A few thoughts and questions replacing AGM with lithium in my Coachmen Beyond

[@Michael]

Originally Posted by booster

Shore power heat of batteries, absolutely, especially if parked outside in the winter and you have power available. ... If you don't have that and leave Minnesota with them in cold shut down and not in a heated area you can't get them back online or have 12v power or 110v to van until you get to a warm enough area to thaw them out and that can take a while if it is only 10* above their cutoff point.

My battery heaters have been (and are) 12V heat pads powered by the batteries, which means that I have to supply external power to the camper in winter. Keep it plugged in and all is good.

It does take much longer than I expected to un-freeze a very cold lithium battery using either the built in heat pads and/or the camper's furnace. That's an argument for continuously heated batteries and continuous 120V power in places that have severe winters.

The other issue is that even with batteries that have low temperature cutoff, the temperature sensor(s) are likely not in the center of the cell pack, but rather near the edge or on top of the cells pack, so the temperature that they measure will not necessarily be the temperature of the center or bottom of the cells. When warming a frozen battery, that needs to be considered. Depending on the location of the heating pads, the low temp cutoff could allow charging of a partially frozen battery unless there is sufficient time for the center and bottom of the cells to warm.

[Davydd]

Originally Posted by booster

The setup you have is pretty common, but for me I would not want it that way in and by itself.


Shore power heat of batteries, absolutely, especially if parked outside in the winter and you have power available. No heat except from batteries when off shore power, no I wouldn't want that. It would be very simple to have a switchable power to heating pads from the van alternator/charging system so they can be warmed that way when shore power is not available or they are offline due to cold. If you don't have that and leave Minnesota with them in cold shut down and not in a heated area you can't get them back online or have 12v power or 110v to van until you get to a warm enough area to thaw them out and that can take a while if it is only 10* above their cutoff point.

I'm not understanding. I think you are saying when shore power is not available you heat the batteries directly from the van alternator/charging system. To me that implies idling when boon docking overnight in freezing temperatures. That's not going to happen.

I also said in my previous post you shouldn't leave lithium batteries outside in cold shut down in Minnesota for many reasons. Also in taking two days to get to above freezing weather including a 0F boon dock overnight you better have a high capacity amp hour battery pack because you can't charge them but you can get power from them and chances are on after a cold shut down you are not going to be fully charged on departure. It would be extremely inconvenient to leave your battery bank shut down until you reached warm weather. That would mean no lights or heat in the cabin.

[booster]

Originally Posted by Davydd

I'm not understanding. I think you are saying when shore power is not available you heat the batteries directly from the van alternator/charging system. To me that implies idling when boon docking overnight in freezing temperatures. That's not going to happen.

I also said in my previous post you shouldn't leave lithium batteries outside in cold shut down in Minnesota for many reasons. Also in taking two days to get to above freezing weather including a 0F boon dock overnight you better have a high capacity amp hour battery pack because you can't charge them but you can get power from them and chances are on after a cold shut down you are not going to be fully charged on departure. It would be extremely inconvenient to leave your battery bank shut down until you reached warm weather. That would mean no lights or heat in the cabin.

I think you are implying what wasn't said. I never advocated running the van overnight. I advocated being able to prewarm the batteries before leaving and/or being able to heat the batteries and have coach 12v available all the way to the warm while driving. Heat from shore power and while driving cover all of the issues easily. Side benefit is the ability to heat them if in cold shutdown for some reason while traveling or to have 12v to the van until you can recover battery connection for what ever reason. Redundancy is good in my world, you may not think so.


Not everybody has the option of not leaving their rigs outside in the winter like you, or I, have. Should they be left out of getting lithium if they can find a way around the cold hazards? That is exactly the point I was making.



A delay in 12v to the coach when you leave for the warm is easy to avoid if you can connect the 12v system from the engine, we do it regularly to save running on the batteries while traveling so they are still full when we arrive.

