Convert to LiFePo4 battery video

[Kevin Cooper]

I just saw a very good video from AZExpert that tells and shows converting to LiFePo4 battery, how parts work, and solutions.
Link: https://youtu.be/-3sHpgQK2R4?si=oU2YbfayT1OtMdBt

[craigav]

It was an interesting video and had good information. However, I noticed a couple of things he stated that he was wrong about which leads to my recommendation to not trust any single source for a new (or existing) setup and make sure all aspects are understood.

For example, I have read where many people believe this but it is not true. At 3:40 in the video the "Expert" states that the BMS will take whatever charge is coming in and regulate that... and adjust the charge accordingly ... as long as the voltage is high enough. Believing that could lead to problems later on as a BMS does not regulate the charge and while modern BMS's have a lot of features like bluetooth, current values, temperatures, etc., they only disconnect at a high or low voltage (or high current or temps out of range, etc.) but they do not to regulate the charge and instead the BMS disconnects the battery internally if needed in order to prevent damage to the battery.

There were a couple of other points made that I wasn't super comfortable with how they were stated, but my point is to beware, that even experts aren't always correct. Overall though, it was informative. ~CA

[RogerR]

As Craigav says above the BMS will prevent overcharge, may prevent damage due to operation in high heat or below freezing if so equipped but will not change the incoming voltage. Mine has a high voltage safety cut off and will stop charging when full.

[Kevin Cooper]

Since you guys are way more into this than I, is there a problem with what he used in the end? Will it blow up his batteries and burn up his alternator? Or will his resolve work just fine? That is the important part in my opinion.

[Camper_bob]

Along the same lines as Kevin Cooper's comment, I have just one 100AH battery going in. What are my risks of over-taxing the alternator?

I have no need to install solar at this point, so charge will come from the converter or the alternator.

I only picked up the Li battery because my house batt needed replacing anyway, and the cost was equal to or less than the AGM battery I would have purchased. Add to that the extended life, access to most of the available storage, and I thought it was a good buy for a "Black-Friday" type deal. Spending another $150 on a new BIM is not attractive but I'll do it if I have to.

[Radar57]

Originally Posted by Kevin Cooper

Since you guys are way more into this than I, is there a problem with what he used in the end? Will it blow up his batteries and burn up his alternator? Or will his resolve work just fine? That is the important part in my opinion.

Agree

[F350guy]

I'm in the middle of converting from 2 6 volt lead acids to a 200ah Renogy. I was not afraid to ask questions as this is a totally new experience for me. Before I ordered a battery I checked my converter to see if it had a lithium setting. It did so ordered the battery thinking this was a plug and play.

I should have quit there but more research and found my charger was a single stage constant voltage on the lithium setting. Most of the battery brands I looked at recommend a 2 stage charger which drops from 14.4 to 13.6 after the battery is charged. Later models than mine may have this. So, I disconnected the converter/charger in my trailer and ordered one with the 2 stage. Some say the single constant charge is ok as the BMS will handle it but I like being on the safe side.

Next is a lot of folks recommend a dc to dc charger because the charge line from the truck does not produce reliable voltage. For now I just found the charge line coming from the trailer side and disconnected it. We generally don't do long travel days so I'm not too concerned about it. I also performed some surgery on the wiring Jayco did and cleaned it up with some bus bars.

Warning. Everything I've said I found on the internet.

[craigav]

Originally Posted by Kevin Cooper

Since you guys are way more into this than I, is there a problem with what he used in the end? Will it blow up his batteries and burn up his alternator? Or will his resolve work just fine? That is the important part in my opinion.

Every LifePo4 12v battery I have seen ever sold has a BMS inside (some specialty versions or DIY setups may not). The BMS is designed for battery protection which even if an improper charge/discharge/overvoltage/etc. circuit is connected, the battery should never blow up.

Will it burn up his alternator? Maybe, maybe not, more details would be needed and keep in mind that what will work fine for his setup doesn't mean the same setup will work fine for another setup. I don't think he (the AZ Expert) really went into a lot of detail regarding what he changed and what he left alone and focused more on what to know and what options are available.

