Upgrading 2004 Itasca Meridian to Lithium: Boost Button Compatibility?

[Mongobird]

The 04 Meridian 34D has a boost contactor which connects the house batteries to the chassis. My house are AGM and the chassis batteries are FLD.

I know the BMS technology of Li batteries is constantly changing. I thought I would ask if anyone knows of or has a house battery system which still allows the connecting of both systems for starting, when one is down or the weather is cold?

Thanks.

 

[dickb46]

I'm not sure but I've used the fla battery with my agm batteries just like if it were a fla battery. I've connected the fla and agm batteries many times. This was on a CAT engine.
Actually the dealer on my new '04 did yesterday also....but that isn't a good.....answer

I've used agm batteries for all most ever in the house batteries. I've always used them to connect with the starting batteries without a problem

 

[Mongobird]

I'm not sure but I've used the fla battery with my agm batteries just like if it were a fla battery. I've connected the fla and agm batteries many times. This was on a CAT engine.
Actually the dealer on my new '04 did yesterday also....but that isn't a good.....answer

Connecting Lithium batteries to the starting batteries may be problematic. The current out of a lithium battery may be very high unless the BMS limits it. Also the Lithium battery may need current limiting under starting conditions. Again, we are talking mixing Lithium with FLD battery types.

 

[Morich]

Not to confuse lithium with AGM!
AGM is Absorbed Glass MAT and that difference from normal lead acid is not all that much for charging or use. The normal lead acid has the liquid in what we might call loose! The AGM has the same lead and acid but the liquid is in glass ( fiberglass?) mats which changes how it moves, leaks, needs replaced. But the charge/discharge are not changed all that much!
Lithium goes into a much different world where they can be used with lead acid but we lose a fair amount of the good aspects of the lithium as we can only charge them as high as the lead acid if we want to avoid damage.
Maybe kind of like hitching a bike to a car, they "could" be used as a team but we would need to limit the use to what the baker could deal with? If we want the full bennies of lithium we need make the whole system upgrade!
Most who want to spend the money for the great deal better batteries will also agree they want to get full use out of that change and not limit their use to the older lead acid limits.
AGM is still lead acid but with improved containers! Lead and acid but stored in a different way?

 

[Mongobird]

OK, so a different question is has anyone changed their house battery installation to Lithium, recently, and what was involved, and did it impact the use of the boost momentary contact switch?

 

[Morich]

I have not gotten too involved, nor done the switch on RV. But there are lots of posts on things which others have done and it can get very involved, due to the difference in lithium and lead acid types.
To get better response from those folks it might be better to start a new post with the different question as a way to catch those folks eye?

 

[JR314]

OK, so a different question is has anyone changed their house battery installation to Lithium, recently, and what was involved, and did it impact the use of the boost momentary contact switch?

I added a single 200 amp hour lithium battery a few years ago. It is connected the same as the old fla batteries, but I have never tried or needed the momentary switch. In general, the lithium house batteries are not rated for cranking. I don’t know why and never checked into it. I carry a jump pack rated for diesel, which is ironically a lithium jump pack. It is probably a different type of lithium. The house batteries are Lithium iron phosphate. I’ve been happy with them. I’m ready to go with a bigger battery bank now.

 

[wytgy]

The 04 Meridian 34D has a boost contactor which connects the house batteries to the chassis. My house are AGM and the chassis batteries are FLD.

I know the BMS technology of Li batteries is constantly changing. I thought I would ask if anyone knows of or has a house battery system which still allows the connecting of both systems for starting, when one is down or the weather cold?

Thanks.

I recently replaced all the batteries in my 04 Sightseer 30b. FLD for the chassis and LiPo for the house. The lithium batteries I chose are internally managed at 12.8v output and are used as an emergency backup for the chassis. I wish I could tell you the make but my RV is presently in storage. I'll suggest you investigate thoroughly before buying. Good luck!

