Switch from Lithium to AGM for Roadtrek Agile

[TerrierTude]

By now, everyone is aware of how problematic Roadtrek's Ecotrek Lithium based systems are. I won't go into my issues, except to say, in the three or so years since I've owned it, my 2016 Roadtrek Agile has been in the shop more than on the road and every single component has been replaced, some at least twice, and the whole rig has been completely rewired. Still not working completely.

Well, at this point, I'm thinking I should just rip the damn thing out and have my service guys reconfigure the whole thing with Old Skool AGM batteries and all the safe as houses systems that used to be part of the bombproof rigs that Roadtrek once made.

Since obviously, this is going to be on my dime as I'm pretty sure EHNA is not going to resurface any time soon to honor the rest of my warranty, I'm looking for people who have done similar retrofits. OR can tell me this is the stupidest idea ever.

Here are more details of my system:

2016 Roadtrek Agile

I have the EcoTrek 400 AMP hr lithium power module. I have a small AGM as well, but all it really does is charge up the Lithium. Also i have a 370 W solar panel with engine generator + VoltStart auto start battery protection.

My fridge is 12V or 110 on shore power and is very tiny. My stove and heater are propane.

I am very frugal with energy and am okay with remaining so. I've only turned on my air conditioner once. Even in the desert, I'm fine with reflectix, open doors and sitting outside under the awning. I've seldom used the microwave/convection oven and would never use it boondocking. For almost everything I cook, I use my 750W Instant Pot that cooks most things in under half an hour. When there isn't a burn ban, I'd use my portable charcoal grill or a cast iron pan over a campfire. My stove and heater are propane.

I happily use a variety of portable solar lights because they cast softer light than the cab LEDs.

I would like to turn on my inverter and run my Instant Pot and charge up my laptop, phone and electronics while boondocking. I am seriously considering a small portable (7 lb) lithium inverter/battery that charges from wall, solar and car cigarette lighter for some of my boondocking energy useage (Instant pot and charging.)

What I'm sick of is what seems to be the temperamental nature of my Lithium system, at least as Roadtrek has configured it. I honestly have never ever in the three years I've owned this rig had everything working at any one time. Murphy's Law has proven that if I'm out in the Mohave Desert in the middle of a Santa Ana windstorm, everything (but the reliable Sprinter) will go out.

I'm just sick of the uncertainty. If I could get myself to the point where everything works reliably and I could have a few luxuries, like maybe watching a 2 hr. DVD (which requires the inverter on) while boondocking. I'd be ecstatic.

Here's the kind of information I'm looking for:

*Has anyone done this and are you happy with it? Or do you have a similar AGM configuration and realistically, how long can you go unplugged?

*Given the different real full charge battery power between AGM and Lithium, would I need to go with more AGMs to get a comparable energy bank?

*Given that it takes longer for the Sprinter engine to recharge an AGM versus just having to top up the Lithium? What are the real world logistics? Would I need to run my engine half an hour, an hour, an hour and a half to get up to full charge with AGM?

*Given the larger footprint and weight of the AGM, what space would I need to dedicate to get comparable power? Obviously space is a huge issue in the tiny Agile.

*If I got a comparable AGM system, what could I expect boondocking in real-world terms: Ability to run off grid for two full days, running Instant Pot for 1/2 an hour, 12 volt systems such as Fantastic Fan judiciously.... Then it would take XX amount of time to recharge. Or would my solar be sufficient to keep the AGM topped up.

*Finally, am I completely crazy?

I'm getting wonderfully good advice over in the general forum, but thought I'd get even more if I posted this under the "electrical/battery/wiring section".


Thanks in advance for all your help

[markopolo]

AGMs will need to be fully charged and that can take a long time. Booster's post here - http://www.classbforum.com/forums/f5...html#post85666 - gives an idea of how long it could take to charge a 440Ah AGM battery bank. I'm sure there are posts about charging a 400Ah or so battery bank via a second alternator.

You would not run the engine to get to full charge as it would take too long when deeply discharged. Instead, you would run the engine to get to 90% or so charged and then let solar do the rest.

[hbn7hj]

Just an opinion but I would do everything possible to make the lithium bank work. Perhaps consulting with AM Solar is the way to go if you are not going to do the work yourself. You already have the lithium batteries so the expensive part is done.

Put in another vendor's BMS and see if you can make it work. Lithium batteries are so much better than lead acid except for temperature tolerance.

What fails in the present set up?

[TerrierTude]

Basically everything has failed at least once.

The dealer kept trying to gaslight me, saying everything was working fine. Even when I took it in and said, "Okay, show me how to make it work" (and they couldn't.)

