Unity on Lithionics Battery Steroids-945ah!
- Thread starter lvuman
- Start date
Air Conditioner runtime on a single Lithionics GTX12V315AH lithium battery (315ah.
Even though I have 3-Lithionics batteries wired in parallel, the fact that each battery has its own battery on/off switch, gives me the ability to turn off two of the batteries so I can run my air conditioner off a single battery if desired. Likewise, I can also run it from 2 batteries by just turning one battery off. I love having the flexibility that the Lithionics battery on/off switch gives you with multiple battery configurations. So, I wanted to run a single battery test to see how long it would run my air conditioner. I've attached a PDF of the following text and results.
The air conditioner in our early model, 2015 LTV MB, Class B+ coach has a 15,000 BTU, Penguin ll air conditioner (with a heat pump). I believe 2015 was the year LTV changed the air conditioner from a 13,500 BTU unit to a larger 15,000 BTU unit. I added the Micro-Air Easy-Start to the unit because it dampens the large amp spike associated with the compressor starting thus allows the A/C to be run from the Lithionics lithium battery using a 3000w Inverter. Our A/C unit draws approximately 20A DC amps when the compressor is off and 165A DC amps when the compressor is running, in addition to the approximate 3.9A DC amps the Victron Multiplus 3000w inverter uses to operate. Sometimes it will be slightly higher when the cooling fan on the Multiplus Inverter cycles on.
The test was conducted on May 8, 2021, during a period with temperatures ranging from 91.5-93F with a test average of 92.15F. The inside temperature varied between 77.6–82F with an average of 79.3F. The coach was parked in full sun with the solar array turned off. The exterior cab windows were covered with magnetic, black mesh, window covers and the main cab’s inside front window was covered with a custom-fit cover. The cab was partitioned off from the cabin with thermal curtains. The skylight in the main cabin was covered inside as well as an additional cover installed from the inside of the shower skylight. The slide was retracted.
The coach was heat soaked at a temperature of 82 degrees prior to starting the test. The compressor ran for 1 hour and 15 minutes before the compressor started cycling off/on. The runtime result would have been longer if the coach temperature was at 78F instead of 82F when the test began. The AC ran for 1 hour and 53 minutes before the Lithionics GTX12V315AH lithium battery discharged to its 10% "NeverDie" SOC (State of Charge) shutdown set point with 32AH remaining. The battery will also shut down if the battery volts were discharged to12 volts at the Low Voltage Cutoff, whichever comes first.
When one of these “NeverDie” battery cutoffs are reached, the battery will shut down but can be turned back on with a momentary push of the battery on/off button. The battery should be recharged as soon as possible once it has reached the NeverDie reserve. Heavier AC loads like the air conditioner, heat pump, microwave, toaster, etc., will quickly diminish the last 10% of charge so it best to use only small AC & DC loads until you start recharging the battery. Charging must commence within 72 hours or the battery will totally shut down.
Even though I have 3-Lithionics batteries wired in parallel, the fact that each battery has its own battery on/off switch, gives me the ability to turn off two of the batteries so I can run my air conditioner off a single battery if desired. Likewise, I can also run it from 2 batteries by just turning one battery off. I love having the flexibility that the Lithionics battery on/off switch gives you with multiple battery configurations. So, I wanted to run a single battery test to see how long it would run my air conditioner. I've attached a PDF of the following text and results.
The air conditioner in our early model, 2015 LTV MB, Class B+ coach has a 15,000 BTU, Penguin ll air conditioner (with a heat pump). I believe 2015 was the year LTV changed the air conditioner from a 13,500 BTU unit to a larger 15,000 BTU unit. I added the Micro-Air Easy-Start to the unit because it dampens the large amp spike associated with the compressor starting thus allows the A/C to be run from the Lithionics lithium battery using a 3000w Inverter. Our A/C unit draws approximately 20A DC amps when the compressor is off and 165A DC amps when the compressor is running, in addition to the approximate 3.9A DC amps the Victron Multiplus 3000w inverter uses to operate. Sometimes it will be slightly higher when the cooling fan on the Multiplus Inverter cycles on.