 

[keithd311]

When I upgraded my house batteries to Lithium, I retained the boost button capability. However, since Lithium works at a higher voltage and can also output a tremendous amount of amps (200Amp per battery in my case), you cannot use this boost button to help start the engine. The best answer that I received for this question was that you can use the boost button to provide an initial charge to the coach battery, but not to use it to provide the starting power. I have done this a couple of times, and that is press and hold the boost button for several seconds which will provide some charging to the coach battery and then release the boost button to try and start the vehicle. If it doesn't work, try again for a little longer. I have a 2004 Winnebago Minnie 29B

 

[JR314]

The 04 Meridian 34D has a boost contactor which connects the house batteries to the chassis. My house are AGM and the chassis batteries are FLD.

I know the BMS technology of Li batteries is constantly changing. I thought I would ask if anyone knows of or has a house battery system which still allows the connecting of both systems for starting, when one is down or the weather is cold?

Thanks.

A quick internet search says that LiFePO4 batteries generally lack the discharge capacity to crank and the BMS shuts them down for over discharge. That makes sense since most are in the 100-200 amp discharge range. It might work if your chassis batteries only need a minor boost. I wouldn’t rely on it though.

 

[BikerMonkey]

The 04 Meridian 34D has a boost contactor which connects the house batteries to the chassis. My house are AGM and the chassis batteries are FLD.

I know the BMS technology of Li batteries is constantly changing. I thought I would ask if anyone knows of or has a house battery system which still allows the connecting of both systems for starting, when one is down or the weather is cold?

Thanks.

Well my 2023 EKKO is factory wired with a boost switch to the engine AGM and the coach LiPro, I’ve never thankfully ever had to use but I guess it means that it’s possible. I should note that the victron BMS is designed for the LifPro lithium batteries

 

[Bnystrom]

When I upgraded my house batteries to Lithium, I retained the boost button capability. However, since Lithium works at a higher voltage and can also output a tremendous amount of amps (200Amp per battery in my case), you cannot use this boost button to help start the engine. The best answer that I received for this question was that you can use the boost button to provide an initial charge to the coach battery, but not to use it to provide the starting power. I have done this a couple of times, and that is press and hold the boost button for several seconds which will provide some charging to the coach battery and then release the boost button to try and start the vehicle. If it doesn't work, try again for a little longer. I have a 2004 Winnebago Minnie 29B

That's the way the boost button is supposed to be used, regardless of the type of house batteries you have. Deep-cycle FLA or AGM batteries don't have the cranking ability of a starting battery, either.

OK, so a different question is has anyone changed their house battery installation to Lithium, recently, and what was involved, and did it impact the use of the boost momentary contact switch?

It depends on the overall battery installation. If you just dropped in LiFePO4 batteries in place of the stock FLAs, the boost switch is unaffected. If you have a larger LiFePO4 battery bank with a DC-DC charger to protect the alternator, that typically disables the boost function unless you include a switch to manually enable the boost solenoid, so you can then use the boost switch on the dash.
As a general rule of thumb, you can drop in up to 200Ah of LiFePO4 batteries without needing to install a DC-DC charger.

 

[BikerMonkey]

Good to know, my 2023 EKKO with 380A battery has a factory installed boost button, luckily I’ve never had to use it.

 

[Morich]

