12v batteries or 24v batteries, this is a question.

[ALLOY]

4 hours ago, oldjohnt said:

GREAT POINTS AND DISCUSSION RANDY, From yet from another "Happily Retired" Electrical Engineer and 49 year RV owner, we basically agree, here are my thoughts:

  Sure Lithiums seem to be "the in thing" and fashionable nowadays (so one has bragging rights) and offer advantages such as,,,,,,,,,,, Much lighter weight,,,,,,,,,,,,,,,The possibility to discharge them deeper then 50%,,,,,,,,,,,,,Fast charging,,,,,,,,,,,,,,,,Supposed (if all works out as advertised ????) less cost per useable Life Cycles over the long run, etc. etc. Of course, the down sides are HIGH UP FRONT COST and the low temperature concerns.

 That being said, I chose AGM, the reasons being at my age I cant say I will be RVing many more years or will keep the same RV very many years IE may never gain any long term cost benefits to offset the initial high cost. If I were younger and know Id be using the same RV for 7 to 10 hears, weight was an issue, and iffffffffff I usually dry camp,  I WOULD BITE THE BULLET AND CHOOSE LITHIUM

 I think his decision to stay with a 12 volt battery bank versus 24 or 48 is reasonable as he avoids yet another component (24 to 12 Converter) although operating at higher voltages has advantages such as lower current and I prefer higher voltages WHERE PRACTICAL REASONABLE AND COST EFFECTIVE....... However WOW using 12 volt batteries requiring (based on actual load) 200+ Amps out of his battery bank to the Inverter is hefty indeed !!!!!!!!!!!!! although with adequate cables and protection is certainly "workable"  

 He hasn't told us of how he is going to configure (or what so called voltage, 12 or 24 or ???) his four panels ?? The method I chose for my four panels was to use "so called 24 volt" units wired in series/parallel so I send "so called 48 volts" down to my charge controller and on a typical day the Voltage I see  down from the panels to my controller is 70+ volts which works well for the many controllers that accept up to 100 PV input Volts. Having no idea of his loads or any energy audit I view his choice of 1300 flat rooftop solar watts as strictly HIS CHOICE and  "reasonable" (but all subject to loads and sunlight etc etc) to charge (based on sunlight, time and SOC) his 600 Amp Hours of batteries. Again not knowing his loads and use, 600 AH SURE SEEMS PLENTY and may be MORE then needed if he runs ALL EXCPET AC, but hey to run AC for a limited time Id rather have too much battery then too little. The thing I run into dry camping in many say Natl Forest camps IS THERE MAY BE A TOTAL SHADE CANOPY  so my 1080 watts isn't near as big as it sounds lol  Again, if there's roof room and in his budget Id rather have too much then to little solar

INVERTER SIZE if he needed to run ALL EXCEPT AC he might get by with a smaller 2000 (4000 peak) PSW Inverter like I chose HOWEVER again to run an AC his choice of 2400 watts "might" be in line subject to the AC and any Soft Start etc.  

Hey there's no necessarily right or wrong answer to some of this, its HIS RV HIS choice HIS budget maybe its different then a couple of us retired engineers may think LOL 

PS that's my "two cents" worth, and I'm NOT any solar expert by any means, I defer to them and the Vendors for their advice.

Pleasure sparky chatting with your Randy, looks like were on the same page. Hope our discussion helps John

John T   BSEE,JD

Hey John

I've always gone with (currently 8x6v - suppose to be 940Ah) FLA. Being cheaper I don't worry about protecting the bank with low/high voltage and temperature disconnects. When we are out in the winter the FLA don't need to be kept above 35-40F.  I've a friend who's brother in law sells new / rebuilt golf carts. He's can only remember 1 brand new $$$$$ cart being ordered with Lithium everything they do is FLA or AGM.

but....