From what I could tell he only added a LI-BMS (not that I wanted to watch it again to know to be sure but based on what I remember I saw). Is a LI-BMS the best option vs dc2dc charger, or even better than the existing disconnect solenoid? The answer into that is not the same for everyone and not the same for every setup. So in the example in the video, the motorhome has a lot of LifePo4 battery capacity (I don't remember if he even said how much), but for discussion to make my point, say 3~400ah. Because of the size of the batteries (in amp hours) if the charge cable from the alternator back to the coach batteries is large enough, then for sure the current draw the LifepPo4's could take certainly equal or even exceed the 100% of the alternators output if not controlled (most LifePo4's can support 1 amp charge or discharge for each ah in capacity, they actually can take even more than that but the BMS will commonly disconnect if there is more current than this for more than 30 seconds or so).

A LI-BMS is smart but also stupid, I say stupid because it is still uses contactors but they are controlled by some logic. The charge control logic opens and closes the contacts (based on voltages) which means when they are closed (on, connected), then 100% of whatever your alternator and cables support will be connected, there is built-in logic (may want to verify) for the LI-BIM will protect your alternator by cycling, where it will connect for 15 minutes then disconnect (off) for 20 minutes and then repeat. So will an alternator burn out at 100% load for 15 minutes, perhaps not, maybe, at minimum I suspect it will get very hot and the life of the alternator will be diminished. The other concern is what if there is installed a 200a alternator installed and there is ~175 amps flowing from the alternator to the LifePo4's and the contacts open suddenly? That is going to result in a lot of excess current for a moment or two and a bit of a surge for sure, excepting that the chassis battery(s) will (should) absorb such a surge. Hopefully so, because the LI-BIM will continue this on-off-on-off for as long as the engine alternator is outputting current. Any current limitation is only provided by the resistance of the cables and the batteries (which is not a great way to limit or control the current). So I am not a big fan of how the LI-BIM works in this regard, full on 15 minutes, full off 20 minutes, repeat. I am confident that most alternators would be happier (longer life, less heat, less surges) with a constant current less than or equal to half the alternators capacity, so say 60 amps steady dc2dc amperage until charged vs 150a (or 100%)off and on over and over until charged. The LI-BIMs do have things I like though, for the most part it is a drop in replacement and has a connection for the aux start switch and logic to keep the coach and chassis batteries charged and at the recommended voltages, which a DC2DC charger does not have these features built-in.

Not to make this much longer, I would be happy to answer specifics based on what I know and my setup and setup plans, but contrast the above with someone who simply installs a single 100a LifePo4. First thing to note is the battery isn't going to take more than 100a at least not for long as the BMS will disconnect it, and second on my Jayco and many other Jayco Motorhomes that I have seen a wiring diagram for, there are two 80a self resetting breakers in the charge line. So that in of itself will keep the alternator current from being above 80a for any extended period of time which will help protect the alternator, but as a third thing to know, is that a single 100a LifePo4 will have more resistance than 4 of them (100a vs 400a), which will result in less current overall and along with the cabling resistance, the charge current will (should) be low enough to be a safe load for the alternator without ever doing anything. I would have to retest because I installed a 100a LifePo4 in mine years ago and if I remember correctly the charge current was ~30a at idle and around ~60a at a higher rpm ~2000 or so.

Point being, with a single 100a LifePo4 the alternator concerns are a lot less than with 4 LifePo4's. I will add that I purchased a DC2DC charger (they have the more optimal charge profile than any BIM and better on the alternator), and I purchased a heavy transformer based inverter / charger with a LifePo4 profile, and in part of my hobby and using LifePo4's for other things around my ranch, I have 100's of amps more capacity that I intended to add to my RV, along with plenty of solar panels. But ... shortly after installing the one 100A LifePo4 I had to get shoulder surgery, and then followed by the other shoulder many months later, and then with other things in life, I never have had time to do anything other than drop in the single LifePo4. I share this information because on my setup, everything has worked just fine without doing anything other than dropping in the battery. In fact it all works so well that I am not sure anymore if I will ever install those other items (I already have a small factory Jayco inverter 800w for the TV and laptops) and while the existing converter is not optimal for fast charging a LifePo4 it does charge it. I am at a point now though that I may want to get back into boondocking and if so, then that changes things as well as to what will work best and in that case I will install the DC2DC charger, and larger inverter/charger and more LifePo4 capacity.