[Davydd]

You don't have any experience with lithium house batteries in a van I take it. AGM batteries are different. They will supposedly tolerate down to -40F and can be charged at below freezing temperature. I stored outside for three years with lithium batteries and 9 years before that with lead acid and AGM batteries before I bought a heated garage. I was connected to shore power that whole time. In Minnesota you don't, can't, leave the van outside with lithium batteries without shore power and a way to keep your batteries warm. It gets routinely, as you know in Minnesota, a -20F and lithium batteries can be damaged permanently at -4F. How long can you hook up a 100v AGM engine battery to keep just one lithium house battery warm without running the engine, which is rediculous? The heat source has to come from the lithium battery through steady charging. If you had another source, then why not just plug into the van?

With shore power the batteries will stay warm and you don't have to warm them up when getting underway. When underway the engine does charge the lithium batteries and in turn the electric heating pads warm the batteries up constantly to take that charge. However you need a fairly large battery bank to boon dock overnight. I survived in the UP at -15F because I had shore power. Most shore power sources are closed down in the north as campgrounds are mostly closed. If you are just advocating shore power in Minnesota winter storage, I said that already.

[JML]

A lot of sales people state that "Dropping in" a LiPO is fine, but that is not entirely true. LiPo's have a different charging profile and if the system you are dropping in the LiPo battery does not accommodate this charging profile, you will not get a full and complete charge to your new battery. When I replaced my lead-acid battery with a LiPo, I also replaced the Progressive Dynamics Charge controller to one that is designed for LiPo, and I changed the solar controller to one that had a LiPo setting. When I upgraded my LiPo from a 100 AmpHr to a 270 AmpHr I ended up going with a DC-DC charger. One issue I had was no matter what I tried - two different Isolators, DC-DC Charger, etc, I could not fully disconnect the house LiPo battery with the starting battery. I think it is because of the disparate voltage difference and the way Pleasure Way ran the cables from the chassis to the house. Like you, I did not want to redo any cables, so I solved the issue by putting a switch on the DC-DC charger and a battery cutoff switch between the starting battery and the house battery. BTW, I just replaced my Renogy solar controller with a Victron Smart Solar controller. The dongle on the Renogy went out three times and the controller failed once (got a free replacement from Renogy). More expensive but cheaper in the long run. I also replace my 450 watt inverter with a 100o watt inverter - that was the largest inverter I could use given the current existing cables. I can only run my AC or Microwave on shore or generator power away - the 1000 watt inverter was needed on the rare occasion when I have to recharge my eike batteries two at a time. Good luck!

[booster]

Originally Posted by Davydd

You don't have any experience with lithium house batteries in a van I take it. AGM batteries are different. They will supposedly tolerate down to -40F and can be charged at below freezing temperature. I stored outside for three years with lithium batteries and 9 years before that with lead acid and AGM batteries before I bought a heated garage. I was connected to shore power that whole time. In Minnesota you don't, can't, leave the van outside with lithium batteries without shore power and a way to keep your batteries warm. It gets routinely, as you know in Minnesota, a -20F and lithium batteries can be damaged permanently at -4F. How long can you hook up a 100v AGM engine battery to keep just one lithium house battery warm without running the engine, which is rediculous? The heat source has to come from the lithium battery through steady charging. If you had another source, then why not just plug into the van?

With shore power the batteries will stay warm and you don't have to warm them up when getting underway. When underway the engine does charge the lithium batteries and in turn the electric heating pads warm the batteries up constantly to take that charge. However you need a fairly large battery bank to boon dock overnight. I survived in the UP at -15F because I had shore power. Most shore power sources are closed down in the north as campgrounds are mostly closed. If you are just advocating shore power in Minnesota winter storage, I said that already.

In this case the OP said the van is stored in an unheated space with one common wall to heated area and it stays above zero. That is above the -4*F that is currently recommended by many manufacturers for storage. I do remember one time yours were locked out when the heaters were off or couldn't keep up and you were crawling under to put a heater under the battery pack. Wouldn't it have been easier to start the engine for a while so you could warm them enough to turn unlock so the shore power could keep them active again?