The test was conducted on May 8, 2021, during a period with temperatures ranging from 91.5-93F with a test average of 92.15F. The inside temperature varied between 77.6–82F with an average of 79.3F. The coach was parked in full sun with the solar array turned off. The exterior cab windows were covered with magnetic, black mesh, window covers and the main cab’s inside front window was covered with a custom-fit cover. The cab was partitioned off from the cabin with thermal curtains. The skylight in the main cabin was covered inside as well as an additional cover installed from the inside of the shower skylight. The slide was retracted.
The coach was heat soaked at a temperature of 82 degrees prior to starting the test. The compressor ran for 1 hour and 15 minutes before the compressor started cycling off/on. The runtime result would have been longer if the coach temperature was at 78F instead of 82F when the test began. The AC ran for 1 hour and 53 minutes before the Lithionics GTX12V315AH lithium battery discharged to its 10% "NeverDie" SOC (State of Charge) shutdown set point with 32AH remaining. The battery will also shut down if the battery volts were discharged to12 volts at the Low Voltage Cutoff, whichever comes first.
When one of these “NeverDie” battery cutoffs are reached, the battery will shut down but can be turned back on with a momentary push of the battery on/off button. The battery should be recharged as soon as possible once it has reached the NeverDie reserve. Heavier AC loads like the air conditioner, heat pump, microwave, toaster, etc., will quickly diminish the last 10% of charge so it best to use only small AC & DC loads until you start recharging the battery. Charging must commence within 72 hours or the battery will totally shut down.
SSTraveler
2014 LTV Unity Murphy Bed
During Lvuman's recent battery testing he discovered a problem with the 300a ANL fuses he used just off his battery terminals. He observed that within just minutes of running the air conditioner the ANL fuse temperature shot up to 200° and a very acrid hot/burning smell was apparent. In fact Lvuman told me at the time that it was so hot, he couldn't hold a finger on the cable next to the lug and the heat smell was oppressive. He had to wait for the ceiling fans to exhaust the air before he could go back inside the motorhome because it was irritating his lungs. This issue only became apparent when he began his single battery test. This was probably because the air conditioner amp draw off a single battery was 177a when the air conditioner compressor was running. It wasn't obvious when using his 3 batteries because the amp draw is divided among the three batteries, at around 60a per battery. The ANL fuse temperature of each battery was 120°, 120°, and 147°. High, but not out of normal operating range. Lvuman tested all the batteries running the air conditioner one at a time to confirm if they all exhibited the high temperature issues, which they did. After testing the fuses on all the batteries, replacing one, and retesting, it was decided to just remove the ANL fuse on the one battery and see how the system operated. He then tried the air conditioner test again. This time everything worked as it should and temperatures among connections and the battery BMS were all monitored, with the highest connector temperature of around 105° and a BMS temperature of 152°. Once Lvuman finished his test he wrote up his ANL fuse issue, testing data, and provided it to Lithionics so we could start troubleshooting the issue with them. Lithionics said the BMS temperature should not exceed 160°. They also said, under a 180A load, the fuse assembly temperature should not have exceeded about 170°. So they were very curious to understand why the ANL fuse got so hot.
While there is nothing wrong with using ANL or MRB Terminal fuses, you must ensure that they are well designed products meant to be used in Marine and RV battery applications. Lithionics recommends Blue Sea or Victron products. Lvuman got his ANL fuse from Windy Nation, https://www.windynation.com/ANL-Fus...L-Fuse-Holder-with-ANL-Fuse/-/1659?p=YzE9Ng==. He connected them to each of his batteries using a copper bus bar which connected to the battery terminal on one side and the ANL fuse on the other. They were as close as possible to the battery, as Lithionics recommends (within 7 inches).
It is important to recognize that fuses work by melting a metal link to break the electrical connection when they exceed their amperage rating, so they do get very hot when operating close to rated amperage. Also, it is important to understand that when 12vdc connections aren't properly made or electrical components like fuses aren't made of high quality copper or even better nickel or tin plated copper, then resistance builds, which causes heat, which in turn causes a voltage drop. Lvuman saw over a 1 volt drop from the battery voltage reading to the inverter 12vdc terminal voltage readings. When you smell a hot/burn smell and know your operation isn't close to the amperage rating, you can only assume the connections are now getting weaker, thus yielding more resistance, generating more heat and dropping in voltage. Basically your 12vdc electrical system enters a failure spiral, building more and more resistance and heat generation, until something has to give; hopefully the fuse blows and/or the holder only melts, before anything worse happens.
