Energy Sources

[Sailfast]

Originally Posted by uncle_bob

Hi

I have a van that AS ships stock with a lithium house battery. I'm not making this up. You can go to the web site and download the manual and see for yourself.

The reason they did this is a sound one. You do *not* want the lithiums put into an engine starting situation. You also (regardless of claims made) want to hook the lithium and lead acid systems together without a DC/DC converter involved.

As noted above, they put a separate solar charger on the chassis battery when they do a lithium / lead acid combo.

Bob

Thank you Bob for the clarification. Airstream have their reasons and methods of doing things and Precision Circuits has theirs. Fact is that we still get the same DC from the alternator, the solar panels and the shore power charging source. What is different for lithium batteries is the way it is managed or regulated.

A DC to DC charger absolutely works (a clean and precise DC voltage/current). I am just pointing out that the folks at Precision Circuits (probably other product too) did their home work.

As far as starting a sprinter van? Yes, any off the shelf 100AH LiFePo4 battery has probably a 100A BMS, maximum 120. I use 200A 4S BMS in my (200AH) batteries and I would not hesitate a minute to start my Sprinter. Besides, each battery has a 200A cube fuse right at the positive terminal, which would blow with any overcurrent. Then the BMS has overcurrent parameters which I can set as not to damage the cells. In the end we do not want to spend thousands on damaged batteries, we want them to last 10, 15, 20 years. How many of you have set the solar charging parameters to 95% SOC? Even my LI-BIM stops short of 100% SOC.

[uncle_bob]

Originally Posted by Sailfast

Thank you Bob for the clarification. Airstream have their reasons and methods of doing things and Precision Circuits has theirs. Fact is that we still get the same DC from the alternator, the solar panels and the shore power charging source. What is different for lithium batteries is the way it is managed or regulated.

A DC to DC charger absolutely works (a clean and precise DC voltage/current). I am just pointing out that the folks at Precision Circuits (probably other product too) did their home work.

As far as starting a sprinter van? Yes, any off the shelf 100AH LiFePo4 battery has probably a 100A BMS, maximum 120. I use 200A 4S BMS in my (200AH) batteries and I would not hesitate a minute to start my Sprinter. Besides, each battery has a 200A cube fuse right at the positive terminal, which would blow with any overcurrent. Then the BMS has overcurrent parameters which I can set as not to damage the cells. In the end we do not want to spend thousands on damaged batteries, we want them to last 10, 15, 20 years. How many of you have set the solar charging parameters to 95% SOC? Even my LI-BIM stops short of 100% SOC.

Hi

Check with your battery manufacturer before you try to start a vehicle with their lithium. All the ones I know of tell you not to do it. A starter motor is a *very* tough load to deal with. The spikes are likely to damage the BMS in the Lithium battery.

Why?

The BMS runs a big MOSFET ( or a set of them ) to manage the output current of the battery. All the battery current runs through the device or devices. Semiconductors have very specific ratings interns of current and voltage. Go past those limits (even for a very short period of time) and you damage / kill the semiconductor.

Bob

[StogieMan]

Originally Posted by uncle_bob

Hi

Check with your battery manufacturer before you try to start a vehicle with their lithium. All the ones I know of tell you not to do it. A starter motor is a *very* tough load to deal with. The spikes are likely to damage the BMS in the Lithium battery.

Why?

The BMS runs a big MOSFET ( or a set of them ) to manage the output current of the battery. All the battery current runs through the device or devices. Semiconductors have very specific ratings interns of current and voltage. Go past those limits (even for a very short period of time) and you damage / kill the semiconductor.

Bob

Hi Bob, I'll concede some of this.

Most Lithium battery manufactures do not recommend using the Lithium batteries to start an engine. If the chassis battery is slightly low using the dash switch to start the engine I see no issue. If the chassis battery is completely dead I would be hesitant to use the dash switch.

[uncle_bob]

Originally Posted by StogieMan

Hi Bob, I'll concede some of this.

Most Lithium battery manufactures do not recommend using the Lithium batteries to start an engine. If the chassis battery is slightly low using the dash switch to start the engine I see no issue. If the chassis battery is completely dead I would be hesitant to use the dash switch.

Hi

If the chassis battery is low enough that it will not start the engine, it also is low enough that it will not do much at all to protect the lithiums. Will it fail first time / every time you try it? Of course not. Just what the starter kicks back is dependent on a bunch of stuff. Eventually it *will* kill the BMS.

Bob

[Sailfast]

Originally Posted by uncle_bob

Hi

If the chassis battery is low enough that it will not start the engine, it also is low enough that it will not do much at all to protect the lithiums. Will it fail first time / every time you try it? Of course not. Just what the starter kicks back is dependent on a bunch of stuff. Eventually it *will* kill the BMS.