Things got better when I found a long-established family-owned independent Roadtrek certified repair place. First thing that happened is that they called Roadtrek and questioned them on on the whole wiring. They sent a schematic and Roadtrek claimed that the dealer had "rewired the rig wrong". That may be ass-covering, but they paid to have the entire rig rewired. But there was something my repair guys called "the ghost in the machine". Everything they put in eventually shorted out. They went through two Lithiums and one AGM before they got everything sort of regulated.

Now my inverter has crapped out. It seems to allow the pass-through of AC when I'm on shore power, but it clicks and can't engage when I'm boondocking. So only DC when I'm off shore power now.

On one hand, I feel like we've replaced almost everything and we're nearly there. On the other hand, I have my husband, who is a boat guy, who has had an AGM and Magnum inverter system that has worked without problem for 9 years in an extreme ocean environment. He's really pushing for old skool.

I'm tempted to replace the inverter with a high end model like a Magnum and see if that fixes things. But I'm getting a lot of pressure to go AGM. My husband does not RV and he's worried about me out in some desert somewhere with all my systems going out. Of course, the advantage of AGM is that any Napa Auto Parts can get you a new battery and I could almost teach myself to add a new one in.

But I'm open to suggestions.

[hbn7hj]

Well, you could replace the inverter charger with something you would get if you went AGM, assuming it has a lithium setting, and see if you can make things work.

The other option is to repair the inverter charger you have. Post the brand and model of the inverter charger and maybe someone has a pitch it or fix it opinion.

[TerrierTude]

Thank you. Such good advice on this site.

[HarryN]

You mentioned that the combo unit inverter / charger / transfer switch / pass through power unit is working when connected to the grid (at home) but not working when boon docking.

By boon docking, are you referring to plugging in at a camp site pedestal, or hooked up to a generator?

The reason I ask is that I have seen similar behavior in victron inverter / chargers with pass through.

These units tend to require quite high quality power (frequency, grounding) and it isn't unusual for a generator or pedestal to have the frequency wander a little, or the ground - neutral bonding might be off. It doesn't take much and the combo unit will not sync up.

It isn't as efficient of approach, but one way to reduce this problem is to use a dedicated inverter and dedicated charger. That is what I do, because dedicated chargers are very resilient to incoming poor power quality.

You could test this concept by just purchasing a dedicated charger for your particular battery type and hooking it up.

Not sure where you are in CA but I have a lot of chargers around and might be able to loan you one for testing.

[TerrierTude]

By boondocking, I mean being on BLM and UNPLUGGED from anything. I don't have a generator per se. The Sprinter acts as my generator. When not on shore power, the Agile cab defaults to 12 volt. Unless, in theory, I turn on the inverter which is supposed to give my cab 110 power. But the inverter has seldom worked. I can hear it click and try to engage and it just can't get itself going.

When plugged in at campgrounds, I"m pretty careful about power. I have line testers to double check the voltage coming from campground hook ups and I have a surge protector.

But thank you for your suggestions. I'm gathering up all the wisdom I get here and will conference with my repair place and see what solution they think is the best going forward.

[Winston]

Originally Posted by TerrierTude

*Finally, am I completely crazy?

Originally Posted by TerrierTude

On the other hand, I have my husband, who is a boat guy, who has had an AGM and Magnum inverter system that has worked without problem for 9 years in an extreme ocean environment. He's really pushing for old skool.

I'm tempted to replace the inverter with a high end model like a Magnum and see if that fixes things. But I'm getting a lot of pressure to go AGM.

Yes, we think you're crazy.

Seems you may be blaming your lithium when the problem is elsewhere? What makes your husband feel that replacing one battery 'type' with another, less capable, will solve your problems? Do you have some reason to suspect something is wrong with your lithiums (or its BMS)?

We're now beginning our third year with 500ah of lithium and a Magnum 2812 - - over 450 days on-the-road and not the slightest hiccup. Our inverter remains on 24/7 - - only going off when an automatic switch-over to shore power occurs. It's surprisingly transparent - - it's hard to tell whether we're on shore or inverter power - - only when a significant load is placed on the inverter does the Magnum 'speak up' with a not-too-loud audible fan.

We're not familiar with Roadtreks, but a friend purchased a Hymer Aktiv (with 400ah of lithium) and we were more than surprised how poorly "instrumented" his system was. He literally has very little idea what is going on. If you're similarly 'in-the-dark' we'd recommend you not only swap-out to a Magnum (and we'd recommend the 2812) but install a good shunt-based battery monitoring system that will provide State of Charge (%) and lots of other very insightful information. Unfortunately my Hymer friends' lithium is divided into two separate 200ah blocks making installation of such an add-on more complicated but there's a solution to everything.

[TerrierTude]

The reason my husband wants me to go to a best of breed AGM system is that he has put one together for his boat: it's simple, it's worked without problem for 9 years, it's easy to service and monitor.

