Trickle Charger Through 7-Pin Connector

[CrazyCooter]

I have a 20a DC-DC charger on my trailer and have had no issues running it through my 7 pin (pretty sure that circuit is on a 30a fuse)

The charger will have no problem with the length of wire going up to the battery. You could have some loss of voltage & current at the initial bulk charge state with a high amperage charger, but that won't be an issue with a trickle charger. It will top off & maintain the battery just like if it were connected in the engine bay.

Are you charging a large lifepo battery in your trailer? Also where do you have your charger mounted?

I'm charging a 280ah lifepo with the charger mounted on the RV. If I get greedy and try to turn up the charging (Output) voltage up, I will see the incoming voltage drop to less than 9V. That's when the amp draw goes up and the plug starts getting warm. Plans to move the charger onto the truck so that the voltage is higher at the plug reducing amps passing through.

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[just_another_guy]

Are you charging a large lifepo battery in your trailer? Also where do you have your charger mounted?

I'm charging a 280ah lifepo with the charger mounted on the RV. If I get greedy and try to turn up the charging (Output) voltage up, I will see the incoming voltage drop to less than 9V. That's when the amp draw goes up and the plug starts getting warm. Plans to move the charger onto the truck so that the voltage is higher at the plug reducing amps passing through.

I'm using flooded lead acid, but that doesn't make a difference in the context of this discussion. The charger is mounted on the trailer similar to yours. Are you measuring the current input as well as the output of the charger?

 

[CrazyCooter]

I'm using flooded lead acid, but that doesn't make a difference in the context of this discussion. The charger is mounted on the trailer similar to yours. Are you measuring the current input as well as the output of the charger?

Charging a lifepo battery is WAY different than an FLA battery! Lifepo has much lower impedance and higher voltage requirements. Combine this with the smart alternator dropping while on the gas, you get the conditions I'm seeing. From memory, I can see input/output voltage and output in watts with this Victron Bluetooth charger.

 

[just_another_guy]

Charging a lifepo battery is WAY different than an FLA battery! Lifepo has much lower impedance and higher voltage requirements. Combine this with the smart alternator dropping while on the gas, you get the conditions I'm seeing. From memory, I can see input/output voltage and output in watts with this Victron Bluetooth charger.

Ohm's law and Joule's law don't care what kind of battery you are charging though, and the input side of the charger is the real concern here. It gets a little tricky with the "smart" alternators on these trucks, but mine stopped working shortly after I bought mine and doesn't drop the voltage anymore so I've got that going for me. Do you have a way to limit the charge current with your charger?

 

[CrazyCooter]

Ohm's law and Joule's law don't care what kind of battery you are charging though, and the input side of the charger is the real concern here. It gets a little tricky with the "smart" alternators on these trucks, but mine stopped working shortly after I bought mine and doesn't drop the voltage anymore so I've got that going for me. Do you have a way to limit the charge current with your charger?

I can limit voltage output which obviously alters charge current. There's a fine line between actually putting 50ah+ into the battery over a day's travel time without melting the plug and only trickling in 15ah in the same amount of time. I have set a low voltage cutout in the charger so that its not boosting the supplied 7v (under load from undersized oe wiring) from the plug up to 13.8v creating a current draw issue. Its interesting that the fuse is 30a, but the wire looks maybe 12 or 14ga?

Its tricky between the smart alternator and the roof mounted solar to get it under optimal balanced conditions. Shade or driving in hilly terrain is constantly changing the volatges. The only decent solution I can come up with is to just plus size the wiring, mount the charger on the truck, and put Andersen connectors at the bumper/tongue. This way the dump trailer could benefit too.

 

[Radio Guy]

I can limit voltage output which obviously alters charge current. There's a fine line between actually putting 50ah+ into the battery over a day's travel time without melting the plug and only trickling in 15ah in the same amount of time. I have set a low voltage cutout in the charger so that its not boosting the supplied 7v (under load from undersized oe wiring) from the plug up to 13.8v creating a current draw issue. Its interesting that the fuse is 30a, but the wire looks maybe 12 or 14ga?

Its tricky between the smart alternator and the roof mounted solar to get it under optimal balanced conditions. Shade or driving in hilly terrain is constantly changing the volatges. The only decent solution I can come up with is to just plus size the wiring, mount the charger on the truck, and put Andersen connectors at the bumper/tongue. This way the dump trailer could benefit too.

I like to stick as much solar panel as possible on the roof of my travel trailer. That makes it self sufficient and independent of the tow vehicle for power.

 

[CrazyCooter]

I like to stick as much solar panel as possible on the roof of my travel trailer. That makes it self sufficient and independent of the tow vehicle for power.

Ya, I would normally agree with you since all of our rvs he past 18 years have had solar and the last 2 rvs have had 1400+ watts on the roof. Now I have this wannabe truck and am trying to keep things as small a light as possible. In the big rv days we were parked for 10+ days, but the point of downsizing was to move every few days.....This would allow us to recharge enroute. 50ah per day is our average consumption and the 190watt panel can keep up with that 100% from May-Sept however we usually like to camp Sept-May!