So always check the specs on your fuses, because most fuses can handle double their current draw for a brief time. If you aren't using BlueSea or Victron products then make sure you are buying equivalent material and specification items. Also, check all your 12vdc cable connections and fuses by taking temperatures and voltage readings post-installation, pre-powerup and during initial testing to identify any resistance, hot spots or voltage drops. If there is, you need to pinpoint the problem and remove it, or replace the fuse. An easy way to do this is to probe your battery positive to battery negative and see what voltage you have. Next, probe the battery negative to various points along your fuse and fuse holder. If you get anything lower than the previous voltage, you have resistance! Do this systematically along your connections, from the battery to the inverter.
Besides poor quality material fuses, having washers or heat shrink where they don't belong will also increase resistance and generate heat. It is interesting that Windy Nation shows a flat washer in between the cable lug and their ANL fuse, Figure 2. This is a big No No! You NEVER want a washer or heat shrink in between the connectors and/or Fuse/Fuse Holder. If you are stacking connectors on a terminal, again, you don't want a washer or heat shrink in between the connectors. They also show the ANL fuse attached directly to the battery, which again is a very bad practice. Figure 3 shows the proper way. Also stack your connectors in a Christmas tree fashion, the largest sized lugs or cable connectors at the bottom decreasing in size to the smallest on top.
Lvuman verified that all his connections were properly made and tight. He included pictures of his ANL fuse/fuse block connections so Lithionics could see how he installed them.
As with anything, the devil is in details and we needed to analyze the data before jumping to conclusions. The goal is to find a spot with relatively high resistance, where most heat is generated. Resistance creates voltage drop, so look for it with Digital Voltage Meter (DVM). Lithionics advised Lvuman to use a DMV in the mV range and try to find out where most of the voltage drop occurs while under load, measuring at different points starting from battery terminal, on the fuse assembly and to cable lug after the fuse assembly. They wanted him to measure mV drops between all adjacent points marked in Figure 1, while under steady load. On at least 2 fuse assemblies, ideally all 3 battery fuses, if they can be reached, so you can correlate temperature rise with voltage drops (Figure 1). Finding where the voltage drop starts will point to the source of heat. They didn't need the voltage tested under 180A load, no need to create extreme overheating again. Even at typical 60A draw you should see measurable values, enough to compare with some baseline. To pass high current from lug to lug or lug to fuse, you have to maximize surface contact area, so washers or nuts or bushings which press 2 contact surfaces together must themselves have a large enough diameter to create an adequate surface area of compression. Lithionics also advised that the problem could be poor contact between fuse and the cable lug.
After a volley of emails, one of the Lithionics Engineers wrote something I thought was particularly informative; there are quite a few factors that go into selecting the correct fuse but to address the immediate issues I want to go over a few things. It was never specified in the Lithionics manuals to install ANL fuses directly to the battery post, MRB Terminal fuses yes, but not ANL. MRB Terminal fuses are designed to be attached directly to the battery post whereas ANL fuse holders are not. The ANL fuse and fuse holder specified in the manual are from a company that has a reputation for quality and tested products (Blue Sea or Victron). The Blue Sea fuse block is rated to 750 amps and is designed to handle the heat that may be encountered when running high currents. The ANL fuse block should be mounted as close to the battery as possible (within 7 inches). It should be noted that the ANL fuse itself should never be connected directly to the battery terminal, a fuse block/holder must always be used. If the conductor is contained within a sheath or enclosure (conduit, junction box or enclosed panel) the fuse can be placed as close as practical to the battery but should not exceed 72 inches. Below is an image of the specified fuse block, as you can see it has large conductive surfaces where the fuse is attached and can handle up to 4/0 cable. While ANL fuses should typically not be a problem, a specific installation at the battery terminal might be better off using MRB Terminal fuses (Figure 5), purely due to mechanical design and shape of the assembly.
