My Interstate Lithium Battery Adventures

[amirm]

Originally Posted by mineralfarme

I am still working on my 480 aH lithium conversion using victron components. One of the questions I have is what limits the amount of current coming from the alternator to the house batteries? There is a 150 amp fuse on The Wire coming back from the alternator so does the alternator somehow limit itself to roughly that amount of current or with a big lithium battery Bank do I have the potential of drawing more than that and blowing the fuse?

With lead acid batteries, it is the batteries themselves which limit how much current is pulled and the voltage drop across that rather long feed. I measured it at a little over 100 amps charging. So well below the 220 amp max capacity of the alternator.

With Lithium, you have three migration problems:

1. The internal impedance of Lithium is much lower than lead acid. This will mean that it can demand a ton of current. My measured internal impedance is around 10 milliohm. This means max current (putting aside the cable) can be 12/0.01 or 1200 amps!

2. The lead acid system uses a battery isolation module (BIM) that controls when to connect the two batteries and uses monitoring to make sure the main engine battery is not discharged. Because the voltages it uses are incompatible with Lithium, you can't use it and with it, you lose this functionality. Without it, connecting the engine battery feed will a) suck all the juice for the lithium and b) when engine off will cause the engine battery to overcharge due to higher voltage of the Lithium cells.

3. Lithium batteries at full capacity have higher voltage than what the alternator puts out. Without some other means even if you solved the above problems, you won't be able to fully charge your cells.

The solution I have found is battery to battery chargers from Sterling. They come in 60 and 120 (input) amp versions. They by definition limit the current and with a boost converter feature, can raise the voltage to what you need. The downside is that they are expensive, require space for wiring, have too small of a heat sink cooled by a tiny fan, etc. But it works and has been doing its job well for the last few months.

Victron has a competing module slated to come out soon that is flat and seems to be passively cooled (i.e. no fan). It too is expensive though when I looked into it last year. And only comes in 25/50 amp. But it sure is cool looking!

https://www.victronenergy.com/dc-dc-...verter-25a-50a

[Boxster1971]

Originally Posted by lewster

Airstream uses a 1/0 cable to connect the alternator (start battery) with the house battery via the Precision Circuits BIM device. ...

Not sure when Airstream started using 1/0 cable from start battery to BIM. I think it was in 2015. But my 2013 model only has 4 gauge cable from start battery to BIM. This was one of the factors in my decision to stay with AGM batteries when I did my upgrade.

[amirm]

Originally Posted by LB_3

Nobody makes a 12->19v power supply in the same wattage as her computer brick so I purchased a 200+ watt DC/DC converter a while back. But the trick with the current Dell computers is that they must receive a verification signal from the power supply before they will charge. I ordered the proper chip almost a year ago but I'm not aware of any affordable chip programmers to encode them. One day I hope to build the proper circuit and serial computer interface but that's a bit beyond my current knowledge base so it will be a while yet.

Here is a complete solution: https://hclxing.wordpress.com/2014/0...al-not-really/

Seems pretty messy but can't see any solution around it given the 1-wire communication it uses (i.e. it is a smart charger).

[LB_3]

Originally Posted by amirm

Here is a complete solution: https://hclxing.wordpress.com/2014/0...al-not-really/

Seems pretty messy but can't see any solution around it given the 1-wire communication it uses (i.e. it is a smart charger).

That's the site that convinced me I could this. I have a breadboard on my desk and everything to complete the project but it dropped on the priority list after I committed to installin an inverter.

[InterBlog]

Originally Posted by amirm

....
Victron has a competing module slated to come out soon that is flat and seems to be passively cooled (i.e. no fan). It too is expensive though when I looked into it last year. And only comes in 25/50 amp. But it sure is cool looking!

https://www.victronenergy.com/dc-dc-...verter-25a-50a

There are only three sellers of this equipment in the state of Texas, and one of them is located just 5 miles from us. The benefits of living next to a huge yachting industry.

[InterBlog]

Originally Posted by amirm

Here is a complete solution: https://hclxing.wordpress.com/2014/0...al-not-really/

Seems pretty messy but can't see any solution around it given the 1-wire communication it uses (i.e. it is a smart charger).

That post is dated 2014, plus it has been probably the better part of a year since I last raised this issue with Dell. I'm going to call them again early in the week and see if they have anything new to report.

[LB_3]

You won't find anything better from Dell because most cigarette lighter outlets are fused at 15A. Dell will want to limit their chargers to a max of about 130 watts to stay under this limit.

[lewster]

Originally Posted by amirm

With lead acid batteries, it is the batteries themselves which limit how much current is pulled and the voltage drop across that rather long feed. I measured it at a little over 100 amps charging. So well below the 220 amp max capacity of the alternator.