Bob

I think Lithium batteries are capable to handle these kinds of loads what does not work is the BMS unless so designed. All those little Lithium jump starters available now, some of them handling up to 3000A. My guess, those use a BMS with a sophisticated contactor which can handle high loads.

[uncle_bob]

Originally Posted by Sailfast

...... My guess, those use a BMS with a sophisticated contactor which can handle high loads.

Hi

Nope ...

The RV battery BMS has a MOSFET in series with the battery. It is not some sort of 1,500A rated mechanical contact gizmo. That MOSFET is one of the things you kill trying to use one of these things as a starting battery.

Bob

[mjacobs]

Originally Posted by Sailfast

All those little Lithium jump starters available now, some of them handling up to 3000A.

Speaking of these, has anyone found a particular unit comfortably capable of starting the chassis battery?

I'll again thank all of you for your time and explanations. I've learned a ton here! I've also found the FB group quite informative (although I've never used FB before and prefer to remain away!). Someone there commented on another post regarding the DC Low Voltage error message that the "TSB 186 Recall" would fix this problem. Are any of y'all familiar with this? If it's such a well-known issue, why wouldn't my dealer (large seller in Tampa) not go ahead and perform this update prior to delivery a few weeks ago!!!

[BruceWayne]

If you are in Facebook you can join the site Airstream Interstate Nineteen and search as there is extensive information related to your questions.

[ChristineM]

Originally Posted by uncle_bob

Hi

What you have:

Alternator charges the house battery ( the lithiums ) and the chassis battery ( the one attached to the engine ). If the house battery goes flat, you still *should* be able to start the engine and head down the road.

Solar charges the house battery, but on your van, I don't think it charges the chassis battery. That feature came out more recently.

Bob

Wanting to comment again for those struggling (like me) to understand the tech on these newest models.

I am the one who after parking and hooking to shore, then a couple hours later in the evening, received various messages concerning a critically-low battery state on the starter.

By about noon-time the next day, the problem went away. I now believe/understand that the solar likely dripped in charge to bring it back.

After re-reading the snippet below from the manual, I now feel fortunate that the starter level did not fall below 11.5. I do recall it falling below 12.0, however I did not take a pic of that.

Still concerned why a starter battery would behave like that after a 5 hour trip. So will see.

Curious to see the responses to trickle charge devices for when the thing may fall short of 11.5.

I also am without a Facebook account so I will be grateful for any who wish to also share that here.

Thanks so much!
Christine


Quote from User Manual 2022 AI19:

The Airstream Touring Coach is also equipped with a dedicated 50 watt solar panel and charge controller to help keep the chassis battery charged. The solar panel and charge controller will not charge the chassis battery if it has fallen below 11.5 volts, or if the chassis battery has been damaged.

NOTE
The solar panel and charge controller are designed to maintain the chassis battery and help prevent it from dying; they are not designed to charge a dead battery. If the chassis battery is below 11.5 volts it will need to be charged by other means.

[ChristineM]

Originally Posted by mjacobs

Speaking of these, has anyone found a particular unit comfortably capable of starting the chassis battery?

I'll again thank all of you for your time and explanations. I've learned a ton here! I've also found the FB group quite informative (although I've never used FB before and prefer to remain away!). Someone there commented on another post regarding the DC Low Voltage error message that the "TSB 186 Recall" would fix this problem. Are any of y'all familiar with this? If it's such a well-known issue, why wouldn't my dealer (large seller in Tampa) not go ahead and perform this update prior to delivery a few weeks ago!!!

I believe the TSB 186 applies to mid-year 2021 units where there was incompatibility with the lithium batteries and the magnum converter/inverter. Could problems be persisting. I certainly wonder....

Airstream TSB 186.pdf

[uncle_bob]

Hi

My van came from the factory with lithium house batteries and the stock AGM chassis battery. The chassis battery needs to stay lead acid to keep MB and the MB "stuff" happy. There is no easy way to go to a lithium chassis battery.

Here's how the factory designed the setup on the van:

1) There is a solar panel dedicated to the chassis battery and a separate solar controller that it hooks to.

2) There is a trickle charger that keeps the chassis battery happy when you are on shore power.

3) There is a programmed DC/DC converter between the MB stock alternator and the lithium batteries. It is set up with a current limit that is "in spec" per the up fitter docs.

4) They changed a bunch of fuses and the like to reduce the current to various 12V circuits. That also helped them stay in spec on the stock electrical system.

5) There is a (larger) solar array hooked to a second solar controller that charges the house batteries.

6) There is an inverter / charger that will charge the lithiums when you are on shore power and run the microwave ( yup, 2 KW ...) when on battery power.