[JonMN]

LOL, suddenly my AGM is looking better and better!

Thanks again for the input. This has been a great thread for me.

Another quirk in the lithium world is the limit on discharge amps. The batteries I am looking at limit discharge (long term) to 200amps. I'm a rookie at 12v conversion to 120v, but to me this sounds like 2400 watts at 12V. If you run this thru my I/C, which is supposed to be at about 85% efficient, I should get 2040 watts at 120. More than enough for the critical morning cup of coffee and toast, as long as I don't run them at exactly the same time. [but please correct me if I calculated wrong]

Additional quirk/consideration is starting the 2800 onan generator. Here the short-term power of the battery should be enough, but would be really annoying if it was not. On a related note, my AGS system is based on voltage, so that might not work out either.

[booster]

Originally Posted by JonMN

LOL, suddenly my AGM is looking better and better!

Thanks again for the input. This has been a great thread for me.

Another quirk in the lithium world is the limit on discharge amps. The batteries I am looking at limit discharge (long term) to 200amps. I'm a rookie at 12v conversion to 120v, but to me this sounds like 2400 watts at 12V. If you run this thru my I/C, which is supposed to be at about 85% efficient, I should get 2040 watts at 120. More than enough for the critical morning cup of coffee and toast, as long as I don't run them at exactly the same time. [but please correct me if I calculated wrong]

Additional quirk/consideration is starting the 2800 onan generator. Here the short-term power of the battery should be enough, but would be really annoying if it was not. On a related note, my AGS system is based on voltage, so that might not work out either.

Yep, there are a lot of considerations for any power system upgrades if you want to get the best results possible. It is good you are taking the time and effort to explore them all.


200 amps should run your stuff unless you stack up a lot of them at the same time. Probably count on 2000 watts max to be safe on startup surges and other variations. Did the manufacturer differentiate between max amps before the BMS trips (if it even trips on amps) and recommended amps and where damage might occur amps?



Do be aware that inverter specs are highly different between models and brands, plus they normally give the efficiency as a "max efficiency" and it will usually be at a quite low output. Best if the manufacturer posts, or will furnish, a full curve for efficiency all the way up to full load. I have seen them with 95% rated, but at full load were under 80%.

[Davydd]

Originally Posted by booster

In this case the OP said the van is stored in an unheated space with one common wall to heated area and it stays above zero. That is above the -4*F that is currently recommended by many manufacturers for storage. I do remember one time yours were locked out when the heaters were off or couldn't keep up and you were crawling under to put a heater under the battery pack. Wouldn't it have been easier to start the engine for a while so you could warm them enough to turn unlock so the shore power could keep them active again?

Trying to jog my memory. I wasn't locked out. The Silverleaf screen inside the van alerted me. That was in February 2015 one month after I took possession of Alvar, my van. There was a system failure and the temperature of the batteries were dropping despite being plugged into shore power. So starting the engine would do no good if the heating pads were not heating. Also, Mercedes Benz recommendation was not to idle over 2 hours without driving in between idling and not a long time fix. Putting an oil heater and leaving it on was a much better solution especially if I had to do it a long time. It did work. Jogging my memory I can't recall how I got it fixed because it was only temporary. User error?

[booster]

Backs up my point completely. Redundancy is good, separate systems for shore power heat and engine running heat would have saved you a crawl under in the snow and you could have just gone for a ride instead of idling if you chose to.

[Davydd]

I didn't crawl under. I put the heater on a creeper and slid it under. I would never drive all night when the heater was there instead needing no attention and the heat from the van would have done no good with the batteries outside under anyway. So what's the point? Yes, redundancy is good. I now have shore power and the good sense of a heated garage for backup.

[@Michael]

Originally Posted by JonMN

]Additional quirk/consideration is starting the 2800 onan generator. Here the short-term power of the battery should be enough, but would be really annoying if it was not. On a related note, my AGS system is based on voltage, so that might not work out either.

