Multiple Output MPPT

[rwells36]

Is anyone aware of an MPPT solar controller with multiple outputs for battery charging (two different banks)?

[Bleemus]

Get one of these instead . . .

[AedanC]

https://www.photonicuniverse.com/en/...PTcontrollers/

[belizesailor]

I have a BlueSky 3000i which has a dump load/secondary charger of 20A, but this is just for excess output (over and above what primary charge load is accepting).

What is the charge load confirguration issue you are trying resolve?

[john61ct]

Multi-output is rarely a worthwhile feature.

I agree best way is a combiner / ACR, and Blue Sea makes good ones.

Put the SC output on the larger most-used bank, usually "House".

If the other is just keeping a Starter topped up, a small-amp combiner or Echo Charger is fine.

If you need big currents flowing across, the the BS ML-ACR rated for 500+A is indestructible.

[john61ct]

MS ​SunSaver Duo used to be well recommended, but apparently has problems with chemistries other than old-school FLA

[belizesailor]

Originally Posted by john61ct

Multi-output is rarely a worthwhile feature.

I agree best way is a combiner / ACR, and Blue Sea makes good ones.

Put the SC output on the larger most-used bank, usually "House".

If the other is just keeping a Starter topped up, a small-amp combiner or Echo Charger is fine.

If you need big currents flowing across, the the BS ML-ACR rated for 500+A is indestructible.

Generally agree, but in order to recommend an appropriate solution, it sure would help to know what the OP is trying to do.

Ive got a multi-output shore power charger and solar controller...dont use that feature on either one, but rather a combiner configuration similar to what you suggest.

[sailorboy1]

Originally Posted by rwells36

Is anyone aware of an MPPT solar controller with multiple outputs for battery charging (two different banks)?

I solved my "need" for a multi output controller (because my house batteries were open FLA and my start was a sealed FLA) by just turning the start battery to OFF. I turn it on once in a while when the charge voltage is since in the start batteries range.

But I bet a cheap controller connected to the output on the MPPT controller would do what you looking for to charge at a lower voltage than what the MPPT controller is powering.

BTW - if you MPPT controller has an Aux relay feature I bet you could use it to only supply power to another batter during the desired voltage range. But I bet that would end up being as expensive as a cheap controller and be more complex.

[txg]

There are dual output MPPTs from german company Votronic:

VOTRONIC - MPP 250 Duo Dig.

We've been using two of those for about two years now and will install a third one soon, great products.

They have a main output and an aux (max. 1amps) which is fine for trickle-charging something like a starter bank.

Much better than an acr which will steal several Ah every day from charging the house bank just for being switched on.

[john61ct]

Originally Posted by txg

an acr which will steal several Ah every day from charging the house bank just for being switched on.

Not a good one.

The biggest Blue Sea ML rated at 500+A consumes at 13mA, or .013A. That's well under a third of an AH per 24 hours.

And it ensures that **all** of your charge sources on **either** circuit are charging both banks.

[GTom]

If your solar array is big enough, probably two controllers would be the best solution.

[john61ct]

No. The Starter batt needs hardly any AH / day input, while House needs as much as it can get.

Even a tiny Echo Charger can take care of the former.

[noelex 77]

It depends how the boat is wired. The start bank can be dedicated to just starting the battery, or it can also be used to power the windlass and/or bow thruster.

If the battery is just used to start the engine (which is the most common wiring seen these days) is it needs little power. Most lead acid batteries benigit from an occasional charge to 100% (or as close as is practical to this number). This is difficult to acieve using the alternator, but rather than installing a multi outlet solar charger, or device like an ACR, periodically, temporarily, switching on the emergancy start switch when the house bank is full is a simple solution.

If the battery powers the windlass and/or bow thruster an ACR or one of the low loss active split diodes is the best solution. This means any single outlet solar controller can be utilised.

The range of multi outlet solar controllers is not great and with the rapid pace of development (and reduction in price) of MPPT controllers generally you are better using seperate devices for controlling the solar power and then for splitting the power into multiple banks.

[Maine Sail]

Originally Posted by txg

Much better than an acr which will steal several Ah every day from charging the house bank just for being switched on.

A Blue sea ACR 7610 draws a maximum of 0.175A (175mA) when closed/operational. It would only be operational once the array could bring the house bank above 13.0V.. I have measured the actual power consumption closer to .139A. Also a simple ON/OFF switch can be installed for any ACR so that when it is not needed you simply disable it and let solar focus on the house bank..

If we were to assume the relay to feed the start battery was closed for about 4 hours per solar day it would consume .7Ah at the max rating or about 0.56Ah based on a field tested measurement.

If your array can't handle this then a Sterling Power ProLatch-R Combining Relay (a magnetic latching relay, only powered during opening or closing) would be a better choice for a small array.

MPPT performance varies widely, some are actually quite pathetic, and spend lots of time lost & looking for the power point when they should be charging. Better quality controllers use better algorithms that can track the power point much, much faster... On a constantly moving boat a fast tracking MPPT controller is important...

I would suggest focusing on choosing a fast MPPT controller, Genasun, Victron, Morningstar, Midnite, Outback etc... over a mutli-output MPPT controller. Start batteries rarely need any more than what the get from running the motor and the starting consumption is extremely low.

[Maine Sail]

Originally Posted by noelex 77

an ACR or one of the low loss active split diodes is the best solution. This means any single outlet solar controller can be utilised.

Most solar controllers, or any worth purchasing, need to sense a battery voltage in order to boot-up. Diode or FET based isolators, have no 12V or 24V signal on the input stud. With no voltage present on the input stud, the solar controller can't boot-up.

I have had to "fix" this issue on numerous boats. I had one owner send back three perfectly good solar controllers when the problem was the Mastervolt Battery Mate "smart isolator" which had 0V present at the input stud so the controller would not & could not boot up. It was actually not a problem of either device just a lack of understanding on the owners part of the compatibility between the two units.