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Topic: Lithium/solar/inverter upgrade: Some questions (Read 722 times) previous topic - next topic
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Lithium/solar/inverter upgrade: Some questions
Hi, I have an '06 Twin Bed with the original converter and two solar panels. It also has an inverter installed by LD that only services a plug at the entertainment center up front. I have two 6 volt AGM batteries that are 5-6 years old.

I'm considering designing a DIY project to upgrade the electrical and solar system to a lithium system with a new inverter (and probably solar controller and converter) to accomplish the following:

- Whole house A/C so that all outlets can be driven by the battery

- Fridge can run off the battery in AC mode

- Air conditioner can run off the battery for a good amount of time also

In thinking about this project and reading previous posts here, I have some questions:

1) The battery compartment and small inverter are on the entry side of the coach. The converter (fed by a surge protector installed
by the late great Mike Sylvester), and solar controller are located on the OTHER side of the coach underneath the sink and top cabinet. Obviously LD fed charge lines to the battery from the converter and solar controller to the batteries on the other side of the coach. First question is how can I feed the output from the inverter to the converter on the other side of the coach and connect it to supply the coach outlets, air conditioner and fridge AC (assume the inverter is

2) Should I buy an inverter that has it's own transfer switch? Any recommendations for the inverter?

3) Will a 12V 460AH Lithium battery suffice?  Has anyone designed a 24v or 48v solution to lower current passing through the cables?

4) It's a separate question and decision on how many additional panels I need to install to charge this battery.

5) Do I need to install a DC-DC converter to insure I don't burn up the alternator when driving?


I don't want to install expensive brand batteries like Victron for this solution.

Thank you for any advice.

Mike S.
'06 30' TB Anniversary edition
'06 30' TB Anniversary Edition
Re: Lithium/solar/inverter upgrade: Some questions
Reply #1 –
Hi Mike, glad to see your 06 rig hasn’t rusted away.

A 460 amp/ hour battery will run the A/C 3-4 hours before it is depleted, requiring a long recharge time. The refrigerator will run about a day.. lithium batteries are great but are not a miricle.
Your 31’ LD has little extra cargo capacity which limits adding a huge bank of batteries.
A depleted 460 amp/hour battery would require 3-4 days or longer to fully recharge with a roof full of solar panels.

You want a pass-through whole house inverter.

A DC to DC charger isn’t a bad idea but is not absolutely necessary.
The solar controller can be wired for higher voltage to reduced cable size.

if you still have my phone number, give me a call.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lithium/solar/inverter upgrade: Some questions
Reply #2 –
Look on YouTube for A/C solutions using a mini-split, not feasible with the rooftop models. Stock fridge is resource-efficient when running on propane but NOT energy-efficient. When running on AC, they are MUCH less efficient than compressor models, so you need to consider switching. Generally, you can improve boon-docking a lot with a big battery and inverter, but don't expect to get by without propane or generator for four-season camping.

Steve
2004 FL
2013 Honda Fit
Re: Lithium/solar/inverter upgrade: Some questions
Reply #3 –
Thank you Larry and Steve.

Larry, I do still have your contact info and I will give you a call. I have more questions and am worried about how to route the wiring.

I'll probably give up on trying to run the A/C from the batteries. As you indicate, more batteries will contribute to weight problems and I couldn't charge the batteries back anyway unless plugged in or running the engine or gen for a long time!

Thanks.
Mike
'06 30' TB Anniversary Edition
Re: Lithium/solar/inverter upgrade: Some questions
Reply #4 –
My solution meets your goals except for air conditioning by battery. I don’t need that goal.

I retained the original FLA batteries so no changes are needed in the engine compartment. The original batteries can handle freezing temperatures.

I retained the original 200 watts of solar. Would add more if I had the room.

Installed 600AH of lithium batteries under the dinette seats. No temperature problems as long as the furnace is running. DC to DC charger charges FLA from lithium batteries if needed.

The 1500 watt inverter runs every receptacle through a transfer switch on the generator line.

A marine battery switch changes coach power from FLA to Lithium. FLA while driving with the 3-way fridge on 12 volt power.

Charging lithium battery is by generator or solar. Generator charge rate is 100-120 amps. two thousand watts of lithium battery chargers installed with external AC input if needed.

Converter can also charge the lithium battery but I am rarely on shore power.

Working very well for the last six years. Would like more solar but no room.
Harry 2006RB
Re: Lithium/solar/inverter upgrade: Some questions
Reply #5 –
I used modified Harry's solution, very easy, cheap and extremly easy to implement. In recent trip to Newfoundland, 14 hours ferry trip, I just run the wire from inverter to fridge and not sure how much power was left in the battery towards the end but after 14 hours fridge was still running.

I installed dc-dc charger which charge the battery and even if we stay at a place for three days, I can use my bipap machine with humedifier and heated tube (this was the only reason to put in the lithium battery, everything else is bonus).

