bit of a different one today . . .
with all this loverly sunny weather (aug 2020) i though i would utilise the shed solar system to charge up the new Lifpo4 battery box.
see the shed setup here:
Solar Sheds & Other Non-T6 Solar Projects - How We Done It - @Pete C requested it, so here it is . . . . . Dell, What do the batteries in your shed power ? I too have a solar powered shed - perhaps we should have a separate thread for sheds :) Pete Lets Post here any NON - T6 related ECO...
www.t6forum.com
and the lifpo4 battery box here:
12v Lithium Leisure Battery Box 138Ah 1766Wh -- How I Done It -- It's about time that I got this long-overdue project sorted out. The missing parts are on order and completion is in sight . . . . . . . . ready for the Post Pandemic 2020 Camping Trips (Hopefully) This is where it started. p1...
www.t6forum.com
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so the idea is im going to use the twin 100ah SLA battery bank via a DC-Dc charger to charge the LifePO4 . .
heres the setup.
I've got the Victron Orion 30A dc-dc charger, fitted with Anderson connectors.
which is connected to the bus bar for the batteries . . .
which is charge from the roof top solar array vis this Victron 100/20 MPPT , , , ,
once connected, then enabled vis the APP & Remote loop . . .
we have this . . . 30A charge rate,
which was great . . . . . but things soon started to heat up . . . .
withing 5mins the heat from the Victron was serious . . .
check out the Alien vision:
this thing was boiling !!!!
far too hot too touch , , , , ,
But why . . . . . ?
well we can see here:
The SLA 2x100ah battery bank was happy & fully charged @ 12.6v and being float charged but the mppt solar @ 13.2v . . . .
BUT . . . . . becuase the Lifepo4 will MAX charge from ANY charger upto almost 100A we maxed out the Victron orion @ 30A.
This then in turn started pulling 30A from the battery bank.
which caused volt drop . . .
you can see below the solar was adding 14.2A into the mix, b ut it wasnt enough.
you can see the volt driop here on the BMV . . .
when drawing 27A the battery bank was being drawn down to 12.2v.
but the Orion was trying to charge the lifepo4 at 14.6v . . .
which caused this scenario . . .
The shed battery bank volt drop was down to 11.9v @ 40A (orion input)
and the output was 14.3v @ 30A (orion output)
The reason the orion was gettingf so hot was due to the volt drop and the extra current being drawn to try and boost up the voltage to charge the Lifpo4.
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Conclusion . . . .
This just goes to show how rubbish standard/sealed lead acid (SLA) batteries are, if you plan on pulling large currents.
they are fine for some basic fairly lights , but thats just about it.
They cant keep up with the current demand and just sag the voltage.
This also goes to show why AGM batteries are much, much better . . . . (much less volt sag under load, and a higher static voltage)
and also shows how awesome the Lifepo4 batteries are and how quickily they can be charged . . . . .
so:
Dont bother with standard SLA, heavy duty, deep cycle etc etc etc batteries for leisure applications.
Only look at AGM or better . . . .
Consider Lifepo4 if you are a power monster =]
Happy Summer peeps . . . .