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Old 11-15-2023, 10:26 PM   #1
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Default Possible much better lithium inverter/charger/solar unit

A recent scare, very recent, about old parts failing and no longer being available sent me again going around looking at the available options for me if our Magnum MS2000/ARC-50/MS-BMK shore charging/inverting system bellies up. Of course the search is different than in the past as it needs to be good for lithium, which really turns out to be the toughest part of it all, I think.


Preface by saying that I don't think that the standard lithium charge profiles offered are very good. Most are charge full out to 14.3v and shut off or maybe hold a while and then go to float or shut off. Nearly all the research I have done says going to that high a charge voltage is not good for battery life. Many also charge at very high rates, especially on smaller battery banks which is also getting shown to shorten life.


That said, I have chosen to shoot for charging at 13.8v or lower and stopping at a point that will put the SOC at rest indicated by 13.35v. Our current system does that by stopping at 13.8v and a charge rate of 60 amps to the 618ah bank.


The hang up point for me is that none of the chargers end with any criteria that is consistent to rest at the 13.35v. Voltage and time don't cut it and vary wildly in rested voltage. I tested that on our test setup trip.


The Magnum is about the only standalone shore charger that can do it because it terminates off volts and amps. An integrated system like Victron can do it but is much more complicated and centralized.


In my searching, I stumbled across a setup that might actually be as good and maybe better than the Magnum for lithium batteries. It is a fairly recent Samlex addition to their line and much more sophisticated than their previous stuff.


https://samlexamerica.com/products/2...ger-evo-2212/#


It is fully programable for voltages and if float or shut off/rebulk, which is an essential set of needs. The thing that puts it over the edge on being useful is that it has an input that is setup for BMS input, but can also, it appears, be used to trigger from any dry contact switching item.


So, what the above does is make it so if you use a Victron battery monitor with the internal relay you can trigger the charger to shut off and rebulk, based on shunt based SOC measurements. I would set it for 95% full and 40% rebulk, probably, although we rarely if ever would be plugged in that long. I would expect very good repeatability with that setup.


Add this that there would be a cherry on the top, besides.


The Samlex has a solar controller input to it also, which is pretty odd as normally you would see the panels on that input not the controller. The manual is well over 100 pages, but it appears that the solar goes through the Samlex and is controlled the same as the shore power so it could be just set at the solar controller for fixed voltage output and the Samlex would stop the charging based on SOC. If this is true it would be a very nice thing.


A setup like this would not replace a fully integrated system like Avanti's Victron one, but would be for those of us that don't really want it all to be fully integrated into a potential single failure point. EG, I want at least on system to keep running if the rest die.


We will have a Wakespeed regulator on the alternator when the upgrade is done and it will charge to volts and amps and be very consistent, so that would also be covered.


We will stay with the Magnum and Blue Sky solar controller for now as it appears I will be able to fix the battery monitor error that the Magnum is getting currently. I have a new BMK kit coming for it as they are still available.


The Samlex shown is not a low cost item like many other Samlex stuff has been in the past, but appears to be ready to take on Magnum, Outback and the other higher end inverter chargers that cost even more.
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Old 11-15-2023, 11:06 PM   #2
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A recent scare, very recent, about old parts failing and no longer being available sent me again going around looking at the available options for me if our Magnum MS2000/ARC-50/MS-BMK shore charging/inverting system bellies up.....
What is the recent scare?
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Old 11-15-2023, 11:19 PM   #3
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What is the recent scare?

The Magnum uses an inverter/charger and an add on remote to get more control and settings, and a BMK kit which is a shunt and interface box that lets the remote control it all based on actual battery amps and volts.


When I got through with some of the clean up and cable rerouting stuff I started it all up to test before moving on to the Wakespeed regulator installation and the Magnum battery monitor was reading 40 amps all the time. I removed and installed the connector to it and cleaned all the connections and after a bunch of fiddling around got it read 1 amp above what it should with no loads in the van except the monitors and propane detector. If I moved the connector it would bounce around like craze on amps and the connector is not available as a spare part.