That's what's keeping me from removing my AGM's completely. I put clamp-on amp meter on the feed to the generator and saw well over 200 amps to the starter motor. I suspect my 200 amp BMS would disconnect if it takes more than a few seconds to start the generator, which is most of the time.

So I'm keeping the OEM Coachmen AGM's under the van just to start the generator, which I never use while camping anyway.

(It's nice to have during a power outage though.)

[avanti]

I, too, believe in maximum redundancy. For example:

The Transit (and the Sprinter as well) can be ordered with a second AGM chassis battery (which from the factory doesn't power anything). In our new van, there is an A/B switch that permits the 12VDC circuits to be powered either from a 24V->12V buck converter (powered by the lithium batteries), or from the auxiliary Transit 12V AGM battery. There is also a switch that selects whether the fridge runs from 24VDC (which is normal) or 12VDC (for emergency use). The battery heater is 12V, so it can be powered either by the chassis or the house battery.

[booster]

Originally Posted by avanti

I, too, believe in maximum redundancy. For example:

The Transit (and the Sprinter as well) can be ordered with a second AGM chassis battery (which from the factory doesn't power anything). In our new van, there is an A/B switch that permits the 12VDC circuits to be powered either from a 24V->12V buck converter (powered by the lithium batteries), or from the auxiliary Transit 12V AGM battery. There is also a switch that selects whether the fridge runs from 24VDC (which is normal) or 12VDC (for emergency use). The battery heater is 12V, so it can be powered either by the chassis or the house battery.

That sounds very much like the kind of system I would want, especially if the batteries were not inside the van. I don't know how reliable the heating pads are long term, but if there were multiple pads wired parallel to get the desired amount of heat it probably wouldn't matter much if one failed so OK there too.



The power system in a van is pretty vitally needed to be able to continue a trip, so if it fails completely and you have no power the trip is probably done at that point. It just makes sense to make that system as reliable as possible.

[Punkinhead]

The discussion is why I'm glad my lithium batteries are inside the coach. If I lived in the south it might not matter, but in the upper midwest it makes life a lot easier. I have indoor insulated but unheated storage and it has to get very cold for quite a few days in a row before the inside of the van drops to dangerous temperatures. A small (350W) space heater or even an incandescent bulb in the closet with the batteries would be enough for those situations. Of course, I'm giving up inside space, but to me it's a worthwhile tradeoff.

[avanti]

Originally Posted by booster

if the batteries were not inside the van.

Originally Posted by Punkinhead

The discussion is why I'm glad my lithium batteries are inside the coach.
....
Of course, I'm giving up inside space, but to me it's a worthwhile tradeoff.

Our van has what I think is an interesting take on the "inside/outside" question, which I will describe systematically along with a lot of other stuff when we take delivery. [van is essentially done. Just need to work out delivery logistics].

[booster]

Originally Posted by avanti

Our van has what I think is an interesting take on the "inside/outside" question, which I will describe systematically along with a lot of other stuff when we take delivery. [van is essentially done. Just need to work out delivery logistics].

I think I can guess what it is, due to past discussions and it how I would do it also. But I plead the fifth to not incriminate myself.

[Davydd]

You can put lithium house batteries outside. I had them for 6 years that way. I never had the problems that I encountered with a propane generator and propane tank and heating pads are an easy fix and losing them doesn't prevent you from driving if inside and designed correctly with inside heat circulating and that is only in the winter which you can do easily. I had a propane regulator failure in the Yukon that ended my Alaska trip in getting home as fast as I could.

In the south you might have no problems with lithium unless you live in heat reaching routinely 106F. That reduces the capacity of your batteries but doesn't ruin them. I read 20% loss over 6 years from one RVer after storing their RV on asphalt. I don't encounter that problem. You do have less problems in the south.

