My Interstate Lithium Battery Adventures

[amirm]

Don't feel too bad. I killed my solar BMS when I was completely done! I simply disconnected the wires to tie them up nicely and bam, it stopped reading any current consumption. Sent it to Dacian and he said a PCB path was blown even though it had SPD protection on either end of it.

I just did not want anything this sensitive in my system so immediately switched to a different solution at a cost of $1,000 and tons of re-wiring and redesigning. The new system is pretty robust although had its own issues I had to sort out.

[amirm]

One of the issues with this design is that it is possible to power parts of the BMS controller without itself being powered. This causes latch-up on inputs of the processors and such, causing instant failure. The only solution is to have a cable connection that disconnects all input when power is removed. My BMS has this type of connector (more or less) which helps with robustness this way.

[InterBlog]

Originally Posted by amirm

....Sent it to Dacian and he said a PCB path was blown even though it had SPD protection on either end of it.
....

Is there a way that you can translate that into less technical language?

Two of us now fried a device that we had believed was un-friable under the prevailing circumstances. I'm going to do my due diligence and RTFM, but I'm not a double-E and so that info is only going to penetrate to a certain depth. At some point I'd like to approach Dacian and ask him to elaborate on ALL the known ways that this thing could be accidentally killed. If it is a problem with inherent fragility, I need to know the full extent of what that means. Obviously it's not a swappable component. If I accidentally do something on the road to kill it, I'm pooched. And that's not a good feeling.

[amirm]

Originally Posted by InterBlog

Is there a way that you can translate that into less technical language?

Two of us now fried a device that we had believed was un-friable under the prevailing circumstances. I'm going to do my due diligence and RTFM, but I'm not a double-E and so that info is only going to penetrate to a certain depth. At some point I'd like to approach Dacian and ask him to elaborate on ALL the known ways that this thing could be accidentally killed. If it is a problem with inherent fragility, I need to know the full extent of what that means. Obviously it's not a swappable component. If I accidentally do something on the road to kill it, I'm pooched. And that's not a good feeling.

Sure. The part that died on mine is what measures current. Those lines as you know connects across an external shunt. Should you touch these lines with static electricity, they would easily damage the integrated circuit that measures such small voltages. So he had put surge protection devices (SPDs) around it. These should have stopped any high voltage from hitting that path. Yet something with lots of energy did and proceeded to destroy the PC board trace! Dacian has no explanation of why it happened and neither do I. He put a wire to replace that trace and sent it back to me but I have not tested, nor looked at the circuit to see what other factors could have caused it.

On your problem here is the issue at hand (I think). Integrated Circuits have power sources and inputs and outputs. The specifications for those inputs says that no voltage above something like half a volt can be applied to them that is higher than the power input. If you remove the power input, now that is at zero so the input cannot go above 0.5 volt. In normal course of operation like sensing the voltage of each Lithium cell, those voltages will obviously be much higher causing a condition called "latch-up" which is fancy way of saying a short is created causing the component to be damaged.

This is my best guess but it can be wrong.

Besides this kind of damage, I got my unit to be confused totally in other conditions. I got it to forget all of its settings, show wrong values, etc. Disconnecting power and restarting fixed these.

My net summary is that this device as clever as it is, is fragile in the way we are using them. That is, connecting disconnecting it multiple times in the process of finishing the installation.

Is it also fragile in use? I don't know. I did not get that far. It is going to get bounced around hard in our use. In Dacian's use in a home this won't happen. Will the screw terminals come loose? There is no positive locking mechanism there like there is in ring terminals.

The other issue is longevity of this option. I don't know how long Dacian will be building/repairing these. And I know for sure I would not want to wait until he fixes one should it break.

For all of these reasons I reluctantly used another system that is designed for electric cars. I already had it in my electric Polaris Ranger so I know its operation is robust. I now have about 12 months in the Polaris with only one glitch that I don't know was caused by it that cleared itself. On my Airstream, knock on wood, it has been solid since I finished the project last summer.

I think a much better solution can be built than either one of these as neither is a perfect situation.

This is all I can share right now. Please make your own choices and don't rely on me. Hate to be responsible for you either way .

[LB_3]

Would you sell us your old SBMS? It would be nice to have a spare.

[InterBlog]

Originally Posted by amirm

....
Is it also fragile in use? I don't know. I did not get that far. It is going to get bounced around hard in our use. ....

The only data I have on that variable is that ours survived a proper pounding as I traversed the Eagle Ford the week before last. I tend to take Texas back roads when possible, as I'm sick of the freeways. The roads in the area of the state are notorious for having been torn up during the unprecedented industrial activity surrounding the recent shale boom. So all I can say right now is that one particular day of rough handling did not precipitate infant mortality in our BMS unit.

[InterBlog]

Originally Posted by amirm

.... I went with the 120 because I measured the system as it was and I was getting in excess of 100 amps into the lead acid batteries. So didn't want to go backward. In mine, the wire leading to the front battery is quite beefy. I forget now but it is something like 2/0 and such. And with 220 amp alternator that was the right strategy....