7) There is a Victron Smart Shunt on the house batteries that will tell you their state of charge.

8) A powered rotary switch "full battery disconnect" run off of a very easy to bump ( apparently ....) switch by the door. I'm *sure* I've never bumped it . Somehow it gets turned off from time to time.

9) No CZone or other super duper control system / panel setup. If you want to turn on this or that light, you go find the switch for that light .... live with it ... ( which has not been very hard ).

The propane only runs the generator and the cook top. The fridge is compressor driven. The heat runs on diesel.

I will not bore you with the list of "gotchas" associated with those items on one of the first batch ever built. For one thing, I'm not 100% sure that I've found all the issues yet ....

I added a couple more lithiums to double the amp hours. With 400AH, we can go for several days "off grid".

Fun !!!

Bob

[ChristineM]

Originally Posted by uncle_bob

Hi

My van came from the factory with lithium house batteries and the stock AGM chassis battery. The chassis battery needs to stay lead acid to keep MB and the MB "stuff" happy. There is no easy way to go to a lithium chassis battery.

Here's how the factory designed the setup on the van:

1) There is a solar panel dedicated to the chassis battery and a separate solar controller that it hooks to.

2) There is a trickle charger that keeps the chassis battery happy when you are on shore power.

3) There is a programmed DC/DC converter between the MB stock alternator and the lithium batteries. It is set up with a current limit that is "in spec" per the up fitter docs.

4) They changed a bunch of fuses and the like to reduce the current to various 12V circuits. That also helped them stay in spec on the stock electrical system.

5) There is a (larger) solar array hooked to a second solar controller that charges the house batteries.

6) There is an inverter / charger that will charge the lithiums when you are on shore power and run the microwave ( yup, 2 KW ...) when on battery power.

7) There is a Victron Smart Shunt on the house batteries that will tell you their state of charge.

8) A powered rotary switch "full battery disconnect" run off of a very easy to bump ( apparently ....) switch by the door. I'm *sure* I've never bumped it [emoji4] . Somehow it gets turned off from time to time.

9) No CZone or other super duper control system / panel setup. If you want to turn on this or that light, you go find the switch for that light .... live with it ... ( which has not been very hard ).

The propane only runs the generator and the cook top. The fridge is compressor driven. The heat runs on diesel.

I will not bore you with the list of "gotchas" associated with those items on one of the first batch ever built. For one thing, I'm not 100% sure that I've found all the issues yet ....

I added a couple more lithiums to double the amp hours. With 400AH, we can go for several days "off grid".

Fun !!!

Bob

Thanks for sharing all this. Quite frankly when the 24x came out, the lack of a czone type controller really appealed to me given my experience.

In my 2022 AI19, I believe the heat is also propane.

One additional question I have be reluctant to wade into, is Do you all roll down the road with battery disconnected. And if connected, do you run your 12v refrigerator also, or instead wait to find shore power. I am guessing you all may be running the frig on, and I have just been nervous to given what I am used to.

Thanks again!
Christine

[mjacobs]

Originally Posted by uncle_bob

2) There is a trickle charger that keeps the chassis battery happy when you are on shore power.

Then why do I continue to receive the low voltage error message on Czone? I have my vehicle in a warehouse, plugged into shore power, and still find the message.

[ChristineM]

Originally Posted by mjacobs

Then why do I continue to receive the low voltage error message on Czone? I have my vehicle in a warehouse, plugged into shore power, and still find the message.

This may be a difference between the 24x and the 19 that we have??

[ChristineM]

Originally Posted by mjacobs

Then why do I continue to receive the low voltage error message on Czone? I have my vehicle in a warehouse, plugged into shore power, and still find the message.

Commenting again, since I am back where I can dig into this.

I am going to call Jackson Center. Have you tried calling them? This support video for the AI19 suggests that shore power should charge the starter battery.

https://support.airstream.com/hc/en-...QDJJ5TX8S5CD27

When I had my issue, 1. My dealer was closed for the day and 2) when I reported to them the next day that somehow my starter was charged, my dealer told me to read my manual….

As a reminder, I arrived to the campground, plugged into shore power, then after darkness fell started to receive warnings/alerts about the starter battery.

I am sorry you are having this issue, but I am thankful too, since you are encouraging me to take the time to investigate/revisit the experience I had.

Christine

[ChristineM]

Originally Posted by ChristineM

Commenting again, since I am back where I can dig into this.

I am going to call Jackson Center. Have you tried calling them? This support video for the AI19 suggests that shore power should charge the starter battery.

https://support.airstream.com/hc/en-...QDJJ5TX8S5CD27

When I had my issue, 1. My dealer was closed for the day and 2) when I reported to them the next day that somehow my starter was charged, my dealer told me to read my manual….

