Dual Battery MPPT Charger

[tnscad]

I have been told two different things that using the Duoracer DR3201N MPPT, that has a main battery and trickle charger output, that I need to put a dc to dc charger on the output side that goes to the starter battery. I have been told from Epever that it is not necessary. I have not used this type of charger. I'm not familiar with a dual charger and really don't want to cause any issues. I just purchased this boat and in the process of replacing the cable, batteries and MPPT. The new battery arrangement is 3-12V230ah lithium and 2-12V Lead Acid Starter batteries.

 

[aliarifat794]

I think the manufacturer is right. No need to use a DC to DC charger. The Duoracer DR3201N should be able to manage both your lithium and lead acid batteries appropriately if set up correctly.

 

[tnscad]

thanks, that would be my assessment.

 

[Suijkerbuijk]

Its in the Manuel.

I have copy it.

Only battery 1 out put you can set for all battery type.
On battery 2 out put its only for lead and you can not program that.

 

[tnscad]

The company that I contacted to purchase the equipment has a dept that helps with your system build, and sells you shit you do not need.
Troy

 

[tpenfield]

I have the EPEver DuoRacer 20 amp model. As stated (by EPEver and others) a DC-DC charger is not necessary on either output. Not sure who/where you were told differently, but so be it.

I would recommend you get the MT-11 remote display as well, if you are interested in monitoring the charging status, since the controller itself often lives below deck in a boat and is not easily viewable.

.
I do have a DC-DC charger in my boat for charging the LiFePO4 batteries from the alternators, but the solar charging relies purely on the DuoRacer.
.

 

[mikefitz]

I'm not familiar with a dual charger

It's not a dual charger, the secondary output is low current, and low voltage maximum 13.8 volts. The primary output will charge the house batteries.
The secondary output is a maintaining voltage, sufficient to compensate for starter battery self discharge, it will not charge a depleted starter battery.
Your conflicting advice suggesting you need a battery to battery charger is valid if you want to charge the starter battery from the house battery. In this case energy is taken from the house battery, hopefully replaced by solar, and converted to a suitable charge voltage profile to charge the starter battery.

 

[Suijkerbuijk]

It's not a dual charger, the secondary output is low current, and low voltage maximum 13.8 volts. The primary output will charge the house batteries.
The secondary output is a maintaining voltage, sufficient to compensate for starter battery self discharge, it will not charge a depleted starter battery.
Your conflicting advice suggesting you need a battery to battery charger is valid if you want to charge the starter battery from the house battery. In this case energy is taken from the house battery, hopefully replaced by solar, and converted to a suitable charge voltage profile to charge the starter battery.

For a Boat use, this is normal .

A boat start battery is only connect on the engine to start it and for the lights outside
A second battery is the house hold for the lights inside, fridge and more .
So for the time your not use the boat to move .
The start battery will only discharge on a normal nature way ( lead battery als way have a small discharge)

Same for a caravan or RV.
You never use the start battery for daily use.

If you like to charge and discharge 2 battery than you need a charger than can do this .



For the rest.

It do not thake battery power from the main battery
It do charger the 2 e battery by solar only .
And charger it with a max of 1 ampère on 13.8 volts ( you can adjust the volt)
With 1 ampère you can charge a battery ( cost a long time )
See manuel .
Part out of the Manuel.


Condition1: BATT2 starts charging when BATT1 reaches the float charging stage, and the BATT2 voltage is lower than the "Charging Return Voltage. Condition 2: BATT2 starts charging when the battery's total charging current is higher than 3A and the BATT2 voltage is lower than the "Charging Return Voltage. 4) Stop Charging Conditions Condition 1: BATT2 stops charging when the PV voltage is no higher than 2Vof the BATT1. Condition 2:BATT2 stops charging when BATT1 is not in the float charging stage and the total charging current for the battery is less than 2.5A. Condition 3: BATT2 stops charging when BATT2 reaches the "Full Voltage."


Personal note
I never go for this charger my self .
If i use power on the main battery its stop charging the 2e battery (start battery)
But again this is make for a RV or boat and normal you do not use a start battery for daily use to set coffee.
And you are not alway on a boat or RV.
Well i'm but that is my life

 

[mikefitz]

For the rest.
No you are wrong .

Perhaps something was lost in translation.
The second part of the reply was my explanation: why it was sugested 'a battery to battery charger is needed' ?
This would be only needed if a charger for the starter batteries, not a maintainer, was required in the system.

 

[Suijkerbuijk]

Perhaps something was lost in translation.
The second part of the reply was my explanation: why it was sugested 'a battery to battery charger is needed' ?
This would be only needed if a charger for the starter batteries, not a maintainer, was required in the system.

I do not know wy the sell have tell that .
And if a translation Fault than its my mistake.

And no he do not need a dc to dc charge.

Only reason i can think of that the seller advice this.
And ts (topic starter) make a mistake or misunderstanding.
And that the seller mean that dc to dc charger on the RV battery side to charge the lipo4 with a alternator.
Than the seller is correct .

I will adjust my other Replay on you to thake out my mistake.

 

[tpenfield]

@tnscad - A bit more information about the boat may be helpful. Powerboat or sailboat?

Also, if you plan on using the engine alternator(s) to charge the LFP batteries, you may have a DC-DC charger in the mix. Otherwise, the size of the solar panels will be an important consideration.

FWIW - The solar aspect of the system that I designed for my boat is intended battery maintenance on both the LFP and LA banks. the EPEver does a nice job of that. If/when bulk charging is needed, it is up to the alternators. I have a recent thread here in the Marine section, if that is helpful.