For me, having maximum charge from the engine was very important. It would allow us to quickly charge the batteries back up with a short drive or idling in the morning. So if at all possible, I would opt for the 120. But you have a lot of constraints to worry about from having to run another wire, to your alternator capacity, over current of SBMS due to your higher solar charge, etc. So not sure what to recommend .

Circling back around to the alternator discussion, last night my husband elicited suggestions on the alternator from me, as the time had come for him to order one.

Of course, with me not having adequate technical knowledge, trying to get that answer is like pulling hen's teeth. So I defaulted to my usual logic of running down partial decision trees (as I lacked the knowledge basis for a full tree) and then all of a sudden, was able to join the mental dots on a real-world anecdote that is relevant to our situation.

There's a journalist named Brent Rose who began vanliving just over a year ago. He regularly appears in Wired, Gizmodo, does some television, etc. Because he owns a 2006 T1N Sprinter and because he has to run a full computer system without a shore power connection, he's the closest analog I've found to my own work-vanlife situation.

Before embarking on this gig, he had AM Solar do a full lithium and solar retrofit and from the standpoint of the system itself, I do not believe he's had any problems. But I realized last night that he appears to have blown two alternators inside of a year, both of them under potentially catastrophic circumstances. The first time, he was in a remote area and inexplicably managed to find a flat-bed tow anyway (lucky). The second time he stalled out in urban rush hour traffic, and without the alternator, could not even activate his hazard lights. He's danged lucky his rig never got smashed to smithereens.

His writing focus is not technical, so I emailed him to confirm that it was indeed two separate alternator failures, as it appeared to be from his anecdotal reporting. And on the basis of his reply which I've excerpted below, I told my husband, "Pick whichever alternator doesn't make us end up like Brent."


***
"Anyway, to answer your technical questions, yes, it seems it was the alternator again and you're absolutely correct that that happened to me at the end of my first month in the van (good memory!). As you suspect, it seems the demands of the lithium system (plus cab battery) were too much for the stock alternator which was a very wimpy 90 amp. Unfortunately when it broke the first time I was in a pretty desperate situation in the middle of nowhere, so when the mechanic was able to find the replacement part I went with it, and sadly it failed again.

This time I replaced it with a 200 amp alternator (which cost just over $500), and so far so good, but then again, that other one seemed fine for a year and a half until suddenly it wasn't. We shall see!"

[lewster]

Interesting!

Quick related story about T1-N alternators. While returning to FL in the Fall of 2009 with my 2004 Sprinter and my Airstream '06 19'CCD in tow, I ran into a ridiculous amount of catastrophic failures on the road in a 5 day period at approx. 115,000 miles.

First was a turbo that was whistling and had a noticeable power decrease; had to be replaced in Denver. OUCH! $$$$$$

Next was the alternator. While traveling between Amarillo and Dallas at night, I noticed that my headlights were starting to dim. Pulled to the side of the highway and checked the battery voltage with the engine running.......11.2VDC. OOOPS!! NOT GOOD!

I found a huge rest area not far down the road and set up camp for the night. Could not find a usable 120VAC outlet to re-charge the van battery anywhere, so I used my 300Ah Lifeline house battery thru the Magnum 2000 watt inverter to operate my 120VAC battery charger on the start battery and went to sleep in the CCD.

Found a Sprinter dealer (Dodge at the time) just north of Dallas and decided to call first thing in the AM to see if they had the part and could get me in. Waited until daybreak to break camp as I didn't want the draw from the headlights to drop the battery level (which went back up to 100% overnight) while driving.

Started out, celled the dealer and got the OK. As I was headed down the road, I noticed that the engine battery level was dropping continuously, meaning that the engine was being electrically powered by the battery with no alternator boost. The voltage continued to drop to about 11.4VDC, and I was again worried that the diesel would shut down with no power to operate the fuel pump.

Then a funny thing happened........as the sun rose in the sky, the engine battery voltage stabilized and actually started to increase ever so slowly!! I had a 400 watt solar array on the roof being powered by an older AM Solar charging system and one of the features was an auxiliary engine battery charging circuit, which was connected.

As the sun got higher in the sky, the engine battery voltage started to increase more....so I WAS EFFECTIVELY SOLAR POWERED!!!! Whew....missed that bullet!!!

Got to the dealer with the engine battery at 12.1VDC, had them replace the alternator (it was the 200 amp version), re-charge the battery and headed back down the road same day.

The catastrophic transmission failure outside Baton Rouge on I-10 a couple of days later is another story for another day.

[73shark]

Wow, if it wasn't for bad luck, you would have had no luck at all on that trip.

[Lotus54]

According to the build sheet on my T1N (thanks to a very helpful member here) - it came with a 150 Amp alternator.

It only had 35k miles when I got it last fall, so I'll bet it still has that original alternator (although I've never checked to verify).

