DC To DC controler

[Voyager1]

View attachment 229094


Not that familiar with DC to DC controller, verifying the solar will charge both batteries and if running the alternator will charge both batteries also. Thanks

 

[heritage]

Running the alternator will charge both batteries, but the solar will only charge the house battery.

 

[dlochner]

Can't speak specifically to the Renogy DC to DC charger as I have a Victron Orion. The Orion will charge the start battery if the voltage on the DC+ bus is high enough. It doesn't matter whether the voltage is coming from the alternator, solar panels or a charger. The DC-DC charger needs to be configured to "turn on" when the voltage on the bus is greater than the resting voltage of the house battery. When the input voltage drops below that level the Orion disconnects so as to not drain the house battery. Works great on my boat.

 

[Stu Jackson]

Why isn't the alternator output connected to the house bank? Let the starter bank be fed thru the DC/DC unit.

 

[Johann]

Why isn't the alternator output connected to the house bank? Let the starter bank be fed thru the DC/DC unit.

The house is probably LFP and the alternator probably internally regulated. In this case most consider it best practice to charge the start battery via the alternator and use a Li compatible DC-DC to charge the house.

 

[dlochner]

The house is probably LFP and the alternator probably internally regulated. In this case most consider it best practice to charge the start battery via the alternator and use a Li compatible DC-DC to charge the house.

In OP's picture the DC-DC controller only acts as a DC+ bus.

 

[Georgedoyle]

I used the Renogy unit when I initially set up my solar array. It lasted about a year. I replaced it with the Victron unit which is significantly more robust. No problems so far after a couple of years.

 

[dLj]

The house is probably LFP and the alternator probably internally regulated. In this case most consider it best practice to charge the start battery via the alternator and use a Li compatible DC-DC to charge the house.

I'd use the term "common practice" rather than "best practice".

I've never really understood why when switching to Li batteries with all the changes one should do to fully support that system, that the Li advantage of being able to absorb huge amounts of current is essentially killed by dropping a lead acid battery in the circuit that then restricts this significant advantage. It always seemed to me "pennywise and pound foolish"...

dj

 

[Johann]

In OP's picture the DC-DC controller only acts as a DC+ bus.

I was curious why there was no MPPT in the diagram so I looked up that Renogy DC-DC. It is a combination of MPPT and DC-DC with logic to charge the house with a set profile from either the alternator, solar, or combination. Apparently once the house is “full” it will also charge the start from solar.

 

[Johann]

I'd use the term "common practice" rather than "best practice".

I've never really understood why when switching to Li batteries with all the changes one should do to fully support that system, that the Li advantage of being able to absorb huge amounts of current is essentially killed by dropping a lead acid battery in the circuit that then restricts this significant advantage. It always seemed to me "pennywise and pound foolish"...

dj

I was only referring to the case where a dumb internally regulated alternator was retained. Most would not advocate charging the LFP house in this case from the dumb alternator, although it can work depending on the specifics of the system.

I agree that the “Best Practice“ when doing the LFP upgrade is an externally regulated alternator to the house for the reasons you stated but it does up the cost a bit.

 

[marcham]

Although I am not familiar with that converter, a quick glance at the manual indicates that the solar output would go to the auxiliary battery first and once charged, to the starting battery.

I'd suggest reading the manual several times, take note of the required fusing and wire sizes. If you've never worked with DC wiring, it may be helpful to have a marine electrical to help you with some of the worst (hardest/longest) part is pulling wires which anyone can do.

 

[dlochner]

Although I am not familiar with that converter, a quick glance at the manual indicates that the solar ouput can be directed at both batteries, with a priority assigned to one or the other.

View attachment 229098

My reading of the manual excerpt says the alternator must be connected to the start battery and that is what the image in the original post shows (although not as clearly as it should). This is a pretty standard and not terribly efficient way to charge LFP batteries from an internally regulated auto type alternator. It works, but not very well.

I am always leery of devices that claim to do everything and even more so given the iffy reputation of Renogy. Claims like that remind of the barkers at state fairs, "why it slices, it dices, it carves, it debones...."

As @Stu Jackson suggests, charging the house bank directly from the alternator with a DC-DC charger to charge the start battery is a better more efficient system, however it does require an alternator upgrade and it is more expensive, but you get what you pay for. It is sometimes tough have champagne tastes on a beer budget, hence that's why Miller is champagne of bottled beer.

With multple stage and input, the battery charger can charge the auxiliary battery with a starter battery