With Lithium, you have three migration problems:

1. The internal impedance of Lithium is much lower than lead acid. This will mean that it can demand a ton of current. My measured internal impedance is around 10 milliohm. This means max current (putting aside the cable) can be 12/0.01 or 1200 amps!

2. The lead acid system uses a battery isolation module (BIM) that controls when to connect the two batteries and uses monitoring to make sure the main engine battery is not discharged. Because the voltages it uses are incompatible with Lithium, you can't use it and with it, you lose this functionality. Without it, connecting the engine battery feed will a) suck all the juice for the lithium and b) when engine off will cause the engine battery to overcharge due to higher voltage of the Lithium cells.

3. Lithium batteries at full capacity have higher voltage than what the alternator puts out. Without some other means even if you solved the above problems, you won't be able to fully charge your cells.

The solution I have found is battery to battery chargers from Sterling. They come in 60 and 120 (input) amp versions. They by definition limit the current and with a boost converter feature, can raise the voltage to what you need. The downside is that they are expensive, require space for wiring, have too small of a heat sink cooled by a tiny fan, etc. But it works and has been doing its job well for the last few months.

Victron has a competing module slated to come out soon that is flat and seems to be passively cooled (i.e. no fan). It too is expensive though when I looked into it last year. And only comes in 25/50 amp. But it sure is cool looking!

https://www.victronenergy.com/dc-dc-...verter-25a-50a

I agree that the Precision Circuits BIM is essentially worthless for any lithium installation. I have removed several and replaced them with a 500 amp latching solenoid to make use of your dash momentary switch to retain the emergency start (boost) feature.

As for voltage, my 220 amp alternator in my 2011 Sprinter regularly measures 14.1-14.2VDC, which is quite sufficient to charge Victron lithiums. We regularly use their Orion DC to DC isolated converters in parallel to provide multiples of 30 amps for lithium charging from the alternator. It is simple to adjust the output voltage of the Orion to 14.2VDC for the perfect lithium bulk charge.

Since these are not 'smart charger' type devices, monitoring the battery SOC levels is required to prevent overcharge.

[FlyFishinRVr]

Originally Posted by amirm

With Lithium, you have three migration problems:

1. The internal impedance of Lithium is much lower than lead acid. This will mean that it can demand a ton of current. My measured internal impedance is around 10 milliohm. This means max current (putting aside the cable) can be 12/0.01 or 1200 amps!

For those that have been following along, THIS is exactly why there have been problems with Li technology. The batteries get overcharged which causes them to overheat which eventually starts a fire....and Li is highly flammable! And the reason they overcharge is because of marketing and/or ignorance. Wait, what?!?! "Fully charge your phone in just 20 minutes!!!!". Sounds great right? Oops....can you say Samsung Note 7's catching fire. Why? Charging that's too aggressive. Remember the kerfuffle a bit over a year ago re. those hoverboards from China catching fire and burning houses down? Combination of cheap ass Li batteries and again, "Charge your board in just 30 minutes!!! Half the time of the competition!!!!". Not good....

Anywho, the point of this is to warn folks who are rolling their own battery solutions to please be cautious and take to heart what amirm, LB3, Lewster, and others are saying about installing Li batteries in your coach. Done right, they are an excellent solution. Much lower weight and much higher energy storage. But done wrong they are a disaster waiting to happen. If you really want Li but don't feel comfortable doing it on your own, hire a pro who makes a living doing it (like our own Lewster...... ). As my old mum used to say, it's better to be safe than sorry.

[InterBlog]

Originally Posted by FlyFishinRVr

...
....Anywho, the point of this is to warn folks who are rolling their own battery solutions to please be cautious and take to heart what amirm, LB3, Lewster, and others are saying about installing Li batteries in your coach. Done right, they are an excellent solution. Much lower weight and much higher energy storage. But done wrong they are a disaster waiting to happen. If you really want Li but don't feel comfortable doing it on your own, hire a pro who makes a living doing it (like our own Lewster...... ). As my old mum used to say, it's better to be safe than sorry.

+1, and as someone who has now "been there", if you are planning this as a Class B retrofit, you better be banking on something close to a 5-figure labor cost if you hire someone. Not necessarily as high as the $40,000 total cost (labor and materials) that Airstream itself has proposed in its questionnaire to prospective owners for lithium/solar as an option, but we are talking about a massive labor commitment to do this properly, especially when the van has to be systematically deconstructed before any meaningful upgrades can even begin. There's just no way to assembly-line or mass-produce anything associated with this kind of retrofit - no economies of scale. It's piece by piece by piece, one step at a time. Working on this has been analogous to watching a surgery video where they are struggling around the clock with tweezers to piece together a human tibia that has been shattered into 256 individual little bone shards.