I've have Lithium in the back of my mind for these reasons: 

Lithium don't need to be fully charged.  Many occasions there is not enough sunlight to fully solar charge FLA batteries. Each time this happens to FLA the bank looses a capacity. My estimate is we really started with 700-800Ah not 940Ah.  After 2 1/2 years of use I'd estimate we've lost another 75-100 usable amp hours.  I'll be surprised if we don't replace the bank in another 2-3 years.

Lithium will accept the full capacity of the solar system.  The solar will start charging at 8-9am. When there is full sun at noon the FLA will not accept the full capacity (100 -200A) of the solar system. At 4-5:00pm when the sun slips behind the trees or mountains the bank is still in absorption or the float charge is only 1/4 - 3/4 complete.

Lithium charger faster from a generator.  In winter there are a few occasion when 2.6Kw of solar is not enough so the generator is needed. I hate running the generator for hours and hours while 1-2 amps (120VAC) are drawn from it so I end up shutting it off before the float charge is complete.

Voltage drop. The 130 amp (12VDC) draw from inverter sets the low voltage (was set at 11.5V and now 11.0V) alarm off.  This means we only use the inverter when battery SOC is above 70%.   F.Y.I....there is 4 - 4/0 cables (all 40" long) from each 6V bank to a 1/2" x 2" copper buss bar then 18" of double 1/0 (recommended by Victron) from the buss bar (thru a 400A fuse) to the inverter.   

 

 

[GlennWest]

AH not a good way to rate batteries. For example my 21k pak is only 368AH at 57v. Now that same pak at 12v is1750 AH. 

[jcussen]

Temp may or may not be a factor when using lithium. Coaches and trailers with batteries out in the open may present a problem, but on many Class A's, and 5th wheels, batteries will be in a compartment that can be insulated and heated if necessary or in the coach itself.  Low wattage heating pads on a thermostat work well. I have mine in a compartment with a 200 watt cube heater on 42-35 degree thermostat.  Have not been in extended below 0 temps, but have never seen my heater come on. Battleborn's for example, claim a discharge down to -4 f and charging down to 25 f.  Their BMS will prevent discharge or charge if not in the proper range. When charging or discharging, there is alway some heat generated inside the battery, so outside temps are not always an indicator of battery usefulness. Storage temps, with no activity are -10 f to 140 f, so if you are constantly below -10 f, would be a good idea to store batteries in a warmer place, but at 30 lbs each, pretty easy to move.

[hemsteadc]

1 hour ago, ALLOY said:

Voltage drop. The 130 amp (12VDC) draw from inverter sets the low voltage (was set at 11.5V and now 11.0V) alarm off.  This means we only use the inverter when battery SOC is above 70%.   F.Y.I....there is 4 - 4/0 cables (all 40" long) from each 6V bank to a 1/2" x 2" copper buss bar then 18" of double 1/0 (recommended by Victron) from the buss bar (thru a 400A fuse) to the inverter.  

Sounds like you should consider higher voltage.

[oldjohnt]

Hey Alloy, GREAT DISCUSSION regarding FLA versus Lithium I ENJOYED IT.

There's NO DOUBT If I were younger and would RV for 5 to 10 years and the way I prefer dry camping ID GO WITH LITHIUM IN A HEARTBEAT NO BRAINER........The reason I chose AGM over FLA was so I didn't have to mess with checking and adding water

I have very low energy requirements in our small Class C but I can run ALL EXCEPT AC with my modest 1080 Solar Watts, 520 Amp Hours of AGM, and a 2000/4000 PSW Inverter with a back up genset if ever required. On bright sunny days I might achieve 100% SOC by mid morning (subject to use) so I get by fine.

Even if I don't need more of a system at my age and our RV lifestyle,  I enjoy helping others .

THANKS FOR THE FUN CHAT

John T

[jcussen]

1 hour ago, ALLOY said:

Hey John

I've always gone with (currently 8x6v - suppose to be 940Ah) FLA. Being cheaper I don't worry about protecting the bank with low/high voltage and temperature disconnects. When we are out in the winter the FLA don't need to be kept above 35-40F.  I've a friend who's brother in law sells new / rebuilt golf carts. He's can only remember 1 brand new $$$$$ cart being ordered with Lithium everything they do is FLA or AGM.

but....

