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Old 11-28-2018, 12:32 AM   #1
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Default 2003 Roadtrek hybrid battery system

More parts yet to arrive but the location for the A-B-Both switch (left of refrigerator, right of access door to water valve and water heater)and the 100 amp hour lithium battery (aft of fender well, driver's side, behind inside access door) Expect to put lithium charger in there, too. Haven't located the DC to DC charger yet. There is room behind the A-B switch but not comfortable putting it in with the water system.

Expect we will forego a dedicated lead acid charger for space reasons and use the DC to DC charger, solar, isolator or the converter.

Battleborn sold the 100 amp hour lithium battery yesterday for $849 so decided to get started.

We have found that a 50 amp circuit breaker connected between the lithium battery and the Kisae charger keeps popping even though Kisae specs a 30 amp breaker. We don't have the instrumentation to figure that out but a 100 amp one seems to work. Obviously a current spike, but why.

We will do the parallel hybrid battery testing as soon as I get the class C back from the shop. (Deer strike) I expect a switchable system to be better than a parallel system but we will see when someone puts one together with more fancy circuitry than I have. A no user input system would be nice.
Harry
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Old 12-17-2018, 04:07 AM   #2
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There is no indication that anyone else is putting in a hybrid battery system but in completing such in the Roadtrek I have made an observation. A fifty amp capable DC switch between the lithium battery and the DC to DC charger is not necessary.

The Kisae DMT1230 charger will not charge the lead acid battery till 12 volts is applied to the control input. The lithium battery can be connected directly to the charger. A switch with minimal current capability is connected between the control input and 12 volts.

Will post the performance of the system when the final connections are made, probably next week. This will essentially triple my battery capacity. I would put in a second lithium battery when/if I go to a compressor fridge.
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Old 12-17-2018, 03:50 PM   #3
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Will post the performance of the system when the final connections are made, probably next week. This will essentially triple my battery capacity. I would put in a second lithium battery when/if I go to a compressor fridge.
Thank you for continuing to keep us updated. I'm not ready or capable of fooling around with our battery systems yet, but I'm still pretty interested in your experiments because I hope to someday take advantage of your results.
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Old 12-18-2018, 04:23 PM   #4
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Thanks for the note. I will confess I don't understand the lack of interest. It works so very, very well. The AGM battery box is not heated so it may as well carry AGM batteries. Adding lithium inside is perfect for them and charging AGMs from the lithium with the DC to DC charger reduces generator charging time by at least 3/4. Solar works better, too. Being able to always use the top 20% of the AGMs, rain or shine, is a plus and keeps them healthy.

We discussed this before and decided many don't understand the importance of keeping the AGMs at 100% daily, some don't like the complexity (grandma can't run it) and the cost of a lithium battery is considerable.

Power is no longer a problem for me. With charge rates up to 130 amps you can always top up before quiet time.

We keep looking for a fire hazard. There doesn't seem to be one with flooded batteries but AGM may be different so be careful.
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Old 12-18-2018, 04:27 PM   #5
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I wouldn't interpret lack of action as lack of interest. I think that the rather small population of people who would feel qualified to attempt such a project mostly already have solutions that are "good enough" not to be immediately discarded for such an improvement.

I, at least, have tucked your very interesting project away for future reference.

Thanks for the effort and for taking the time to report.
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Old 12-18-2018, 05:08 PM   #6
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"I wouldn't interpret lack of action as lack of interest."

Agree, and thanks for posting and posting all of the updates, but........ This has occurred over time and not a couple of weeks. You could post sort of a:

-summary of what is involved
-the application(s)
-pros and cons compared to the conventional lithium or lead-acid solutions

might even assist someone, somewhere in the Hymer Euro-land
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Old 12-18-2018, 06:40 PM   #7
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I have followed with interest. My present electrical system is adequate but if I get a compressor fridge I will need more power available. Please continue to post your progress, as it is a great asset to this site.
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Old 12-19-2018, 04:58 AM   #8
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May as well have the discussion here.

Lithium is a better battery than lead acid. It charges like adding fuel to a fuel tank: the same rate till full. A full lithium system would be the best except for the temperature problem. Victron sells a 200ah full lithium system for $7k. I don't know where all the money goes but you can build your own 200ah system using the batteries with the built in BMS for ~$2k.

