Hello all, first time poster.I am currently doing a special purpose conversion of my enclosed gooseneck and am at the point to figure out electricity. I have a lot of 12V equipment, especially strip lighting that takes up more amps than shore power (coming from the generator) can provide. The 120v equipment/AC will use about 24a. The 12v equipment will use about 90a and each job for the trailer will be about 2 hours so a total of 180a will be used, so my idea was to use two deep cycle batteries as the main source of power with the batteries being charged while driving/hooked up to truck or when connected to shore power.I thought a DC to DC charger like the Renogy DCC50S 12V 50A DC On-Board Input MPPT Charger would work but Renogy told me that using shore power with an AC to DC converter would not work with the device in lieu of solar power. So I am trying to find a device that would charge the batteries from 2 different sources. Its very unlikely that the 2 power sources would be used simultaneously to charge batteries (but possible?). I've put a rough draft schematic below to give you all an idea. Would love to hear your thoughts. Thanks very much in advance.

So you’re planning on running shore power and generator at the same time to get your 24A AC power? On the DC side I’d think the converter would go straight to the batteries, not thru the DCDC charger. And you’re not going to pull enough power off your trucks 12V pin on the trailer plug to power a 50A DCDC or even a 30A DCDC.And you’re going to have to pull a full load on the converter to keep just 2 batteries alive for 2 hours pulling 90ah. Better get a big one. Or more/better batteries.

Grit dog wrote:So you’re planning on running shore power and generator at the same time to get your 24A AC power? On the DC side I’d think the converter would go straight to the batteries, not thru the DCDC charger. And you’re not going to pull enough power off your trucks 12V pin on the trailer plug to power a 50A DCDC or even a 30A DCDC.And you’re going to have to pull a full load on the converter to keep just 2 batteries alive for 2 hours pulling 90ah. Better get a big one. Or more/better batteries.No the generator is what is going into the shore power.Why couldn't two batteries with 115ah each handle 90a load?

"I have a lot of 12V equipment, especially strip lighting that takes up more amps than shore power or the generator can provide."You are using more than 90 amps for lighting? What are you lighting?

Hi,Two possible routes.1. get a hybrid inverter charger. These allow for load support. That means power may be drawn from the battery bank to make up temporary shortfalls in power.2. There are some inverter chargers that have 2 AC input sources.A side question. Why do your dc strip lights draw so much power, and what are they being used to light up?On my last trip I often only had 15 amp shore power with no access to the breaker panel. I set my hybrid inverter/charger to not draw more than 13 amps. When using the microwave I do see over 200 amps being drawn from the batteries.Be aware that "load support" is not "voltage support". To have voltage support one needs an autoformer.

halhawkins wrote:No the generator is what is going into the shore power.Why couldn't two batteries with 115ah each handle 90a load?Gotcha, genny = shore power.Batteries 2 115ah 12V FLA, SLA or AGM batteries have theoretically 230ah total at brand new 100% charged. So at 90ah of draw, no charging, they are in need of being recharged in less than an hour (keeping with the 70-80% min charge for max service life) or in just over an hour they are dead as doornails at 50% SOC.Rough numbers, you need to be feeding the 2 batteries, idk, around 50-60amps of charging just to barely hold your own in a perfect world scenario. Happens to also be that around a 25A rate is about the max you can charge a typical 12V deep cycle like you're proposing.So if you had a 60A converter charging full tilt the whole time, theoretically you have "just enough" charging and capacity to maintain that load and not kill or shorten the battery life significantly.Say you're pulling about 10A AC from the genny to run the converter, you're still looking for another 25A AC (per your calcs) for the A/C and AC outlets. 15A is LOW for the A/C when it cycles. So all in, you have marginal battery reserve power ("marginal" being generous), full max charging out of a BIG converter that basically will try to charge the batteries too fast (it actually won't, it'll be putting all its power straight to the load basically) and it will all require a 4kw + generator, basically putting you out of the "quiet" generator market without spending big bucks there.So yes with a big generator and a big converter, you can make the milquetoast battery capacity work, but everything will be running full throttle at basically 100% load and duty cycle.All this without also considering inefficiency losses due to converting and inverting power.Simple solution is to provide more DC power storage capability since you're already spending a bunch of money and give the batteries and the rest of the hardware a break. This assuming your power draw calcs are right and not low, which makes the situation worse, or considerably high which lessens the issue.There's a reason there's a sort of "practical limit" on what your proposing which is pulling more juice than most all RVs and many homes and why "houses" don't use DC power and why solar power arrangements have huge battery banks when they're providing significant power. Youd be better off figuring out how to NOT pull most of your power DC and get it most/all to AC and find a nice big generator setup like a diesel Onan to run the whole show and keep the batteries for what they were intended for.

MPPT/DC to DC Charger for Trailer Build | Good Sam Community

pianotuna
Nomad III
Oct 31, 2022
Hi,

Two possible routes.

1. get a hybrid inverter charger. These allow for load support. That means power may be drawn from the battery bank to make up temporary shortfalls in power.

2. There are some inverter chargers that have 2 AC input sources.

A side question. Why do your dc strip lights draw so much power, and what are they being used to light up?

On my last trip I often only had 15 amp shore power with no access to the breaker panel. I set my hybrid inverter/charger to not draw more than 13 amps. When using the microwave I do see over 200 amps being drawn from the batteries.

Be aware that "load support" is not "voltage support". To have voltage support one needs an autoformer.
Lwiddis
Explorer II
Oct 31, 2022
"I have a lot of 12V equipment, especially strip lighting that takes up more amps than shore power or the generator can provide."

You are using more than 90 amps for lighting? What are you lighting?
halhawkins
Explorer
Oct 31, 2022
Grit dog wrote:
So you’re planning on running shore power and generator at the same time to get your 24A AC power?
On the DC side I’d think the converter would go straight to the batteries, not thru the DCDC charger.
And you’re not going to pull enough power off your trucks 12V pin on the trailer plug to power a 50A DCDC or even a 30A DCDC.
And you’re going to have to pull a full load on the converter to keep just 2 batteries alive for 2 hours pulling 90ah. Better get a big one. Or more/better batteries.

No the generator is what is going into the shore power.

Why couldn't two batteries with 115ah each handle 90a load?
Grit_dog
Navigator
Oct 31, 2022
So you’re planning on running shore power and generator at the same time to get your 24A AC power?
On the DC side I’d think the converter would go straight to the batteries, not thru the DCDC charger.
And you’re not going to pull enough power off your trucks 12V pin on the trailer plug to power a 50A DCDC or even a 30A DCDC.
And you’re going to have to pull a full load on the converter to keep just 2 batteries alive for 2 hours pulling 90ah. Better get a big one. Or more/better batteries.

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