* on any given summer day. So, depending on the length of the heat soak, the internal temp of the cell pack could be that high. As the above video mentions, even in the BattleBorn...only one temp sensor and it is on the top, outside of the cell pack.
Then to top things off, where do we put the batts in our trailers? Small enclosed compartments with little to no airflow.
Again, I love lithium technology, I am just not willing, yet, to spend the amount for a complete conversion into an environment which is detrimental to the battery's longevity.
BTW, while we are on the subject. Don't use or charge your charging bricks, vacuum batteries, e-bike batteries, etc. immediately after heat soaking all day in the RV or TV. Also, always try and park your e-bikes in the shade or remove the batt and take with you in a backpack or something. Those suckers get really hot in the sun.
I love the latest and greatest, but there are some valid decision points here.
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Hi
In RV service, we don't run discharge rates over C/1. Indeed the way most of us put systems in, even *with* the inverter C/4 is about the max. When I tear apart EV battery packs I note:
1) They are set up for charge / discharge rates up in the C * 2 to C * 5 range.
2) I have yet to see *any* pack from any manufacturer that has fittings for heating / cooling. That includes packs from most of the big guys.
3) The chemistry in the EV packs often is something exotic and not the more durable LiFePO4 stuff that we use ...
Lots of variables ....
Bob
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08-14-2020, 11:18 AM
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#15
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by uncle_bob
Hi
In RV service, we don't run discharge rates over C/1. Indeed the way most of us put systems in, even *with* the inverter C/4 is about the max. When I tear apart EV battery packs I note:
1) They are set up for charge / discharge rates up in the C * 2 to C * 5 range.
2) I have yet to see *any* pack from any manufacturer that has fittings for heating / cooling. That includes packs from most of the big guys.
3) The chemistry in the EV packs often is something exotic and not the more durable LiFePO4 stuff that we use ...
Lots of variables ....
Bob
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Well then apparently you have never torn down a GM nor a BMW pack. I'll speak for my GM training only. Volt has many(I'll refresh my memory and get the number, if you'd like) thin metal "radiators" between cell groups. They are circulated with (separate cooling system) propylene glycol which is heated or cooled electrically (a/c compressor or electric element) as required. If ambient are modest, that coolant system has a separate chamber in the front radiator and air will regulate the coolant temp.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
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08-14-2020, 11:25 AM
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#16
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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My volt has lithium manganese oxide battery cells. Not sure what you call exotic. Cruising down the highway my discharge rates are observed at C/.6 to C/1.5 Typical acceleration from a stoplight is c/2.5
Obviously, a hot rodder or very hilly terrain can produce peaks.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
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08-14-2020, 11:39 AM
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#17
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Rivet Master
2022 25' Flying Cloud
NCR
, Ontario
Join Date: Feb 2017
Posts: 3,077
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Battle Born Lion and Victron Lion battery( just two examples) have built in BMS.
The OEM know their batteries, thus their BMS design do the best for their batteries.
Thus it's best to get an integrated BMS on any Lion batteries, vs home brew
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08-14-2020, 11:43 AM
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#18
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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I should add that those numbers are artificially inflated from true capacity of 18.4kW to the 14.1kW " useable" capacity.
There is buffer at the top and bottom.
__________________
-Rich-
"If the women don't find you handsome, they should at least find you handy." - Red Green
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08-19-2020, 10:51 AM
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#19
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2 Rivet Member
2015 Interstate Ext. Coach
Mesa
, Arizona
Join Date: Nov 2017
Posts: 90
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I have the exact same system, all Victron. The inverter kicks off if you try to overload it. I’m guessing the BMS does virtually the same thing. Mine was installed by AM Solar, Springfield, OR. They would answer your question.
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08-19-2020, 12:27 PM
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#20
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Rivet Master
2007 30' Classic
KW
, Ontario
Join Date: May 2012
Posts: 993
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Just because a battery has it "built in" doesn't mean it is controlled properly. The battery systems we build rely on a proper controller which is built into the vehicle. There are 2 main companies making the Isospi systems. We are currently using the ones from Nxp. There is a lot of things that need to get programmed into this interface to make it work properly. This is no small task. Most people have no idea what it takes. I'm currently working with the engineers on testing systems of these batteries.
I would have to agree with the statement that these batteries are not ready yet for the trailer market.
Currently we have designed battery systems for many auto manufacturers including the most popular ones. Sorry can't give more details than that.
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