Verify TV charges TT battery

[ependydad]

Originally Posted by babock

Your lithium batteries get charged at almost the exact same voltages as flooded lead acid batteries.

The problem with trying to charge from the tow vehicle is that the alternator in the TV is sensing the voltage local which is the starting battery. Typically this battery charges up fast after start. The battery in the trailer is trying to put a load on the battery but because of the low gauge wire between the trailer and the alternator, the voltage drop is so much that the voltage at the trailer battery is not much more than float voltage hence the reason so little current flows.

Also, any corrosion on your 7 pin connector is going to make matters even worse.

Kind of surprised you don't have solar or is that in the plans?

If you want the TV to charge camper batteries better...run a very large gauge wire from the engine compartment(through a circuit breaker/fuse) to the trailer connector and a large gauge wire from the connector to the battery bank.

Good explanation. Solar is in the plans, but probably after I move everything over to the next rig. For now, I’ll use campground power and a generator to top up.

[babock]

Out of curiosity, where do you have the negative lead that comes from your trailer connector? Since the Battery monitor uses a shunt on the negative cable, that negative wire from the TV cannot go straight to the battery. It needs to go to the frame so that the current from the TV goes through the shunt to the battery.

[babock]

If you really wanted to see the theoretical power that the TV could charge the batteries at, connect a large gauge jumper cable from the positive battery post in the TV to the positive battery post of the battery bank. Connect the negative to the negative battery post in your TV and the other end to the trailer frame. Don't even bother connecting the trailer so you can use a short jumper cable.

[ependydad]

Originally Posted by babock

Out of curiosity, where do you have the negative lead that comes from your trailer connector? Since the Battery monitor uses a shunt on the negative cable, that negative wire from the TV cannot go straight to the battery. It needs to go to the frame so that the current from the TV goes through the shunt to the battery.

I honestly don't know - it's likely grounded to the frame. It's whatever came from the factory. I dropped the batteries into the place of the existing 12v.

I'm sure there are improvements that I can do- namely making sure there is a proper wire between the 120v converter/charger and the batteries themselves.

Originally Posted by babock

If you really wanted to see the theoretical power that the TV could charge the batteries at, connect a large gauge jumper cable from the positive battery post in the TV to the positive battery post of the battery bank. Connect the negative to the negative battery post in your TV and the other end to the trailer frame. Don't even bother connecting the trailer so you can use a short jumper cable.

Interesting test. This could lead me down the path of actually wiring up a good charge from the truck. We regularly drive 4-6 hours when we move, so I could definitely see the value if going between boondocking locations.

[babock]

Originally Posted by ependydad

namely making sure there is a proper wire between the 120v converter/charger and the batteries themselves.

I am moving my convertor to be right next to the batteries.

[bluewoo]

Originally Posted by babock

All flooded acid batteries charge at the same voltage.

I disagree in the point of a marine battery charger has a lower peak voltage vs a regular charger.
Obviously if I put either one is a car/truck yes it will charge @ what ever the vehicle is putting into it - I was saying my charger in my camper does not go over 15 volt vs my home charger for my truck (old sears None marine charger) can get up to 17/18 volts.

Marine batteries cannot take a higher voltage like a reg battery can, and my camper is floating @ lower 13 volts - vehicle plugged in I don't think it changed if I remember right.

If you have ever jumped another car you can here the load it puts on your alternator so if the camper battery is dead there is no way it could handle a direct connection like that, everything would have to run through the RV battery and charging slowly via the tow vehicles alternator.

So probably if the OP left the vehicle running for a little while maybe the camper batt would get some juice in it but not as soon as you plugged it in as the battery was completely dead.

*Breakaway needs a charged battery to work also*

[ependydad]

Originally Posted by babock

I am moving my convertor to be right next to the batteries.

Yeah, my area got full. I'd have to ceiling mount it *if I can* (if the converter allows mounting in that direction).

To do so, I need a 20amp outlet near the batteries and would have to run a line from the converter's 12v output to the distribution panel (or not and just switch it on/off like it's only a charger). Basically, I'm lazy and that all sounds like work!

[m2kamp]

I remember reading on here that GM trucks need a fuse or relay moved/added to get 12V at the trailer plug.

Could that be the problem?

[babock]

Originally Posted by bluewoo

I disagree in the point of a marine battery charger has a lower peak voltage vs a regular charger.
Obviously if I put either one is a car/truck yes it will charge @ what ever the vehicle is putting into it - I was saying my charger in my camper does not go over 15 volt vs my home charger for my truck (old sears None marine charger) can get up to 17/18 volts.

Marine batteries cannot take a higher voltage like a reg battery can, and my camper is floating @ lower 13 volts - vehicle plugged in I don't think it changed if I remember right.

If you have ever jumped another car you can here the load it puts on your alternator so if the camper battery is dead there is no way it could handle a direct connection like that, everything would have to run through the RV battery and charging slowly via the tow vehicles alternator.

So probably if the OP left the vehicle running for a little while maybe the camper batt would get some juice in it but not as soon as you plugged it in as the battery was completely dead.

*Breakaway needs a charged battery to work also*

You can believe what you want. It's just a chemical reaction....Lead and acid. Marine is just a label they put on the outside of the case along with various sizes of the lead plates in contact with the acid.

If you have a charger that is putting out 17/18 volts with a battery connected to it, you need to throw it away. If you are measuring voltage with no load on it, that is not a valid test.

BTW, I own 2 boats. They both charge at close to 14V while the engine is running.