The only advantage of a hybrid system, which someone else mentioned, is startup of a cold soaked RV (15F?). Turn on the AGM system and warm the place up then lithiums are good to go. You can add lithiums, as we are doing, for 1/3 the cost of a Victron system or an AM Solar sold system.

In a temperate time of the year leave the switch on lithium and keep your AGMs at 100%. It certainly won't hurt them and the complexity is gone.

Camping with a low of 12F I will go through the night on lithium leaving the AGM at 100% to start the generator in the morning. Starting a generator at 12F is not a sure thing and takes a few starts and a bit of battery to get it warm enough to run. The auto choke comes off too early and the thing putt putts until it warms up a bit. Last time it took six starts to get it warm enough to run.

AGM to me means flooded lead acid. AGM is easier to write.

The advantage to us is that our coaches already have the AGM system in a non temperature controlled area so why leave it empty. Heating pads, to me, are not a viable option.
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Old 12-19-2018, 03:04 PM   #9
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AGM to me means flooded lead acid. AGM is easier to write.
AGM does NOT mean "flooded lead acid". The two are disjoint. AGM batteries are a species of Valve-Regulated Lead-Acid (VRLA) batteries. They are not "flooded"--there is no liquid electrolyte present in VRLA batteries, and they have significantly different characteristics.

I am not trying to be pedantic, but we don't want to confuse people.
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Heating pads, to me, are not a viable option.
Why is that?
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Old 12-19-2018, 03:19 PM   #10
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"Heating pads are not a viable option"

"Why is that?"

Waste of energy and we have so little. Were we talking of 800ah systems it would be different, I think.

I'll take your admonition. And use the terms flooded or flooded lead acid to describe the batteries I have.
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Old 12-19-2018, 03:52 PM   #11
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"Heating pads are not a viable option"

"Why is that?"

Waste of energy and we have so little. Were we talking of 800ah systems it would be different, I think.

I'll take your admonition. And use the terms flooded or flooded lead acid to describe the batteries I have.

FLA is commonly used for the wetcells, and good for us lazy typers.
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Old 12-19-2018, 04:10 PM   #12
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I am actually not really surprised that there haven't been any others jumping in to try the hybrid system.



As Avanti mentioned, most of the people that are willing and able to put together home built upgraded systems already have. Others that want/need better systems have been going with newer vans that include them. This all leaves a pretty small number of potential people for jumping in.


The only real hope for acceptance across a larger audience may reside with how the Hymer system performs, if they really do start to implement it in a lot of product after the owner change. If a workable system is used and proven, the a much larger group of potential users would open up in the add-on market also, as then they would just be getting and installing parts (or having it done at an RV dealer).


I thought the minor modifications that could be added to a system with a Blue Sea charger to make it an accurate, amps based, charging system at a much lower cost than any others, would catch on with a sizable amount of people, but it did not catch on either. I think there is very little interest in the DIY crowd to just copy something else, as they would prefer to do their own design, which I totally understand
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Old 12-19-2018, 07:23 PM   #13
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I am actually not really surprised that there haven't been any others jumping in to try the hybrid system.
I am very interested in this system. I am waiting to see how it works in the field for a while. I am also hoping the Lithium batteries will drop in price.

Other new systems are coming out, like high voltage systems (48v). These are attractive too, but again at a very high price.

So I am waiting to see how these new systems play out. I am holding out until I absolutely need to upgrade, as my current system is working OK.
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Old 12-19-2018, 09:55 PM   #14
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I am very interested in this system. I am waiting to see how it works in the field for a while. I am also hoping the Lithium batteries will drop in price.

Other new systems are coming out, like high voltage systems (48v). These are attractive too, but again at a very high price.

So I am waiting to see how these new systems play out. I am holding out until I absolutely need to upgrade, as my current system is working OK.

I am sure there are quite a few others with very similar thoughts, especially since the Hymer system appears to be a drop in lithium without a lot of other parts, although you might need the same batteries they use.


If anyone manages to make a high voltage setup that is an easy retrofit, all the game will change, I think.
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Old 12-22-2018, 01:37 AM   #15
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System installed, passed the smoke test. The DC to DC charger charges whether or not the control input is high or low. There is a menu input to make that happen but it is set in the mode where it shouldn't do that. Till I figure it out I'll have to use the charger on/off switch.

