best charging method?

[Buffalobillcody]

we have a jeep wrangler rubicon pulling a home made offroad trailer. it is set up with brakes, and 7 pin charging set up. The trailer has a simple electrical system that runs a 12v fan, some led lights, and charges phones etc. We just bought a 12v fridge that will be on sliders in the trailer for a upcoming week long trip to new mexico, and i want to be prepared. The trailer has a 100ah agm battery and in the past stayed topped off from the jeep. We tend to have 6-8 hours of driving roads/trails everyday.

on or upcoming trip, we dont plan to stay in one spot more than one night, and have the typical 6-8 hours travel time planed. A fridge is new to us, and im wanting to be ready for the trip as this will be its maiden voyage. how likely is the battery to stay full just with the jeep? The 7 pin has either 12 or 10 gauge wire for the charging wire. We planned on solar some day, but were hoping it wouldnt be needed. If the jeep cant keep up, what are the most budget friendly options? suitcase solar set up? small generator and batt charger?

thanks!

 

[dreadlocks]

a robust setup would be a fixed solar panel on your trailer, at least 100W if your going to do it, build for at least 200W expansion ability.. when driving in good sun the solar panel would likely double your charge output and give you a good comfortable hassle free setup like you are used too.

Most trailer plugs only output ~4-6A of charge current, and then the fridge is gonna use 2-4A if you got a good efficient one when it kicks on.. in the trailer all closed up if its really hot it could be running quite high duty cycles which means your battery would only be getting a trickle of a charge when thats on.. with it running all night and this extra day load it could increase the battery charge time higher than your drive time.. only way to know for sure is testing it in some worst case situations.

 

[Buffalobillcody]

a robust setup would be a fixed solar panel on your trailer, at least 100W if your going to do it, build for at least 200W expansion ability.. when driving in good sun the solar panel would likely double your charge output and give you a good comfortable hassle free setup like you are used too.

Most trailer plugs only output ~4-6A of charge current, and then the fridge is gonna use 2-4A if you got a good efficient one when it kicks on.. in the trailer all closed up if its really hot it could be running quite high duty cycles which means your battery would only be getting a trickle of a charge when thats on.. with it running all night and this extra day load it could increase the battery charge time higher than your drive time.. only way to know for sure is testing it in some worst case situations.

i really would like to run one on the trailer, but havnt figured out how. the RTT covers pretty much the entire thing.

 

[dreadlocks]

any photos of your rig? mebe some sort of support that lifts it over your RTT and hinges out of the way really easy..

otherwise your looking at a DC-DC charger back in the trailer to keep voltage from sagging and boosting how much charge it can give.. you could go up to ~10A DC-DC charger off stock 10awg wiring more than likely.. Something like a Victron Orion-Tr 12/12-9 as close to your trailer battery as you can install it.. you can adjust the pot on it so it outputs ~8A solid of 14.2-14.6v even if the input voltage drops down to ~11v over that length of wire.. you'll want your trailer plug 12v line to be switched with ignition so its not draining your starter battery when engine is not running.. Or you run a dedicated line/plug to the trailer for charging purposes with a heavier gauge wire and then you could get a 15-30A DC charger which would be considered ideal for that size battery to recharge it faster, but this is considerable work and expense. could serve dual purpose for a rear winch or something.

Solar would be more ideal because it can continue to absorb you back up to up after you are done driving, and will take fridge load off the battery when your not on the trail, but you seem to do enough driving most of the time you could fully charge a deeply discharged battery on the trail if you are consistently pounding that many hours behind the wheel.. for most that rarely works out because few are willing to spend more time on the road than camping and only get a partial charge from an engine.

 

[rayra]

solenoid, 4awg cable, Anderson SB50 connectors. paralleling your trailer 7-pin, such that the maximum juice from your vehicle alternator is available / applied to your trailer battery. Total cost about $100.

 

[Buffalobillcody]

solenoid, 4awg cable, Anderson SB50 connectors. paralleling your trailer 7-pin, such that the maximum juice from your vehicle alternator is available / applied to your trailer battery. Total cost about $100.

I like that idea. I've got a spool of 2awg in the shop from making welding leads. I'll have to look into that...

What's a good option for suitcase solar setups? We also have a big enclosed trailer we use for "toy hauler" to hit trails with our rzr. A solar setup that could be used on it would be handy also. Dual purpose is king.

Here's a few pics. Havnt got the instagtam worthy ones off the camera yet.

