Thinking about replacing solar with an AGS system.

[Wrinkledpants]

We're 99% sure we're going lithium on our Sprinter 144. This means a 2nd alternator dedicated to the lithium system. Given that lithium can take up to a 400A charge all the way to 100%, and you can fit at least twice the battery capacity for the size and weight of an AGM setup, we're really thinking about skipping solar.

The benefits I see with solar with an AGM battery bank is getting that slow charge all day during the absorption phase, and keeping the battery topped to run the fridge when you're away from the van for extended periods of time.

A 2nd alternator will put out 150A at idle, and 230A at high-idle (on a Sprinter with the high-idle feature). Many Ford guys have said high-idle is rough on the motor, but MB has said it's fine on the Sprinters as long as you can drive for 30-40 minutes at some point after using it. Their engine warranty is 5yr/100K miles.

The lithium batteries can take up to 400A in charge all the way to 100%. You could easily maintain 100% charge by idling the van for under 20 minutes a day. Or, high-idle to fully recharge the batteries in an hour.

Magnum makes an auto generator start feature that you can tie in with an auto engine start. For us, we could use that for those times when we're away from the van but want to keep the fridge running. If we have a 330 Ah lithium battery, we could be backpacking for 15 days and the van might need to start once to idle for an hour.

The benefits I see of not having solar is freeing up roof space (which we'll need every square inch we can get), less complex wiring and monitoring, and you could invest that solar money into a larger battery bank. With 330 Ah of lithium, we could survive 3-4 days without having to idle the van, and then just drive for an hour and a half to fully recharge it. The AGS system will fire up the engine if needed when we're away from the van.

I just want to make sure I'm not missing something here with solar. I can see how it makes total sense with AGMs mounted in a vehicle like an older Ford that is quite loud when idling. With a Sprinter, at least, you're getting more power than a Honda generator, it's more quiet, and it requires no additional maintenance or space, extremely fast recharge times, and an auto gen start will take care of the batteries during extended times away from the van (or if you have pets and need to run the AC - which we don't).

Is there anything I'm missing? SMB mentioned doing it for the resale because so many people are used to having solar, but in 5-10 years I just don't see where solar is going to have a roll. For eco-minded individuals who will spend a lot of time being stationary, it makes sense. But, it seems like most of the people here are usually on the move after a few days (including us).

[Tapatio]

How often will you be taking trips? I leave my fridge on all the time, solar keeps the batteries topped off between trips.

[86Scotty]

I understand your roof space concern, and that can be a real issue, but I can't get my head around this system being 'once and done' like solar. Lithium has too volatile a history for me to trust this system being on autopilot while I'm away from my van for a long time, especially in remote places. Also, Sprinters in general (I know I'm going to piss some people off here) are just too finicky and advanced to be trusted to just work as they should. I also think that would be pretty weird and most definitely off putting to anyone around to have a vehicle starting up on it's on randomly.
Sure, people should mind their own business, but they don't. You'll come back to your van and find the rescue squad surrounding it one day. "Hey honey, that Sprinter over there hasn't moved in days but it starts up every now and then and it's idling real high. Seems like a fire hazard. I'm calling the law."

I wish you luck. I hope it all works as it should.

[Wrinkledpants]

Our van will be stored at an RV facility that has private indoor bays with plugins. We live downtown Denver with no place to store it here. So, it'll be plugged in most of the time as we'll be taking trips most weekends. The drive back from the mountains will top off the batteries, and if it doesn't, the drive from Denver into the mountains certainly will. When it's plugged in, the batteries will be disconnected from the system.

[Wrinkledpants]

Originally Posted by 86Scotty

I understand your roof space concern, and that can be a real issue, but I can't get my head around this system being 'once and done' like solar. Lithium has too volatile a history for me to trust this system being on autopilot while I'm away from my van for a long time, especially in remote places. Also, Sprinters in general (I know I'm going to piss some people off here) are just too finicky and advanced to be trusted to just work as they should. I also think that would be pretty weird and most definitely off putting to anyone around to have a vehicle starting up on it's on randomly.
Sure, people should mind their own business, but they don't. You'll come back to your van and find the rescue squad surrounding it one day. "Hey honey, that Sprinter over there hasn't moved in days but it starts up every now and then and it's idling real high. Seems like a fire hazard. I'm calling the law."