I've have Lithium in the back of my mind for these reasons: 

Lithium don't need to be fully charged.  Many occasions there is not enough sunlight to fully solar charge FLA batteries. Each time this happens to FLA the bank looses a capacity. My estimate is we really started with 700-800Ah not 940Ah.  After 2 1/2 years of use I'd estimate we've lost another 75-100 usable amp hours.  I'll be surprised if we don't replace the bank in another 2-3 years.

Lithium will accept the full capacity of the solar system.  The solar will start charging at 8-9am. When there is full sun at noon the FLA will not accept the full capacity (100 -200A) of the solar system. At 4-5:00pm when the sun slips behind the trees or mountains the bank is still in absorption or the float charge is only 1/4 - 3/4 complete.

Lithium charger faster from a generator.  In winter there are a few occasion when 2.6Kw of solar is not enough so the generator is needed. I hate running the generator for hours and hours while 1-2 amps (120VAC) are drawn from it so I end up shutting it off before the float charge is complete.

Voltage drop. The 130 amp (12VDC) draw from inverter sets the low voltage (was set at 11.5V and now 11.0V) alarm off.  This means we only use the inverter when battery SOC is above 70%.   F.Y.I....there is 4 - 4/0 cables (all 40" long) from each 6V bank to a 1/2" x 2" copper buss bar then 18" of double 1/0 (recommended by Victron) from the buss bar (thru a 400A fuse) to the inverter.   

Good point on voltage drop, my lithiums at 20% SOC, voltage will only drop into the mid 12's when running a 130 amp microwave load.

 

 

[oldjohnt]

All the talk about DC to DC Conversion, battery voltage choices, energy, components and other decisions brings me back to the basic concepts I learned when practicing engineering.

THERES NO FREE LUNCH,,,,,,,,When deciding on RV electrical energy options such as voltages and conversions and solar and inverters etc etc there are ENGINEERING TRADE OFFS required.

1) There are obvious advantages of higher battery voltage but then you need a DC to DC Converter to supply the typical 12 VDC RV loads.

2) Neither Chargers or Controllers or Inverters etc etc are 100% efficient. There's always I Squared R heat energy losses anytime you have to convert THAT GOES WITH THE TERRITORY its a law of physics lol One thing is for those with HUGE Inverter loads, say 3000 watts or more THATS WHERE 24 OR 48 BATTERY VOLTS REALLY SHINES.  Consider 3000 watts at 12 volts that's a whopping 250 amps out of the battery, compared with ONLY 62.5 if it were a 48 volt battery. Now having to use a 48 to 12 DC to DC converter don't sound bad even if not 100% efficient !!!!!!!!!!!!!!!   who gives a hoot right lol

3) If one wants to be strict you have to compute all the costs and heat energy losses and any necessary conversions and put it all in a calculator and crank out the best results HOWEVER there's the other side where personal preferences and budget might make it such that THERES NO NECESSARY RIGHT OR WRONG ANSWER. Just because an engineer like those of us here may choose one method (and perhaps it is best engineering wise) DOES NOT MEAN OTHERS ARE OBLIGATED TO DO THE SAME.   

Back to Johns choice of a 12 Volt Battery bank, 1300 solar watts, and a 2400 Watt Inverter HEY THATS REASONABLE ENGINEERING WISE. It may not be the best,,,,,,,,,,, it may not be the worst,,,,,,,,,,,,,,it may or may not be the same an engineer would choose,,,,,,,it may or may not be what others here may choose, BUT ITS JOHNS CHOICE of which I was glad to help in any way I could.