More from information from Lithionics; Stainless or carbon steel nuts used as risers or spacers will also have a negative impact in many ways (resistance, heat rise, or lack of heat sinking). When using the Blue Sea ANL fuses they do need to be used with the corresponding Blue Sea ANL fuse holders, not used directly on a terminal as the Windy Nation pictorial shows. The same for Class J or T Fuses. The MRB Terminal Fuse Holder is the only one designed for direct attachment to a battery terminal. Another detail that did not make sense, it appears the Windy Nation ANL fuses themselves are made of brass or brass plated.
Lvuman did more research and realized that the Blue Sea ANL fuses are made of copper and plated with Nickel, which is better than just plain copper because it greatly reduces oxidation. Oxidation adds resistance over time. It should be noted that Brass is only 28 percent copper, so if a fuse is made of brass or brass plated, you are losing 2/3 of your IACS (internal annealed copper standard) rating. Based on this information Lvuman was able to determine that the ANL fuses he installed from Windy Nation were a big mistake! The fuse block that came with the Windy Nation 300 amp ANL fuse is clearly not rated for high amperage and the fuse, upon closer examination certainly looks like it's made of brass or brass plated. There is evidence on the bottom of the fuse block that it was starting to melt. Lvuman decided to go with the Blue Sea terminal fuse block and a Blue Sea 300a terminal fuse. He just installed them, one on each battery, and will be testing them this week. He told me he learned a lot from his exchanges with Lithionics and now he is not at all surprised by the issues he encountered with the cheap Windy Nation ANL fuses. He told me, "Quite an education! I'm very eager to try the Blue Sea Terminal fuses. This looks like a case of “you get what you pay for! A Quick search for genuine Blue Sea products shows approximately. $60 for one ANL fuse and one holder, while Windy Nation shows $16 for 2 fuses and one holder. These brass fuses and plastic holders are obviously cheap knockoffs, so no surprise with the end results. This experience was a great lesson learned!"
While there is nothing wrong with using ANL or MRB Terminal fuses, you must ensure that they are well designed products meant to be used in Marine and RV battery applications. Lithionics recommends Blue Sea or Victron products. Lvuman got his ANL fuse from Windy Nation, https://www.windynation.com/ANL-Fus...L-Fuse-Holder-with-ANL-Fuse/-/1659?p=YzE9Ng==. He connected them to each of his batteries using a copper bus bar which connected to the battery terminal on one side and the ANL fuse on the other. They were as close as possible to the battery, as Lithionics recommends (within 7 inches).
It is important to recognize that fuses work by melting a metal link to break the electrical connection when they exceed their amperage rating, so they do get very hot when operating close to rated amperage. Also, it is important to understand that when 12vdc connections aren't properly made or electrical components like fuses aren't made of high quality copper or even better nickel or tin plated copper, then resistance builds, which causes heat, which in turn causes a voltage drop. Lvuman saw over a 1 volt drop from the battery voltage reading to the inverter 12vdc terminal voltage readings. When you smell a hot/burn smell and know your operation isn't close to the amperage rating, you can only assume the connections are now getting weaker, thus yielding more resistance, generating more heat and dropping in voltage. Basically your 12vdc electrical system enters a failure spiral, building more and more resistance and heat generation, until something has to give; hopefully the fuse blows and/or the holder only melts, before anything worse happens.
So always check the specs on your fuses, because most fuses can handle double their current draw for a brief time. If you aren't using BlueSea or Victron products then make sure you are buying equivalent material and specification items. Also, check all your 12vdc cable connections and fuses by taking temperatures and voltage readings post-installation, pre-powerup and during initial testing to identify any resistance, hot spots or voltage drops. If there is, you need to pinpoint the problem and remove it, or replace the fuse. An easy way to do this is to probe your battery positive to battery negative and see what voltage you have. Next, probe the battery negative to various points along your fuse and fuse holder. If you get anything lower than the previous voltage, you have resistance! Do this systematically along your connections, from the battery to the inverter.
Besides poor quality material fuses, having washers or heat shrink where they don't belong will also increase resistance and generate heat. It is interesting that Windy Nation shows a flat washer in between the cable lug and their ANL fuse, Figure 2. This is a big No No! You NEVER want a washer or heat shrink in between the connectors and/or Fuse/Fuse Holder. If you are stacking connectors on a terminal, again, you don't want a washer or heat shrink in between the connectors. They also show the ANL fuse attached directly to the battery, which again is a very bad practice. Figure 3 shows the proper way. Also stack your connectors in a Christmas tree fashion, the largest sized lugs or cable connectors at the bottom decreasing in size to the smallest on top.
