Matching Generator, Battery Charger, Battery

[DougE]

Although I'm getting ready to purchase a Yamaha 2000w generator that produces 12v power to charge a battery, the forum doesn't seem to agree that this built-in capability is the best way to accomplish that function. I have a Group 27 AGM battery dedicated to powering a 12v fridge and a separate battery to power lighting, inverter, etc in the trailer. Rather than a dedicated charger/inverter mounted on the trailer I need a stand alone battery charger. Your suggestions as to a charger that would best match the generator's capabilities while being suitable for an AGM battery would be greatly appreciated.

[DougE]

Thanks! Forgot about the amps vs power thing. Who has a reliable charger?

[pianotuna]

Hi DougE,

Convert to watts.

40a x 14.4 v = 576 watts

13.3a x 115 v =~ 1529 watts

So, no issue at all.

In real life measurements my PD 40 amp does draw 725 watts--but that is running it flat out--still no issues even with a 900 watt generator.

DougE wrote:
There's no issue using a 40a charger powered by a 13.3a generator?

[time2roll]

DougE wrote:
There's no issue using a 40a charger powered by a 13.3a generator?

13.3a (120vac)generator will drive about 70a to 90a (12vdc) charger without any issues. 40 amps will be a breeze.

[DougE]

There's no issue using a 40a charger powered by a 13.3a generator?

[MEXICOWANDERER]

I went a different route but subsequently sold the unit to an RV'er who begged me to sell it to him.

6.5 Horsepower Honda horizontal engine. 160 ampere alternator. 3-stage cruising sailboat voltage regulator. Ohmite 30 ohm 50 watt rheostat for over ride.

The engine couldn't quite get up enough oomph for 160 amps so 148 had to do. But when the charge rate decreased as the batteries filled I backed off the throttle. For the last 10% or so, the regulator was bypassed and I rheostated the balance, manually. The rheostat and slowed engine speed also served as as an equalization system.

The buyer went nuts when he saw the system. Offered me a thousand dollars worth of pesos, and a brand new Gold Star window air conditioner unit that he ended up rejecting because running his Onan boondocking was just too expensive.

Now I have the Kubota.

[EsoxLucius]

While agms are clumped together on this forum as to what charging current requirements should be attempted to be met, if one finds the manufacturer recommendations, one will find a much wider variety. Some want all the amps you can give them, others say to limit bulk current.

Exactly.

Lifeline AGM batteries want 14.4V bulk and adsorption, and 13.3V float at 77 degrees F, minimum bulk current 0.2 x 20 hour AH capacity, maximum bulk current 2.5 x 20 hour AH capacity, in-rush current maximum 5 x 20 hour AH capacity. Time to Reach Full Charge = {(DOD/100) x Rated Capacity (Ah) ÷ Rated Output of Charger (Amp)} + 2 hours.

Fullriver AGM batteries want 14.7V bulk and absorption, and 13.65V float at 77 degrees F, recommended minimum bulk current 0.2 x 20 hour AH capacity and maximum current 0.35 x 20 hour AH capacity.

[DougE]

I checked my battery. It is a Group 34 Diehard Gold 775 CCA AGM. My fridge is a chest type (12v or 120v) Edgestar (5.4a @ 12vdc). All batteries are brought up to full charge with a 4.3a Ctek charger before starting a trip. Batteries are connected to a 30a, 10ga power circuit from the tow vehicle battery while traveling.

[landyacht318]

What brand of AGM battery?

While agms are clumped together on this forum as to what charging current requirements should be attempted to be met, if one finds the manufacturer recommendations, one will find a much wider variety. Some want all the amps you can give them, others say to limit bulk current.

Once you find the manufacturer recommendations as to voltages and currents, then specific charger recommendations can begin

[pianotuna]

Hi,

Let's not loose sight of his AGM battery bank. 14.4 might be pushing it too hard. We want fast charging but no gassing voltages.

[RoyB]

X2 on the 12VDC PANEL OUTPUT of most generator sets. I have no idea what the purpose is for the 12VDC panel outputs. You certainly cannot charge a deep cycle battery in a very quick time using this low current DC output panel connector. Keep in mind the rule of thumb to re-charge a deep cycle battery in a quick three hour charge time you will need a regulated source of around 14.4VDC with the capacity of 20 amps per battery. Having less than 20AMPS of DC current per battery available the battery may be recharged but will take many hours to accomplish the charge. This is battery science so not many ways to get around it.


I use my 2KW Honda EU2000i generator to charge my OFF-ROAD Battery bank in two way.

My preferred way is to connect the trailer shore power cable directly to the 2KW Honda Generator 120VAC Panel Receptacle using a RV 30A-15A "DOGBONE" adapter (WALMART). This allows the generator to power up the trailer ON-Board SMART MODE Converter/Charger to recharge my battery bank in a quick 3 hour generator run time.


My alternate way is to plug my portable B&D VEC1093DBD 40AMP Smart Mode battery charger directly to the 2KW Honda Generator 120VAC Panel which will allow me to charge two batteries in my battery bank in a quick three hour generator run time.


This is how I use my 2KW Honda Generator to re-charge my OFF-ROAD POPUP battery banks when camping off the power grid...

just my thoughts

Roy Ken

[2oldman]

I guess any standard car battery charger will do. Is the 12v fridge strictly a '12v fridge' or do you mean it's gas?

[pianotuna]

Hi,

The yamaha genny only does 8.3 amps with an unregulated voltage--that's BAD news for the battery except "in a pinch".

I'd recommend a Vector 50 amp charger. Vector