WBjr and balancer (converter)

[kitestrings]

So I have a question-

We don't currently have a Wzbr', but I hope to add one this summer.  We have a 48V bank with a 12V "tap".  We rely on Solar Converter's "DC Auto Transformer" - a misnomer really, but it is a bi-directional converter - to balance the two battery sections.   The converter has then a 48V (hi) positive and a 12V (low) positive terminal, but a common negative terminal.  My question then is if the negative lead is tied to the shunt will it introduce any inaccuracy to the WBjr being that not all of the current through it is: a) at the 48V nominal voltage, and b) moving in the same direction.  We charge at 48V, so most of the time the 48V bank is delivering to the 12V nominal tap, but it can be received as well.

May not be enough load to worry about, but had me wondering.

~ks

[CDN-VT]

Wiring diagram  or a sketch of your wiring hookup would REALLY help!
I use a 48VDC converter to 12Vdc on the outside of the shunt towards the load side  . Only battery - NEG is on the battery side.
Im reading your tapping off a battery bank to get 12Vdc.

Not recommended/good.

VT

[SolarMusher]

So I have a question-

We don't currently have a Wzbr', but I hope to add one this summer.  We have a 48V bank with a 12V "tap".  We rely on Solar Converter's "DC Auto Transformer" - a misnomer really, but it is a bi-directional converter - to balance the two battery sections.   The converter has then a 48V (hi) positive and a 12V (low) positive terminal, but a common negative terminal.  My question then is if the negative lead is tied to the shunt will it introduce any inaccuracy to the WBjr being that not all of the current through it is: a) at the 48V nominal voltage, and b) moving in the same direction.  We charge at 48V, so most of the time the 48V bank is delivering to the 12V nominal tap, but it can be received as well.

May not be enough load to worry about, but had me wondering.

~ks

Kit,
See Solarconverter, a ppt 48/12 converter would be far better. No need to tap your 48V bank and your WBjr will be accurate.
A+
Erik

[kitestrings]

Here's the wiring diagram (see 'Connected as a Battery Equalizer'):
https://www.altestore.com/store/media/pdfs/solarconverters/i-8038%20eq%2012-48-30.pdf

"Not recommend/good."

I would say, it is not   i d e a l,   but it works fine, and has for years.  We started with a small 12V system years (actually decades) ago.  When we finally made the leap to 48V - a good move and one I don't regret - we had, and still have, numerous 12V lights, a 12V DC fridge, two 12V water pumps, DC plugs/USBs, dimmers...  We also had a 12V source - a small wind turbine - up until just a few years ago.

The fridge is nigh on to 30+ years and still keeps the beer cold.  While we transitioned many loads over time to 48V or 120VAC, I couldn't see throwing away perfectly good "goods".  Lighting to this day is still available in a much wider range of temps, CRI, and options in 12V than 24V; certainly 48V.  Now one could say those options are also available with 120VAC, but they may not have been around long enough to remember just how far inverter efficiency and reliability have come.  And, the efficiency of say three or four LED lights on a 3, 5, 7 kW inverter is pretty dismal.  Folks tend to overlook this part of the power curve.

Erik, we do use a small PPT stepdown, and it works fine for a load within its capability.

There are some advantages of a "tap", with an balancer.  The converter does not have to handle the single highest, coincident load of the 12V loads.  The battery does that just fine, and balancer catches up in time.  Also, with a stepdown converter, if the thing fails you're potentially without critical loads - lights, water, COLD beer - if my converter/balancer fails, I go grab a battery charger and there's no rewiring while the repair is made.

There are reasons not to tap a bank - long term it affects longevity of the lower voltage cells - but using ,or not using, a Wzbjr is certainly not a good one IMHO.

~ks

PS, note to mod's - none of the quote, font, emoticons, etc. are working for me tonight for some reason.

[CDN-VT]

They way I read your post was "You tapped off one 12Vdc section of a Bank" """We have a 48V bank with a 12V "tap". """
Now using a converter as I do . your not quite tapping !
I use the same as your posted pix .so the load is still equal split on all cells .
Weird they show 36V + 12V batterys to mean 48Vdc, Better to use Symbols of electricity & keep things on an ISO.


Next "
We don't currently have a Wzbr', but I hope to add one this summer."
My question then is if the negative lead is tied to the shunt will it introduce any inaccuracy to the WBjr being that not all of the current through it is: a) at the 48V nominal voltage, and b) moving in the same direction.

NO if you connect the WBjr as per instructions .

I do the same for a few systems .

VT

Your thinking in the right direction

[kitestrings]

VT,

No, we do have a 12V tap.  Look at the schematic labeled "Connected as a Battery Equalizer", and described in Section 4.  We didn't buy it here, but this is the unit:

https://www.altestore.com/store/charge-controllers/battery-to-battery-dc-chargers/solar-converters-eq-1248-30a-dc-to-dc-updown-converter-p1291/

When we first went to 48V we had a both 12V loads, and a 12V charge source.  This unit handled both, it just works to keep the 12V section always at 1/4 of the full nom 48V) bank.  It's pretty slick actually.

We also have a small 48V/24 stepdown converter that runs a submersible water pump and a 24V Steca freezer.  Sorry for the confusion.

Perhaps the bigger deterrent to using the Wzbjr for us is the fact that we'd have to give up one of the Aux2 spots.  We have two, but I'm using one for load diversion (on waste not Hi), and the other for a homemade clipper for our turbine.  I'm considering moving the diversion to Aux1 and using that spot, but Aux2 is sooo smooth and fast.

~ks

[CDN-VT]

So All's Great & the WBjr is nice after you get to know how to go MM/Charge/Time/limits & see where you stand on that DAY !!
Then again run e-net & MM and do it that way , BUT still needs a WBjr.

VT

[kitestrings]

Sorry, what is "MM"?

[grgdgreek]

Mymidnite2.com