LiFePO4 coach battery conversion for an Itasca Meridian 34Y

[mpl239]

Anybody having done a Li conversion for coach batteries for a Meridian 34Y, I would appreciate some guidance. I have a 40 ft sail boat with 600 ah CALB prismatic cells, charged by solar, shore, and alternator charging. I changed the alternator to a 125 amp Hamelton Farris marine alternator with a Balmar 614 external regulator and a Xantrex 2000 watt Freedom SW inverter/charger. Using a Blue Seas ACR to separate the AGM start from the Li house batteries. All systems are connected to buss bars. Each system has a different voltage set for charging, with the solar being lowest and shore the highest. This allows all, except the alternator to turn off when they reach target voltage. I have a group 24 lead acid in parallel to the Li, as a surge protector, to protect the alternator, if not shut down by turning off the field off first to minimize the alternator shut down spike as the field collapses slowly with a normal engine shut down.

On the 34Y I do not want to change the alternator, I intend to use a 30 amp DC-DC charger or a Battle Born Li 225 BIM to limit the charging current. The 34Y has shore on board charger stock Cummins alternator and solar. Looking at the wiring diagrams and speaking with Winnebago folks, I am somewhat confused on how to wire this. It is my intent to charge to 13.5 V (I am ok with a 70% - 80% charge on Li. to simplify my install). With the stock installation, it looks like charging sources feeds the coach solenoid which feeds the existing BIM which feeds the coach batteries with a pass through for chassis batteries. I am thinking that if I put the DC-DC after the coach solenoid and before the BIM I should be ok. Since this is the girlfriends RV and not my boat, causing things to melt and smoke would not be good for my life or relationship.

Has anybody gone down this path or something similar willing to share information and pointers.


Michael

 

[bpcannan]

I have a 2010 Winnebago Journey Express 34y (near equivalent to the Itasca Meridian 34Y) and converted to LiFePO4 in 2022.

Parts used were
o 3 X 100AH 12V Battleborn LiFePO4 Batteries
o 3000W 12V, 50AMP 2 X 120V Victron Multiplus Inverter/Converter
o 225AMP Lithium Battery Isolation Manager, Battery Guard Autoselect
o Victron Digital Mulicontrol Panel, Victron BMV-712 Battery Monitor
o 14-2 NMG and 6/3 NMG Wire used in installation
plus a shunt and fuse setup.

The shop putting it in for made a cover in the battery bay to close that opening and minimize dust dirt.

Our objective was to convert the whole coach to 50 AMP 120V service. To Avoid extensive cost and re-wiring the installer devised a workaround whereby a switch was installed in the shorepower bin (next to the battery bin) that meant when we plugged our 50AMP shorepower cable into that switch and flipped the NORMAL button to BYPASS on the Progressive Industries interior wall monitor we drew from he batteries and all outlets were HOT.

We did not have an objective to run the AC off the batteries nor any thing more than a minutes use of the Microwave - so this worked for us. Would need at least 300AH more for that.

We like it and added 3X200W Bouge RV CIGS solar panels this winter to help keep them charged in state parks without hookups.

Good luck.

 

[Riverguy42]

<snip>I have a group 24 lead acid in parallel to the Li, as a surge protector, to protect the alternator, if not shut down by turning off the field off first to minimize the alternator shut down spike as the field collapses slowly with a normal engine shut down.<snip>


Michael

I've never seen an FLA in parallel with LiFePO4, never seen it recommended or approved by any manufacturer or any standards in any jurisdiction, and can't imagine how you manage to keep it from boiling the electrolyte away, given that your LiFePO4's need a constant 14.5-14.6 to charge. THIS IS UNSAFE.

I've seen a lot of DIY and professional installations (mostly on big boats) and done a dozen or so myself, but never seen that. The ABYC standards for Lithium batteries (following the US CFR's and the USCG regs) absolutely forbid mixing any kind of Lithium chemistry with Lead-Acid in any battery bank, (for good reasons).

I would say that FLA in parallel is a constant hydrogen source, waiting to explode on you.

Also, what made you think that the LiFePO4's can't handle a momentary current spike from the alternator's output? During 'field collapse', current may spike but as it does so, voltage is ALSO dropping so the actual POWER (Watts = Voltage x Current) fades gracefully and once the Lithiums see less than 13.2v, they stop accepting charge current anyway.

For your coach, given your use case, I would use a DC-DC converter to charge the LiFePO4's from the existing 12VDC (non-lithium) charging systems. AFAIK (and pretty sure I DO know) you MUST keep LiFePo4 (or any Lithium chemistry) battery banks totally isolated from any Lead-Acid chemistry batteries. Hydrogen goes boom.

 

[mpl239]

I've never seen an FLA in parallel with LiFePO4, never seen it recommended or approved by any manufacturer or any standards in any jurisdiction, and can't imagine how you manage to keep it from boiling the electrolyte away, given that your LiFePO4's need a constant 14.5-14.6 to charge. THIS IS UNSAFE.

I've seen a lot of DIY and professional installations (mostly on big boats) and done a dozen or so myself, but never seen that. The ABYC standards for Lithium batteries (following the US CFR's and the USCG regs) absolutely forbid mixing any kind of Lithium chemistry with Lead-Acid in any battery bank, (for good reasons).

I would say that FLA in parallel is a constant hydrogen source, waiting to explode on you.

Also, what made you think that the LiFePO4's can't handle a momentary current spike from the alternator's output? During 'field collapse', current may spike but as it does so, voltage is ALSO dropping so the actual POWER (Watts = Voltage x Current) fades gracefully and once the Lithiums see less than 13.2v, they stop accepting charge current anyway.