 

[just_another_guy]

I can limit voltage output which obviously alters charge current. There's a fine line between actually putting 50ah+ into the battery over a day's travel time without melting the plug and only trickling in 15ah in the same amount of time. I have set a low voltage cutout in the charger so that its not boosting the supplied 7v (under load from undersized oe wiring) from the plug up to 13.8v creating a current draw issue. Its interesting that the fuse is 30a, but the wire looks maybe 12 or 14ga?

Its tricky between the smart alternator and the roof mounted solar to get it under optimal balanced conditions. Shade or driving in hilly terrain is constantly changing the volatges. The only decent solution I can come up with is to just plus size the wiring, mount the charger on the truck, and put Andersen connectors at the bumper/tongue. This way the dump trailer could benefit too.

Running heavier gauge wiring and moving the charger back to the truck to mitigate losses are the two best things you can do if maximizing the charge rate is your only concern. You're wanting more than the stock system can handle, but it sounds like you've already figured out what you need to do to overcome that.

 

[CrazyCooter]

Running heavier gauge wiring and moving the charger back to the truck to mitigate losses are the two best things you can do if maximizing the charge rate is your only concern. You're wanting more than the stock system can handle, but it sounds like you've already figured out what you need to do to overcome that.

Yes, its not rocket science, but it just takes time and I've been busy putting out more important fires. Its not like these trucks have a ton of cool dry places to add more equipment either. If I'm going to run new wire, may as well just upgrade to a decent sized charger like 40A+

 

[ShadowsPapa]

In my opinion charging through the rear trailer connector has a lot of wire to the battery and a charger's sensing circuitry may not give an accurate charge. I think the pins labeled charge are for charging the trailer battery from the truck while driving.

I keep my Gladiator on a 60w solar panel most of the time since it doesn't get driven much. Due to my radio hobby, all of my 12V accys and solar panel chargers have Anderson Power Pole connectors and I have a chassis mount version that I plan on installing in the front grill which will connect right to the battery. That is close to the battery and will provide easy access for the solar panel or external charger or will power my portable air compressor and other items needing power.

A two circuit trailer connector under the hood connected to the battery will also work and I would look for one with 10ga wire attached.

He's talking trickle. That wire will handle over 30 amps.
At 1 or 1.5 amps true trickle, I can't see any appreciable voltage drop if they are keeping drop under 2% at over 30 amps.

 

[ShadowsPapa]

Hi everyone. I'm trying to find a better way to put a maintainer on my battery whenever I leave my truck for extended periods. Right now I have to open the hood and clip on to the posts each time, and I do it frequently enough that I'm hoping to find a better way.

The way I park in the garage, I would love it if I could connect the trickle charger at the rear of the truck instead of the front. This has led me to think about using the 7-pin trailer connector in some way to feed current to the battery since it has both +12v and ground connections. It would be the most convenient and the cleanest solution. I get conflicting information on if this is do-able when I look into the question, so I figure I'd ask here and see if anyone had some practical knowledge about how this would work on a Gladiator.

I know there are some considerations here I need to be aware of, such as the run of the wiring from the 7-pin to the battery (and the expected loss over said run), how it's pathed and fused back to the battery, and how this would affect maintaining both the main and aux batteries. If anyone has some insight on this, I would really appreciate it. Just trying to cover my bases before I do my own trial-and-error setups.

IMO, no issue. Think of the size of the wire and the fuse. That wire is large enough to handle over 30 amps, I believe it's fused at 30.
You are talking trickle, what, maybe 1 or 1.5 amps? That's what my battery tenders are. One is 1,000 and the other 1500.
If that wire is sized to keep the voltage drop 2% or less at 30 amps, it's going to be really small at 1 amp. There are online calculators that will give you the voltage drop over a given wire size and length for a given load.
It wouldn't be hard to put a 1 amp load on that wire and check the voltage at the back compared to at the battery.

 

[sharpsicle]

So here's what I ended up doing. I drilled a hole to the right of the license plate, and mounted a marine quality 12v socket there. I tapped that socket into the wires feeding the 7-pin plug, routed the wire, and taped everything off. I also retrofitted a male cig adapter onto the end of the trickle charger cable, and viola. The result is a socket that I can use to maintain the battery, but also use to power 12v accessories from the truck. Plus, if I drive off on accident, the charger end will just pop out of the socket.

The trickle charger is reading the battery just as well as it did clamped directly to it. Obviously you couldn't use this to recover a drained battery, but to maintain it, it's working just fine.

Thank you everyone for the help!

 

[ShadowsPapa]

I have this adapter that plugs into the trailer connector and turns it into a 12v outlet........

But yours is a more permanent solution and a bit more convenient.

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