Lvuman verified that all his connections were properly made and tight. He included pictures of his ANL fuse/fuse block connections so Lithionics could see how he installed them.
As with anything, the devil is in details and we needed to analyze the data before jumping to conclusions. The goal is to find a spot with relatively high resistance, where most heat is generated. Resistance creates voltage drop, so look for it with Digital Voltage Meter (DVM). Lithionics advised Lvuman to use a DMV in the mV range and try to find out where most of the voltage drop occurs while under load, measuring at different points starting from battery terminal, on the fuse assembly and to cable lug after the fuse assembly. They wanted him to measure mV drops between all adjacent points marked in Figure 1, while under steady load. On at least 2 fuse assemblies, ideally all 3 battery fuses, if they can be reached, so you can correlate temperature rise with voltage drops (Figure 1). Finding where the voltage drop starts will point to the source of heat. They didn't need the voltage tested under 180A load, no need to create extreme overheating again. Even at typical 60A draw you should see measurable values, enough to compare with some baseline. To pass high current from lug to lug or lug to fuse, you have to maximize surface contact area, so washers or nuts or bushings which press 2 contact surfaces together must themselves have a large enough diameter to create an adequate surface area of compression. Lithionics also advised that the problem could be poor contact between fuse and the cable lug.
After a volley of emails, one of the Lithionics Engineers wrote something I thought was particularly informative; there are quite a few factors that go into selecting the correct fuse but to address the immediate issues I want to go over a few things. It was never specified in the Lithionics manuals to install ANL fuses directly to the battery post, MRB Terminal fuses yes, but not ANL. MRB Terminal fuses are designed to be attached directly to the battery post whereas ANL fuse holders are not. The ANL fuse and fuse holder specified in the manual are from a company that has a reputation for quality and tested products (Blue Sea or Victron). The Blue Sea fuse block is rated to 750 amps and is designed to handle the heat that may be encountered when running high currents. The ANL fuse block should be mounted as close to the battery as possible (within 7 inches). It should be noted that the ANL fuse itself should never be connected directly to the battery terminal, a fuse block/holder must always be used. If the conductor is contained within a sheath or enclosure (conduit, junction box or enclosed panel) the fuse can be placed as close as practical to the battery but should not exceed 72 inches. Below is an image of the specified fuse block, as you can see it has large conductive surfaces where the fuse is attached and can handle up to 4/0 cable. While ANL fuses should typically not be a problem, a specific installation at the battery terminal might be better off using MRB Terminal fuses (Figure 5), purely due to mechanical design and shape of the assembly.
More from information from Lithionics; Stainless or carbon steel nuts used as risers or spacers will also have a negative impact in many ways (resistance, heat rise, or lack of heat sinking). When using the Blue Sea ANL fuses they do need to be used with the corresponding Blue Sea ANL fuse holders, not used directly on a terminal as the Windy Nation pictorial shows. The same for Class J or T Fuses. The MRB Terminal Fuse Holder is the only one designed for direct attachment to a battery terminal. Another detail that did not make sense, it appears the Windy Nation ANL fuses themselves are made of brass or brass plated.
Lvuman did more research and realized that the Blue Sea ANL fuses are made of copper and plated with Nickel, which is better than just plain copper because it greatly reduces oxidation. Oxidation adds resistance over time. It should be noted that Brass is only 28 percent copper, so if a fuse is made of brass or brass plated, you are losing 2/3 of your IACS (internal annealed copper standard) rating. Based on this information Lvuman was able to determine that the ANL fuses he installed from Windy Nation were a big mistake! The fuse block that came with the Windy Nation 300 amp ANL fuse is clearly not rated for high amperage and the fuse, upon closer examination certainly looks like it's made of brass or brass plated. There is evidence on the bottom of the fuse block that it was starting to melt. Lvuman decided to go with the Blue Sea terminal fuse block and a Blue Sea 300a terminal fuse. He just installed them, one on each battery, and will be testing them this week. He told me he learned a lot from his exchanges with Lithionics and now he is not at all surprised by the issues he encountered with the cheap Windy Nation ANL fuses. He told me, "Quite an education! I'm very eager to try the Blue Sea Terminal fuses. This looks like a case of “you get what you pay for! A Quick search for genuine Blue Sea products shows approximately. $60 for one ANL fuse and one holder, while Windy Nation shows $16 for 2 fuses and one holder. These brass fuses and plastic holders are obviously cheap knockoffs, so no surprise with the end results. This experience was a great lesson learned!"