Will be traveling the next 10 days so we will see how it works. This one is different from the other one. The only way I can charge the lithium from solar is to use the both setting on the battery switch. The FLA battery charges from the alternator, solar, or from the lithium through the DC to DC charger. It does not have a dedicated FLA charger.

There is a possibility you could get a simple system by leaving the DC to DC charger on 24/7 and drawing from the FLA battery only.
Maybe that would be the same as shorting the two together. The lithium discharges first. Gotta think about that a little more.
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Old 12-22-2018, 05:14 AM   #16
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Hello, I am new to this site.

I am a 200 ah battery that my son built for me a couple of years ago. I have only one flooded 105ah trojan house battery in my 1999 coachman. My new refrig (dometic RM2554) is using a lot more DC power even when on gas than my old refrig. So I am looking to make use of my lithium battery either by charging up my flooded trojan with it or perhaps using my 200 amp inverter and plugging it in through my "shore power" connection when my trojan gets too low. I do have a 2800 onan generator but it is very noisy and so slow if using it with the charge/converter which seems to only allow a trickle charge to the trojan... hate to use it!

I am thinking if I can figure out how to charge the trojan from my lithium (dc to dc) and then just charge then both up with independent chargers using the generator or shore power every 4 days or so.

Any ideas or experiences would be much appreciated.
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Old 12-22-2018, 05:22 AM   #17
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My new refrig (dometic RM2554) is using a lot more DC power even when on gas than my old refrig..
Your refrigerator should not be using much electricity when on gas. I have a RM2554 in my 2006 Roadtrek and I can go 2-3 days on 2 old lead acid batteries while running a fridge cooling fan and other minor loads like lights. Something else is pulling a load or perhaps the fridge control system is activating the 12v heating element.
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Old 12-22-2018, 06:56 AM   #18
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Hello, I am new to this site.
I am thinking if I can figure out how to charge the trojan from my lithium (dc to dc) and then just charge then both up with independent chargers using the generator or shore power every 4 days or so.

Any ideas or experiences would be much appreciated.
You are just baiting us, right? This group has been working on just that the last year. It is not a trivial job but can be done. This thread is about that very thing without the details.

Peteco is correct. The current draw from your refrigerator is around 1 amp when the flame is on and less than 1/3 amp with the flame off. I suspect your refrigerator is working properly and you just don't have enough power for everything else.

Following are two threads from the past year with more detail. The install is in a class C. A class B install will require a different marine battery switch but everything else the same.

http://www.classbforum.com/forums/f2...read-7658.html

http://www.classbforum.com/forums/f2...stem-7451.html

Should you still be interested in such a system and can install it or know someone who can, let us know.

How are you charging your lithium batteries?
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Old 12-22-2018, 04:58 PM   #19
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Thank you. good to know it can be done. I called the dometic folks and they said the refrig draws 1.5 - 2.5 every hour so I just took the middle value. GOOD to know that it isn't that bad!!! I only have one lead acid and no good way to add a 2nd lead acid so need to come up with a different system. Maybe go with 2 AGMS or making better use of the lithium. ...which I have carried mainly for microwave use and back up by plugging it in through the inverter to the shore power receptacle on the side of the van

I will look at the threads you mentioned. Thank you.

My lithium is usually just charged at home with a 10 amp smart lithium charger. I don't really use much electricity when I travel. So I only needed to charge it one time with shore power on a trip. I sometimes travel in my subaru forester and then the battery travels with me for microwave use and a sm heated blanket.

My lithium is not permanently installed in my van but rather in a portable case that my son puts into the Class B when I want to travel.

My son is installing a trimetic 2030 as my christmas present. Lucky me!! Then I will be able to have a much better picture of useage.

Thank you for all the help glad I found this site ...Happy Holidays to all, mary
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Old 12-22-2018, 05:45 PM   #20
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Wow! been reading the links mentioned in the post above.... my head hurts! I see a few folks have seriously been working on this whole issue since at least the beginning of 2018.

It will take days for me to read through all this info as busy with Christmas prep.

Thank you for the help and leads to figuring this out. mary
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