Solar questions...

[Dockmaster]

I still don't understand why you can't simply plug the Moho into the trailer and charge through your trailer inverter? Your trailer inverter is only charging your trailer batteries if it is plugged into shore power or a generator. Otherwise your trailer batteries are only being charged from the solar panels via your charge controller direct to the batteries. If your trailer inverter is tripping when you plug in the Moho just reduce your charge rate on your Moho inverter as others suggested. But I doubt that the charging alone is what is tripping your trailer inverter. What else does your Moho inverter provide power to? A residential fridge? Some outlets, etc. ? I would try shutting everything off in the Moho and see if you can power the inverter in charge mode only. 

I don't know what size your Magnum trailer inverter is. But if it is a 2,000 watt it should have more than enough to power a 125 amp charger in your Moho inverter. Your 15 amp trailer outlet at 120 volts A/C is equal to 165 amps of DC at 12 volts and would be 1,800 watts. So you have little reserve to power other items depending on your charge rate. 

You can try to shut down the Moho and maybe charge while you are out riding and nobody's at camp? 

 

[Lord of the Dunes]

I still don't understand why you can't simply plug the Moho into the trailer and charge through your trailer inverter? Your trailer inverter is only charging your trailer batteries if it is plugged into shore power or a generator. Otherwise your trailer batteries are only being charged from the solar panels via your charge controller direct to the batteries. If your trailer inverter is tripping when you plug in the Moho just reduce your charge rate on your Moho inverter as others suggested. But I doubt that the charging alone is what is tripping your trailer inverter. What else does your Moho inverter provide power to? A residential fridge? Some outlets, etc. ? I would try shutting everything off in the Moho and see if you can power the inverter in charge mode only. 

I don't know what size your Magnum trailer inverter is. But if it is a 2,000 watt it should have more than enough to power a 125 amp charger in your Moho inverter. Your 15 amp trailer outlet at 120 volts A/C is equal to 165 amps of DC at 12 volts and would be 1,800 watts. So you have little reserve to power other items depending on your charge rate. 

You can try to shut down the Moho and maybe charge while you are out riding and nobody's at camp? 

Using the trailer inverter to charge the moho batteries through the moho charger introduces a lot of losses into the system. Charging the trailer batteries already loses about 15% of the solar power, then the trailer inverter loses 8 - 10% converting that to AC power, then the moho charger loses another 10% and then the moho batteries lose another 15% in the charging process. Added all up, that's roughly 50% of the solar harvest. 

Connecting both sets of batteries via cables essentially turns both batteries into one larger capacity battery. This shared cap. means it only loses 15% of whatever charging power is provided. This also allows the batteries to share the load under high draw situations in both directions. This reduces the depth of discharge of both sets of batteries and prolongs their lives. For example he has 4 GC batteries in the trailer, assuming he has 4 GC batteries in the moho, when connected together they behave like an 8 GC battery bank which would be drawn down 1/2 as much by a large load as it would if it was a 4 GC bank. I see this a lot in yachts where they've installed 8 or 12 GC batteries and the loads from their electrical system weren't that large so the battery bank was operating from 100% down to 85% instead of 100% down to 50%. This allowed the battery bank to last 8, 10 yrs or more due to the gentle discharging and allowed longer periods between recharging if the sun wasn't shining or they didn't want to fire up the genny.  

 

[EmpirE231]

Using the trailer inverter to charge the moho batteries through the moho charger introduces a lot of losses into the system. Charging the trailer batteries already loses about 15% of the solar power, then the trailer inverter loses 8 - 10% converting that to AC power, then the moho charger loses another 10% and then the moho batteries lose another 15% in the charging process. Added all up, that's roughly 50% of the solar harvest. 

Connecting both sets of batteries via cables essentially turns both batteries into one larger capacity battery. This shared cap. means it only loses 15% of whatever charging power is provided. This also allows the batteries to share the load under high draw situations in both directions. This reduces the depth of discharge of both sets of batteries and prolongs their lives. For example he has 4 GC batteries in the trailer, assuming he has 4 GC batteries in the moho, when connected together they behave like an 8 GC battery bank which would be drawn down 1/2 as much by a large load as it would if it was a 4 GC bank. I see this a lot in yachts where they've installed 8 or 12 GC batteries and the loads from their electrical system weren't that large so the battery bank was operating from 100% down to 85% instead of 100% down to 50%. This allowed the battery bank to last 8, 10 yrs or more due to the gentle discharging and allowed longer periods between recharging if the sun wasn't shining or they didn't want to fire up the genny.  

The motorhome has 8 AGM's (4 dedicated to the fridge, 4 dedicated to the rest of the "house) and it has 2 separate inverters (one dedicated to the fridge, one to the house)

so In all, when tied to the trailer, it will be 12 total batteries. 

 

[Lord of the Dunes]

The motorhome has 8 AGM's (4 dedicated to the fridge, 4 dedicated to the rest of the "house) and it has 2 separate inverters (one dedicated to the fridge, one to the house)

so In all, when tied to the trailer, it will be 12 total batteries. 

The GC batteries are connected in series to give you 12v, so 4 GC batteries looks like 2 12v batteries. Still, 10 batteries sharing the loads will last longer than 2 sets of batteries.

