Now that I am back from my work trip, I am going to installed my two UT1300 batteries on the passthrough of my 2021 Imagine 2800BH. It looks like GD is using 8 awg from the battery to the distribution panel. My question is can that size wire really handle the 12V loads from the trailer or should I be looking to upgrade to 6 awg. By the way the stock converter/charger is going to be disconnected a 60 amp lithium charger install close to the batteries.
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Originally posted by Giesis View PostNow that I am back from my work trip, I am going to installed my two UT1300 batteries on the passthrough of my 2021 Imagine 2800BH. It looks like GD is using 8 awg from the battery to the distribution panel. My question is can that size wire really handle the 12V loads from the trailer or should I be looking to upgrade to 6 awg. By the way the stock converter/charger is going to be disconnected a 60 amp lithium charger install close to the batteries.
Since you're going to mount your new charger close to your batteries (a good idea regardless) I assume the higher amperage won't travel over 8 AWG wires so it won't be a concern. For anyone considering doing a one-for-one swap of their converter for a lithium-capable converter/charger thus using 8 AWG-I'd be concerned and would urge upgrading the wiring.
I'm tired, so if that's not worded clearly hopefully someone much smarter than me on this stuff (lots like that here!) will clarify. Jkwilson , TucsonJim are two of many...Last edited by howson; 11-15-2020, 07:25 AM.Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.
2017 Ford F-350 DRW, '19 315RLTSPlus
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Originally posted by howson View Post
If I remember correctly, this was a discussion (offline) between the moderators and Grand Design. GD assured the moderators that 8 AWG was sufficient and meets code for the expected loads.
Since you're going to mount your new charger close to your batteries (a good idea regardless) I assume the higher amperage won't travel over 8 AWG wires so it won't be a concern. For anyone considering doing a one-for-one swap for their converter for a lithium-capable converter/charger thus using 8 AWG-I'd be concerned and would urge upgrading the wiring.
I'm tired, so if that's not worded clearly hopefully someone must smarter than me on this stuff (lots like that here!) will clarify. Jkwilson , TucsonJim are two of many...2018 RAM 3500 Big Horn, CC SB 6.7 Cummins HO/Aisin
2021 GD Imagine 2800BH
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Originally posted by Giesis View PostNow that I am back from my work trip, I am going to installed my two UT1300 batteries on the passthrough of my 2021 Imagine 2800BH. It looks like GD is using 8 awg from the battery to the distribution panel. My question is can that size wire really handle the 12V loads from the trailer or should I be looking to upgrade to 6 awg. By the way the stock converter/charger is going to be disconnected a 60 amp lithium charger install close to the batteries.
For your question in using the OEM 8 awg, I am using the original wiring to power the rig from the passthrough mounted battery with no issues since the loads to run the rig are low. Both my charger and battery were relocated to the passthrough where 4 AWG was used. As a result, the high current charger to the battery is approximately 1.5 ft away. The original WFCO was left in place with the breaker turned off.
Here is a link to the install methods used on my Imagine.
https://gdrvowners.com/forum/operati...-lithium-power
JimLast edited by Guest; 11-15-2020, 09:07 AM.
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Originally posted by MidwestCamper View Post
I performed this conversion where a single 100ah AIMS battery was used with a 60 amp Progressive Dynamics lithium charger. 4 awg was also used in my rig in the passthrough for battery charging. An ampacity chart is useful when determining wire size based on load.
For your question in using the OEM 8 awg, I am using the original wiring to power the rig from the passthrough mounted battery with no issues since the loads to run the rig are low. Both my charger and battery were relocated to the passthrough where 4 AWG was used. As a result, the high current charger to the battery is approximately 1.5 ft away. The original WFCO was left in place with the breaker turned off.
Here is a link to the install methods used on my Imagine.
https://gdrvowners.com/forum/operati...-lithium-power
Jim2018 RAM 3500 Big Horn, CC SB 6.7 Cummins HO/Aisin
2021 GD Imagine 2800BH
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Giesis ,
I've done the same where I am using the frame mounted breaker at the front as a junction block now. I installed a 30 amp breaker in the docking station to back feed this wire and installed a Busman 60amp resettable breaker right on top of my battery with industrial Velcro. Both wires on my battery switch were moved to one side of the switch and free side of the switch was connected with 8 awg to the positive busbar and on to the battery with 4 awg welding cable.
One thing to keep in mind when modifying wiring is your brake system break away switch that connects to the frame mounted breaker is on the copper (battery) side which means it is directly wired to the battery. So my break away switch is currently powered through my battery switch which will now kill all power to the rig.
The way I plan to get around this is to install a Curt (or similar) brake system break away kit that will incorporate its own dedicated charger and battery. Plan to install it in the spring.
https://www.ebay.com/i/262730643480?...e44882c3a86bbc
Similar to the Curt
https://www.etrailer.com/Trailer-Bre...50-85-313.html
JimLast edited by Guest; 11-16-2020, 06:15 PM.
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Originally posted by MidwestCamper View PostGiesis ,
I've done the same where I am using the frame mounted breaker at the front as a junction block now. I installed a 30 amp breaker in the docking station to back feed this wire and installed a Busman 60amp resettable breaker right on top of my battery with industrial Velcro. Both wires on my battery switch were moved to one side of the switch and free side of the switch was connected with 8 awg to the positive busbar and on to the battery with 4 awg welding cable.
One thing to keep in mind when modifying wiring is your brake system break away switch that connects to the frame mounted breaker is on the copper (battery) side which means it is directly wired to the battery. So my break away switch is currently powered through my battery switch which will now kill all power to the rig.
