Update on our lithium "test" bank in 07 Roadtrek 190P

[GeorgeRa]

Originally Posted by booster

We have done charging from multiple sources to tail amps at the same time for many years as they seem to play together just fine.


It was always two sources though, as there isn't really a case where we would have all the sources running at the same time. It was solar/shore or solar/alternator.


Both the solar and the shore charger will automatically and independently charge to the reading of amps from the same shunt. Minor differences make them shut off at slightly different times, but close together if set to be that way.


The alternator charging was done manually as I drove by watching an ammeter on the dash and shutting off the charging when it was done or the solar could produce enough to finish the charge automatically.


Hopefully, the Wakespeed will make the alternator charging also automatic so I don't have to worry about watching it. The lithium amps change very rapidly at the desired end point so if you are in traffic or other attention needing conditions it is easy to miss manually so automatic will be very nice to have if it works.


The solar and shore chargers are fully settable for voltages, tail amps, and/or hold times. The current regulator is the weak spot with only preset voltages, IIRC about 4 options, and the current is set via putting a cap on field % and only limits charge rate. Alternator charging now is not automatic but should be in the future with full amps/volts ect setability.

Thank you.

Using the same shunt, I think you mentioned it earlier, I missed it. I agree, 3 sources wound never be used simultaneously.

At some point a company will come up with a system capable to:

IN - take 3 power sources
OUT – charge Lithium batteries, AC power
IN/OUT – control/monitor panel.

Perhaps they exist but I am not up to date with the current leading edge.
Thank you for updating your progress.

[booster]

I have been working on understanding how the #@%$* to make sense of the Wakespeed updating, modification of configurations, and transferring them to the unit.


I am used to having at least a basic interface to enter data, but this appears to be totally programmer language type stuff, which is a foreign language to me.


I think I finally did get the unit updated to current firmware and managed to install the basic "gentle" lithium charge profile after about 3 hours of frustration because all of the videos are from before a bunch of website changes and for phones mostly now. I am on a pc.


Now that I look at how to edit it gets totally different because you have to download the basic configuration and open it as a text file in something like Notepad. The settings are just numbers in strings of numbers with no identifiers except where they are, so you go a list of what they are that relates to where they are. There are about 100 individual settings, but some are locked out so you can't set that many.


You then have to reload the modified config to the unit.


Long learning curve for me, though.


I will be trying to make the modified to my preferences config in the next few days, to see how it goes.

[booster]

For those that are somewhat geeky, they have a 4 hour, yes 4 hour, video of their initial training of installers that is pretty interesting, at least to me.


They do a very, very good job of explaining why the volts and amps charging control is by far the best way to go. I have believed and done that kind of control on our AGMs for many years so good to see a manufacturer who totally understands it and is addressing it.


https://youtu.be/3uWWysz4blw


Bring a beer and chips, maybe a 6 pack and pizza as 4 hours is a long time

[Urlauber]

How are you handling the battery BMS taking them offline while being solar-charged? Or is that unlikely because you're running several in parallel?

[booster]

Originally Posted by Urlauber

How are you handling the battery BMS taking them offline while being solar-charged? Or is that unlikely because you're running several in parallel?

That is still a work in progress until I finally decide if I should leave the system as a parallel system or take the second alternator off on it's own as a standalone. Neither way offers a suitable solution, though, if there is a full cutoff by the batteries unless I leave the starting battery in the circuit all the time and I have yet to test if that would work well or not. With the AGMs we always disconnected the coach from the engine once charging was done while driving and while not driving. The solar is a tough one because of the availability of the high voltage from the panels if the controller loses it's power source and reference voltage. Our system is wired as parallel 12v on the panels so not as bad as a 24v or higher setup, but still could get 21+volts. I am kind of surprised that no product has come out to protect against this kind of issue, like they have for the alternators. As of right now, I think having some kind of battery that stays in the system with the lithium off is probably the only way to address it. Our 3 batteries are unlikely to go off all at the same time, but could be very close together in a high or low voltage problem.



I did check with Magnum and they claim that the shore charger will not through a spike if the batteries suddenly disconnect at full charge rate, so that is safe, I think.


It is areas like this one with the solar where the fully integrated systems that use BMS output signals probably really are a lot better than the built in BMS systems that don't communicate. They would be able to send a signal to shut off the panels before any cutout just like they would do for alternator charging or shore charging.

[Urlauber]

Originally Posted by booster

It is areas like this one with the solar where the fully integrated systems that use BMS output signals probably really are a lot better than the built in BMS systems that don't communicate. They would be able to send a signal to shut off the panels before any cutout just like they would do for alternator charging or shore charging.

I wonder why there are no (commonly available) solar controllers which have this feature, where they sense the load disappearing and cut the panel input accordingly, basically just shutting off the 12V circuit. Maybe it's not that easy.

Having a small AGM battery integrated somehow as a buffer might be a good idea.

[booster]

Originally Posted by Urlauber

I wonder why there are no (commonly available) solar controllers which have this feature, where they sense the load disappearing and cut the panel input accordingly, basically just shutting off the 12V circuit. Maybe it's not that easy.

Having a small AGM battery integrated somehow as a buffer might be a good idea.

I think the problem is that all of it has to happen too quickly to be able to shut off anything.


They would actually need to shut off the panel input, not the 12v which would actually cause the same issue. The spike comes from the panels not having the controller handling the voltage control because it has lost it's power and 12v reference from the battery. In a solar spike it is probably common for the controller to be damaged as well as it passing through and damaging other parts.


I will need to see how having the starting battery in the circuit all the time will work out for backward charging of it from the lithium bank which will be running 13.35v and under when not on charge. It probably will be just fine at that voltage and has plenty of capacity to cover the parasitic.