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If okay I just want to add what holds for cheap knock-off fuses applies to cheap ring terminals as well. I would recommend to everyone only to buy from a reputed brand and to use a proper crimping tool. I was surprised when I could pull a cable out of a cheap ring terminal bought from Amazon and from that point on I subscribed to buy the crimping tool and ring terminal from the same manufacturer.
Klipstr
2018 Wonder FTB
I used the BlueSea ANL fuse holder in my install but did not use the BlueSea fuse. I will get one and swap it out. Might be time to buy a thermometer but then I might know the temperature of things and then I would have to start doing research and set my DVM on microvolts and... Love you lvuman for running this to ground (pun intended). Gave the Professor something to do today as well!
From a different forum (not by me) to help explain the ANL burn:
"You can use MRBF fuses on the battery terminals. They have high DC Current interrupt ratings. So do Class T. The problem with ANL fuses is that a battery can produce thousands of amps for a short time. The interrupt ratings for MRBF and Class T are about 10,000 to 20,000 amps. The high current will flow for a short time before the fuse blows.
With an MRBF and Class T, the fuse will blow and the arc will stop because it is below the interrupt rating. For ANL fuses [with a lower interrupt rating], it may arc over and current will continue to flow across the blown fuse, possibly causing a fire.
Think of it as a welder if you have any experience with that. Once the arc is struck, you can move the electrode away from the work and the arc will continue. The ANL fuse will blow, the arc will start, and even though the fuse melts back, the arc will keep going. In the Class T or MRBF, the arc will stop."
"You can use MRBF fuses on the battery terminals. They have high DC Current interrupt ratings. So do Class T. The problem with ANL fuses is that a battery can produce thousands of amps for a short time. The interrupt ratings for MRBF and Class T are about 10,000 to 20,000 amps. The high current will flow for a short time before the fuse blows.
With an MRBF and Class T, the fuse will blow and the arc will stop because it is below the interrupt rating. For ANL fuses [with a lower interrupt rating], it may arc over and current will continue to flow across the blown fuse, possibly causing a fire.
Think of it as a welder if you have any experience with that. Once the arc is struck, you can move the electrode away from the work and the arc will continue. The ANL fuse will blow, the arc will start, and even though the fuse melts back, the arc will keep going. In the Class T or MRBF, the arc will stop."
hilld
Well-known member
Is TIG welding acceptable?
As SSTraveler mentioned, there was a problem running high amps (170+) through a cheap ANL fuse to run the air conditioner on one battery. It wasn't an issue on my 3 battery array as the amp draw is divided between batteries but became apparent when doing a test on just one battery. I replaced the cheap ANL fuse with a Blue Sea 300A Terminal fuse mounted in a Blue Sea fuse block. I was able to do another single battery test today with the new fuse setup and it went very well. The run time with no solar and slide retracted.
Air conditioner run time: 2 hours, 4 minutes
Average outside temperature: 91.06F
Average inside temperature: 78.9F
Average positive battery terminal temperature: 126F (101-137F)
Average Blue Sea Fuse temperature: 124F (104-138F)
Average BMS temperature: 131F (87-143F)
Amp draw varied from 23 amps with the compressor off to 173 amps with the compressor on.
The full technical PDF is attached
Since the Blue Sea fuse holder has a 3/8" terminal hole and the terminal
post bolt is a smaller M8 bolt, I added a larger copper washer (ACE Hardware) between
the fuse block and lock washer for additional contact area.