I went looking for a place to get a new BMK kit and tripped across some posts about Magnum that indicated there were serious questions as to whether or not they would survive the slowdown during covid. It appears they are in better shape now, but they are in a vulnerable place with all the Asian competition in the same markets as them. I do have what should fix it coming, but it did make me think ahead just in case as that is my nature.


If the Samlex works as it appears it would, the fact that the solar is also controlled would put it as more useful than the Magnum is. You would also have to buy or already have a Victron battery monitor though.
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Old 11-16-2023, 04:10 AM   #4
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I have Magnum MS1000 with BMK and ARC, no issues, hopefully they will last.
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Old 11-16-2023, 09:06 AM   #5
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I have Magnum MS1000 with BMK and ARC, no issues, hopefully they will last.

It appears that the connector is one of the biggest issues with the BMK as it can lose tight fit it gets bumped or just from bouncing down the road. The twisted pair of wires they use is very stiff so no forgiveness of pressure on the connector. Ours still worked, just more resistance so higher readings and they don't have zeroing like many other monitors do.
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Old 11-16-2023, 05:00 PM   #6
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It appears that the connector is one of the biggest issues with the BMK as it can lose tight fit it gets bumped or just from bouncing down the road. The twisted pair of wires they use is very stiff so no forgiveness of pressure on the connector. Ours still worked, just more resistance so higher readings and they don't have zeroing like many other monitors do.
I hope my wires are locked in place and will not cause problems. Changing Mgnum/Magnum ARC/Mornigstar to Samlex would be a major project, I hope it will never make it to my to do list.
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Old 11-18-2023, 09:35 PM   #7
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I hope my wires are locked in place and will not cause problems. Changing Mgnum/Magnum ARC/Mornigstar to Samlex would be a major project, I hope it will never make it to my to do list.

The new unit showed up and I put in place today. interesting that it has a label on it the says "lithium battery compatible". I had run across some posts in searching the problem and found some that said they had trouble with lithium accuracy if they used SOC as their readout. We use amp hours so it probably didn't show up on our test trip. We will see if this different or not.



If appears to have fixed the issue.


I did test the old connector on it and the old unit and the connector and cable were fine, but the old unit had the 1 amp error even with the new connector and cable. Odd because the connector could make it get worse, but never better than one amp off.


Since I needed to remove the solar controller to put on the new BMK module, I decided to put in the new solar controller I already had on hand. I got it when I thought the controller might be failing but it turned out to be a bad phone cable data plug. It also says lithium capable, but all they did, I think, is make on more selectable preset for lithium and nothing else


When all was in and tested it appears both monitors, the Magnum and Blue Sky solar controller, match at no added load at .5 amps but both will flicker to .4 so probably more like 3.7 or so. About as close as I could reasonably expect though.


If the Magnum had a zeroable option like many monitors that run off shunts do, I probably wouldn't have needed a new unit, bummer.
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Old 11-22-2023, 04:22 PM   #8
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A recent scare, very recent, about old parts failing and no longer being available sent me again going around looking at the available options for me if our Magnum MS2000/ARC-50/MS-BMK shore charging/inverting system bellies up.
You had us alarmed as well as we have been very happy with the quality and reliability of our Magnum 2812 and have contemplated up-dating/up-grading our system to 48 volts using Magnum's equivalent higher voltage unit. We do not, however, use Magnum's BMK unit as we have been satisfied with simply setting the Magnum to a Constant Voltage (Magnum's CC/CV mode) corresponding to the State of Charge desired. From our prior conversations we do understand your desire to use a combination of voltage and current to set your charging profile as it allows you to charge faster by initially setting the charge voltage higher but, ultimately, to revert to a charge voltage that corresponds to your desired State of Charge. We can do that, but only manually. But our reality is . . . we are generally connected to shore power only when at a campground and, then, for a minimum period of "over night". With this amount of time, using Magnum's straight CC/CV approach has never been a problem.

But what really got our attention was your discussion of using a Victron or other battery monitor/BMS to control the Samlex. We have always been of the opinion that our battery monitor/BMS should be an emergency means of shutting down battery charging if one of our independently programmed chargers (programmed to a lower SoC/voltage than the BMS) fails to terminate charging as programmed.
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