Asking the right question about generator&battery charger

[path1]

I'm trying to ask a question that I know very little about. So in this posting I'm trying to find out what "ingredients" I need to include, so that I get the right answer.

Couple days ago I posted about what type of generator I should buy to replace mine that was stolen from my carport.

I've been looking at a lot of spec's and options etc and still have some questions.

I've read on here more than once that a battery charger plugged into a generator and then connected to the batteries is better than using the charging system in RV.

Is that correct or is it depending on what charger I have in RV? Or maybe what type of battery charger (running from generator) I'll be using? I don't even know if charging directly from charger is always better or sometimes or usually, or even better at all.


What info do I need to provide.... so I get the best answer.

[path1]

OK thanks folks...

I'll gather all the info that people have posted so that I can post a question that makes enough since to get a answer.

I do know that my converter is at end of TT, along with elec cord and batteries are at other end mounted on tongue.

I keep and run my generator next to the tongue (rear of pick up) when using it. So that distance alone is 30 feet.

Heading out today to do some shopping for RV stuff today for couple little things and will see what they want to generators.

Thanks again

[jrnymn7]

path1,

Mr Wiz brings up an important point. I mentioned abs voltages, earlier. If the wire run from converter to bank is long, and of too small a gauge, you will see considerable 'voltage drop'. So even if the converter is putting out say 14.4v, only say 14.0v may make it to the batteries, thus extending charge times considerably; not to mention possibly chronically undercharging the bank, which leads to sulfation and progressive capacity loss.

So proper wiring is an essential element to any good charging system. And as stated, connecting a portable charger (or power supply) directly to the bank can often be a more desirable "fix" than re-wiring, or relocating the converter closer to the bank.

[MrWizard]

if there is a long wire run in your RV between the converter and the batteries
an external charger connected directly at the batteries might do a faster recharge

several years back i installed a NEW WFCO 98100 (100amp smart converter)
I have been happy with
i also carry a B&D Vector 40amp charger
i have two battery banks, and a long "detoured" wire run between the wfco and the second bank
so occasionally i put the B&D 40 on the second bank for a full top up
I also use the B&D to condition one bank while running off the other
whether or not an external charger is the best option for you
depends on the current installed converter and its location and wire run to the batteries

[pnichols]

path1 wrote:
Is that correct or is it depending on what charger I have in RV? Or maybe what type of battery charger (running from generator) I'll be using? I don't even know if charging directly from charger is always better or sometimes or usually, or even better at all.

Just to be precise .... it also depends upon the type of batteries you're talking about.

Since you didn't say, all the comments above were probably based on an assumption that you meant wet cell RV batteries. Some of the responses might be different it you had certain types of dry batteries in your RV.

[pianotuna]

Combining external and internal is a fine idea. If you have deep pockets you can go to a magnum 3000 watt hybrid inverter charger. That will send up to 125 amps to the battery bank and will do so on a 15 amp circuit.

No one in their right financial mind will do 85% to 100% state of charge on a generator. Shore power and solar work well for that.

[Dakota98]

According to your profile you currently own a 2013 Arctic Fox TT.

Check your converter & share the make & model number with the Forum.

[MEXICOWANDERER]

One of the "biggie" questions is: How long do your camping trips last?

Some folks are frugal with power. Others like me squander it.

Using or not the heater is an important question.

The make and model of your converter

The chassis brand of your rig? Ford, Chevy? Year? Length?

The TYPE and number of batteries you may wish to upgrade to.

What is the history of your rig and it's batteries?


That otter get things rolling...

[jrnymn7]

Generally speaking, you need a converter or charger that will hold Vabs (absorption stage voltage) at a suitable level... usually in the 14.4v - 14.8v range. Most converters drop to ~13.6v for abs charging, which results in about a 70% drop in current (amps to battery). This results in MUCH longer charging times/ generator run times.

Ideally, you want to charge as fast as possible, and in most cases, it will be your generator that will limit this, as BFL pointed out, above. For example, my 430Ah bank of four 6v's could easily handle 100+ charging amps, but my Honda eu2000i (1600w/13.3a) can only handle a 60a charger (75a, if power factor corrected); staying well within its "continuous" rating.

To give you an idea of charge times, a 70-100% charge on my bank, using a 45a charger, takes about 8 1/2 hours; most of which is taken up doing the top 10%. (the 70-90% portion takes about 2 hours). A 75a charger would get the 70-90% done in about 1 1/4 hours... saving about 45 minutes of generator run time... and the top 10% would be the same as using a 45a charger. That 6 1/2 hours of getting the top 10% done is best achieved using solar, thus saving enormous amounts of generator run time.

[RJsfishin]

Are you wanting a small generator ? Fine, but you will be limited to a 45 amp converter or charger, which is also fine for 2 batteries, and even 4 would work.
I love my PD9245 45 amp converter on my EU 1000 Honda. And some solar, and you have no problems ever.

[jrnymn7]

You need to provide:

Battery Bank... 6v or 12v batteries? "group size"? 20hr Capacity in Ah's.

On board converter... make, model, specs (especially bulk and abs voltages, and amps)

Daily usage... including all "leach" loads, like fridge controls, inverter, gas detectors, etc.; and heavy loads like cpap, furnace, a/c, laptop, etc.; and for how many days at a time (i.e; camping habits).

Future plans... more boondocking, longer trips, addition of solar, etc.

[BFL13]

You also have to match the converter or charger to the ability of the generator to supply the 120v to run the charger at its rated DC output. Big amp charger needs a big watt gen. With that, you can also choose a PF corrected charger to be able to run more DC amps from the same amount of 120v.

The first thing is to decide how long you want to run the gen for how often while camping.

Your daily AH usage from however big your battery bank tells how long before the batts are down to 50%. Then you will do a "50-90" recharge and we know how long that takes for various "charging rates" (DC charging amps wrt AH size of bank)

Now you pick a charging rate that fits your chosen recharge time for your size bank, and get a charger/gen combo that can do that.

[tenbear]

I carry an external charger with me even though I have a 3/4 stage converter. The converter is very good at keeping the RV battery charged.

I tow a car and TTs have a tow vehicle. I have had to use my charger to recharge the car I tow several times. It's worth it to me to have the charger available.

[KD4UPL]

There's no inherent benefit to an external charger plugged directly into a generator. Electrically plugging a charger directly in is the same as plugging the RV in with it's internal charger connected.
It all depends on which RV converter and which external charger we're talking about. Personally, if the one in the RV isn't multi-stage or doesn't have a high enough output I would just upgrade it instead of spending money on an external charger.

[wa8yxm]

path1 wrote:
I've read on here more than once that a battery charger plugged into a generator and then connected to the batteries is better than using the charging system in RV.

Is that correct or is it depending on what charger I have in RV? .

That... Was the right question: Here is the answer.
It depends on what charger you have in the RV.

Most modern RV's have 3 or 4 stage smart chargers (4th stage is equalization) and if this is what you have, and if it is the right size (Amps = about 30$% of battery bank C/20 rate) then this is the best way to recharge.

On the other hand if you have say 4 Pair of GC-2. (That is about 900 amp hours) and a 45 amp converter.. A big external may be better (That much battery can suck nearly 300 amps bulk mode)

Some RVs though (oldr ones) may have a Magntek 6300.. If you do, please UPGRADE your batteries will thank you (Progressive Dynamics 4600 series works.. Replaces JUST the converter part. Lighter too)

Some lower end newer units have the Parallex 7300.. this too is a single stage and an external may be faster.

other models you need to read the spec sheet.