However, you don't get the true benefit out of lithium unless you shuck all propane and generator and even solar and that means probably 400ah or more I think and then you need a second alternator to recharge that capacity in a reasonable time. Solar and driving with just a chassis alternator would not do it. Driving in the winter doesn't produce enough charge to use you battery source to heat them above freezing without high capacity lithium batteries. You can't get the 800ah or the Volta system to run air conditioning in the south with AGM batteries. Roadtrek tried that and failed miserably besides loading up the inside of the van with batteries.

So, just replacing your existing AGM with lithium or even upgrading a modest amount of capacity is maybe a fool's game and you better have shore power as I have said repeatedly.

I have four group 27 standard casings - 144ah batteries with 576ah and inverter under my single bunk bed. I could have put in 864ah but thought the two drawers were more valuable and with my experience and travel habits over 6 years with lithium I didn't need 864ah.

[JonMN]

Thanks all for the replies! This has been really helpful.

Regarding storage, I do think there are a couple approaches I can take. I could purchase a heated battery and leave it on shore power. In fact, this is what Lithiumhub recommends if I go with their battery. If I went with an unheated, I could come up with a heated method during storage, or just not worry about it as our storage would not go below -4. While the battery will be under the van, I could easily add a layer of insulation.

I do agree that having the battery in the van is ideal. But every layout has pros and cons. We were really attracted to the rear bath layout. It's so open in the front. We have a lot of overhead storage and a very nice wardrobe area in the back. But we are short on "bulk" storage that we could retask for battery use. (When Coachmen builds this version in lithium, they move the fresh water tank to the outside and keep the batteries on the inside. Our water tank is above the van floor.)

Right now I am narrowing down my choice of batteries. I know there are several good batteries out there. I am limiting to 8D size so I can mount in the cage under the van. So I do check them for their IP rating for water/dust ingress.

Battleborn: 270AH; max continuous discharge 300A, peak 500A for 30 seconds. Pretty impressive, but not heated.

Enduro: 300AH; max continuous 250A, peak 400A for 5 sec. Supposedly has vibration protection and the best IP rating. Again, not heated.

Ionic from Lithiumhub. 300AH; max continuous 200A; peak 350A for 3 sec. Good IP rating. This one is heated. Also the only one with a bluetooth monitor. Just few reviews in the RV world, but lots of positive reports in the boating world.

I am leaning towards the Ionic. (By the way, Sterling came out with a new line of DC-DC that looks really nice. Wide range of amps and they seem to run cooler than other brands. Expensive, but several nice features and easy to program/install. Non-isolated too, which makes sense if just replacing something like a BIM-160.)

Various anecdotal reports indicate that any of these will start my Onan generator.

[booster]

There is getting to be way to much self serving diversion and confusion going on here, I fear.


Bottom line is that we want to help the OP make the right decision for his system. He stores in an unheated space with one warm wall in Minnesota. He thinks he wants lithium but isn't positive on that I think, the storage area is said to never go below zero degrees F in the winter, he wonders if he needs heated batteries and didn't mention what type of heat desired if he did decide he needed it.


It appears that with the listed storage conditions his lithium batteries would be in cold weather, no charge, maybe no discharge mode and would need to be warmed up before leaving home if use of the batteries is wanted before getting to warm weather. They should not need heat when stored as above the -4*F said to be minimum storage temp. My conclusion is that heat would be needed if use wanted upon leaving or some time after that before getting to warm area.



What style and how controlled has many options from manual to automatic, heat from batteries themselves or shore power or alternator power or whatever other way that could be devised. IMO, this is the main thing that the OP needs to be able to figure out if he wants his heat system to match his use patterns and needs.


So I think that the OP and the rest of us need to do a reset here and find out his needs and wants before going any further with all this other stuff. Without knowing what the OP desires going to deeply into often complex discussions will just be confusing.


Keeping lithium warm enough is a big deal if you are from Minnesota and doing that heat may or may not be a disqualifier for different people. Depending on the needs and wants of the OP, it could be inexpensive and probably manually run or increasingly expensive and complex as automation and redundancy is built into it.