So, there is no best setup that will be best for every RV, and there is no best components that are best for everyone's intended usage, it all depends on what already exists, what one's plans (needs) are for battery usage, and what one prefers based on what is available and what can be achieved. ~CA

[Kevin Cooper]

Craig, thank you very much for your insight and knowledge. In the video, James noted that his battery would allow 125 amps maximum, and that his alternator was over 200a rated. He said unlike Ford chassis RV’s.
So, bottom line, if you add 1 or 2 (not massive) LiFePo4 batteries so that they will not draw large excessive current, his solution would work fine.
Question, do LiFePo4 batteries (unlike LA) draw the same current until fully charged or does it lower as the amount of charge increases like LA?
Again, I appreciate you!

[F350guy]

Also a thank you. I know you guys have motorhomes and I have a fifth wheel but I assume the basics are the same. My expertise is extremely limited and my lithium conversion has been done with a lot of help from others on this forum and my research. Even with that I still have my doubts about what I'm doing. We don't boondock ever and all I'm trying to do is upgrade from the 2 Trojan 105 6 volts that have been inadequate from the day we got our Pinnacle. On the occasions I needed to operate the jacks without shore power they could barely do it. We recently had them quit in the middle of a hook up. Fortunately the shop we had it in for a new roof had a 50 amp receptacle close enough to get us going.

Kevin has a good question that I wrestled with on my charger/converter. Renogy said they recommend a 2 stage charger which goes from 14.4V to 13.6V I guess once the battery is fully charged. They also said my constant 14.4V on my current converter/charger would be okay as long as I monitored it. I guess that means shut it off when the battery was full which would be very inconvenient. I decided the easiest thing was just get a converter that had the 2 stage.

[craigav]

Originally Posted by F350guy

Also a thank you. I know you guys have motorhomes and I have a fifth wheel but I assume the basics are the same. My expertise is extremely limited and my lithium conversion has been done with a lot of help from others on this forum and my research. Even with that I still have my doubts about what I'm doing. We don't boondock ever and all I'm trying to do is upgrade from the 2 Trojan 105 6 volts that have been inadequate from the day we got our Pinnacle. On the occasions I needed to operate the jacks without shore power they could barely do it. We recently had them quit in the middle of a hook up. Fortunately the shop we had it in for a new roof had a 50 amp receptacle close enough to get us going.

Kevin has a good question that I wrestled with on my charger/converter. Renogy said they recommend a 2 stage charger which goes from 14.4V to 13.6V I guess once the battery is fully charged. They also said my constant 14.4V on my current converter/charger would be okay as long as I monitored it. I guess that means shut it off when the battery was full which would be very inconvenient. I decided the easiest thing was just get a converter that had the 2 stage.

To share some thoughts and also with Kevin's question. I looked back at the video and at the 53 second mark (so I didn't have to watch long) showed what was installed which was a 460ah LifePo4 that is rated for 120ah charge rate and 250a discharge rate (the ratings are due to the BMS limitations). I realize what I wrote was long but going back to my earlier point, the charge rate is not controlled by the battery and instead is something that needs to be controlled external to the battery. So, for every LifePo4 I have seen, the max charge rate listed is max charge rate that the battery should ever have going to it, not the max charge rate that the battery would allow for (except again for the overcurrent protection BMS disconnect). The BMS in a LifePo4 is (from those I have repaired, perhaps all) are transistorized and will simply disconnect the internal cells to the battery case terminals in an overcurrent\overvoltage situation. The BMS protection circuit though should be considered similar to a self-resetting circuit breaker and not intended to control the current or the voltage and it would be best to never have the BMS go into protection mode. (another story but that is how I got a lot of LifePo4's over the years very inexpensively due to them having damaged BMS boards).

Question, do LiFePo4 batteries (unlike LA) draw the same current until fully charged or does it lower as the amount of charge increases like LA?
A LifePo4 can\will draw a lot of charge current (depending on the battery itself, its size, and its BMS, which is why the charge current needs to be limited) from 0% to around 90% at which point it will taper down. This is why you can fully recharge one much faster than a LA battery.


