Lithium battery upgrade questions

[rubicon327]

Originally Posted by Centex

Isn't it the case that when a trailer has the inverter (with or without transfer switch) as installed by ETI that turning off the 'main breaker' does not turn off the inverter? IOW one must turn off the 'main breaker' and separately verify the inverter is "Off" to ensure all circuits are 'dead', just as when one pulls the shore power cord on a trailer so equipped? I'm basing that understanding on review of the wonderful schematics of ETI setups posted by tdf-texas.

Correct. The inverter will always be providing 120V AC power if turned 'ON' because the 12V power source is wired directly to the batteries. If the "all-outlets" inverter option was provided by ETI the inverter provides its power to the subpanel breakers via the transfer switch. The breakers in the subpanel would need to be turned off as well to isolate those outlets. For the inverter option without the transfer switch the dedicated outlet wired to the inverter would be live unless the inverter was turned off. I don't believe that ETI ever provided any type of intermediate breaker. This is all a prime example of why a smart electrician always tests circuits with a multimeter to ensure power is dead.

[rubicon327]

Originally Posted by Centex

BTW Greg A, rubicon Dave, and semievolved Dave ... my appreciation is growing for your notion of using the BMV-712 to trigger a conservative (well-over 10V) LVCO for the purpose of ensuring plenty of battery reserve.

Do any of y'all have a particular make/model of 200A contactor in mind that you 'like' for that application?

Alan: This is the one that Dave (semievolved) sent me a link to:
https://www.electriccarpartscompany....r-120v-dc-coil

BUT my thinking is that it might be better to use a normally CLOSED contactor that opens with the 12V coil voltage from an intermediate relay. This allows the intermediate relay to be normally open and not provide a contant coil voltage to the contactor to keep it closed. Dave said the intermediate relay is required because the BMV-712 can only provide 1A output and the contactor needs more. I haven't bought it yet but I am eyeing this contactor:
https://www.electriccarpartscompany....-contactor-set

This intermediate relay:
https://www.amazon.com/PACK-AMP-Wate...Q2xpY2s9dHJ1ZQ==

and wiring it all up like the attached graphic shows

If anyone is more experienced with contactors and relays I'm all ears...

[MVA]

Originally Posted by rubicon327

Any comments from the electrical gurus? The only thing I don't like about this design is that the converter will stay live if the 30A main is turned off. That is not intuitive for anyone working on the trailer in the future. Typically you would expect that all 120V devices would be off when the main is off. I guess it is ok if I label it appropriately and provide a means to shut the converter off with its own breaker.

I am scoping out a similar upgrade (solar and lithium) to our 19'. I noted that you removed the thermal circuit breaker that is stock on the line to the 12V line to the power center (see circled on attached diagram). I assume that is intentional since the power center is already fused at 60A?

Thanks

p.s. - thanks to tdf-Texas for the base schematics

[Centex]

Originally Posted by rubicon327

....
and wiring it all up like the attached graphic shows

If anyone is more experienced with contactors and relays I'm all ears...

Gotchya, Dave, thanks.

I understand your thinking about NO vs NC with such a contactor.

I'm wondering if there's such a device as a 'latching contactor' (probably the incorrect term) which only requires a brief current to the coil to toggle between 'open' and 'closed' and will hold its position without ongoing power-demand to the coil? I know there are "latching relays" that function that way, but don't know if such is available at a reasonable cost with the needed 200A rating.

IF one were, that could use both the 87 and 87a pins on the intermediate relay to provide the 'toggle' based on the 712 relay being 'set' or 'clear'? And thereby not present an ongoing drain on the battery to hold the contactor coil in either state?

[rubicon327]

Originally Posted by MVA

I am scoping out a similar upgrade (solar and lithium) to our 19'. I noted that you removed the thermal circuit breaker that is stock on the line to the 12V line to the power center (see circled on attached diagram). I assume that is intentional since the power center is already fused at 60A?

Thanks

p.s. - thanks to tdf-Texas for the base schematics

MVA: Unfortunately every trailer seems to a little bit different but I'll try to connect the dots. Our trailer only had a 30A thermal reset breaker in that position that you circled. (Not sure how the "55A" WFCO charger was even able to charge the battery without it tripping that breaker but I digress) Anyhow I didn't have a fuse originally at the battery so I added a 60A Maxi-fuse when I upgraded the wiring to 6AWG. Best practice is to have it as close to the battery as possible. I then added a 40A thermal reset breaker on the tow vehicle charge line as that seemed prudent and moved the 12V feed to the breakaway switch to the battery side of the disconnect switch so it could never be turned off. See original wiring and final wiring attached. Hope this helps.