WOW what a fun and deep technical discussion, thanks to all who took part, I truly enjoyed it and hope we helped John

 

John T   BSEE,JD Retired EE and one happy camper

Edited September 3, 2020 by oldjohnt

[hemsteadc]

1 hour ago, oldjohnt said:

.. for those with HUGE Inverter loads, say 3000 watts or more THATS WHERE 24 OR 48 BATTERY VOLTS REALLY SHINES.  Consider 3000 watts at 12 volts that's a whopping 250 amps out of the battery, compared with ONLY 62.5 if it were a 48 volt battery.

Many  mfrs do not even make a 3000w or greater inverter at 12v.  Yeah, you can find the real cheapos like that, but I doubt they really produce 3000w.

[Nwcid]

10 minutes ago, hemsteadc said:

Many  mfrs do not even make a 3000w or greater inverter at 12v.  Yeah, you can find the real cheapos like that, but I doubt they really produce 3000w.

Intersting.  I find them from most of the major makers like Victron, Magnum and Xantrex.

I did not need a 3000w inverter, but I wanted the hybrid feature found on MSH3012 as I use that feature a lot. 

[jcussen]

42 minutes ago, hemsteadc said:

Many  mfrs do not even make a 3000w or greater inverter at 12v.  Yeah, you can find the real cheapos like that, but I doubt they really produce 3000w.

Have a 12 volt Victron multiplus 3000 hybrid, so load sharing with shorepower if necessary, bluetooth control. best inverter I have ever used, programmable to any type of lithium or lead acid battery. Been used by boaters for many years, only in the last 5 years have they become popular with rvers. I routinely run my 15000 btu ac off of it with no problems.

https://www.victronenergy.com/inverters-chargers/multiplus-12v-24v-48v-800va-3kva

Edited September 3, 2020 by jcussen

[noteven]

When I do a tour of my Cirrus truck camper I’ve been asked “What size inverter do you have?” 

I rummage the one upper locker and produce my $10 Walmart one that charges my shaver and Dyson vac as needed. 

Deer in headlights look often follows.

I then mumble something about, “my energy needs are low” and “converting energy from one source to another” and “DC to AC confuses me...” and “I’m thinking SiO2 batteries...” usually gets me off the hook of showing how stupid I really am...

 

[Johnxhc]

On 9/3/2020 at 2:34 PM, oldjohnt said:

All the talk about DC to DC Conversion, battery voltage choices, energy, components and other decisions brings me back to the basic concepts I learned when practicing engineering.

THERES NO FREE LUNCH,,,,,,,,When deciding on RV electrical energy options such as voltages and conversions and solar and inverters etc etc there are ENGINEERING TRADE OFFS required.

1) There are obvious advantages of higher battery voltage but then you need a DC to DC Converter to supply the typical 12 VDC RV loads.

2) Neither Chargers or Controllers or Inverters etc etc are 100% efficient. There's always I Squared R heat energy losses anytime you have to convert THAT GOES WITH THE TERRITORY its a law of physics lol One thing is for those with HUGE Inverter loads, say 3000 watts or more THATS WHERE 24 OR 48 BATTERY VOLTS REALLY SHINES.  Consider 3000 watts at 12 volts that's a whopping 250 amps out of the battery, compared with ONLY 62.5 if it were a 48 volt battery. Now having to use a 48 to 12 DC to DC converter don't sound bad even if not 100% efficient !!!!!!!!!!!!!!!   who gives a hoot right lol

3) If one wants to be strict you have to compute all the costs and heat energy losses and any necessary conversions and put it all in a calculator and crank out the best results HOWEVER there's the other side where personal preferences and budget might make it such that THERES NO NECESSARY RIGHT OR WRONG ANSWER. Just because an engineer like those of us here may choose one method (and perhaps it is best engineering wise) DOES NOT MEAN OTHERS ARE OBLIGATED TO DO THE SAME.   