For your coach, given your use case, I would use a DC-DC converter to charge the LiFePO4's from the existing 12VDC (non-lithium) charging systems. AFAIK (and pretty sure I DO know) you MUST keep LiFePo4 (or any Lithium chemistry) battery banks totally isolated from any Lead-Acid chemistry batteries. Hydrogen goes boom.

Just saw your response. Based on discussions with marine installers, it is not the LI batteries I am protecting with the FLA, but the attached electronics( Nav, radar, wind direction and strength, radios, depth sensor, etc.) which are sensitive to transient spikes. Based on this graph, I keep my maximum charge voltage to 13.8v When 13.8v is reached, shore power turns off charging. While running under motor power, the alternator, puts out a continual charge, up to 13.6v, then backs off on amps, maintaining the running load, at 13.6 v. Yes I am trying to stay in the working zone of the Li batteries. When away for any long period, Li batteries are charged to 60% theoretical, then disconnected from the system and a trickle charger put on the FLA. This provides power to the Inverter/charger brain, so it can not loose its mind. FLA is stored in a vented compartment with no chance of H2 accumulating. There have been many reports of instrument and regulators. The FLA idea came from the folks at Balmar. I have been running this system for about 5 years and no issues, probably because I do not do a full spectrum charge. The voltage spike can run up to 150Vdc for a few milliseconds, enough time and voltage to take out instruments.

 

[creativepart]

Probably best not to complicate your RV discussion with your marine set up... but it sounds like you're on the right track with your RV conversion.

So, let's take it a step at a time.

Charging from shore power - you just need to update your onboard Converter Charger to provide a Li Charge Profile. It's not a big deal, not expensive and is usually the first step.

Charging from Alternator - first decide do you want a DC2DC charger OR a LiBIM.?

If you go with the LiBIM it just replaces your existing BIM. Done.

But if you go D2D charger you need to remove the OEM BIM and then connect the D2D charger to a power source and then to your Li Batteries. I connected mine directly to the motorhome's chassis battery and from there to the Li Battery. I used a Victron D2D charger which automatically turns on when it senses output from the alternator at the chassis battery. Other brands will require a trigger wire from the alternator. You can find one of those on the now disconnected OEM BIM.

Charging from Solar - usually just a process of changing the battery type setting on the charge controller..

I didn't have a Journey, but my Adventurer was setup pretty much the same as the Journey. I went with the D2D charger but I think the LiBIM would have probably been just fine and easier. I never found the D2D charger all that necessary because the Li battery changed so quickly that my rooftop solar did just about all the charging I needed when driving.

I made this conversion about 5 years ago. If I needed to do it again I'd use the LiBIM. My motorhome came with an Inverter Charger and no Converter. So, I didn't need to make that upgrade. I know plenty of folks say just use the old non-lithium capable Converter but really, it's not that difficult to change out the Converter and not that expensive so just bit that bullet and go for the upgrade.

Oh, one other thing I learned along the way if you remove the OEM BIM. You will also need to add a means to charge your chassis batteries when on Shore Power. The BIM usually does that job, so when you remove it then you have to find a way to replace that function. This is another reason the LiBIM is a good choice. It charges your chassis battery when on shore power. It will also keep the emergency battery switch on your dashboard working if you need it. Without the OEM BIM you lose that functionality.

 

[tim myers]

Interesting discussion albeit dated. I am in the process of purchasing a couple 12v WattCycle 314 AH LiFePO batteries for my Journey. I will also replace my converter with a lithium compatible unit and will install a dc 2 dc charger between the chassis and house batteries. the BIM will be defeated by removing the coil voltage and i will use the terminals as connection points for the dc 2 dc charger. Now for my question, as I tend to overthink things has anyone had any issue with starting their generator using the Lithium Batteries? I have the 8kw quiet diesel genset and it per my research it draws between 100 and 200 amps to start, and the batteries I am about to purchase have a rating of 200A continuous output. I think I am ok but wondered what everyone's real life experiences have been.

 

[wahoonc]

Interesting discussion albeit dated. I am in the process of purchasing a couple 12v WattCycle 314 AH LiFePO batteries for my Journey. I will also replace my converter with a lithium compatible unit and will install a dc 2 dc charger between the chassis and house batteries. the BIM will be defeated by removing the coil voltage and i will use the terminals as connection points for the dc 2 dc charger. Now for my question, as I tend to overthink things has anyone had any issue with starting their generator using the Lithium Batteries? I have the 8kw quiet diesel genset and it per my research it draws between 100 and 200 amps to start, and the batteries I am about to purchase have a rating of 200A continuous output. I think I am ok but wondered what everyone's real life experiences have been.

A bit late on the reply here...
I found a thread on the sister site that had several guys stating that a 200-300 BIM was marginal for starting the larger diesel generators, however they had no problems with 400+, apparently when you parallel the batteries the BIMs combine and give you sufficient capacity.

I am in the middle of my upgrade on my 2014 Itasca Meridian 34B. Most of the parts are here for the conversion to a pair of heated 300AH Lithiums. I just need to rig something to remove the 6 beasts from the bay.

Aaron

 

[tim myers]

During my install, I had a period with only one 314 AH battery connected, and needed to start the Generator. It started easily on one battery with a 200Amp limit from the BMS. Now that is is complete the 400Amp has no issue starting the genset.

 

[creativepart]

I found a thread on the sister site that had several guys stating that a 200-300 BIM was marginal for starting the larger diesel generators, however they had no problems with 400+, apparently when you parallel the batteries the BIMs combine and give you sufficient capacity.

Aaron

I think you mean BMS not BIMs in this case. Don’t you?

 

[wahoonc]

I think you mean BMS not BIMs in this case. Don’t you?

Yes, I had Battery Isolation Modules on the brain.

Aaron