P.S. If you compare closely you will see that the final wiring is the basis for my lithium upgrade schematic posted earlier in the thread.

[MVA]

Originally Posted by rubicon327

MVA: Unfortunately every trailer seems to a little bit different but I'll try to connect the dots. Our trailer only had a 30A thermal reset breaker in that position that you circled. (Not sure how the "55A" WFCO charger was even able to charge the battery without it tripping that breaker but I digress) Anyhow I didn't have a fuse originally at the battery so I added a 60A Maxi-fuse when I upgraded the wiring to 6AWG. Best practice is to have it as close to the battery as possible. I then added a 40A thermal reset breaker on the tow vehicle charge line as that seemed prudent and moved the 12V feed to the breakaway switch to the battery side of the disconnect switch so it could never be turned off. See original wiring and final wiring attached. Hope this helps.


P.S. If you compare closely you will see that the final wiring is the basis for my lithium upgrade schematic posted earlier in the thread.

Thanks for the insight. We have a 2017 19' and ETI clearly made changes to the design over time.

--Steve (a.k.a MVA)

[Brian B-P]

Originally Posted by Centex

Isn't it the case that when a trailer has the inverter (with or without transfer switch) as installed by ETI that turning off the 'main breaker' does not turn off the inverter?

True - the main breaker isn't really a main breaker with the transfer switch set up to supply only some circuits. So whether the main breaker is turned off or the shore power cable is unplugged, there may still be a power source. You need to kill all sources, or shut off breakers between all sources and all branch circuits. In the normal Escape installation of an all-outlets inverter, turning off all of the required breakers means including the two that are buried in a cabinet in the sub-panel.

[MVA]

I did not see the following question on this or other threads. The forum input would be useful. I believe this question belongs here; if incorrect, I will start a different thread....

A related item to a lithium battery design is the increased voltage. The DC-DC converter will protect the tow vehicle, but my concern is the DC powered components in the trailer: refrigerator; water pump; furnace blower; igniters on water heater and furnace; lighting. Given that the lithium system will be 1.5-2 V higher, has anyone on the forum reviewed these components for compatibility? Is ETI addressing this in their lithium package in some manner?

--Steve

[rubicon327]

Originally Posted by MVA

I did not see the following question on this or other threads. The forum input would be useful. I believe this question belongs here; if incorrect, I will start a different thread....

A related item to a lithium battery design is the increased voltage. The DC-DC converter will protect the tow vehicle, but my concern is the DC powered components in the trailer: refrigerator; water pump; furnace blower; igniters on water heater and furnace; lighting. Given that the lithium system will be 1.5-2 V higher, has anyone on the forum reviewed these components for compatibility? Is ETI addressing this in their lithium package in some manner?

--Steve

Steve: For context (and this is somewhat anecdotal) I believe the problems you may have heard about with the 12V appliances have stemmed from multiple issues: one being users with solar controllers set to equalize at higher voltages of 15.6V+ to attempt to satisfy the charging specs for the Interstate 6V lead acid batteries (without isolating the battery when doing so), second being very cheap LED lights that Escape used for awhile that seemed to flake out and strobe at any voltage above 12, third an issue with some temperamental MaxxFan boards possibly subjected to voltages above their limit and/or condensation.

The DC-DC charger is used to provide the proper charging voltage to the lithium batteries and keeps a lithium from draining the tow vehicle battery with ignition off and no isolation relay (some 7 pin charge lines stay hot with engine off). Regarding proper voltage we have not personally had any problems with the onboard charger/converter providing 14.4V. That was with the stock WFCO and now upgraded Progressive Dynamics PD4655L Wildkat unit. Never did (or could) equalize at higher voltage unless we had put batteries on a stand-alone charger. The lithium battery I will be using is nominal 12.8V (4 cells @ 3.2V) to be charged to 14.4-14.6. Most others are the same including the GoPower GP-LIFEPO4-100 battery apparently being used by Escape. There is no equalization with lithium. Personally I don’t expect to see any significant difference in the operation of these systems related to voltage.

[MVA]

Thanks for the reply and information. I will hope our trailer (2017) is new enough that a lithium battery does not turn our trailer into a bad 1970's light show with strobe lights. :-)

[dstreight]

I opted to go a slightly different route, given 99% of our time is spent away from shore power and reliant upon 12v nominal battery power: The Xantrex Freedom X (3000w) serves as the automatic transfer switch if/when we have shore power available. A separate 120v charger (Victron) is then used to supply 120v to 12v charge current to the LiFePO4 6500w battery.