[lewster]

Originally Posted by interblog

+1, and as someone who has now "been there", if you are planning this as a class b retrofit, you better be banking on something close to a 5-figure labor cost if you hire someone. Not necessarily as high as the $40,000 total cost (labor and materials) that airstream itself has proposed in its questionnaire to prospective owners for lithium/solar as an option, but we are talking about a massive labor commitment to do this properly, especially when the van has to be systematically deconstructed before any meaningful upgrades can even begin. There's just no way to assembly-line or mass-produce anything associated with this kind of retrofit - no economies of scale. It's piece by piece by piece, one step at a time. Working on this has been analogous to watching a surgery video where they are struggling around the clock with tweezers to piece together a human tibia that has been shattered into 256 individual little bone shards.

a-men!!!! :d

[amirm]

Not only that, you need to add combat pay/premium given how nasty some of the labor is. I had to pull out the fridge to run wires behind it and man was that a pain to do. I also spent a few hours trying to do it without it to no avail. My knees were also killing me by the time I was done from all the work I had to do down low. And let's not talk about crawling under the thing....

[LB_3]

Originally Posted by amirm

Not only that, you need to add combat pay/premium given how nasty some of the labor is. I had to pull out the fridge to run wires behind it and man was that a pain to do. I also spent a few hours trying to do it without it to no avail. My knees were also killing me by the time I was done from all the work I had to do down low. And let's not talk about crawling under the thing....

You're not kidding. I spent most of the afternoon Sunday wiring up the generator/shore power priority switch. Due to the limited space available under my fridge I don't have room to stash excess cables so I spent 4 hours on my belly arms at full extension stripping wires with a razor and making blind mates. And that was just the one box. Next weekend I hope to get the circuit breakers and the microwave/AC select switch shoehorned in that same volume.

[InterBlog]

It's been suggested at least casually that my husband and I consider going into business for ourselves.

I don't even want to ask my agent what Worker's Comp would run for the two of us in a welding, electrical, power tool, etc. working scenario. I already have to carry Worker's Comp on myself even as I work for myself as an industrial inspector and general paper-pusher (permitting and compliance consultant) - I don't even have process control on anything and Worker's Comp is already very difficult for me to even buy. I have to have it because if I get injured working for myself, there's no way that my husband's spousal medical insurance would cover it. They'd either decline or if they did cover it, they'd turn around and sue my LLC to recoup their loss, which would be worse because then I'd have to pay for a doctor AND a lawyer. Forget that.

None of this stuff can be toyed with or dabbled in. If we started a business, I already know how to run the numbers. Sweet God, they're gruesome even before I put them on paper. Worker's Comp, General Liability, business premises, and all the other overhead, even before we get to raw labor hours or materials. It's a financial crap show.

[lewster]

Originally Posted by InterBlog

It's been suggested at least casually that my husband and I consider going into business for ourselves.

I don't even want to ask my agent what Worker's Comp would run for the two of us in a welding, electrical, power tool, etc. working scenario. I already have to carry Worker's Comp on myself even as I work for myself as an industrial inspector and general paper-pusher (permitting and compliance consultant) - I don't even have process control on anything and Worker's Comp is already very difficult for me to even buy. I have to have it because if I get injured working for myself, there's no way that my husband's spousal medical insurance would cover it. They'd either decline or if they did cover it, they'd turn around and sue my LLC to recoup their loss, which would be worse because then I'd have to pay for a doctor AND a lawyer. Forget that.

None of this stuff can be toyed with or dabbled in. If we started a business, I already know how to run the numbers. Sweet God, they're gruesome even before I put them on paper. Worker's Comp, General Liability, business premises, and all the other overhead, even before we get to raw labor hours or materials. It's a financial crap show.

WELCOME TO MY WORLD!!!

[InterBlog]

A project update here with an assurance that I will butcher this explanation. My husband may jump in with a clarification.

We accidentally fried an integrated circuit in the new ElectroDacus BMS. It's worth mentioning as a previously-unknown failure pathway for the sake of other people who might be considering this unit.

The good news is that Dacian (its inventor) immediately recognized the issue from LB_3's email description of the outcome, and offered to replace the chip at no cost. The bad news is that I had to Priority Mail the unit up to his post office box in remote Saskatchewan which means we'll be without it for hopefully not longer than a couple of weeks (the Canadian postal system has always been a nightmare).

It happened when LB_3 was getting ready to hook up the inverter. Remember we've been road-testing on 12 volt alone and I took the rig on a cross-Texas boondocking trip the week before last with just that part of the system connected, and everything worked perfectly.

In prep for connecting the inverter, LB_3 disconnected the positive from the battery array AND two grounding connections that are on the negative side. Theoretically, there should have been no electricity flow pathway remaining to be completed. But the sun had not yet totally set and there was a little bit of juice still originating in the solar panels. Despite having no travel path that was obvious to us, it completed a circuit of some sort anyway, and damaged the BMS.