Air conditioner run time: 2 hours, 4 minutes
Average outside temperature: 91.06F
Average inside temperature: 78.9F
Average positive battery terminal temperature: 126F (101-137F)
Average Blue Sea Fuse temperature: 124F (104-138F)
Average BMS temperature: 131F (87-143F)
Amp draw varied from 23 amps with the compressor off to 173 amps with the compressor on.
The full technical PDF is attached
Since the Blue Sea fuse holder has a 3/8" terminal hole and the terminal
post bolt is a smaller M8 bolt, I added a larger copper washer (ACE Hardware) between
the fuse block and lock washer for additional contact area.
There was not enough head space to place the Blue Sea 300 amp terminal fuse on the battery terminal so I have it attached to a Marinco 650 amp busbar. It's under the red rubber cap. I have a class T between the busbar and the inverter (the bottom picture is before I moved the battery cable and installed the terminal fuse and Lithionics battery).
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SSTraveler
2014 LTV Unity Murphy Bed
What rig do you have? You should add that to your profile or post signature.
I did the same thing, a 350a Class T fuse between my battery and inverter connections. I followed Xantrex's recommended application for installation of their inverter, to use a Class T fuse and direct battery connection when less than 5 feet from the battery.
I did the same thing, a 350a Class T fuse between my battery and inverter connections. I followed Xantrex's recommended application for installation of their inverter, to use a Class T fuse and direct battery connection when less than 5 feet from the battery.
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I have a 2020 Winnebago Porto 24P on the new chassis. I have a 250A fuse right now and per spec the working range is up to 150% of the nominal current which should be plenty capacity for the currents I draw.
Today, I ran a 2-battery test (630AH). Because of time constraints, it was abbreviated and not temperature monitored, however, the coach was set up like the day before. When the test started at 2:31PM, the outside temp was 94.3F. Two hours into the test, the outside temp was 92.5F. When the test ended at 7:19PM, the outside temp was 87F. The inside temp averaged 78.5F.
The test ended when the two batteries were discharged to the NeverDie, 10% SOC cutoff. The air conditioner run time on two Lithionics GTX12V315AH batteries was 4 hours, 48 minutes. The test went smoothly without any issues.
For my coach, with the Penquin 2, 15K BTU air conditioner, I'm going to use a rule-of-thumb of 2 hours AC run time per one Lithionics 315AH battery without solar. It will vary, of course with outside temps, whether the slide is in or out, whether in direct sun or shade etc. and whether I can use my 650 watts of solar.
The test ended when the two batteries were discharged to the NeverDie, 10% SOC cutoff. The air conditioner run time on two Lithionics GTX12V315AH batteries was 4 hours, 48 minutes. The test went smoothly without any issues.
For my coach, with the Penquin 2, 15K BTU air conditioner, I'm going to use a rule-of-thumb of 2 hours AC run time per one Lithionics 315AH battery without solar. It will vary, of course with outside temps, whether the slide is in or out, whether in direct sun or shade etc. and whether I can use my 650 watts of solar.
SSTraveler
2014 LTV Unity Murphy Bed
So to summarize all three of his tests: 1-Lithionics 315ah battery ran his 15,000 btu Dometic Penguin ll AC (with EasyStart) in around 95° temperatures for 2 hours and 4 minutes. 2-Lithionics 315ah batteries ran his AC for for 4 hours and 48 minutes, and 3-Lithionics 315ah batteries ran it for 6 hours and 32 minutes. When he did the tests and included his 650w of solar in full sun, it added an extra 45 minutes to the AC run time. So his rule of thumb to plan on 2 hours AC run time from each Lithionics 315ah battery and for the solar contribution, if in full sun, would be add an extra run time of 30 minutes for 400w and 45 minutes for 600w. You can't always count on sun so knowing what you can expect on battery only is most valuable. Thanks Lvuman, you are awesome for taking the time to do all this testing!