Back to Johns choice of a 12 Volt Battery bank, 1300 solar watts, and a 2400 Watt Inverter HEY THATS REASONABLE ENGINEERING WISE. It may not be the best,,,,,,,,,,, it may not be the worst,,,,,,,,,,,,,,it may or may not be the same an engineer would choose,,,,,,,it may or may not be what others here may choose, BUT ITS JOHNS CHOICE of which I was glad to help in any way I could.

WOW what a fun and deep technical discussion, thanks to all who took part, I truly enjoyed it and hope we helped John

 

John T   BSEE,JD Retired EE and one happy camper

Sorry I did not get a chance reading the thread in last two days.

Hi,John,

Yes I am 51 years young ::) thinking if I sell my gas RV for a diesel in the future I can easily move the lithium battery out if I can's get my battery money back.

 

Thank all of your for the help, I have not bought anything else yet (except the lithium batteries), since your guys are so helpful, I would like to get your blessing on my design  (I am not 100% sure about yet).

1) I am thinking about put 4x 310w solar panel on the driver side (my only option because the layout of the roof on the passengers) and  the size of the 310w panel, the panel will be over the edge of of the RV wall by 3-4", hopefully this is not going to be a big issue.

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipMT-ZLQstGe9RwV9HeBK9qGM6-ToNoeb12wlvYx?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

I am think put unistrut channel first and put solar panel on top of it, get my idea from 

https://www.youtube.com/watch?v=UY98-WQ0VTw&ab_channel=TravelNewTrails

2) I have three possible place to add inverter/charge , MPPT and batteries

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipNTs1F1oLlsMP08JMeh7dZ9jRNWehxyFdRDwyyN?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

 

Option 1) The current battery compartment is very small, I will have to stack the batteries sideways to make all the other components to fit, maybe it maybe very tight if it fits. please see

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipMf6p7RUuM60AB_cQGNhbO6LhvQb9txzjYvHhBi?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

 

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipPt66OwgqwJqfFdY2WqQmRCTzTrGVPZmqiepko8?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

Even everything fit this compartment, I see two problems here 

   a) My hydronic jack is inside the compartment, it has a fluid container I have to add fluid to it, it will be very hard for me to add fluid to it(but since I do not need to do it very often, it may not be a big issue if I have to move the battery every 2-3 years.

  b) this compartment is half open to outside, (because it is using ACID battery), I may have to seal it for the inverter/charge and lithium batteries (cold weather), there is definitely no place for me to add a heater to warn the battery if I  go to cold place,( maybe put a heated flex pipe somehow inside to warn it?)

If I can somehow solve the above two issues and fit everything here, this will be the best, because everything is in the same SMALL place

Option 2) Remove my small frig in the washer/dryer area, Move all components (Inverter/charge, MTTP, control etc) except battery to the old frig area , leave the battery the way it is

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipNlg3QN7AAirdffZGLxnVYvfCXFox9lkhPHMfky?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipM3qJGtGckp2-nsnyA6MX8aokKnIE5CizAfL6Zv?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

The problem with this is the inverter and battery is about 8'-10' away, there are going to be some energy loss, in this design I may need to consider 24v battery system?

 

Option 3) Remove my small frig in the washer/dryer area, Move all components (Inverter/charge, MTTP, control etc.) INCLUDING battery to the old frig area ,

 

The problem I see in this design is because moved the location of the batteries, I am worry about the weight distribution of the RV, according to someone I heard, it is best to leave the battery the way it is because the manufactory has done the weight distribution test and I do not have anything over 120lbs that I can put in the current battery compartment.

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipOK583BBpkKfLs2hRigut7yM-pdR61TKWDCRkMi?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

Option 4)  Move all components (Inverter/charge, MTTP, control etc.) Except battery to the 3rd compartment on the driver side

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipP4dRxBCSqekSETCSY8gOIEVu9w7lGodz-3Y8AR?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

The problem with this is the invert and battery is about 8'-12' away, there are going to be some energy loss, in this design I may need to consider 24v battery system? Also this is on driver side, where I put all my 140 lbs. solar panel, add more weight on this side could have a weight balance issue?

