​Victron BlueSolar MPPT as generic DC-DC charger?

[john61ct]

This line looks excellent for its flexibility in accepting inputs and programmable output setpoints.

Would it work in a non- (actually pre-) solar context, outputting a precise voltage, from a mix of inputs at different voltages and current levels?

Obviously you'd need to be careful the total voltage didn't exceed the input spec, but it seems going higher than rated current is OK, the unit just limits the output current going into the battery.

There is a minimum "start voltage" requirement of +5V over the bank's, but even a very low-current say 24v source would take care of that.

I'm thinking, since I want to be set up for a future solar install, going this way may save me having to also buy a high-amp Sterling battery-to-battery charger for split-charging banks of unlike chemistries.

[mbartosch]

The Victron MPPTs are nice devices, and they do not have to be powered by solar panels, any DC source in rated range should do. Not so sure about DC sources with some ripple, though.
However, note that they do not step up voltage. The manual clearly states that for the regulator to work the input voltage must be a few volts higher than desired output voltage.
The regulator losses are higher at the extremes of the input voltage range, optimum efficiency is somewhere in the middle of rated voltage range.

The Sterling DC/DC chargers are the only battery to battery chargers I found which actually step up voltage. AFAIK they are the only way to properly charge a 12 V lead acid battery from a 12 V source.

[noelex 77]

Originally Posted by mbartosch

The Sterling DC/DC chargers are the only battery to battery chargers I found which actually step up voltage. AFAIK they are the only way to properly charge a 12 V lead acid battery from a 12 V source.

Mastervolt also produce something that will do this. 12v to 12v or 12v to 24v or 24v to 12v.
Mastervolt - Innovative power systems<br>for autonomous use

[john61ct]

All on my list to investigate, I'm sure many/most do boost: Votronic, Projecta, Redarc, ABR Sidewinder, Tecmate, Thunder, Intervolt, Ironman

Some do include a low-end MPPT solar controller like the CTEK Dual. But most are designed to feed off a running alt, very few specify they will run a static Bank1 down to feed Bank2.

Neither use case is specific to this thread topic, just keep the actual charge sources open-ended, whole point is to be able to accommodate pretty much any source type.

I do like the Sterling line, and would consider other traditional DC-DC options as well, as long as they have the ability to program custom voltage output setpoints.

And **ending** Absorption based on a low-CURRENT setpoint would be ideal, or at least lowering voltage to a custom float a distant second.

That last so far I've only seen in the solar controller world.

It's the flexibility on input that really intrigues me with the Victrons, long as you keep your stacked-series voltage within spec, a wide range of high or low currents will keep topping up the target bank.

[baycruiser]

I dont like complications so I use a basic multistage real good charger from my pure sine 1500w inverter which is powered by 24v bank(2n70 100$each) to charge my 12v(same) bank when I am not there my system is all working gently and seems to be very affective .when I am onboard (most times) I manually switch on and off 12v charger and water heater (10l electric ) as needed this is good as it keeps me aware of status .My panels are standard house 24v panels work well and cheap .This system has been thru many years of experimentation and I use my boat on anchor NO marinas too hot and gossipy for me hate power leads,rent,ins,etc so I just use what ive got and NO MORE .The TOTAL cost of this system was under 2K,, batts,reg,inv,panels,charger.hot water heater,gene I live most times near tropic or cap never use cheapest possible gene good ones dont last and I dont use them enuf .DONT LET AN ELECTRICIAN NEAR MY BOAT EVER . My policy if something fails I will try to fix once or replace new ( mistakes are an opportunity to learn),Surprising how many geeks out there who can fix anything and usually when they fix it stays fixed
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[john61ct]

Running an AC --> DC converting charger off an inverter that is converting DC from a battery bank --> AC does not seem "simple" nor energy efficient, but I can see if you have lots of solar maybe not much of an issue.

I am hoping to avoid AC powered appliances completely, so may not need an inverter at all.

But thanks for outlining your setup, sounds like it's working well, for you.

[baycruiser]

Originally Posted by john61ct

Running an AC --> DC converting charger off an inverter that is converting DC from a battery bank --> AC does not seem "simple" nor energy efficient, but I can see if you have lots of solar maybe not much of an issue.

I am hoping to avoid AC powered appliances completely, so may not need an inverter at all.

But thanks for outlining your setup, sounds like it's working well, for you.

During the day from 9am I have plenty of solar so waste is irrellevent but I also use 240 freezer set up as frig which runs 24/7 these appliances I dont find at all inefficient and in use daily I am aware of all the so called xpirts but my experience is absolutely all positive with ac pwer via solar to inv to ac just use most in daylight hours 240 appliances are MUCH cheaper easier to replace and very efficient my whole system costs less than a12v frig .dont dismiss it too soon .I have tried a lot of sysems and I live my system dont theorise it.. O I know they will all poo.poo it ,I still use a 12v system for water,lites,loo,tv,anchor winch.etc no probs I am VERY happy but hard to even get others to open their minds to opportunities opened up by 24v panels good qaulity reasonably priced inverters