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hoosierrun
Active member
I was pretty surprised to find out how much the outside temperature affects the current draw from the compressor. We are in Arizona desert country where temperatures have been up to 108 to 112 in recent days. DC current draw has exceeded 190 amps when Air Con is powered through the inverter and has been running for at least 15 minutes all out. When it was cooler I was drawing about 145 amps (about the same as the microwave). I suspect the inverter is running less efficient too in this heat. Fortunately the only time I am running the Air Con off the batteries is when we take mid day lunch or rest breaks. Our campsites have had electric hookups thus far. Time to head for the mountains. LOL
Thanks for posting your AC experience so far. Were the 190 amps just the air conditioner or did that include the inverter, refrigerator, etc..? I was drawing 165 amps from just the air conditioner when doing tests in Arizona with temps in the low to mid 90's. When we get back to AZ in a few weeks, I'm planning on doing another test starting at around 9 PM to see what the difference is without any sun on the coach. I'll post it here. We are in the Colorado mountains now (Telluride) and the batteries are doing a great job.
hoosierrun
Active member
Yes, it does include minor draws from other items operating plus it includes the inverter.... so that is the load on my battery bank with AC running through my inverter as measured through the shunt measuring device. The 145 amp measurement (through the same shunt) was at temps in the high 70's to low 80's.
Note that the fridge is the old absorption type and does not run off the inverter. It is on propane. I should have about 1-1/2 amps carried to other minor items such as control boards, display, or memory retention modules.
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SSTraveler
2014 LTV Unity Murphy Bed
You don't say what brand battery(s) you have or capacity. The battery terminal temperatures or BMS temperature would be an important data point if you captured those. Having a draw of 190a off the battery is certainly pushing the technical boundaries of the Lithionics battery, as it is recommended not to exceed 200a draw. Lithionics also doesn't recommend exceeding a BMS temperature of 160°F. I too am very keen to test my air conditioner operation from my single Lithionics battery in 95-100 degree temperatures because I know it will significantly challenge my system and reduce the amount of AC run time I can expect. It is important to me to understand what I can reliably expect before I trust it to keep my coach cool for my dogs.
I found this explanation on the internet, "The air conditioner has to work harder when it has to work against a higher outside temperature, which causes a great temperature difference for cooling. This changes the relative pressures inside the cooling unit, which puts more back pressure on the compressor, which puts more load on the motor, which draws more power. This means that as it gets hotter, so the resistance of the wires, motor windings, etc., all increases requiring more power. One can see a 25-50% increase in power requirements in extreme high temperatures which is certainly a causal factor of brown outs or blackouts." I certainly see greatly reduced power quality at State Parks in South Carolina when the outside temperatures are above 95° and everyone has their AC cranking.
I found this explanation on the internet, "The air conditioner has to work harder when it has to work against a higher outside temperature, which causes a great temperature difference for cooling. This changes the relative pressures inside the cooling unit, which puts more back pressure on the compressor, which puts more load on the motor, which draws more power. This means that as it gets hotter, so the resistance of the wires, motor windings, etc., all increases requiring more power. One can see a 25-50% increase in power requirements in extreme high temperatures which is certainly a causal factor of brown outs or blackouts." I certainly see greatly reduced power quality at State Parks in South Carolina when the outside temperatures are above 95° and everyone has their AC cranking.
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I'm in a waiting pattern for our Unity RL; its been one year since we ordered it, so hopefully we are close. I'm hoping others will ask the same question you asked as to efficiency. There are several class B coaches claiming 10 hours of Air Condition run time on 615ah. I contacted the manufacturer of the AC unit and they provided me with a spec sheet and a quote. I'm able to follow along as you all discuss the electrical upgrades but I'm not able to join the fun yet. I know the Unity is ducted so I'm not even sure if the ProAir unit will work. Finally, I have no idea as to changing out wires as I imagine 120 VAC vs 12 VDC will require this.
hoosierrun
Active member
If those figures are correct for a 20,000 BTU 12 volt DC Air Con unit, that is a huge improvement. I wonder how difficult it would be to retrofit an LTV unit?
I would say you need at least 2/0 wire run up to the compressor on that unit. Other than the fact that they are not designed for ducted units yet, it should be a breakthrough to the RV industry once they start going in and proven reliable. It is probably a few years away for the RV makers to adopt these units, but in the meantime I suspect there will be an increasing number of custom installations and retrofits.
I would say you need at least 2/0 wire run up to the compressor on that unit. Other than the fact that they are not designed for ducted units yet, it should be a breakthrough to the RV industry once they start going in and proven reliable. It is probably a few years away for the RV makers to adopt these units, but in the meantime I suspect there will be an increasing number of custom installations and retrofits.
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