Again, a little unusual given many Escape owners here seem to utilize a higher % of their time connected to shore power, however the above arrangement has worked out perfectly for us. And since our 15A is a 2014 model and we bought it a couple years ago from the original owner, the WFCO FLA charger wasn't something we could utilize anyway.

[rubicon327]

Originally Posted by dstreight

I opted to go a slightly different route, given 99% of our time is spent away from shore power and reliant upon 12v nominal battery power: The Xantrex Freedom X (3000w) serves as the automatic transfer switch if/when we have shore power available. A separate 120v charger (Victron) is then used to supply 120v to 12v charge current to the LiFePO4 6500w battery.

Again, a little unusual given many Escape owners here seem to utilize a higher % of their time connected to shore power, however the above arrangement has worked out perfectly for us. And since our 15A is a 2014 model and we bought it a couple years ago from the original owner, the WFCO FLA charger wasn't something we could utilize anyway.

Dan: How are you wired to ensure the Victron 120V battery charger is never being run off the inverter?

[MVA]

Originally Posted by rubicon327

Hoping to get some feedback. I put together a wiring diagram using the schematic from tdf-texas as a base and reconfiguring as required. Need this to help visualize what I'm going to do.

Some things you will notice:
-Rewiring the converter/charger to be powered off the shore power side of the transfer switch which allows the main distribution panel to be powered by the inverter. Selective powering of microwave, outlets, mini-split A/C possible without the need for a sub-panel. (Thanks to Greg A for the idea)
-The Victron BMV-712 battery monitor N.O. output will be used to drive a contactor to shut down power to the inverter once the battery reaches a pre-programmed level. In my case 11.2-12V which is the preferred low point for lithium (2.8 -3V per cell). Not interested in letting the battery ever get down to the internal BMS cut-off of 10V which is 2.5V per cell. (Thanks to Semievolved for the idea)
-Victron Orion Smart 18A DC-DC charger will be installed to regulate proper tow vehicle charge. If charge is not needed while towing it can be isolated with the battery disconnect switch.

Any comments would be appreciated.

Thanks for posting this schematic.

I noted that you have a 60A fuse protecting the battery. If both the shore power (55 A max) and solar power (30 A max) are on, you could blow the fuse. Is your intent to only have either shore power or solar power on at one time?

[dstreight]

Originally Posted by rubicon327

Dan: How are you wired to ensure the Victron 120V battery charger is never being run off the inverter?

I haven't actually installed it yet (low priority on my list of stuff I need to get done given we seldom to never go to RV campgrounds...but still something I want to have "just in case"), however my plan is to run it off the 120v leg of the Xantrex which is 120v pass through when shore power is connected.

[rubicon327]

Originally Posted by MVA

Thanks for posting this schematic.

I noted that you have a 60A fuse protecting the battery. If both the shore power (55 A max) and solar power (30 A max) are on, you could blow the fuse. Is your intent to only have either shore power or solar power on at one time?

I guess in theory the lithium’s can take as much as you can give it so could be a concern with a lot of solar. Haven’t planned it out yet. In reality I think it could be landed direct to the battery so the solar branch would be on the other side of that fuse. Maybe others will weigh in.

[Vermilye]

Originally Posted by rubicon327

I guess in theory the lithium’s can take as much as you can give it so could be a concern with a lot of solar. Haven’t planned it out yet. In reality I think it could be landed direct to the battery so the solar branch would be on the other side of that fuse. Maybe others will weigh in.

That is the way Escape wires the solar & the way I did mine. Since the solar has its own fuse, no problem wiring it on the battery side of the 60 amp fuse. When you add solar, if it is rooftop be sure to add a fuse or breaker between the controller & solar panels so you can shut off the panels prior to disconnecting the batteries.

[Perry Butler]

Originally Posted by Vermilye

That is the way Escape wires the solar & the way I did mine. Since the solar has its own fuse, no problem wiring it on the battery side of the 60 amp fuse. When you add solar, if it is rooftop be sure to add a fuse or breaker between the controller & solar panels so you can shut off the panels prior to disconnecting the batteries.

I installed this breaker to disconnect our portable solar and to protect the controller. We have one on each side (overkill?) of the Victron 100/20 controller. The one side is to our Zamp port for our 100 watt portable panel and the other to our batteries. And yes, it doubles as a solar disconnect. Been using them for the past year.