 

[67cj5]

I like that idea. I've got a spool of 2awg in the shop from making welding leads. I'll have to look into that...

What's a good option for suitcase solar setups? We also have a big enclosed trailer we use for "toy hauler" to hit trails with our rzr. A solar setup that could be used on it would be handy also. Dual purpose is king.

Here's a few pics. Havnt got the instagtam worthy ones off the camera yet.

You need to swap that Noco charger for their 15A "G15000" model if you are going to charge a 100Ah AGM battery or if you want to add a second battery the G15000 will work fine, I am running 2 X 110 deep cycle batteries and I use the Noco G26000 26A I also have the G15000,

The reason for using the bigger models is because when using a Generator to power the Charger you want to get the most amount of charge back in the battery in the shortest possible time, Charging a lead acid battery charges fast with a normal charger than they do using any of the Noco's.

 

[Buffalobillcody]

You need to swap that Noco charger for their 15A "G15000" model if you are going to charge a 100Ah AGM battery or if you want to add a second battery the G15000 will work fine, I am running 2 X 110 deep cycle batteries and I use the Noco G26000 26A I also have the G15000,

The reason for using the bigger models is because when using a Generator to power the Charger you want to get the most amount of charge back in the battery in the shortest possible time, Charging a lead acid battery charges fast with a normal charger than they do using any of the Noco's.

Yeah, that one is way to slow. I only use it at home to top it off after a trip, or maintain it if it sits. Got a smokin deal on it Black Friday.

 

[67cj5]

Yeah, that one is way to slow. I only use it at home to top it off after a trip, or maintain it if it sits. Got a smokin deal on it Black Friday.

I have the G3500, G15000 and the G26000, I use the G15000 for charging the 80Ah AGM in my Van and the G26000 for charging 2 110Ah Lead Acid Deep cycle batteries which I am about to swap out to a 38Ah Normal Charger, Even using the G15000 on my 80Ah AGM can take up to 5 hours until the green light comes on Solid but then it can sit there clicking away for anything up to another 8 hours until the battery has done the equalizing thing it does once the 100% light says it's fully charged and using it on 2 110Ah Lead Acid batteries it can take 8 hours or more to charge them and then it will sit there clicking for anything from 10 hours up to 40 hours later, today it finished charging them and it was doing that pulse click thing for another 33 hours and that is after the green 100% charge light turned solid,

The reason for the 38Ah Charger is that I f I use 30 to 50 Ah during a 24hr period I want to be able to put it back in 2 to 4 hours, Solar power was my main goal but due to the lack of roof space I can't use the 6 X 150w panels I bought, So I bought 2 X 120w fold up panels until decide which way to go with all this gear,

To power the Charger I have a 2000w Generator and a 1500w/3000w 240v pure sign wave inverter So what the inverter chews up I can put back with the generator and the 38Ah charger,

Although AGM batteries are faster charging than lead acid batteries they are not fast enough given the limited sun light hours I have over here, back in Australia Sun light was not a problem but in the UK Sun Light hours are a rare thing for most of the year so now I am looking towards Lead Crystal batteries because they have the power of lithium at a quarter of the price and they charge faster than AGM but they use the same charging profile as AGM so the big Noco would really blast a 100Ah battery,

Charging time is the main problem with what we are trying to achieve, Sure we can do it that's not the problem but if we are on the road a lot then we don't want to be sitting at a camp site some place for 6 to 8 hours every other day to charge batteries So in your case I would be sticking a 150/200w panel on the roof that should give you 7 to 15Ah per hour that should be more than enough to give you a solid system to work with,

Hope that helps.

 

[Buffalobillcody]

any photos of your rig? mebe some sort of support that lifts it over your RTT and hinges out of the way really easy..

otherwise your looking at a DC-DC charger back in the trailer to keep voltage from sagging and boosting how much charge it can give.. you could go up to ~10A DC-DC charger off stock 10awg wiring more than likely.. Something like a Victron Orion-Tr 12/12-9 as close to your trailer battery as you can install it.. you can adjust the pot on it so it outputs ~8A solid of 14.2-14.6v even if the input voltage drops down to ~11v over that length of wire.. you'll want your trailer plug 12v line to be switched with ignition so its not draining your starter battery when engine is not running.. Or you run a dedicated line/plug to the trailer for charging purposes with a heavier gauge wire and then you could get a 15-30A DC charger which would be considered ideal for that size battery to recharge it faster, but this is considerable work and expense. could serve dual purpose for a rear winch or something.