I am not aware of the faster discharge of lithium being a problem. I thought the problem was more involved with overheating the alternator as the lithium can take far more current than some alternators are desgined to handle. They can overheat the alternator if we leave the RV as built makng the chassi and coach connect through teh mode solenoid or BIM.
One solution to assure this doesn't happen is discussed fairly frequently on this forum and seems fairly easy to do if thay is the factor yu want to deal with and prevent.
One method mentioned pretty often involves putting a switch inline to control when the two are connected together.
On both the mode solenoid on older RV and the newer BIM, there is a wire labeled LR.
Wire FM is the ground side of the circuit. When we want the connection from chassis to coach for charging the coach as we drive, LR brings battery from a point often called 'igntiopn hot". As the name implies that point is hot when the ignition is on. That 12VDC feeds a coil in the solenoid or BIM and goes to ground on FM!
When energized that coil closes contacts between chassis and coach, either as we hold the switch or as we drive.
It has two functions. We can geta jump start by holding thw switch as it isa momentary switch and we only hold it as long as we need to crank.
The problem is that we may not want that igniton hot point to keep the alternator putting out the higher current lithum will take as it may overheat. So one simple solution to the second issue is putting a simple switch in wire LR to turn off the contact closure when driving but leave it available to close if we want a jump start!
One handy thought is to put in near the driver but in a place or type of switch that will not get turned on without us knowing it!
But I like to check these things before saying too much and that is a problem as there is no 2004 Meridian 34 D listed??
Possibly 34 H?

Wiring Diagrams

 

[Morich]

WHOOOPS!
I need to correct this as the 2004 meridian doesn't have the same operation as I described. In some ways it may make change to lithium somewhat easier but with some thought?
Looking at some of the 2004 models, the modes solenoid seems to have been in the middle of a switch in design that made it being not a fully automatic operation when we drive. They had a "dual battery switch" instead of what I described which does the connection automatic.
What this might get down to is there might not be a need to add a switch to keep the mode solenoid from connecting while we drive. At this age group, the operation of the mode solenoid was not auto but they gave us a manual switch to use when we want to combine the two battery groups!
That would make it somewaht less handy to combine as we drive as we would have to remember to switch to dual. But on the other hand, now that we are beginnng to thnk lithium, it may be simply a matter of flipping the switch to dual when we want them combined but remember to switch off dual when we might worry about overheating the alternator?
For a short term jump[ start, Iwould see no problem with combining the two as long as we remember to disconnect them while we drive if concerned about overheat on the alternator!
Maybe a simple flag to alert you when they are combined. One problem with forgetting they are combined might be if we dry camped and ran BOTH battery groups down to strand us!

The more time I spend looking at these drawings the less I find RV are the same!

 

[Bnystrom]

Interesting...
If it works as you describe it, there should be no problem using it. The problem is that if...

You have a large LiFePO4 battery bank...​

and you forget to turn off the switch...​

you could damage your alternator.​

 

[Morich]

Yes, very much the same situationwhen we might add our own switch as several have done here. One of the questions seems to be how much heating for how long to make the alternator fail and that is not going to be one we can really know until too late!
So if we want to do that, several have looked at putting the switch out of the way, in some compartment or some have used switches with safety covers to avoid hitting them whan not meaning to do it. Mention has been made of leaving a tag over the switch?

But part of the question has to involve exactly WHICH RV as things we which are common now are not what the 2004 year may have used.
As I look at the electrical info we are now finding online from Winnebago compared to what we had a few years ago, I see it gradually being reduced, so the future planning is going to get more difficult!
What I am finding now is a good deal less usable than what we got a short time back as they now have dropped some of the drawings like the actual schematics for the 12VDC coach systems and also the amount of info has been reduced in small ways about how it is presented!
This is one that is near killer for me as it makes reading the info so much more tedious when wires that leave a sheet to another sheet are not labeled.

With the newer methods, I can't simply scan the ID at left for wire LR! To find LR, I have to go back to an item like a plug where LR is tagged and trace it across the sheet and then when moving to the next sheet, it requires counting or sorting which wire LR shows up as on the next sheet!
IF it was a simple change in the way drawings are drawn, that is one I could understand but this new sytem seems designed to avoid many of us being able to work with it! And it is not just on newer RV but going back into the drawings from the late '90's!
Life changes!! I have enjoyed passing slack time with reading these drawings but when things are designed to make a job difficult, I tend to look for other ways to pass the time!
But what does the tech at a shop do for info? Do they have some system of reading this and I simpy don't get that training? Shop techs in RV have never been what I consider the best, top grade trained folks on electrical and this is not going to improve that in any way I can see!
Maybe AI is meant to save us? But I sure don't see it at this point!