For Jim in particular. I think you are going about it in the right manner. With the difference in a motorhome vs 5th wheel you have a lot longer charge line and connections (from the truck alternator to the rv's battery). Without boondocking and perhaps an overnight without shore power, a 100ah LifePo4 should work fine for you (assuming just lights, radio/tv and maybe some furnace runtime). Regarding your charger/converter, do you know what you already have installed and what you purchased? One, two, or 3 stage could all work fine (depending on their output voltage) but I would prefer a two or three stage over a single stage. Also, do you happen to know what the current draw of your heaviest load would be (I suspect the heaviest load would be the landing gear at around 30 amps) so a 100ah LifePo4 would work just fine. I know we have all read that if you go LifePo4 you need a LifePo4 compatible converter, however that is not necessarily correct, what would be more correct is that for an optimal charge profile a LifePo4 converter would be best. But even then "best" is subjective and I wouldn't want one that is a single stage 14.4v ~ 14.6v output (or even 14.4v) as keeping a LifePo4 at 100% forever will reduce its overall lifespan. A single stage at such a voltage may be fine though for someone that stays in a campground once in a while and wants to fully charge their LifePo4 before boondocking a few days. ~CA

[craigav]

BTW, the question and answer above should be clarified, the reason the current tapers down when the LifePo4 is close to being fully charged is due to the charger's regulation (alternator, converter, etc) and not the battery itself. So if the converter is able to put out 50 amps and has a voltage of 14.4v, then you will see a charge current of ~50a up until the LifePo4 is close to 14.4v and then the current needed to maintain the 14.4v will start dropping and taper off. If there was no regulation of the voltage with the converter, then the current would remain high up until the battery's BMS disconnected.

[F350guy]

Thanks, again. I'm not meaning for this to be about my situation so hopefully your answers and information will be helpful to others.

I have a Renogy Core 200ah battery on order. The specs show it has a "true" 200ah BMS and can handle a 400a discharge for a few seconds before the BMS says no. It is probably overkill for what I need but I guess if I need it it's there. I have an Equalizer 6 jack system with auto level. The tag on the motor says 160 amp. It doesn't say that is start up amps or what, just 160.

I have a Progressive Dynamics PD4560K converter. It does have a lithium switch on the circuit board. I called PD and asked how the charger worked and they told me it would produce 14.6V of continuous charge and that's it, no step down. Their later models have the 2 stage. What I replaced it with is a PowerMax PM3-55LKL converter/charger. It has a switch for the 3 different types of batteries. The lithium mode provides 14.4V and the goes to 13.6 once the battery is charged if I'm saying that right. I went with it because I read about some issues with the auto detect types.

I have a Victron dc to dc charger in my Amazon cart but understand I would probably need to run a line to the truck battery and do a second connection in addition to the 7 pin. We have a new Ford F350 on order so I really didn't want to set this up on my current truck. If and when we get the truck then I will revisit it. Thanks.

[craigav]

Originally Posted by Kevin Cooper

Craig, thank you very much for your insight and knowledge. In the video, James noted that his battery would allow 125 amps maximum, and that his alternator was over 200a rated. He said unlike Ford chassis RV’s.
So, bottom line, if you add 1 or 2 (not massive) LiFePo4 batteries so that they will not draw large excessive current, his solution would work fine.
Question, do LiFePo4 batteries (unlike LA) draw the same current until fully charged or does it lower as the amount of charge increases like LA?
Again, I appreciate you!

I know I have written a lot, so in an effort to be more succinct which with some topics is hard for me to do. Whether or not his solution of using a LI-BIM would work fine really would need to be tested out on any RV by measuring the current flow. Remember that the max charge rate listed on the battery is to be controlled external to the battery. The max charge rate possible could be much higher and it would be unique to each battery's BMS. For your bottom line question, if you installed a more common LifePo4, say 2x100ah LifePo4 and if you have large enough cables going from the charge source to the battery(s), then that could easily cause the alternator to stay at 100% and that would not be optimal (in fact likely damaging especially with time). I think (if I remember) that my alternator is 135 amps, so with the LI-BIM and if I didn't have 80a self resetting breakers on the charge cable, then the alternator would run a 100% load for the LI-BIM's timed 15 minutes on 20 minutes off. However Jayco did install 80a self resetting breakers on mine (and likely most Jayco Class C's, perhaps Class A's as well) so that protection exists but how many times can a self-resetting breaker break before it fails?

I would say in general, that if you have ample size charge cables, multiple LifePo4's, and an alternator that has an output less than the LifePo4's batteries and charge circuit (cabling) could pull (which means the alt would be at 100% for extended periods of time), then the best option is a DC2DC charger which will limit the current flow, a LI-BIM is just on and off (full load, no load) which again, gives me concerns as I mentioned earlier.