These come in many sizes.

We have two controllers: one for the rooftop and one for the portable panel. When I replaced the ETI supplied GoPower controller with a Victron 100/30 I just swapped the controllers, so no additional breaker. I rely on ETI's installed breaker.

Enjoy,

Perry

[MVA]

General question on solar controller, DC-DC controller, and power center (WFCO or PD) functionality.

Assuming that most of you wire your systems so that all three of these charging circuits are in parallel to the battery, what is the functionality of these controllers when more that one in in operation? For an example, consider the concurrent use of shore power and solar. Both controllers appear to be constant voltage, variable current controllers. Hence, when the power center outputs 14.6V on the battery, the solar controller should drive the current to near zero since the output voltage of the solar controller is at 14.6 V. Hence, my original thought that currents from each of the controllers are additive may be incorrect.

Has one of you measured the current to the battery when for example shore power is connected and then solar is turned on? My thought is that the current will not increase significantly with two sources, and the current will not be the sum of the currents to the battery when each source is individually charging.

Experimental evidence would be appreciated.

Thanks

[Centex]

Originally Posted by Vermilye

... When you add solar, if it is rooftop be sure to add a fuse or breaker between the controller & solar panels so you can shut off the panels prior to disconnecting the batteries.

I'm trying to understand a couple of things relating to the rating and location of this fuse; for me that goes to understanding the 'roles' of a fuse between a PV controller and a battery and would appreciate any clarification that can be offered ....

It seems that there are 3 possible roles for that fuse (or breaker):

1. Protect the wire between the controller and the battery
2. Protect the battery from over-amps from the controller
3. Provide a method of disconnecting the controller>battery interconnect (by pulling the fuse)
4. I don't list protecting the controller from the battery because the controller is not a 'load' so current never flows from the battery to the controller(?)

Re: #1, protect the wire: The wire needs to be rated for the maximum output of the controller and the length of run. Folks having batteries distant for the controller (e.g. batteries in a front box with controller inside the trailer) may have a risk of a wire-short in that run, in which case the fuse should be rated less than the wire ampacity and located near the battery since that's the major source of overwhelming current in case of wire-short. I suppose the same applies when the controller is very near the batteries, but then the wire-run is often very short and direct so this risk is minimal . Does that make sense?

Re: #2, protect the battery from over-current from the controller: As long as the maximum out put possible from the controller is less than what the battery can handle, is a fuse for this purpose necessary? Is the 'need' based on a notion of redundant protection based on the possibility that the controller could go totally haywire and somehow send a current so large that it could damage the battery?

Re #3, provide a 'disconnect' between the controller and the battery: All of the controller installation instructions I can find recommend that the controller be connected to the battery before the PV panels are connected to the controller. That implies that there may be risk to the controller if the battery is disconnected from the controller while the PV panels remain connected to the controller? If that's the case, then one would need to have a method and observe the sequence of always disconnecting panels from the controller before pulling a fuse between the controller and the battery; is that correct? (noting that Perry's arrangement with breakers before and after the controller provides for that)

Re #4, protect the controller from the battery: I suppose there could be a short or failure within the controller that would invite high-current from the battery to the controller. That would be a version of the failure described in #1, would it not?

Sorry this is running long, so cutting to the chase ...

• A fuse or breaker rated slightly higher than the controller output is recommended (whatever it's protecting?).
• The fuse should be located at the 'battery-end' of the wire (?)

Is ^that^ correct?
Does one in reality need to be careful to not pull this fuse before disconnecting the PV array from the controller input-side?

[Vermilye]

Since you generally connect the solar controller directly to the battery, a fuse or circuity breaker is necessary to protect both the wire & the controller from the hundreds of amps possible if a short developed between the battery side of the wire & ground. I would fuse for the wire size or controller rating, which ever is smallest.

As to the addition of a circuit breaker, switch, or fuse between the solar panel & controller, unless you wish to climb up on the roof & cover the panels or disconnect the wiring from the solar controller input every time you disconnect the batteries or the connection between the controller & batteries, one of them is necessary.

Most controller manufacturers bury somewhere in their manual a statement to always connect the battery side first, and disconnect the solar panels before disconnection the battery side. While portable panels obviously don't do this, even the manuals for them usually has this statement. Built in systems often operate closer to the upper limits of the controller, and following the correct sequence is probably a good idea.