I wish you luck. I hope it all works as it should.

We wouldn't have the AGS use the high-idle feature. And it definitely won't be starting all the time. Maybe it starts once in a 7-10 day period and idles for an hour. You can program them to only turn on during certain times of the day so as to not annoy the neighbors. Several Class B OEMs use an AGS system with lithiums (Road Trek, Advanced RV, etc).

I can understand the distrust in a Sprinter, or anything German. I trust it, but I've only owned German cars. In the past 10 years of driving Audi's and Porsches, most over 200K miles, I can count on one finger the amount of times one has left me stranded somewhere. All from a $20 blown coolant hose. I think it just comes down to what you're used to.

Good feedback, though. Definitely food for thought.

[86Scotty]

No problem. Just FYI, I'm a german car fan too. I grew up helping my dad wrench on his beloved older Mercs (couldn't afford anything near a new one) and I have a love for BMWs up to about 06. When they started offering an electronic sensor in place of, not in addition to, a dipstick that was it for me. I hear they are piping in engine sounds into the stereo speakers nowadays. I can only go so far.

I actually love the T1N Sprinter and drove one for a few hundred thousand miles for work. I have no experience with the new ones but all I can say is that our mechanics hate the new ones. DEF (Not the Germans fault by any means) and all the modern electronics are just beyond what my billion dollar company can keep up with. That's not a good sign to me. That said, I don't see Sprinters on the side of the road much. I'm not a curmudgeon. I like lithium batteries and I'm no enemy to progress, but this system seems a bit more than I would want. It sounds like you've thought of how to mitigate some of the possible issues and that's what it takes to do what we do. Lots of compromises and forethought make the happy van camper.

[Glider]

This brings up a set of questions I have been wondering about. In a solar setup, there is a charge controller that regulates voltage and amperage to the batteries in a very specific way--bulk, absorption, and float.

1. With lithium batteries, it appears that the classic 3-stage charge is not needed--it is a bulk charge all the way to 100%. Is that correct?

2. Assuming the answer to #1 is yes, then--in a second alternator setup with lithium, is a charge controller of some type needed? There has to be something between the alternator and the batteries, no? Assuming so, what do you use?

3. In a second alternator setup with flooded or AGM batteries, is a charge controller of some type needed? If not, why not? If so, what do you use?

4. Is anyone aware of an up to date book that discusses batteries and charging systems for RVs?

And a couple of thoughts regarding the specific system Wrinkledpants is contemplating:

A. Regarding the auto gen start (AGS) module by Magnum: As I understand it, the AGS kicks on the generator based on a classic wet cell battery charge management technique: battery voltage. For a wet cell or an AGM, this works great. But lithium batteries maintain a level voltage profile all the way to the end.

Not long ago, a manufacturer of Class B RVs introduced a system similar to what Wrinkledpants is talking about, with lithium batteries and an AGS tied to the vehicle's engine. It wasn't until the first batch of rigs were out on the road that they discovered that the voltage monitor on the AGS was not getting tripped by the lithiums until the batteries were dead--and, at that point--ruined. That company ended up tying an AGM battery into the system as the canary in the coal mine--the AGS monitors the AGM's voltage as a round-about way of estimating charge level of the lithiums.

The moral of the story: if you are going to go with lithiums and an AGS, be sure you have a solid plan for identifying the state of charge of your lithiums that will work with your AGS.

B. What are your thoughts about temperature control for the lithiums--specifically, how are you going to keep them above freezing when charging?

[Wrinkledpants]

Originally Posted by 86Scotty

No problem. Just FYI, I'm a german car fan too. I grew up helping my dad wrench on his beloved older Mercs (couldn't afford anything near a new one) and I have a love for BMWs up to about 06. When they started offering an electronic sensor in place of, not in addition to, a dipstick that was it for me. I hear they are piping in engine sounds into the stereo speakers nowadays. I can only go so far.