He doesn't necessarily think AGM is better than LIthium, he thinks the way Roadtrek has cobbled together their system is kludgey and it's new enough that not a lot of service places seem able to find the "ghosts in the system". Hell, Roadtrek can't even figure out what's going on. One component is always shorting out our compromising another. YOu fix one thing and another starts acting up. Add to this that Roadtrek put in a lot of proprietary systems instead of best-of-breed proven components.

Speaking of monitoring: this is definitely one of the issues. There is virtually none. I only have one of those four light touch things that shows me that I'm either fully charged, 3/4 charged. 1/2 charged or done. One of the things my husband wanted with a new system was a reliable detailed monitoring system such as he has on his boat.

With the excellent advice I'm getting here, I"m now kind of leaning to one last stab at getting my Lithium system up to speed. Since I'm pretty sure EHNA is going to screw me on the remaining years of my warranty, I might as well look at pulling together my own best-of-breed system. As one poster suggested, maybe a Magnum inverter that would also work for AGM should I eventually have to go that route. Maybe look at replacing some of the other components and certainly having my repair place wire in some meaningful monitoring systems.

[HarryN]

Originally Posted by TerrierTude

By boondocking, I mean being on BLM and UNPLUGGED from anything. I don't have a generator per se. The Sprinter acts as my generator. When not on shore power, the Agile cab defaults to 12 volt. Unless, in theory, I turn on the inverter which is supposed to give my cab 110 power. But the inverter has seldom worked. I can hear it click and try to engage and it just can't get itself going.

When plugged in at campgrounds, I"m pretty careful about power. I have line testers to double check the voltage coming from campground hook ups and I have a surge protector.

But thank you for your suggestions. I'm gathering up all the wisdom I get here and will conference with my repair place and see what solution they think is the best going forward.

Thanks for the clarification.

Unfortunately, transfer switches fail fairly regularly. There certainly are not as good and better models, but they all will still fail eventually. RV forums are full of people with similar symptoms.

Even if it isn't under warranty, many inverter / chargers / transfer switch combos can be repaired by the original mfg. Depending on what is installed, this might be an option. Do you happen to know the brand and model?

I mostly work on 24 and 48 volt based systems. Is that what your battery pack is or the older 12 volt concepts? I am guessing that your husband is very familiar with 24 volt for the boat.

The alternator charging concept is very good. One of the interesting challenges is that these higher powered alternators can generate so much power that if there isn't any significant load, the current exceeds what the battery pack can absorb.

With a pack like a Lifeline AGM, it isn't really a problem because they are designed to bulk charge at these high rates. In order to support air conditioning without a generator, designers are pushing alternator output into current output ratings that are actually too high for many LiFe packs. It is a common challenge.

[avanti]

Originally Posted by HarryN

One of the interesting challenges is that these higher powered alternators can generate so much power that if there isn't any significant load, the current exceeds what the battery pack can absorb.

With a pack like a Lifeline AGM, it isn't really a problem because they are designed to bulk charge at these high rates. In order to support air conditioning without a generator, designers are pushing alternator output into current output ratings that are actually too high for many LiFe packs. It is a common challenge.

Could you document these claims? I am not familiar with this "challenge".

A typical second-engine alternator (such as the Nations/Balmar pairing) comprise a fully-programmable 3-stage charger, with voltage feedback and battery temperature monitoring. The actual output of the alternator is completely determined by the regulator/charger. The absolute capacity of the alternator is irrelevant. Such a system, if properly set up, will not simply push arbitrary numbers of amps into the battery. I honestly don't know what you are talking about.

[booster]

I have done quite a bit of testing on our 440ah AGM setup with massive over current capability if we wanted to (over 500 amps available).



Our Lifelines have been very consistent in that if they are down 80% they will flash at about .8C when first put on charge if that much is available. This is consistent with what Lifeline told me when I was trying to select fuse sizes for the system. It doesn't stay there long, dropping to about .65C within 10 minutes. For deep discharges, Lifeline recommends a minimum of .2C for recharging and up to .4C. What I have found is that the .4C is also just about the point where the battery temps start to climb very quickly, with the beginning of temp compensation, so that is realistically about as high as you would want to charge at continuously. Temp comp is imprecise at best, especially at high charge rates, due to thermal reading locations and lagged response to the insides of the batteries, IMO, so staying away from it is a good idea if possible.


As it turns out, .4C of a 440ah bank is 176 amps, which is higher than the hot average output that we normally see in single big alternator engine generator systems that will be 270 or 280 amp rated alternators. When hot and running a cycling thermal turndown from a Balmar they seem to be netting and average of about 165 amps, so a very good match for the 440ah AGM banks, at in Lifeline batteries.