If I remember, a second alternator was an option? Perhaps getting the brackets for that and using it to charge the house batts? (through a proper Lithium regulated DC/DC charger I would assume)

Mark

[amirm]

Wonder if the standard 220 amp Bosch alternator can be used with T1N? I was looking for aftermarket alternators until I found its specs:



As you see, it has an excellent design in how it produces all of its power at very low RPMs. Even hot it is able to put out in excess of 100 amps.

Oh, I just remembered that this is a smart alternator controlled by the engine ECU so likely can't be put in older vehicles.

[LB_3]

I had the dealer print out my build sheet yesterday. We only had a 115A alternator so I will be upgrading to 200A alternator this weekend.

[lsbrodsky]

I am real late to this thread and my experience with high output alternators is with boats. I just installed a Lithium system in my TT and during the research it became clear that alternator charging of Lithiums was an issue that needed to be addressed.
The AM Solar Coach approach is to use the Victron BMS input as a shunt limiting the current from the alternator. Fine, but my experience with any car or boat application and Pb-acid cells is that the alternator may run at full load for a bit, but eventually drops to a fairly low output and stays there as the voltage regulator manages the battery charge.
My experience with Lithiums, so far, is that they take a bigger charge for a longer period of time and I wonder whether alternators are really intended to charge at that output, that long. I think I am saying that maybe a really oversized alternator is needed for Lithium applications if the serious battery charging is involved.
Larry

[FlyFishinRVr]

Originally Posted by lsbrodsky

My experience with Lithiums, so far, is that they take a bigger charge for a longer period of time and I wonder whether alternators are really intended to charge at that output, that long.

Larry

Has anyone asked and received an answer from MB or AS re. how much capacity is available from the stock alternator (the new 220A monster) for "other things" once all the van/house loads are accounted for?

It seems to me that until that question is asked and answered, guessing at what size alternator to use is just that, guessing, and that's never a good thing.....

[InterBlog]

SMH... Mark's (Lotus's) alternator is 150 and ours is 115, both as stated on the respective build sheets, both on the same year of Sprinter, which also happens to be the same Interstate build - only the color schemes appear different. I don't get it.

[Lotus54]

I thought yours was a 2007?
I notice quite a few differences (more black around the windows, covered sink and stove, No 'step' rear bumper and the recent water pump plumbing differences) a Dodge rather than Frieghtliner, but I would think that is the least difference.

But I agree, it seems strange. Did they start ordering smaller alternators later? I wonder how many other differences?
Better drive it up here in the summer to cool off and check out differences.

Would you still install larger alternator if it had a 150?

Mark

Originally Posted by InterBlog

SMH... Mark's (Lotus's) alternator is 150 and ours is 115, both as stated on the respective build sheets, both on the same year of Sprinter, which also happens to be the same Interstate build - only the color schemes appear different. I don't get it.

[InterBlog]

Now that I look at your pic, I see that yours does appear to be a year younger. Your ID tile lists 2006 but that's often populated with the year of the Sprinter, not the Interstate (ours is a 2007 Interstate on a 2006 Sprinter, and my ID tile says 2006).

Nevertheless, why they'd downgrade equipment across one model year is still a mystery to me.

[LB_3]

The Sterling battery-battery charger I'm using limits the draw from the chassis to 60A. I assume the Sprinter chassis draws no more than 90A so if I had a 150A alternator I might be inclined to keep it. But as discussed above, it's hard to really know what an alternator's reliability should be when operating at peak power.

In a perfect world I would have installed a second alternator with a custom regulator to enable the A/C to run off the alternator. But T1N second alternator kits are pretty scarce now. Additionally, the tax rebate for the battery is prorated based on the percent of sun power used by the system so I plan to keep the alternator charging turned off much of the time. (Just in case my future auditor is reading this thread.)

[Lotus54]

Mine is a 2006 Airstream based on a 2005 Sprinter.

Originally Posted by InterBlog

Now that I look at your pic, I see that yours does appear to be a year younger. Your ID tile lists 2006 but that's often populated with the year of the Sprinter, not the Interstate (ours is a 2007 Interstate on a 2006 Sprinter, and my ID tile says 2006).

[FlyFishinRVr]

Originally Posted by LB_3

I assume the Sprinter chassis draws no more than 90A

What is the source of this assumption? Is there data somewhere that suggests this number??? Just curious as I'd like to know if there is a data source that can also be tapped for this type of info re. the newer Interstates.

@amirm, in the Bosch data that you found, was there anything that indicated how long that unit can deliver that amperage? For example, at 1500 RPM can it deliver 171A indefinitely, assuming the temp never exceeds 171*F? Is there another chart that shows how temperature effects the output given that they list temperature as a factor in the table you linked? I ask because I'm assuming the longer the unit runs, the hotter it gets, but where's the temp limit and how does it behave at that limit (does it step down significantly, or just shut off)?