dc to dc conversion using outback mx60 units

[Dreadstar]

 I recently asked for dc to dc conversion but most of what i find is very small amperage units. And prices are not that great for the higher amp ones. So question is:

  Take my panels and hook them to my MX60 controller for 48vdc out to my battery bank. run the cables into the house. then use a second mx60 to step the battery bank 48vdc down to 12vdc and distribute.

 If i do this should i hook atleast 1 decent size deep cycle battery between the loads and the mx60 or direct connect it? I know it is using a battery bank to charge another bank but. Would limit the stress on the 2nd mx60 during transmit cycles on the ham gear .

 Would i have less loss this way or more than if i get some step down converters for each load as applicable and run the distribution network at 48vdc some of the runs are fairly long 50'.

thanks

 Takes a college education to break the aircraft. Takes H.S. diploma to repair it.

 If your helicopter is not broken it soon will be.

  couple of ancidotes for ya. thanks for looking.

[Flux]

Assuming that a MX60 can charge one battery from another this should work fine.

If you are taking heavy loads at 12v then you will have better voltage stability with a decent battery across the load. As you say large converters are not easy to find.

You will have to satisfy yourself that the MX60 can be used in this mode, I suspect it can, but this is not the same as a current limited solar or hydro supply.

It is rather an expensive solution with the cost of an expensive controller and another battery but the battery would have a reasonably easy life and the second MX60 should as well.

Flux

[electronbaby]

Im pretty sure it CAN be used this way. Ive also heard that the mx60 can be used bi-directionally. It just has to do with changing some code. It is very versitile. My question is, if you are concerned with voltage drop into a 12 volt system and you cant change the bank voltage, why are you coming off the PV at 48v? the mx60 can take up to 125v (less voltage drop) and still go down to 12 v.  ??  maybe you only have 4 12v nom. modules??

[mungewell]

Outback are releasing the FLEXmax80, which is a soup'ed up mx60. I believe that this is tailored to work with micro-hydro (continuous supply voltage similar to your suggested arrangement).

The MX-60 isn't that cheap, but is rated for 60A output on the low DC side.

I don't understand why you need a second set of batteries (running at 12V), with a DC-DC converter the output voltage should be stable enough without and you won't have the wastes associated with charging/discharging. You might be able to attach a large cap instead.

What sort of loads are you talking about?

Simon

[boB]

>>I don't understand why you need a second set of batteries (running at 12V),

For one, the MX60 does not "come alive" with voltage from the PV (high voltage) side, as is.  And you can't just wire the input to the output without doing a bit of work... like maybe adding a smaller buck regulator that say, switches out once things get up and going (very carefuly)

And two, I think that the low voltage side (12V, 24V, etc.) voltage regulation response time to changing loads will be much better because a battery, even some

small battery, being more of a voltage source, will help while the slower responding charge controller has more time to regulate.

A buck converter can be made to have a fast response time, but being a charge controller, it's not quite ~THAT~ fast.

boB

[Dreadstar]

 i have 4 110ah batteries so i can go 12 24 or 48vdc the length of the run from the shed to the house is my primary concern since most of my equipment is 12vdc and losses are very high even using 2 pair of 6ga cables. Panels are 2 sharp 208 watt panels and i wire them in series to get the incoming voltage to the mx60 as high as possible. specs on the panels are Sharp 208U1 Vpm 28.71V Ipm 7.3A 12.8% efficiency. And since i can't add more panels at this location and since the panels are only about 60% as effective as they should be do to the smog here in anaheim. I am trying to lower the amount of wattage wasted inside wire.

 Also see that you are a ham. so....KI6EOD

 Hope this clarifies why i wish to do it like this. thanks