I was not expecting, but when we are parked and after solar charge coach AGM batteries, voltage from Solar goes to Lithium battery via AGM batteries. I can simulate it myself by changing dc-dc parameters but do not want to mess up AGM batteries but do not mind current flow to lithium batteries once AGM are fully charged.

I am lazy but one of these days I do need to run the wire from inverter to microwave .....
Re: Lithium/solar/inverter upgrade: Some questions
Reply #6 –
Thank you Harry and Mohammed.

Mohammed, unless I misunderstand your post, you have your AGMs and a Lithium battery connected in parallel? Is your DC-DC charger connected to this system from the alternator in the coach? Are your solar and converter settings set to charge at Lithium voltage levels or AGM levels. (I watched your videos of your MB. Beautiful coach!).

Thanks,
Mike S.
'06 30' TB Anniversary Edition
Re: Lithium/solar/inverter upgrade: Some questions
Reply #7 –
Since Mike wants to switch to lithium only, a hybrid system is not needed, I doubt if he, or the majority of LD owners, want the complexity of a hybrid system. I know I wouldn’t. KISS

Larry

Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lithium/solar/inverter upgrade: Some questions
Reply #8 –
Quote from: schafir  - 
Thank you Harry and Mohammed.

Mohammed, unless I misunderstand your post, you have your AGMs and a Lithium battery connected in parallel? Is your DC-DC charger connected to this system from the alternator in the coach? Are your solar and converter settings set to charge at Lithium voltage levels or AGM levels. (I watched your videos of your MB. Beautiful coach!).

Thanks,
Mike S.

Mike,
Sorry for confusion. I will not put AGM and Lithium togather .... 

I have wire coming from agm battery to dc-dc charger (I do not want to bring the wire from alternator and I know alternator is connected to agm battery). This is the only connection between two batteries. I do run Lithium simple circuit independently. I have 2000W inverter which is only connected with Lithium. I have a 12V circuit coming out from the Lithium battery which I put as close to bed room as possible. I use it for my bipap system. Inverter is seldom used for some 120 v appliences.

Hope explanation is worded correctly. If not, let me know and I will put more words but again agm and Lithium are not in parallel and not connected any way shape or form.

Sorry if I gave the impression that I put AGM and Lithium in parallel. This is big no no .....
Re: Lithium/solar/inverter upgrade: Some questions
Reply #9 –
I understand. Thank you and that makes much more sense.

Mike S.
'06 30' TB Anniversary Edition
Re: Lithium/solar/inverter upgrade: Some questions
Reply #10 –
I see the maximum amp draw on these batteries is around 100 amps. With the generator requiring more the 200 amps while cranking, I would think your would need 2 or even 3 Li-On batteries to handle this brief, temporary load.  Anyone with experience on this?
Thanks,
Karl
2016 Mid Bath
Re: Lithium/solar/inverter upgrade: Some questions
Reply #11 –
Quote from: airbusguy  - 
I see the maximum amp draw on these batteries is around 100 amps. With the generator requiring more the 200 amps while cranking, I would think your would need 2 or even 3 Li-On batteries to handle this brief, temporary load.  Anyone with experience on this?
Thanks,
Karl
Per the Onan spec sheet, an Onan QC-4000 generator requires a minimum of 350 Cold Cranking Amps to start (400 if below freezing). Most 12V lithium-ion batteries we're talking about here have a 100A Continuous Discharge Rate and a 200A to 400A Peak Discharge Rate. So, if you replace two GC2 6V batteries with two 12V lithium-ion batteries, you won't have a problem. Also, the newest lithium-ion batteries have higher Peak Discharge Rates.

Charles
Harvest Hosts + Boondockers Welcome #23975
Escapees SKP #138195
2007 23.5' Twin King
Re: Lithium/solar/inverter upgrade: Some questions
Reply #12 –
Two 100 amp/hour lithium batteries starts our LD”s V10 fine, the generator is a piece of cake, requiring less power than the V10.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lithium/solar/inverter upgrade: Some questions
Reply #13 –
Hi Karl;  Two years ago while planning my LiF upgrade, I found a spec of 46 Amp draw to start my 4KW Onan Emerald Plus.  The two SOK batteries in parallel, at 100 A each easily start my Onan.  You probably have the newer Onan MicroQuiet. Instead of a two cylinder engine, your generator is a one cylinder and runs at twice the RPM. I would think that would be easier to start.  Starting the main engine of course should remain the job of the chassis battery.  (Thanks Larry, I hope to never have to use my emergency start (the old LD relay that 2015's come wired with) to start my V10)
   I think that the Onan spec of 350 CCrA, is more a reference of what the battery rating should be, rather than the expected drain of the generator starting motor.  A lot may depend on how cold the generator is while you are trying to start it. My Generator is about three feet max from the batteries by wire length. The batteries are sitting on top of the genset, (in a T/K).
   I did test the starter drain with a clamp on DC Ammeter, and it was less than 50A peak.  (Hall effect sensor) I didn't bother to look up the peak response time. Even one time at 7000 feet (summer) before I remembered to manually adjust the genset from sealevel and winter, it started fine with two LiF batteries. It didn't run very well, and I could tell that the choke wasn't right.  I don't use the generator very often, mostly maintenance runs in my driveway at home, about 500' altitude, and not very hot.   RonB  
RonB (Bostick) living in San Diego
Original owner of "Bluebelle" a '99 TKB
 