BTW, I doubt I would be concerned with damaging the alternator if I were Jim though (5th wheel setup), as I suspect that there wouldn't be more than ~30a through to truck's wiring, trailer connector, and trailer wiring anyway so damage to the alternator wouldn't be a concern although I would test the current flow with a clamp style DC ammeter to be sure and wouldn't want to overload any component (not just the alternator). ~CA

[craigav]

Originally Posted by F350guy

Thanks, again. I'm not meaning for this to be about my situation so hopefully your answers and information will be helpful to others.

I have a Renogy Core 200ah battery on order. The specs show it has a "true" 200ah BMS and can handle a 400a discharge for a few seconds before the BMS says no. It is probably overkill for what I need but I guess if I need it it's there. I have an Equalizer 6 jack system with auto level. The tag on the motor says 160 amp. It doesn't say that is start up amps or what, just 160.

I have a Progressive Dynamics PD4560K converter. It does have a lithium switch on the circuit board. I called PD and asked how the charger worked and they told me it would produce 14.6V of continuous charge and that's it, no step down. Their later models have the 2 stage. What I replaced it with is a PowerMax PM3-55LKL converter/charger. It has a switch for the 3 different types of batteries. The lithium mode provides 14.4V and the goes to 13.6 once the battery is charged if I'm saying that right. I went with it because I read about some issues with the auto detect types.

I have a Victron dc to dc charger in my Amazon cart but understand I would probably need to run a line to the truck battery and do a second connection in addition to the 7 pin. We have a new Ford F350 on order so I really didn't want to set this up on my current truck. If and when we get the truck then I will revisit it. Thanks.

It doesn't appear that Progressive Dynamics states the charge profile for your converter outside of the LI setting. It is common though for many non-li converters to charge at 14.4 until the current is below 5a or timed out (often 4 hours) and then drop to 13.6 and then if no load (or little load) down to 13.2 until a higher current load is placed on the converter (or the voltage drops further), such a profile is not a concern even for a LifePo4 setup. Just that if you had a lot of LifePo4 capacity then it would take longer to reach 100% charge. I have a PM3 that is not two stage (the model prior to the LI model) and has either constant voltage (adjustable) or 3 stage. With it set at 3 stage, then it behaves as I described above and what I prefer. Keeping a LifePo4 at 14.4~14.6 forever will decrease the overall life of it.

I wouldn't make any changes to the new truck until after you determined what the current flow (amps) is to the trailer. If you don't have a clamp style dc digital ammeter, then that is what I would order first and then determine if installing a dc2dc charger is needed. Having even a small (say 20a) dc2dc charger in the trailer at the battery location is likely what I would install as having it would keep the charge current to the trailer low enough to not to have to worry about overloading anything. Keep in mind that if you pull over at a non-shore power location for an overnight, that you need to unplug the trailer connecter otherwise your truck battery itself could run down if you used too much power in the RV overnight or if the DC2DC charger kept charging off of the truck's battery. If you installed a 20a renogy (likely victron as well) and installed that in the truck itself instead of in the trailer (under the hood somewhere perhaps) then the dc2dc charger does have the ability to turn itself off based on whether or not the key is turned on, so in that case, once you turn off the truck, you wouldn't have to worry about unplugging the trailer connector. Point being, I likely would install a DC2DC charger, although I would check the current flow first to see if I really needed one, but for the key off disconnect, that could be of value in of itself otherwise you will need to unplug the trailer each time. ~CA

btw, I suggest a 20a dc2dc charger more to protect the truck's existing wiring, not necessarily for the alternator. A 20a output dc2dc charger will likely pull ~25a on the input side and I wouldn't be surprised to find the existing charge circuit in the truck to the trailer connecter to be rated\fused at 30 amps. Anything larger would likely require running new and heavier cables all the way from the trucks battery/alternator to the RV's battery.

[Kevin Cooper]

Being an electrical design engineer for construction, I do not have this type of knowledge. Yes it’s electrical, but a different world. So, when given some information, my brain wants more. So, digging into LiFePo4 charging, I found that there are 4 methods of charging 1. Constant voltage, 2. Constant current, 3. Constant current and constant voltage, 4. Chopping wave charging.