 

[EmpirE231]

http://www.lslproducts.net/ALS_Overview_Page.html

This would be the cheapest, easiest way. Hook this up in the trailer, make a set of leads on your coach from the batteries to the hitch,  and from this to the hitch as well. It'll just be an extra connector to hook up when you hitch up. When the trailer batteries are being charged (via solar) it will send 15 amps to the coach batteries. Fully automatic, nothing to fuss with. 

I use one in my motorhome to charge chassis batteries while the generator is running. Monaco had some huge overly expensive unit, when it crapped out I bought this. Works perfect. 

This does seem like a super basic setup (which is right up my ally lol)

it looks like it prevents backflow, which is nice...

now is 15 amps a decent amount of juice to help keep up 4 6v batteries?  Like I mentioned before.... I am not trying to eliminate generator use... just trying to reduce it if I can... due to a residential fridge running 24/7. I am assuming a system like this won't create any overcharge issue if it were running, and someone fired up the genny?

@r3meyer what do you think about this setup Vs. what you posted above?

I'd like to go all crazy and dial this thing.... but at the same time don't want too invest too much time and money, because I am not sure how long I will be keeping this trailer / moho combo.  So if I can somehow just fix my current solar issue w/ a new charge controller, and then do this basic setup to transfer juice from the trailer to moho... that would be perfect. 

 

[r3meyer]

This does seem like a super basic setup (which is right up my ally lol)

it looks like it prevents backflow, which is nice...

now is 15 amps a decent amount of juice to help keep up 4 6v batteries?  Like I mentioned before.... I am not trying to eliminate generator use... just trying to reduce it if I can... due to a residential fridge running 24/7. I am assuming a system like this won't create any overcharge issue if it were running, and someone fired up the genny?

@r3meyer what do you think about this setup Vs. what you posted above?

I'd like to go all crazy and dial this thing.... but at the same time don't want too invest too much time and money, because I am not sure how long I will be keeping this trailer / moho combo.  So if I can somehow just fix my current solar issue w/ a new charge controller, and then do this basic setup to transfer juice from the trailer to moho... that would be perfect. 

Yeah this is a much better way to go with a system your size.  I forgot about the AMP-L-Start, but its because they didn't have a lithium option where it looks like now they do.

You wont have to worry about hurting anything.

15 amp x 24hrs = 360AH of possible power to transfer to the coach each day.  Dont think you will make that much solar so you should be able to consume everything you make that is in excess.

 

[Dockmaster]

Using the trailer inverter to charge the moho batteries through the moho charger introduces a lot of losses into the system. Charging the trailer batteries already loses about 15% of the solar power, then the trailer inverter loses 8 - 10% converting that to AC power, then the moho charger loses another 10% and then the moho batteries lose another 15% in the charging process. Added all up, that's roughly 50% of the solar harvest. 

Connecting both sets of batteries via cables essentially turns both batteries into one larger capacity battery. This shared cap. means it only loses 15% of whatever charging power is provided. This also allows the batteries to share the load under high draw situations in both directions. This reduces the depth of discharge of both sets of batteries and prolongs their lives. For example he has 4 GC batteries in the trailer, assuming he has 4 GC batteries in the moho, when connected together they behave like an 8 GC battery bank which would be drawn down 1/2 as much by a large load as it would if it was a 4 GC bank. I see this a lot in yachts where they've installed 8 or 12 GC batteries and the loads from their electrical system weren't that large so the battery bank was operating from 100% down to 85% instead of 100% down to 50%. This allowed the battery bank to last 8, 10 yrs or more due to the gentle discharging and allowed longer periods between recharging if the sun wasn't shining or they didn't want to fire up the genny.  

Yes, I totally agree there is a loss to convert from DC to AC then back to DC. I just figured if he wasn't using the solar now once the trailer batteries are charged he's loosing all of it anyway. So even 75% is better than nothing. I also agree there are other ways to do this without those losses. 

I'm actually surprised more people don't put a bunch of solar panels on their trailers to do this with. Lots of real estate up on those roofs and super easy installation to catch all that sun and put it to good use. 

 

[Lord of the Dunes]

Yes, I totally agree there is a loss to convert from DC to AC then back to DC. I just figured if he wasn't using the solar now once the trailer batteries are charged he's loosing all of it anyway. So even 75% is better than nothing. I also agree there are other ways to do this without those losses. 

I'm actually surprised more people don't put a bunch of solar panels on their trailers to do this with. Lots of real estate up on those roofs and super easy installation to catch all that sun and put it to good use. 

I agree, more people should do it. I think the biggest problem is I've been seeing a lot of posts on FB where people are showing off their new solar system that they paid $10k to $16k for and due to poor planning, hiring an RV shop with a lack of knowledge of the basics of solar and electrical system planning, they end up paying that much and end up with a system that can run 1 A/C for a few hrs and essentially is good for running the microwave. Meanwhile, I've built a similar system with comparable LFP batteries, comparable inverter power and solar harvest for about $3600. Few people want to spend $10-16k when they can just buy a portable gen for $800 and skip the getting ripped off part.