Solar would be more ideal because it can continue to absorb you back up to up after you are done driving, and will take fridge load off the battery when your not on the trail, but you seem to do enough driving most of the time you could fully charge a deeply discharged battery on the trail if you are consistently pounding that many hours behind the wheel.. for most that rarely works out because few are willing to spend more time on the road than camping and only get a partial charge from an engine.

i think i like this option, sounds pretty safe. ill order that dc-dc charger. This will also allow it to work with most tow vehicles without modification. I'd prefer to get more then 8a charge rate if I can. I still need to look into some solar options. What do you recommend for suitcase style set ups? a home made system, or something like the renogy 100watt system? id like the charge controller to be mounted with the pannels, so that i can use this on other applications as well.

This is becoming more complicated than I would like. I hope this fridge is wort it.

 

[rayra]

I have a folding panel kit from a defunct company that I built a custom roof rack mount for, with a hinged / locking side. My panel kit could have been a prototype for the Renogy folding kit, they are that similar. Lives on the roof full time, but retains the ability to quickly unlock and dismount for use on the ground. Used the small 15A anderson couplers on the panel wiring so it's easy to connect and re-arrange, or even lend out. Have a few other wiring adapters so it can be used with battery clamps or a 12v cig. socket. so it can power other things like ham radio, cellphones, etc. That's besides all the options I built into the 'power module' in the back of my Sub, which is itself connected to my under-hood Aux battery with some very heavy 1/0 cable. Which was run to enable a rear-/carrier-mounted winch solution. Which I also just recently completed.
Lots of details and picks buried in my build topic, link in my sig below.

/eta oh man, the cursed idea of a DC-DC charger is more contagious than Covid-19

 

[dreadlocks]

since your depending so heavy on the engine to charge I would use a DC charger in this case, when its your primary charge supply its important you get your battery fully charged and thats often really hard to do in a trailer with the voltage drop and extended driving time required.. most people relying on charging through a 7 pin trailer plug never actually get the battery fully charged just due to the nature of it.. that circuit is intended to trickle maintain a small battery for electric breakaway, and not much more.

~8A@14v is not a great amount but given its just a fridge and your driving pretty much every day I think it'll work fine for you.. I mean its ~110W for 7-8h a day and you dont have to worry about cloudy days, only days your not driving.

If you were using solar in unison you could rely on that for topping off the battery and making sure it gets fully charged from time to time.. then putting in the DC charger just for a few more amps would not really be worthwhile, especially if you can utilize it on the road combined with your tow vehicle.

 

[Buffalobillcody]

since your depending so heavy on the engine to charge I would use a DC charger in this case, when its your primary charge supply its important you get your battery fully charged and thats often really hard to do in a trailer with the voltage drop and extended driving time required.. most people relying on charging through a 7 pin trailer plug never actually get the battery fully charged just due to the nature of it.. that circuit is intended to trickle maintain a small battery for electric breakaway, and not much more.

~8A@14v is not a great amount but given its just a fridge and your driving pretty much every day I think it'll work fine for you.. I mean its ~110W for 7-8h a day and you dont have to worry about cloudy days, only days your not driving.

If you were using solar in unison you could rely on that for topping off the battery and making sure it gets fully charged from time to time.. then putting in the DC charger just for a few more amps would not really be worthwhile, especially if you can utilize it on the road combined with your tow vehicle.

I ended up snagging a good deal on a suitcase 100 amp kit to have with us just in case. Plus, I've built 2 different tongues for this trailer. One for my truck, more of a developed campground scenario, and our 4 door jeep, for the more remote trips. So this set up will work for both town rigs. And the solar kit can be moved to whatever.

What kind of voltage should I set the charger at for a newer agm battery?
Thanks for all the help. This subject has alot of variables.

 

[dreadlocks]

whatever your battery manufacturer specifies, usually AGM is ~14.6v

 

[broncobowsher]

Charge while parked, solar is the winner. You might be a good canidate for a portable solar, set the panels next to the trailer.
That storage box on the front of the trailer looks good for about 50W of solar if you want fixed panel.
Remember you don't need 100% charge capacity on solar. If you are staying put for a couple of days then drive again a little solar to help charge during the day so the battery doesn't get too low and when you finally drive again it will top up.

My 70W with a PWM charge controller (might be a realistic 50W real output) will run my ARB fridge without a battery while parked in the shade with low sun. Freeze mode is a killer on the battery but fridge it is fine. couple days parked isn't an issue and it I also my starting battery (yea I am doing it wrong, but doing it wrong for 8 years).