I actually love the T1N Sprinter and drove one for a few hundred thousand miles for work. I have no experience with the new ones but all I can say is that our mechanics hate the new ones. DEF (Not the Germans fault by any means) and all the modern electronics are just beyond what my billion dollar company can keep up with. That's not a good sign to me. That said, I don't see Sprinters on the side of the road much. I'm not a curmudgeon. I like lithium batteries and I'm no enemy to progress, but this system seems a bit more than I would want. It sounds like you've thought of how to mitigate some of the possible issues and that's what it takes to do what we do. Lots of compromises and forethought make the happy van camper.

Yeah - reliable and cheap to own are definitely not the same thing. We would consider a Ford, but they don't make anything with factory 4x4 and with the safety options the MB has. The white feather conversion is just too beefy and expensive for us.

And honestly, if we were buying a used setup, we'd be fine with AGMs. But, given the cost to convert to lithiums down the road, and the fact that our build date isn't until next fall, we are *so* close to having lithiums be mainstream that we feel the risks of being on the leading edge of that are worth the reward. Even SMB said if they had another 5 years to test and establish some best-practice rules, they'd be all about it. But, they're realizing that the demand is increasing faster than the time they have available to test. I feel confident in the technology, but there just isn't the integration yet that AGMs have, at least outside of the big OEM builds.

[Wrinkledpants]

Originally Posted by Glider

This brings up a set of questions I have been wondering about. In a solar setup, there is a charge controller that regulates voltage and amperage to the batteries in a very specific way--bulk, absorption, and float.

1. With lithium batteries, it appears that the classic 3-stage charge is not needed--it is a bulk charge all the way to 100%. Is that correct?

2. Assuming the answer to #1 is yes, then--in a second alternator setup with lithium, is a charge controller of some type needed? There has to be something between the alternator and the batteries, no? Assuming so, what do you use?

3. In a second alternator setup with flooded or AGM batteries, is a charge controller of some type needed? If not, why not? If so, what do you use?

4. Is anyone aware of an up to date book that discusses batteries and charging systems for RVs?

And a couple of thoughts regarding the specific system Wrinkledpants is contemplating:

A. Regarding the auto gen start (AGS) module by Magnum: As I understand it, the AGS kicks on the generator based on a classic wet cell battery charge management technique: battery voltage. For a wet cell or an AGM, this works great. But lithium batteries maintain a level voltage profile all the way to the end.

Not long ago, a manufacturer of Class B RVs introduced a system similar to what Wrinkledpants is talking about, with lithium batteries and an AGS tied to the vehicle's engine. It wasn't until the first batch of rigs were out on the road that they discovered that the voltage monitor on the AGS was not getting tripped by the lithiums until the batteries were dead--and, at that point--ruined. That company ended up tying an AGM battery into the system as the canary in the coal mine--the AGS monitors the AGM's voltage as a round-about way of estimating charge level of the lithiums.

The moral of the story: if you are going to go with lithiums and an AGS, be sure you have a solid plan for identifying the state of charge of your lithiums that will work with your AGS.

B. What are your thoughts about temperature control for the lithiums--specifically, how are you going to keep them above freezing when charging?

Most of the big named chargers and inverter/chargers (including Magnum) now have lithium profiles. Because you need a regulator that is specific to lithium, most people go with the 2nd alternator with a lithium regulator that is dedicated to just the lithium batteries. The primary alternator is is just for the van and starter battery. You can connect the two systems with a switch if you have a dead starter battery but fully charged lithiums, but that's the only connection between the starter battery and the coach lithium battery.

If you have an adjustable charge controller, then you can simply program that for the lithium requirements. I think the biggest difference is that your float charge is a bit lower than with AGMs.

[Flux]

Lithium is definitely compelling. Where do you plan on keeping your batteries? What kind of electronics do the batteries themselves have?? Temp considerations?

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