Hi, how can I best charge an 48V bicycle battery by using 12V solar panel? I still want to have the MTTP function integrated. I do not find any application within VICTRON database. Could it be handled with a 12V PV (17-22V)=> DC/DC => 60V IN / MTTP Controller => 48V (48-56V)Battery? Any idea?
Rule with MPPT is that the panel voltage must be 5V higher than the battery. So for a 48V battery you need close to 60V.
Chances are that it's not going to work, even with a boost converter as the MPPTs are designed to go direct to a battery, not to a converter which will present a fluctuating load.
You'll either need to find a higher voltage panel, or use multiple panels in series to increase the voltage into the MPPT. Panel voltage of 24V is nominal. The figure you need is the open circuit voltage, usually referred to as Voc. Two 24V panels in series may work.
I have no idea, sorry, but if I understand your question correctly, you are looking for a "dc booster" or a "reverse buck converter".
Not sure how this would work, but I guess if it would work, the charge would be slow (unless current is big from solar panel) as you would have to account for some efficiency.
Q1: Could Orion-Tr 24/48-8,5 (400 W) be used as a "linear" "boost converter" (without regulation) together with SmartSolar MPPT 100/20 for charging 16S LFP with solar power from one/two/three "12 V" 100W Rigid Solar Panel(s) connected parallel? Orion-Tr (IP43) preferable located close to the solar panels to prevent cable losses by using higher voltage and lower current.
Solar panel(s) (100W): 20,3 V VOC, 17,1 V VMP, 5,9 A IMP and 6,3 A ISC (=> 3xIMP = 17,7 A, 3xISC = 18,9 A). Three panels in series is 60,9 V VOC and 51,3 V VMP (LFP 51,2 V @ 20 % SOC), not enough to charge 16S LFP with SmartSolar MPPT 100/20.
1) Data sheet: "Orion-Tr DC-DC converters isolated" 100 / 250 / 400 Watt
file: "Datasheet-Orion-Tr-DC-DC-converters-isolated-100-250-400W-EN.pdf" [no date on data sheet, pdf created on 27.2.2023]
"Orion-Tr 24/48-8,5 (400 W)
Input voltage range: 20-35 V (1), Under voltage shut down: 14 V, Under voltage restart: 15 V
Nominal output voltage: 48,2 V, Output voltage adjust range: 40-60 V
Cont. output current at nominal output voltage and 40°C: 8,5 A [x 48,2 V = 410 W]
Maximum output current (10 s) at nominal output voltage minus 20%: 15 A [x 38,56 V = 578 W]
Cont. output power at 25°C: 480 W
Efficiency 89 %
No load input current (2) < 120 mA
1,6 kg IP43 130 x 186 x 70 mm (5.1 x 7.3 x 2.8 inch)
(1) If set to nominal or lower than nominal, the output voltage will remain stable within the specified input voltage range (buck-boost function).
If the output voltage is set higher than nominal by a certain percentage, the minimum input voltage at which the output voltage remains stable (does not decrease) increases by the same percentage."
2) Orion manual: 4. Adjustable output voltage:
The default values are 12,2 V, 24,2 V or 48,2 V, depending on the model.
The output voltage can be set between approximately - 15 % to + 25 % of the default output voltage by turning the potentiometer.
3) Case 1:
Set Orion output (VOUT) to 60 V = +24,45 % to start SmartSolar MPPT 100/20 for 16S LFP (="5 V above").
Input voltage range: starts at 20 V +24,45 % = 24,8 V (?) vs. solar 20,3 - 17,1 V (= solar voltage is under the adjusted nominal range => VOUT from Orion varies according to the input?).
Q2: Does this setting affect the "Under voltage shut down" or "Under voltage restart" voltages?
If yes then:
=> Under voltage shut down 14 V +24,45 % = 17,42 V (= below VMP, not ok !)
=> Under voltage restart 15 V +24,45 % = 18,67 V (= below VOC, ok)
4) Case 2:
Set output +22,1 % to lift Orion 14 V shut down to the panel VMP 17,1 V.
Then VOUT = 1,221 x 48,2 V = 58,85 V (this is just "5 V above" for MPPT in order to start charging (16S LFP 53,6 V @ 90% SOC and Victron LFP: "Charge voltage [2x] 28,4 V recommended" = 56,8 V).
Q3: could there be a new and efficient Victron SmartSolar MPPT with boost function from 12/24 V solar panels to charge 48 V batteries serving all old panel and new single panel users?
MPPT input should be from panels, not from a DC-DC converter. Wire your array correctly, to achieve the required vBatt +5v input to charge your 48v battery bank, or alternatively you can look into a Boost controller from another manufacturer such as Genasun, who specializes in very niche applications such as you require.