As a reminder, I arrived to the campground, plugged into shore power, then after darkness fell started to receive warnings/alerts about the starter battery.

I am sorry you are having this issue, but I am thankful too, since you are encouraging me to take the time to investigate/revisit the experience I had.

Christine

I had one other event that I did not even realize also until the next day. My GFI outlets were not-working/tripped. Re-setting that breaker fixed those. I think this is unrelated to the starter battery tho since it was almost restored in by the time I discovered the tripped GFI.

[ChristineM]

Greetings,

Had a great call with Airstream support. Have a better understanding of the power flow.

Regarding what charges the Start Battery. That is either the engine alternator when the engine is running or the Airstream power system.

With the Airstream power system (either on shore or generator power), that system will only send power to the Start Battery once the House Batteries are full (according to airstream). So in my "first night at camp after a 5 hour drive" situation, since I plugged into shore, then turned on almost everything, Truma for heat, Frig (12v compressor), those were likely loading and using the lithiums so that everything coming in from the shore, was going to the house. Not until the next day when the sun came out and the extra was coming in from solar is when my Start Battery started to be replenished.

The remaining elephant in the room is why did my Start Battery get so low after a long drive. Could there be a parasitic draw? I had all but 1 key fob deactivated, though I did open and shut the doors often while setting up. Each time the MBUX would wake up.

So I have more data points, yet still looking for the final word.

I asked about indoor storage and on shore power, and the airstream tech service person was struggling to see why that setup would not be charging the Start Battery.

Back in my "trailer" days, when stored indoors and on shore power (probably 15 or 20 amp), I had to set the battery disconnect switch to "on/connected" in order for the batteries (not lithium) to receive a charge.

Can you tell us how you have your battery disconnect switch set.

Thanks!
Christine

[ChristineM]

Originally Posted by ChristineM

This may be a difference between the 24x and the 19 that we have??

This is false, I would delete this reply if I knew how.

Sorry.

[mjacobs]

Originally Posted by ChristineM

Can you tell us how you have your battery disconnect switch set.

First of all, I'm relieved to know that I'm not the only (no offense meant) neurotic, OCD dude/dudette in a van! Fluoxetine has helped a ton but gosh this stuff really requires attention to detail and persistence, especially when dealing with the dealers (as an aside, I brought my vehicle straight to the MB dealer next to my office as soon as I drove it home from Tampa as the center speaker in the dash was killing me; after several days and "serious digging", they identified a service bulletin to fix the problem. However, nothing really changed until I unplugged the white wire myself after reading about this exact problem on this and the FB forum!).

As of now, given my limited knowledge, and have not touched the battery disconnect switch set.

When is this something I should consider using?

I've received this low voltage message since I picked it up a few weeks ago. It is always plugged in when I'm not driving. Granted, no solar access while parked indoors, but that shouldn't matter with shore power, right?

[ChristineM]

Originally Posted by mjacobs

First of all, I'm relieved to know that I'm not the only (no offense meant) neurotic, OCD dude/dudette in a van! Fluoxetine has helped a ton but gosh this stuff really requires attention to detail and persistence, especially when dealing with the dealers (as an aside, I brought my vehicle straight to the MB dealer next to my office as soon as I drove it home from Tampa as the center speaker in the dash was killing me; after several days and "serious digging", they identified a service bulletin to fix the problem. However, nothing really changed until I unplugged the white wire myself after reading about this exact problem on this and the FB forum!).



As of now, given my limited knowledge, and have not touched the battery disconnect switch set.



When is this something I should consider using?



I've received this low voltage message since I picked it up a few weeks ago. It is always plugged in when I'm not driving. Granted, no solar access while parked indoors, but that shouldn't matter with shore power, right?

Yes, in this together. I just ran out to my van and turned it on a bit. The starter battery was at 14.1, first time I have seen it above 12.6, though this is also the first I will be watching it like a hawk. FWIW, I leave the House battery disconnected and everything off.

I am a bit flustered at this point.

According to the manual, there is no requirement to have the House battery connected or disconnected (shore power connection should trickle charge both the House and Starter).

What I learned today was that the house batteries take priority.

I find Mercedes so reluctant to engage when they realize there is an upfit situation. I am going to try and watch the status of that darned start battery.

I also have a little rodent visitor, which really depresses me.

Will stop ranting! Tomorrow is another day and we will get these issues figured out.

To end on a bright note, the tech service woman I spoke with at airstream, was super nice and seemed very knowledgeable. She was trying to explain to me about battery load and status thresholds before a battery would receive a charge, but that was lost on me.

Please keep us informed.