12 VDC in my offroad trailer

F250inTX

F250inTX

Adventurist
OK, I have what may be a stupid question. I have a MinnKota 220D dual battery charger I'm installing in my trailer. I also have 2 batteries I want hooked in parallel ( I think). Looking at schematics it's Positive to positive and negative to negative. The question is... my charger has two outlet cables for charging two batteries separate. If in parallel do I just use one side? Seems like if I use the two they would sense each others voltage???

I know probably stupid question but MinnKota not open until Monday :(

Does anyone have a schematic? Do I need some sort of separator... they are not charged from Truck and only power trailer. Do I just leave each battery separate and run different items from different batteries? Right now not planning on that way :(

Thanks in Advance!
 
If you connect them in parallel, then one charging bank will do the job, but I dont see why you couldnt plug in the second bank, since the voltages will be the same across both batteries. The charger will just think that its charging two batteries that happen to have the same voltage.

You should not keep them separated (although you should install a circuit breaker between the two and flip it off when in storage to avoid voltage drop between the two).
 
Yes, between positives. I dont have a specific recommendation, but here is an example. It should depend on what you are going to be pushing back there. For example, if the most that you see your accessories needing back there is 50 amps during normal operation, then put in a 100 amp breaker.
 
I would normally say to only connect one set of leads, but it appears that this charger is "smarter" than a standard charger so I am going to say hook up both. The owners manual talks about the batteries in series (not what you are doing) and says
NOTE: If batteries are connected in series for 12/24 - 24V, the series connection wire should be left in place during charging.
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This most likely applies to parallel as well so I would give it a shot and see what it does.

as for the fuse / breaker you if the batteries are right next to each other than there is no need to fuse. If the batteries are separated than you want to put the fuses or breakers on the positive line at each end as close to the batteries as possible. The fuse is the safety, and anything between the battery and the fuse is unprotected. So think of it this way. example You have a battery under the hood, and one at the back of the vehicle. You have 20' of wire between the 2 with a fuse 1' from the under hood battery. Where the cable runs under your firewall it rubs and dead shorts to the frame and trips the fuse, you still have the second battery feeding the line.

Hope that makes sense.

as for what size fuse or breaker you have to look at multiple things. How much power are you expecting to draw? What is your wire rated for, and how long is the run. Your fuse / breaker should be the weak point in the system. If your wire is rated for 50 amps in the conditions you have you don't want it fused at 100 amps. I am a Theatrical lighting Tech, and our standard is 20%. So if your wire is rated for 100 amps, you fuse at 80.
 
Cris, this is a standalone 12v system, no connection to the vehicle.

Roger, Cris mad some good callouts in the post above, particularly about fusing the positive leads to protect your accessories. For the battery connection, I am assuming that you are using something like 4 gauge wire that can handle the amps that you are pulling plus a lot more. Remember that garden hose analogy about power. The size of the hose is the size of the wire (voltage will impact this, but we will just assume 12V constant). The flow rate is the amperage. The amount of water actually being pushed through is the wattage. You want the hose to be appropriate for the amount of flow, and remember that the longer the hose, the more pressure its going to take to get the job done.
 
THANKS!!! I think I'll hook up both leads. The batteries are right next to each other so no fuse. I am running those hots to a Blue Sea fuse box with common too. All the batteries run are 2 inside switched LED lights, 2 outside switched LED lights the on demand water pump and an Inverter. I also have a Solar trickle charger hooked up for extended maintenance. Hope to finish wiring today... :)
 
OK finished my Diamond plate install so was able to install new batterybox. Hopefully I will buy batteries tomorrow and hook them up... I have all the wiringterminated and just need the 12VDc to test... fingers crossed. Tomorrow I'll also re-hook the outside faucet and the fill adapter for the fresh water.
 

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OK me again :(

I want to charge my camper batteries while driving off the alternator. I already can charge from shore power and solar. Just adding a degree of additional charging while off grid charging from alternator.

I have looked at many posts and see different setups. I am installing a solenoid between the vehicle battery and camper. I will add a fuse between battery on each side of solenoid at vehicle and camper.

The question is what amperage will I need? I see some as low as 20 amp and I see some as high as 100 amp in their write ups? I won't be powering anything just charging as camper will be separated by solenoid when stopped. BLKWGN I have >3ft of 14 gage from vehicle battery to solenoid. Then maybe 10-12 ft of 14 gage to the 7 blade connector on Jeep. Then 4 more feet to batteries on trailer 14 gage too. Would 20 amp be sufficient at each end... I think that would be the max for the wire I've run?

THANKS!!!
 
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Ok, so this is getting into different territory. You want to charge the battery in the camper but you don't want it to be connected to the truck during startup. Luckily, there are products out there specifically designed for this. Personally, I like the national Luna intelligent solenoid. It will kick on a few minutes after startup to begin charging your aux batteries. I like the fact that it also comes with a gauge that enables you to manually connect / disconnect the separate battery banks (in case you drain your primary by leaving your lights on all night... Ask me how I know). This setup runs about $400. There are cheaper versions, but this is the one that I trusted in my 4Runner and is in the build plan for my pickup, which will soon be running the fridge off of my marine battery in the shell.

EDIT: Wait, are we talking about the camper now or the trailer?

Update: For charging trailer batteries from a rig, there are two ways to so it.

1) direct hook up with circuit breaker. Just flip the switch and you are charging. If you want to go this route, keep the amperage low, as this will be charging until you turn it off.
2) battery isolator solenoid. I mentioned a system earlier in this post, but it is certainly not the only option. The solenoid comes with a lot of benefits in terms of protecting your equipment, and works well in conjunction with a circuit breaker. I checked amazon briefly and saw lots of options with good reviews. I cant help further, as the only thing Ive ever worried about charging on a trailer from the rig before was a brake buddy.

Sent from my LG-V410 using Tapatalk
 
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Mike, that is a bit more than I want to spend :( if possible. I bought a battery isolator relay it is designed to be activated by 12vdc from ignition. I guess I could make it switched from a 12 vdc source I could turn on after starting my jeep?
 
xjintx said:
Mike, that is a bit more than I want to spend :( if possible. I bought a battery isolator relay it is designed to be activated by 12vdc from ignition. I guess I could make it switched from a 12 vdc source I could turn on after starting my jeep?
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I got confused in the last post as to whether you were talking about the trailer or the camper on your pickup.

Ill update the previous post.

Sent from my LG-V410 using Tapatalk
 
Yea I "HOPE" the FWC has whatever is needed. I know that was part of their setup fee and such. I'm setting up my Jeep and off road trailer and looking to charge from alternator too. Another wrench just thrown in when I looked on National Luna site :( They state that if I have and use a winch (I do) that can't use fuse because the winch can draw 300 amps??? Not sure how you experienced guys handle this ? :(
 
I have the T-Max Dual battery system, it works very well. I got mine on Amazon, much less expensive than the National Luna.
 
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