Please advise.

 

Thanks again.

 

[oldjohnt]

15 hours ago, Johnxhc said:

The problem with this is the invert and battery is about 8'-12' away, there are going to be some energy loss, in this design I may need to consider 24v battery system?

John, for now at least I'm ONLY addressing this ONE question.

If you use this line voltage drop calculator (no idea if accurate or not,,,,,,,, no warranty,,,,,,,,,,cant say I used it correctly) 

https://www.calculator.net/voltage-drop-calculator.html?material=copper&wiresize=0.1608&voltage=12&phase=dc&noofconductor=1&distance=10&distanceunit=feet&amperes=250&x=123&y=16

Based on 250 amps (Probably MORE then you will use),,,,,,,,,,,based on 12 feet,,,,,,,,,,,,,,,,based on 4/0 cable you get

0.29 Voltage drop = 2.45% 

THAT ALONE WOULD NOT DISCOURAGE ME FROM USING A 12 VOLT BATTERY BANK

If I have time later I will look at your other questions

John T

 

 

 

[oldjohnt]

15 hours ago, Johnxhc said:

the panel will be over the edge of of the RV wall by 3-4"

PS I DO NOT like the idea of the panel protruding over the edge any at all

John T

[jcussen]

Agree with John, having panels sticking out farther that coach width is asking for problems. Lot easier to run 120 volt wiring to and from your inverter than running 12 or 24 volt cables. I would try to put all my low voltage equipment in one compartment and just modify your 120 volt lines to your inverter.

[Nwcid]

7 minutes ago, jcussen said:

Lot easier to run 120 volt wiring to and from your inverter than running 12 or 24 volt cables. I would try to put all my low voltage equipment in one compartment and just modify your 120 volt lines to your inverter.

This is what I did on mine.  It required running conduit under the trailer from the front pass though to roughly mid way back and up into where my breaker box was located.  The conduit protects the wire and makes it much easier to run.  Also running appropriate size 120v wire is much easier than running appropriate size 12v wire. 

 

[Johnxhc]

2 hours ago, oldjohnt said:

PS I DO NOT like the idea of the panel protruding over the edge any at all

John T

The problem is the solar panel I am looking at it is 39" and I only have 36" space, but if you look at 

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipPnBFvTe6qWPE1BPw2wDob6N5Emki11UjVXcZ7f?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipOVaB1ygP5jslOiShBPULh9PEqF_AlQuQ9owYK3?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

 

I have a whole wall slide 28' long slide on the driver side (where I want to install solar panel) and the is a 4" awning protrude over the edge, Also on passenger side, there is big awning also the same that's why I am thinking it may be ok

 

[Johnxhc]

Great! so I will put Inverter/charge in new location, where do guys guys think is the best location  I should put it?

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipNTs1F1oLlsMP08JMeh7dZ9jRNWehxyFdRDwyyN?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

1) The washer/Dryer compartment

2) Driver side compartment?

Should I leave the battery at the same compartment? ( that compartment is half open for the acid batteries) 

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipMf6p7RUuM60AB_cQGNhbO6LhvQb9txzjYvHhBi?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

that means I need to seal the battery compartment? how do I do that? with plywood?                                                                                                                                                                         

[jcussen]

48 minutes ago, Johnxhc said:

Great! so I will put Inverter/charge in new location, where do guys guys think is the best location  I should put it?

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipNTs1F1oLlsMP08JMeh7dZ9jRNWehxyFdRDwyyN?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

1) The washer/Dryer compartment

2) Driver side compartment?

