Best way to charge batteries when Boondocking?

OP Summary: Regardless of what PD unit you have that 29' to the batteries will not allow "best" charging hence you need a good sized charger mounted next to the batteries. Charger size depends upon the battery capacity and for 2xGC2s a 40-50A charger would be good. The length of the AC wires is not a concern.

50-90% SOC dry camping is common but it may take extra time from 80 to 90% and a lot of extra gen time for "best" which is 100%. That's where a smaller solar setup can provide "best" charging by finishing where the gen leaves off.

Add sufficient solar wattage to run the rv the way you camp.

An external battery charger would have to have the capability of charging at the same number of amps as the converter. But that also assumes a 3 stage converter that actually works.

path1 wrote:
(little bit long but I don’t want to miss any details)

I pull my 29 foot(30 amp)cord from the left rear of trailer to the hitch area where the generator is located at the back of my pick up and then I plug in 30 amp cord.

Then elec goes 29 feet through 6 awg wire to a progressive dynamics convertor also located in rear of TT, but on right side of TT. So add another 7 feet. Then the convertor sends the elec back again 29 feet to the 12 volt batteries on the front hitch.

Wouldn’t it make more since to just hook the generator up on the DC side to batteries and save 65 feet? Or through a portable battery charger?

One person said it is better off charging the batteries through the converter/charger. Because you are running AC to the converter, voltage loss is not generally an issue.

Another person told me, elec routing is always the shortest trip the elec will have to make.

Could I charge batteries faster using the 30 amp cord and a portable battery charger?

As you can tell I’m confused. What are your thoughts on best way to charge batteries?

Thanks

The 120 volt power cord from the generator to the circuit breaker box and on to the converter/charger is going to be about 75 feet of #10 and #12 wiring. It probably will be such a low voltage drop that it would be difficult to measure the voltage drop at 4 amps @120 VAC. In other words if there is 120 volts at the generator you should have 118 - 119 volts at the plug where the converter/charger is located.

Once through the converter and it is putting out 14 volts, then the amperage might be 30- 40 amps, and having this low voltage wire as short as possible will enhance charging. Yet unless you are charging a significant number of batteries, the amperage will quickly fall below 30 amps as the 2-4 batteries start to fill up.

I noticed that my charger quickly went from 55 amps to only 35 amps as the 4 deep cycle batteries started to fill up, so I never ran my generator more than 1 hour at a time to recharge the batteries. Normally I would only run it 1 hour, then let my 400 watt solar system finish the charger.

Check out solar pricing here. SunElec.com They had a 140 watt 12 volt panel there a month or two ago for $229. It is fairly easy to install it yourself, and they can not be beat for a silent way to charge the battery.

Fred.

Classic.

"Best way" is 3 stage charging at correct voltages to full 100% with temperature compensation. Without solar as the finishing stage you won't get 100% unless you run generator all day long. You don't have solar and don't have grid power to run some good 3-stage charger day and night, so forget about best :).
But it can be improved a little.

If your converter is not 3 stage with adjustable setpoints and temp comp, then you need a better converter or standalone 120V charger.

If voltages at Bulk and Float - measured on converter output - are what they should be according to battery specs, but on battery terminals they are lower than should be - then you need a shorter or thicker DC cable to battery. If DC cable inside the trailer is not good enough, it will be a pain to replace it. Will be easier getting a good 3-stage charger and hook it up to battery with a short cable.

Solar and a generator. As said check and remove as much voltage drop between the batteries and converter as possible. If needed up grade the converter

CA Traveler wrote:
Place a good 3 stage charger adjacent to the batteries and plug it into 120V.

This, and make sure the 3 stage charger puts out 14.8V in bulk mode, if you have a lead acid battery.

I like charging my batteries with the 125 amp 4 stage charger in my Magnum. The cable between the charger and the batteries is about 3 ft, and is 0/4 (0000) gauge, sized for the 450 amp surge my inverter can draw starting heavy loads.

One 2000 watt generator will allow it to run at full power around sea level, or about 90 amps at high elevations.

Haven't noticed the length of my AC cord affecting the charge. Sometimes it's a 30 ft 12ga cord, sometimes its a 50 ft 10ga cord

Research what converter you have.
Most of them are cheap, inefficient and easy to overheat.
I just measured my converter takes almost 3 amp @120V when all the breakers on it are off and battery disconnected.
"Power that goes nowhere"
Than the build-in charger goes over 14V what on long run will boil batteries and overheats very easy with high charging current.
The best way for charging I figure out is to take my computerized 25amp charger and power it from 800W generator that Harbor Freight sells for $89.
This way you have efficient charging without danger and don't wear out expensive generator. (I also like to have back-up and light generator fits the bill just fine)
Obviously I am timing generator run with using my coffee maker or running microwave.
The 800W generator handle both just fine.

Place a good 3 stage charger adjacent to the batteries and plug it into 120V.

path1 wrote:
What are your thoughts on best way to charge batteries?

The way that pumps the most amps into them. Of course that requires sufficient voltage. Measure that at the batteries next time using your converter and tell us what that is.