We don't have a Balmar on ours, but the AmplePower we do have has two stages of switchable output, which is really handy. One is set at .4C and one at .8C. We use the .4C for normal charging when driving and the .8C is intended only for a 20 minute rapid recovery emergency as that is how long the batteries could handle it before getting too hot (we have not ever needed to use the .8C in real camping, though).


I can't speak for lithium systems and how much they can actually handle. Some suppliers talk about 5C and more charge rates, and others severely limit the charge rate, so no consistency that I could see. In an RV, they are unlikely to run into a system that can charge faster than about 165 amps average, so only small systems would be of concern.

[TerrierTude]

Thank you all. The many informative posts here have convinced me to try to upgrade my Lithium system with some best of breed components.

I will get a complete list of what I have under the hood and under the chassis and return here for recommendations/suggestions for replacements.

[HarryN]

Originally Posted by avanti

Could you document these claims? I am not familiar with this "challenge".

A typical second-engine alternator (such as the Nations/Balmar pairing) comprise a fully-programmable 3-stage charger, with voltage feedback and battery temperature monitoring. The actual output of the alternator is completely determined by the regulator/charger. The absolute capacity of the alternator is irrelevant. Such a system, if properly set up, will not simply push arbitrary numbers of amps into the battery. I honestly don't know what you are talking about.

I might be wrong, but the regulators I have worked with could control voltage, but I could not find a "max current ever output control" setting on them.

For optimal cycle life, the higher end commercial LiFe battery supplier I use recommends C/2 charge rates max, even though discharge rates can be much higher.

My hands-on experience with battle borns indicates that C/2 is a good typical design place to run both charge and discharge on those, regardless of the spec sheet. (blew out some BMSs at less than 1C continuous in case you are curious)

In other words, a 400 amp-hr x 12 volt LiFe bank may or may not be able to charge at 200 amps, and I didn't find a "never charge faster than 200 amps" setting on the regulators.

Did you find a setting like that on the balmer?

[booster]

Originally Posted by HarryN

I might be wrong, but the regulators I have worked with could control voltage, but I could not find a "max current ever output control" setting on them.

For optimal cycle life, the higher end commercial LiFe battery supplier I use recommends C/2 charge rates max, even though discharge rates can be much higher.

My hands-on experience with battle borns indicates that C/2 is a good typical design place to run both charge and discharge on those, regardless of the spec sheet. (blew out some BMSs at less than 1C continuous in case you are curious)

In other words, a 400 amp-hr x 12 volt LiFe bank may or may not be able to charge at 200 amps, and I didn't find a "never charge faster than 200 amps" setting on the regulators.

Did you find a setting like that on the balmer?

Balmars have a 50% thermal turndown that can also be switch controlled to activate, and also have belt load adjustment that can be set in % from 50-90% IIRC. Of course, they are not running off actual amps, what they control are field voltage max. Our AmplePower has two pots that you can set the max field output with and control off external switches, and they can be set to a full range of outputs. I just watched an ammeter as I set the pots in full charge mode.

[avanti]

Originally Posted by HarryN

I might be wrong, but the regulators I have worked with could control voltage, but I could not find a "max current ever output control" setting on them.

For optimal cycle life, the higher end commercial LiFe battery supplier I use recommends C/2 charge rates max, even though discharge rates can be much higher.

My hands-on experience with battle borns indicates that C/2 is a good typical design place to run both charge and discharge on those, regardless of the spec sheet. (blew out some BMSs at less than 1C continuous in case you are curious)

In other words, a 400 amp-hr x 12 volt LiFe bank may or may not be able to charge at 200 amps, and I didn't find a "never charge faster than 200 amps" setting on the regulators.

Did you find a setting like that on the balmer?

First of all, I have been talking about AGM, not Li, so perhaps we have been talking past each other to some extent. I don't have enough direct experience with Lithium to comment.

To answer your question: Constant current chargers DO exist, but they are not appropriate for AGM batteries, and most manufacturers forbid their use. IMO, the correct way to deal with current modulation is temperature compensation. When current gets too high, the battery will rapidly get hot and a proper charger will reduce voltage accordingly. Here is what Deka has to say about this:

Temperature also affects charging. If the right voltage is used for the temperature, a battery will accept charge at its ideal rate.

and:

Q: What is a safe charge rate or voltage setting for outdoor applications with wide temperature fluctuations if a temperature- sensing charger is not available?

A: NONE! As the chart on page 11 (Effect of Temperature on Recharge Voltage) shows, charging voltage varies widely with temperature. There is no fixed voltage setting or current that will work. A temperature-sensing, voltage-regulated charger must be used. Anything else will damage any battery and cause premature failure!

There do exist "smart" chargers that can recognize the current signature of thermal runaway on AGM batteries, but IMO battery-side temperature compensation is more than adequate.