The way I plan to get around this is to install a Curt (or similar) brake system break away kit that will incorporate its own dedicated charger and battery. Plan to install it in the spring.
https://www.ebay.com/i/262730643480?...e44882c3a86bbc
Similar to the Curt
https://www.etrailer.com/Trailer-Bre...50-85-313.html
Jim2018 RAM 3500 Big Horn, CC SB 6.7 Cummins HO/Aisin
2021 GD Imagine 2800BH
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To your original question...You can't go wrong using wire a size bigger than what you think is 'good enough'.
The only downside is your $$ outlay and sometimes finding connectors that will work with the bigger wire.
Finer strand wire is also better. But...costs even more. DLO, diesel locomotive cable is awesome for current carrying capacity. Costs A LOT.
2018 Dodge 3500 6.7 Cummins w Aisin and 9 cup holders
Not to brag or anything about my finances, but my bank calls me about every day to tell me my balance is OUTSTANDING!
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I'm attaching chart that shows 8 AWG is "enough" for your application.
Most of your rigs have a 30 amp breaker in line with the battery supply line. After the breaker, the wire continues to different branch circuits that divide and carry the load to items such as lights, control boards, furnace fans, etc. The maximum current will be limited by that 30 amp breaker. This is applicable to the general construction of most rigs. There are some rigs such as those with hydraulics that have their own higher current needs. This discussion is not focused on those specific applications.
The maximum current expected in the general purpose circuits should be less than 30 amps. If more, the breaker should trip. With that in mind, the next consideration is the length of the circuit from the batteries to the branch circuits and back. Based on what I've seen, this is approximately 8-12 feet, depending on the model. So for the purposes of calculating wire size, I'll use 15 feet.
The chart I'm attaching indicates that a 15 foot circuit at 30 amps can anticipate no more than a 3% voltage drop when using 8 AWG. This chart is based on ABYC E-11 requirements which are defined for the boating industry. The requirements are a great guideline for the RV industry, but are not actually called out. A 3% loss means that if your batteries were putting out 13.5 volts DC, you could expect to measure 13.1 volts where the wires branch into their individual circuits.
You should be fine with 8 AWG as long as you don't overload the circuit. And if you do overload it, the breaker will helpfully protect you. If you ever add a high draw item such as an inverter, it should have its own appropriately sized wiring connected to the battery and protected with its own fuse or breaker.
Jim and Ginnie
2024 Solitude 310GK
GDRV Technical Forum Moderator
GDRV Rally Support Coordinator
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Originally posted by TucsonJim View PostI'm attaching chart that shows 8 AWG is "enough" for your application.
Most of your rigs have a 30 amp breaker in line with the battery supply line. After the breaker, the wire continues to different branch circuits that divide and carry the load to items such as lights, control boards, furnace fans, etc. The maximum current will be limited by that 30 amp breaker. This is applicable to the general construction of most rigs. There are some rigs such as those with hydraulics that have their own higher current needs. This discussion is not focused on those specific applications.
The maximum current expected in the general purpose circuits should be less than 30 amps. If more, the breaker should trip. With that in mind, the next consideration is the length of the circuit from the batteries to the branch circuits and back. Based on what I've seen, this is approximately 8-12 feet, depending on the model. So for the purposes of calculating wire size, I'll use 15 feet.
The chart I'm attaching indicates that a 15 foot circuit at 30 amps can anticipate no more than a 3% voltage drop when using 8 AWG. This chart is based on ABYC E-11 requirements which are defined for the boating industry. The requirements are a great guideline for the RV industry, but are not actually called out. A 3% loss means that if your batteries were putting out 13.5 volts DC, you could expect to measure 13.1 volts where the wires branch into their individual circuits.
You should be fine with 8 AWG as long as you don't overload the circuit. And if you do overload it, the breaker will helpfully protect you. If you ever add a high draw item such as an inverter, it should have its own appropriately sized wiring connected to the battery and protected with its own fuse or breaker.
There is a good source of really good quality battery cables online I have used. www.batterycablesusa.com You specify length, color, and end connections and they custom make them for you. And reasonably priced. Re-wired my son's boat and added a second battery and stereo system and sub. Wired my second RV battery using them too.Tony G
2020 Chevy Silverado 3500 Highcountry
2016 Grand Designs Reflection 303RLS
KTM 250XC
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Originally posted by tgodrich View Post
The only thing upsizing from 8 gauge would give you is lower voltage drop. Not sure you would need it. 6 gauge would be overkill I think. I used 8 gauge when I installed my second battery.
There is a good source of really good quality battery cables online I have used. www.batterycablesusa.com You specify length, color, and end connections and they custom make them for you. And reasonably priced. Re-wired my son's boat and added a second battery and stereo system and sub. Wired my second RV battery using them too.
https://www.amazon.com/IWISS-Termina...NsaWNrPXRydWU=
And Rings like this:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
It is really nice to be able to cut them to length and not have terminals on them when pulling them through the rig.Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.
Neil Citro
2018 Reflection 28BH Pepwave
2019 F350 6.7L Long Bed Crew Cab
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Based on Jim's Ampacity chart a 60 amp charger would need 6 AWG with a 60 amp charger in the passthrough feeding the batteries. So to go with 4 AWG with the charger in close proximity to the batteries would be fine. Your original 8 AWG can be used from the passthrough to feed the camper and will be good according to the chart. This is what Jim is illustrating.
Another Jim
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You guys are great!!! Love this forum. Yeah I don't think, based on Jims illustration, I will overload the wire based on my needs.
Hopefully everything works out the way I hope. Once I am done with this upgrade I’ll post what I did just in case anyone in the future needs to use it as a guide. I am going to draw the schematic also.2018 RAM 3500 Big Horn, CC SB 6.7 Cummins HO/Aisin
2021 GD Imagine 2800BH
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