Neither of us really comprehended Dacian's explanation. We sat down with pen and paper and drew out the electrical schematic to see if we could identify with pictorial assistance how this happened. I still don't get it. If Dacian had said that the resulting situation was like an arc fault, that I would be able to understand. But apparently it was closer to being an induction effect.

Anyway, the lesson here is that there needs to be a redundant physical cut-off switch between the system and each of its external inputs. Under ordinary operational circumstances, the BMS is supposed to be able to know whether or not to accept charge from the solar panels, but its decision-making is not going to happen successfully if there's an unanticipated pathway. So we will be adding knob switches into the line between the solar panels and the BMS, and another line switch between the eventual alternator connection and the BMS.

I'm sort of kicking myself for not having pursued this sooner. I knew from experience that our previous Vanlife went to hell when we didn't have the ability to electively cut off both the alternator and the solar panels. Our previous system was quite different from this new one and we never did completely understand why those things were true - we just knew from the observed results that we needed those abilities. And now we obviously still need them.

[lewster]

Originally Posted by InterBlog

A project update here with an assurance that I will butcher this explanation. My husband may jump in with a clarification.

We accidentally fried an integrated circuit in the new ElectroDacus BMS. It's worth mentioning as a previously-unknown failure pathway for the sake of other people who might be considering this unit.

The good news is that Dacian (its inventor) immediately recognized the issue from LB_3's email description of the outcome, and offered to replace the chip at no cost. The bad news is that I had to Priority Mail the unit up to his post office box in remote Saskatchewan which means we'll be without it for hopefully not longer than a couple of weeks (the Canadian postal system has always been a nightmare).

It happened when LB_3 was getting ready to hook up the inverter. Remember we've been road-testing on 12 volt alone and I took the rig on a cross-Texas boondocking trip the week before last with just that part of the system connected, and everything worked perfectly.

In prep for connecting the inverter, LB_3 disconnected the positive from the battery array AND two grounding connections that are on the negative side. Theoretically, there should have been no electricity flow pathway remaining to be completed. But the sun had not yet totally set and there was a little bit of juice still originating in the solar panels. Despite having no travel path that was obvious to us, it completed a circuit of some sort anyway, and damaged the BMS.

Neither of us really comprehended Dacian's explanation. We sat down with pen and paper and drew out the electrical schematic to see if we could identify with pictorial assistance how this happened. I still don't get it. If Dacian had said that the resulting situation was like an arc fault, that I would be able to understand. But apparently it was closer to being an induction effect.

Anyway, the lesson here is that there needs to be a redundant physical cut-off switch between the system and each of its external inputs. Under ordinary operational circumstances, the BMS is supposed to be able to know whether or not to accept charge from the solar panels, but its decision-making is not going to happen successfully if there's an unanticipated pathway. So we will be adding knob switches into the line between the solar panels and the BMS, and another line switch between the eventual alternator connection and the BMS.

I'm sort of kicking myself for not having pursued this sooner. I knew from experience that our previous Vanlife went to hell when we didn't have the ability to electively cut off both the alternator and the solar panels. Our previous system was quite different from this new one and we never did completely understand why those things were true - we just knew from the observed results that we needed those abilities. And now we obviously still need them.

Sorry that you had to discover this the hard way, but all of my installations have what seem like redundant disconnects at various points of the circuitry: main disconnect (on negative battery cable for lithium systems and positive for AGM),
inverter positive cable, both sides of the solar charge controller (array disconnect switch and marine DC circuit breaker on the charge side) and for the possibility of alternator charging.....another on the positive charge line headed to the house batteries from the alternator.

Nothing is activated until all connections are checked/torqued 3 times.

Bummer that you blew out the circuit but great that the designer is doing a N/C repair.

Keep the faith!!!!!!

[InterBlog]

Originally Posted by lewster

... all of my installations have what seem like redundant disconnects at various points of the circuitry...

This is the only sane way to do it. There are so many moving parts in these systems that it's impossible to predict every potential outcome in the decision tree. Turn the solar on only when you need it, even if theory says that it should not make any difference whether it's on or off at that point under those circumstances. Turn the solar feed off when you don't need it. Period.

[FlyFishinRVr]

Originally Posted by InterBlog

This is the only sane way to do it.

I think Lewster's solution also makes a lot of sense for troubleshooting problems and replacing components. Need to replace a solar panel? Disconnect, replace, reconnect. Need to swap out the inverter? Same thing.

[LB_3]

I disconnected the negative on the battery, not the positive. Tthe solar was still energized so I then disconnected the solar negative. With no ground path on anything, I thought I was safing the system however there was still a large inductance on the positive solar so the integrated circuit measuring the solar voltage saw a big voltage spike and some electrons jumped their tracks in the integrated circuit and wrecked the charge controller.

Next time I will disconnect the solar and alternator inputs and power down the fragile BMS before disconnecting anything else.