I currently have a solarc 15 inverter and a 1000ah lead acid 48 volt battery. My old system still has some life in it and I use the inverted power to power a 110ac/48v dc battery charger to move power from the old battery Bank onto the new one on rainy days. Is there a more efficient way of doing this? Is there a DC to DC charger of some sort to eliminate inverting the power back and forth. Or is what I'm doing a reasonable plan?
Moving power between battery Banks
- Thread starter tylarson
- Start date
sunshine_eggo
Happy Breffast!
Looking at just the battery to battery portion, what you're doing is about 75-80% efficient. DC-DC is going to be 85-90% efficient.
Lead acid requires you input about 15% more input than you use due to charging inefficiencies, so you're up against that no matter what.
The more efficient method would likely be to take your old system offline and add the PV/controller to directly charge your main battery.
Otherwise, if it's working for you, don't fix it if it ain't broke.
Lead acid requires you input about 15% more input than you use due to charging inefficiencies, so you're up against that no matter what.
The more efficient method would likely be to take your old system offline and add the PV/controller to directly charge your main battery.
Otherwise, if it's working for you, don't fix it if it ain't broke.
pollenface
Solar Addict
What is the voltage of the other bank?
I sometimes use a boost converter to move power from my 12v bank to the 48v bank.
I sometimes use a boost converter to move power from my 12v bank to the 48v bank.
The older battery bank is 24 volt lead acid battery
sunshine_eggo
Happy Breffast!
How is it being charged?
DIYrich
Solar Wizard
Victron Orion-TR 24/48-8.5
The 24 volt battery bank is being charged by its own solar field going through an Outback charge controller
sunshine_eggo
Happy Breffast!
Not really.
Now you're maybe 5-15% more efficient in an already inefficient process, per above:
Now you're spending $200+ on 400W of charging, and that's not a charger, it's a converter that only puts out a specific voltage you select.
Is the 24V system actually in use? Why not decommission the system and hook the Outback MX/FM-60/80 to your 48V battery directly and get to 95% efficiency?
sunshine_eggo
Happy Breffast!
You motivation makes more sense now.
If nothing is running off the 24V system, turning the inverter off will consume less power as they consume power sitting there even with no loads active.
DIYrich
Solar Wizard
If you time the 24v to 48v transfer for the right time, the power can be used right away, and not be stored in the battery. That will get you a few more % efficiency.
The victron has 2 wire on/off control. If you can tap into the minisplit, it might be able to turn on the victron when it is running.
This is a really great idea. thank you
Thank you again for all the help you guys. Okay, so I've learned from you that going from 24vdc to 120vac and then back to 48vdc is inefficient but not that big of a deal. If I measure the power going into the charger it's 120 vac/ about 10 amps and when I measure the power coming out of the charger it's 52 vdc at about 10 amps. Does that mean I've lost roughly half the power? Also the meter on the beleeb battery charger says 17 amps at 52 volts are going into the battery. I wonder if I should believe the display on the charger or or my fluke meter. What are your thoughts? Thanks in advance.
I learned something interesting, I bought a chargeverter from eg4 and it is extremely efficient compared to the beleeb battery charger that I've been using. The conversion inefficiency has been consistent with what you have posted, thank you for your input or I probably would have been using that inefficient charger for another decade
