Disappointing thing is the onboard genny 12v system looks like only 6amps. So I'm thinking of going to a 'bench' charger when required. I found this one I like so far.

https://www.amazon.com/BLACK-DECKER-BC15BD-Battery-Alternator/dp/B00KNMKRU8/ref=sr_1_14?ie=UTF8&qid=1512309639&sr=8-14&keywords=battery+chargers+automotive

What I like:

Auto adjustment of amperage with high at 15a

Car start mode (never know if you'll need it)

Maintainer (pulse mode to de-sulfate the battery)

Onboard battery voltage meter

Runs on <2.5amps (120v)

Cons:

The typical I find with all genny's... You start with DC power (lots of it!), convert to AC, only to convert back to charge the battery. Drives me nuts!! LOL

I'll have to research Black+Decker genny's some more to see if even 'they' incorporated their charger into 'their' genny. Probably not, it would just make to much sense to do something like that.. LOL

  

The trailer battery controller I really don't know for certain what it can or can not do. That concerns me. Also it's mean for 'general usage. I doubt very much it has mode selection for proper charging.

When I refer to Genny it's short for generator. Yes, the Yamaha I'm looking at also has a DC connect and cables to charge direct, but only at 6amps and not controlled.

The stand-alone charger is meant just to charge and properly. Auto select for current and maintenance modes. I doubt the trailer one is setup like this. I just don't know quite yet..

My intent is to dry camp as much as possible. So with determined power usage (my power audit) I see up to 3.5 days before re-charge. 3 days of rain, well, I have to do something. Since I will be buying a generator (1000w), an additional $60 for a very good charger/controller seems well worth the money spent and peace of mind.

Again MHO and my intents.

Yes, the DC charging feature of inverter generators, at least all of those I've seen, is close to worthless.  An uncontrolled charge of your battery is far from optimal.  And if you ever really needed to do this, you can just connect your RV battery to your vehicle's battery with jumper cables and let the running vehicle charging your RV battery.  I've been forced to do this in the past, and it gets the job done.

Having a backup charger is certainly not a bad idea if you're boondocking as it wouldn't be pricey or take up much weight or space.  And if your battery ever gets significantly discharged, you can actually run both the onboard charger and an additional charger at the same time, at least until the chargers move from bulk charging to absorption charging (when the batteries reach ~80% state-of-charge).

There is another option for charging batteries.  Most people focus on generators and solar panels, but another very viable option is to use a solar charge controller in conjunction with your tow vehicle.  When a vehicle is idling, the voltage is high enough to 'activate' a 12 volt solar charge controller, and it can then charge your batteries just as though the input power was coming from solar panels.  An electrical engineer I know showed me this trick, and it works perfectly.  In fact, you can hard wire the vehicle's battery to the charge controller and then wire that directly into your RV batteries; the controller will only charge when the vehicle is running (without the alternator running, the voltage is too low to activate the charge controller), and it will charge the batteries as a 3 stage charger should.  The electrical engineer had this separate up for an emergency battery bank comprised of golf cart batteries in the toolbox of his pickup truck (he also had inverters, 12 volt sockets, a 21' set of jumper cables, extension cords, and a spare inverter and 120 volt charger).

Being able to invest as little as $20 in a charge controller and a bit of wire to charge the RV battery from a car is, IMHO, very worthwhile and may be a better investment for your money than an $800 inverter generator (that's what the 1kW Yamaha and Honda models go for), especially since a 1kW generator will not run your microwave or air conditioner.

Heh.. Don't have nor intend to have either the Micro or AC. Not how 'we' roll when camping. LOL 

Followed your link and read a bit. Thank you for the link and the response!

 It is a 3 stage charger, but, what they don't state is amperage or wattage for charge (well, as far as I can see anyway..). Seems like a decent charger, just wish they'd state wattage on charge.

Really would like to know if it's a 10-15amp charger. I'd be real happy if it was!

What I have learned, subject to interpretation, 6amp charge with no stages or control. 

Now, that's bad for general charging, but for the 'beef-up' charge.. not a bad thing if you know what you're doing.

  

There is is theory of 'over-charge' reaching 15.5v (read on 6v systems) that obviously extends the Ah without hurting the Batteries. The claim is to use a 'constant' charge (which the generator would do) for no longer than 2hrs (or reaching 15.5v). Remember, to all that try this, this is a theory being processed. 

So far sounds good but... Only still a theory.. 

Pushing beyond chargeable rates could reduce cycles of charge..

On top of that, as soon as the charger gets AC power, it will also power all of the 12 volt circuits in the Pod, adding to the power draw.

A big reason why so many people are unable to run their air conditioner with a 2kW generator is because their charger is often drawing significant power to charge their battery and run all of the 12 volt items.

Edit: deleted quote from a spammer

Well, I'm so far past this now (this was back in 2017) and never did buy a 'geeny', I've had no need. Between the solar I added and the DC/DC charging (from the TV). Good power management, solid quality batteries have done it for us!

Am curious as to what style batteries you ended up purchasing.  I ask because one of my 12v deep cycle batteries is no longer holding a good charge, in fact after giving it a 24 hour 2 amp trickle charge and letting it rest for 6 hours before taking a reading it only reads 12.49 v.  Then again it will be 11 years old come this December.  It is a group size 24 Interstate.  The other one (same name and size) is 4 months newer and still performs very nicely for this boondocker.

I am seriously looking at the Trojan T-1275 (12v).  Weight is 85 lbs and comes with a 150 amp hour rating.  They are not as popular in the golf cart industry as they once were, most 48 volt systems have gone to the 8v batteries, which obviously won't work for our application on the 177.  I am not worried about tongue weight as I added a couple used rotors to the front so I can keep my tongue weight over 300 lbs and that is with a full FW tank, which is located behind the axle.

Now with the Overlander, I'm running a 90ah lithium and using a DC/DC system from the trucks alternator. I do have 120w of solar as a backup for any extended stay.

I'm a big fan of lithium, just not a big fan of the 'overpriced' batteries/setups out there. 

Safe Travels

OG.  Question time. How low can I take a golf cart battery down before 'hurting it.'  Seems like a dumb question coming from a golf course superintendent who has worked a lot with electric golf carts but honestly all we ever did on the electric side was to keep corrosion off cables, keep electrolyte levels up, keep batteries and surrounds CLEAN, and charge after so many rounds of golf.  In addition there were times where a cart or two would get missed, get sent out, and then run out of juice to the point it was unable to move at all and would have to be towed in.

My other reason for moving in this direction is weight.  With the additional nearly 40# tongue weight I can now rid myself of carrying some old brake rotors in the front stow area freeing up valuable storage space under my table seating area. 

I was looking for discharge rates on the Trojan website but didn't find what I was looking for.  How much do I lose per week and I suppose temp enters into that equation as well.  It has been rather simple for the 12v deep cycle Interstates: 24-36 hours at 2 amps first week in November, let sit on the concrete floor in an unheated garage and 'hibernate,'  the following late April or early May repeat the charge cycle that was done in November and then re-install thereafter. 

Would I be looking at a monthly or maybe every 2 months doing a trickle charge?  I would monitor things weekly anyway but figure you probably already know 'the numbers.' Thanks

Now being on lithium, I bring them inside and use them as a UPS as we lose power during the winter.