Should I leave the battery at the same compartment? ( that compartment is half open for the acid batteries) 

https://photos.google.com/share/AF1QipNx1xRmo46mnFyBdiqlvmfCVJVD4crG_yFMl079x0rlzYCgzYiep7AH0zWpse-Etw/photo/AF1QipMf6p7RUuM60AB_cQGNhbO6LhvQb9txzjYvHhBi?key=UE96VU1CTldHbDJiQ1Z3X01DeXpadHZXY3BNN0V3

that means I need to seal the battery compartment? how do I do that? with plywood?                                                                                                                                                                         

Lot of variables here. Hard to tell from pictures. Probable best to put batteries inside coach if possible, inverter and charge controllers as close to them as possible. Need to consider high voltage runs also, compromises will have to be made any way you do.

[jcussen]

37 minutes ago, jcussen said:

Lot of variables here. Hard to tell from pictures. Probable best to put batteries inside coach or a sealed compartment if possible, inverter and charge controllers as close to them as possible. Need to consider high voltage runs also, compromises will have to be made any way you do it.

 

Edited September 7, 2020 by jcussen

[oldjohnt]

2 hours ago, Johnxhc said:

I have a whole wall slide 28' long slide on the driver side (where I want to install solar panel) and the is a 4" awning protrude over the edge, Also on passenger side, there is big awning also the same that's why I am thinking it may be ok

Hey John it don't sound so bad given your new information. Hey its YOUR RV and YOUR choice so if it suits you it suits me lol

Given my voltage drop figures above and also the fact you will seldom if ever draw anywhere near 250 amps for any time, I don't see a problem if your Inverter were 12 feet from your battery bank using 4/0 cables HOWEVER if you have a better place now fine. Also if in a compartment where its heated to any extent at all you wont have the low temperature Lithium concerns, but be sure you provide adequate ventilation to dissipate all the heat !!!!!!!!!!!!! Of course provide catastrophic over current protection for those huge cables and high current capacity  

keep us posted, fun project

 

John T

[Johnxhc]

1 hour ago, oldjohnt said:

Hey John it don't sound so bad given your new information. Hey its YOUR RV and YOUR choice so if it suits you it suits me lol

Given my voltage drop figures above and also the fact you will seldom if ever draw anywhere near 250 amps for any time, I don't see a problem if your Inverter were 12 feet from your battery bank using 4/0 cables HOWEVER if you have a better place now fine. Also if in a compartment where its heated to any extent at all you wont have the low temperature Lithium concerns, but be sure you provide adequate ventilation to dissipate all the heat !!!!!!!!!!!!! Of course provide catastrophic over current protection for those huge cables and high current capacity  

keep us posted, fun project

 

John T

Hi,John,

The Victron Inverter/Charge has 2,400w but peak power is 6,000w, when I select wire (I assume it is 4 gauge?) should I consider the 6,000w peak power?

Right now in the battery compartment, it is ventilated, as you can see from the picture

https://photos.google.com/photo/AF1QipNW6BntUo7ozNFKNZw15e1u-B3cFs_uv-RK778y

Actually I was just worry too much ventilation , lol. there are a area 6.5" x 37" area is open to outside, but reading your post, I looked at it again, after I stack up 6 batteries there , it will pretty much cover close the open area.

I guess I can open some holes in the bottom of the compartment, but question is will all the fuses, breaker, MTTP charge controller has any problem with potential moisture , hot, dust get in the area?

Please advise.

Thanks.

 

[GlennWest]

Amps at your voltage is what you base wire size on, not wattage

Edited September 7, 2020 by GlennWest

[Johnxhc]

24 minutes ago, GlennWest said:

Amps at your voltage is what you base wire size on, not wattage

is Amps = wattage / voltgage(12v) ?

[jcussen]

52 minutes ago, Johnxhc said:

is Amps = wattage / voltgage(12v) ?

Yes, would not worry too much about surge, that will probably be less than a second. I size for the normal full output of the inverter, but bare in mind you will seldom be running at full output of inverter. I have a lot of gear in my coach, and seldom draw more than 2000 watts off my 3000 watt inverter.

I use this chart for sizing wire.

https://www.bluesea.com/support/articles/Circuit_Protection/1437/Part_1%3A_Choosing_the_Correct_Wire_Size_for_a_DC_Circuit