 

[tim myers]

I recently upgraded my 2007 Journey to LiFePO4 2 x 314 AH, and I defeated the BIM and in turn the Boost feature. The wires that provide the 12 VDC coil voltage to the BIM are the same wires that connect the chassis batteries to the house batteries for charging heading down the road, and I removed them and made them safe to defeat that solenoid.

Couple reasons, to prevent alternator overheating and subsequent destruction I inserted a DC2DC charger between the two battery banks which limits the charge from the chassis side to the house side to 50Amp.

If I were in dire straights I could reconnect the wires and use the boost to put some charge into the chassis batteries but I wouldn't try to start the diesel engine with the Lithium batteries. My two chassis batteries are capable of 900+ amps of starting current each for a total of nearly 1800 amps, where my Lithium at 200 Amps each would only provide a theoretical 400 Amps of starting current a drop in the bucket compared to the chassis batteries.

 

[Morich]

Sounds like a workable plan but I might worry a little less on the problems of starting.
If we assume the chassis has at least some power left, connecting the coach lithium battery for a short term start help, is not likely to do any damage as the starter will only draw the current needed to turn it for short term.
Not to charge the chassis but only to make that power available att eh post for as long as it takes to crank.
I look at the overheating as not just a simple matter of how much currtent is flowing but also how long as the time is a big factor in heating.
But doing the extra to reduce the worry is often a good move!

I might also add that there appears to be some confusion when we speak of charging the coach battery. We all know it is a very slow chemical process when we charge a lead acid battery. That takes hours to charge one!
But when we connect one good battery to another it is a small techie point but when we look at the post and see a much higher voltage, it is not that we have charged that weak battery! It's a misleading voltage reading that we often call surface charge. A fake reading which really doesn't mean we have taken the hours it takes to "charge" the battery by changing the chemicals all down through a battery!
Whether we are speaking of the high voltage we see almost immediately when we put a lead acid obn a charger or when we connect it to lithium, it is not a true charging situation, omnly a temporary higher voltage we are putting at the posts where the starter can use it.
When we take the charger OR the lithium off, we will see a temorary high voltage but it goes away almost as soon as we remove the item giving the higher voltage. The lead acid battery is not charged more than a fraction when we put a higher voltage on for 5 minutes or less! It takes hours to charge a lead acid battery!

 

[Mongobird]

Well, interesting discussion.

Regrettably, I had a friend, a former Navy pilot, who has no family, and needed hospitalization, rehab, and the like after a stroke, and I have been sidelined with taking care of his affairs from 1100 miles away. The good note is that he is making good progress in recovery, and has moved to his third facility as he heals.

So now I am back, and would like to clarify some of the questions I had in mind.

-are there BMS systems / battery assemblies, which will support providing adequate charge currents for starting the traction engine?

-are there BMS systems / battery assemblies, which will sensibly manage charge current for the house batteries when the traction motor is running (idle and underway)?

-what adaptations are needed to handle the operation of the diesel genset, so that charge currents are managed when running the genset? [My guess is that a new inverter is needed to manage the charging of the house batteries, but that could also be managed with a BMS on the Li batteries.]

-are there BMS for Li which can provide some or a larger part of starting current for the traction engine starting. [As I understand it, cold weather charging is the principle concern for Li chemistries, where as large currents can be drawn for without as much concern for starting. But I have not fully dug into this issue.]

There are also hybrid strategies, such as using an inverter to take 12V from the Li, and buck it up to 15.5V to permit a pre-start charge to ease starting with FLD batteries.

---

So probably my questions lie in what changes have been made with Li BMS specific to the motor home, with a BOOST button capability.

I am partial to the concept of the BOOST button, as it saved my bacon early in RV ownership, when the pickup ferry trip was rudely interrupted by an alternator failure on the traction engine, and I utilized the genset to provide 12V to keep things running until I got home.