From, https://www.improvecn.com/articles/l...harging-method

(4) Chopping wave charging method: Use the chopping method to charge. In this method, the current of the constant current source is unchanged, and the switch tube is controlled to turn on for a period of time and then turn off for a period of time, cyclically. The advantage of this method is that when the battery is charged through an external circuit, The ion generation inside the battery requires a certain response time. If it is continuously charged, its capacity potential may be reduced. After charging for a period of time, adding a turn-off time can allow the ions produced at the two poles of the battery to have a diffusion process, giving the battery a time to "digest", which will greatly increase the utilization rate of the battery and improve Charging effect.

So, I looked up the Li-BIM 225 that was used by James in the video. I found that Battleborn has information on that exact unit. It tells how the unit works and seems to me to be the #4 charging method. Note, this was considered the best by the author
https://battlebornbatteries.com/wp-c...uick-Guide.pdf

So, in my mind (right or wrong) if I were installing LiFePo4 batteries and not going over around 200 amp hours, I would not be afraid to install the LI-BIM unit to control charging from an alternator in a Ford chassis gas engine RV while driving. Installing a larger amount of batteries would need more consideration of the alternators capacity.

[craigav]

I will say that I have read of a lot of RV'rs using the LI-BIM and happy with it, so they do work, it is more about that I don't like how they work (again except for what I mentioned earlier with the aux start and drop in replacement). I suspect many RV'rs (Jayco motorhome owners in particular) who have one installed don't realize that their ~80a self resetting breakers inline with the charge cables are breaking and resetting often (with a less than fully charged LifePo4(s)) and in particular if the overall cabling resistance (including the battery(s) can support 80+ amps which would be likely, but I haven't tested mine).

If you notice in your second link the LI-BIM is rated for 225 amps. So that is a lot of current and will likely cause the alternator to put out 100% for the 15 minutes (if nothing else limits the current), and then off for 20 minutes. That is what I don't like about them, they don't limit the current in any manner when the contacts are closed and I don't believe a full load on the alternator will provide the same longevity vs a 50% load, even if the full load is only 15 minutes at a time.

Everything is a balance and a trade-off, what is best for the battery vs what is best for the RV (or tow vehicle). Somewhere in the middle is best IMO, excepting for each users individual needs. If you were boondocking, then having the fastest charge time possible would prevent the need to run the engine or generator as long each day or two but, if you never boondock then a slower more controlled charge would be better as the batteries likely will never be fully discharged before they are charged again. ~CA

[Kevin Cooper]

Craig, I agree. The point is, if you are going to stay small, one or two batteries total and you have a Ford gas engine, you could buy a LI-BIM 160 amp and be confident it will work. In many comments, we see things like, can I put a 4000 watt inverter in my 24’ RV? Can I buy 6 LiFePo4 batteries and install in my small Class C RV? The answer to these questions in many cases is “Yes but”. And then it all comes to “How much money do you have”.
Again Craig, thank you very much for your input! It is great to think again after retirement.

[craigav]

Kevin, my career has been with industrial automation and controls and I had drawn out in the past what I believe is the most optimal design for my RVing needs although perhaps deeper than what many would prefer to setup in their RV. In that design I would have a double throw\center off switch installed on my lower dash somewhere controlling one or more solenoids (one I suspect) and change the wiring (minimally) where I could choose the lower charge current dc2dc charger along with its optimal charge profile, or switch to the existing solenoid (maybe replaced with a LI-BIM) which would provide the aux start functionality and a maximum charge rate, or in the center off position, just turn off charging to the coach from the chassis altogether. It wouldn't be all that challenging of a setup really. I think for most of us that RV with shore power available each night that you would never draw down a 100a LifePo4 during the drive time anyway, therefore not even charging the coach battery(s) while driving is not going to result in any issues. Not to mention, even though it isn't noticed for most, an alternator charging at ~100 amps will require about ~5 horsepower out of the engine, resulting in a little less fuel mileage and less power when pulling hills... not a lot less though but 5hp is measurable and is that reduction even needed if you are going to be back on shore power by the end of the day? That is why I say that each RV'rs planned usage also comes into play with determining what is optimal. ~CA

[Kevin Cooper]

Craig, You know what? It’s a good thing we didn’t do plumbing design for a living! We would be trying to build a fountain on top, with an automatic wash wax system for the coach, and a totally automatic sewage dump system.
Get your system installed and tested. Then you can make a kit, start selling them and make that money you always wanted. ��