Re: Lithium/solar/inverter upgrade: Some questions
Reply #14 –
Quote from: Larry W  - 
Two 100 amp/hour lithium batteries starts our LD”s V10 fine...Larry
Did you start with only the lithium batteries? Or was the usual lead/acid chassis battery still in the circuit, effectively in parallel with the lithium batteries? I disconnected the solenoid that connects the coach battery to the chassis battery when I installed the lithium coach battery, because I was concerned about the alternator harming itself, trying to charge a lithium battery that was, say, 80% discharged.  That disconnecting disables the "jump-start" feature, of course, which I really liked, even though I've used it only a couple times in 20 years.

Eric
2005 Jayco 24SS
Re: Lithium/solar/inverter upgrade: Some questions
Reply #15 –
Quote from: Eric Greenwell  - 
Did you start with only the lithium batteries? Or was the usual lead/acid chassis battery still in the circuit, effectively in parallel with the lithium batteries? I disconnected the solenoid that connects the coach battery to the chassis battery when I installed the lithium coach battery, because I was concerned about the alternator harming itself, trying to charge a lithium battery that was, say, 80% discharged.  That disconnecting disables the "jump-start" feature, of course, which I really liked, even though I've used it only a couple times in 20 years.

Our LD had lead-acid batteries until three years ago when they were replaced with lithium.
It has never had mixed chemistry batteries, only lead-acid or lithium.
When the rig was two years old, a marine battery switch and heavy cables were installed to allow the engine to start from the coach battery. It has worked flawlessly for twenty years, with both lead-acid or lithium batteries able to spin and start the engine without effort.

Alternators have internal circuitry that limits the charging current if the alternator overheats, a feature that has been used for many decades. I cannot remember hearing anyone on the forum or in general having a modern-era alternator burn up from overcharging.

Larry
Larry
2003 23.5' Front Lounge, since new.  Previously 1983 22' Front Lounge.
Tow vehicles  2020 Jeep Wrangler Rubicon, 2001 Jeep Cherokee
Photo Collection: Lazy Daze
Re: Lithium/solar/inverter upgrade: Some questions
Reply #16 –
Quote from: Larry W  - 
Alternators have internal circuitry that limits the charging current if the alternator overheats, a feature that has been used for many decades. I cannot remember hearing anyone on the forum or in general having a modern-era alternator burn up from overcharging.  Larry
I give Larry an A+ for this one. After reading his comments, I reconnected the solenoid that connects the coach battery to the engine alternator, and put a space heater on my inverter to draw my 200AH Li coach battery down to 28%. At that point, I started the engine, ran it up to 2500 RPM, and the coach battery reported (via Bluetooth) it was charging at 38 A. OK, I'll run it that from now on, since that's well within the amp capacities of the alternator and battery. I can occasionally check the charging current easily while driving, using the Bluetooth info from the battery.

Eric
2005 Jayco 24SS
Re: Lithium/solar/inverter upgrade: Some questions
Reply #17 –
Quote from: schafir  - 
I understand. Thank you and that makes much more sense.

Mike S.

Mike for my use this cheap solution (<1500 for 400ah) is good enough. For last few stops we are close to 8K ft in north NM and Colorado and fridge refuse to cooperate. This setup with use of strategic use of charging lithium battery from generator via dc-dc and running the wire from inverter to back of fridge (when generator is not running) give additional benefit beside specific bipap usage. In this case I litterally have lot of icecream in freezer :-)

Battery installation idea from this group. Running the wire back to fridge from this group.



Hope picture give more info ....
Re: Lithium/solar/inverter upgrade: Some questions
Reply #18 –
Muhammed, you keep a pretty squared away ship there, mister!  What kind of fan is that installed above the rear bed in this video?

https://www.youtube.com/watch?v=3dgYG881A3A
Greg & Victoria
2017 Mid-Bath  “Nocona” towing a manual 2015 Forester
Previously a 1985 TK
SKP #61264
Re: Lithium/solar/inverter upgrade: Some questions
Reply #19 –
Quote from: HiLola  - 
Muhammed, you keep a pretty squared away ship there, mister!  What kind of fan is that installed above the rear bed in this video?

https://www.youtube.com/watch?v=3dgYG881A3A

I will let you know ... I like this fan and want to order second one once I have enough time at home. It is very quite and can be rotated easily. I must have found the name here in the form. You can also take the picture and use the lense, now similar tool is integrated in the Amazon as well. You know what, let me see if I have info in Amazon order history.

As for your comment, I will pass to the boss. She was not happy that I did not give her any time. One of the member was interested and I just made a quick video.

Edit: Caframo Kona. 12V Weatherproof Fan for Marine Use. IP55 Rated, Direct Wire. White, 7.0” x 7.5" x 9.5"