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Add 36V Battery Block to 48V Battery System
#1
Hi,

ChrisD gave me a hint last year how he combined a 36V Battery to the 48V Main Battery System.
The short description is using a dc stepup module for loading the 48V Battery with the 36V one.
I thought about it and wonder how to load that 36V battery again.
I don't think that connection a step up in one direction and a step down module in the other direction is the right way, at least not without switching between them.



So another Idea was to find a bidirectional converter module, but up to now I did not find one fitting the needs of 36V to 48 Volt.



Does anyone have an idea of such an equipment that can deliver maybe 1500W?
Or any other solution that fits the needs to combine 36V and 48 Volt Batteries?

I also asked Chris via PM for a description of his system, maybe that already would fullfill the requirements, but I'm still curious about any other idea.

thanks in advance

cadric
1. Grid-Tie System 09.2017 16,5kWp:  55 x 300Wp BenQ, SMA Tripower 15000-TL30 (18-east/17-south/20-south)
2. Offgrid System 09.2019 7,5 kWp: 25 x 300Wp Solarworld (5x( 3S + 2S )), 2x PIP-5048MS, Batrium WM4, 1st Battery Bank: 840 cells in 14S60P with 80Ah cap in use, 2nd Batterybank 840 cells in14S60P with 90Ah in use, more to be build.
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#2
Step up/down at any kind of serious power level doesn't sound practical.   How many amps are we talking here?

Maybe rebuild the 36v battery packs into a 48v configuration?
OR
2 parallel systems? - e.g. 2 x Charge Controllers (one to charge 48v battery bank and 1 to charge 36v battery bank) and maybe 2 x Inverters?
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#3
A good quality step up/down converter will have a 10-20% loss is power conversion... it's pretty significant, along with the cost of the converter.

Its viable for smaller loads, but a poor solution for a pack/system voltage mismatch on a large system.
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#4
Hi,

I have 2 PIP5058 that I planned to cascade for the 48V system.
But as the main source now are 36V 10S e-bike batteries I didn't want to take these apart any more,
because that always destroise some of them and  aditionally makes a lot of work afterwards.
20% loss is not a problem, because the Batteries are free except the Converter and BMS.

Regards

cadric
1. Grid-Tie System 09.2017 16,5kWp:  55 x 300Wp BenQ, SMA Tripower 15000-TL30 (18-east/17-south/20-south)
2. Offgrid System 09.2019 7,5 kWp: 25 x 300Wp Solarworld (5x( 3S + 2S )), 2x PIP-5048MS, Batrium WM4, 1st Battery Bank: 840 cells in 14S60P with 80Ah cap in use, 2nd Batterybank 840 cells in14S60P with 90Ah in use, more to be build.
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#5
How much current do you need to be able to handle?
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#6
I don't know how much current. I thought about 4 to 6 batteryblocks connected to one dc-,dc convertermodule , so maybe Up to 30 to 40 A. Compareable to the DC Booster Module ChrisD used.
1. Grid-Tie System 09.2017 16,5kWp:  55 x 300Wp BenQ, SMA Tripower 15000-TL30 (18-east/17-south/20-south)
2. Offgrid System 09.2019 7,5 kWp: 25 x 300Wp Solarworld (5x( 3S + 2S )), 2x PIP-5048MS, Batrium WM4, 1st Battery Bank: 840 cells in 14S60P with 80Ah cap in use, 2nd Batterybank 840 cells in14S60P with 90Ah in use, more to be build.
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#7
(09-16-2020, 06:05 PM)cadric Wrote: I don't know how much current. I thought about 4 to 6 batteryblocks connected to one dc-,dc convertermodule , so maybe Up to 30 to 40 A. Compareable to the DC Booster Module ChrisD used.

I would use the Victron Orion Isolated DC-DC.  They are fully isolated so you can put them in parallel.

https://www.victronenergy.com/upload/doc...00W-EN.pdf

The 48/48-6 (280W model) accept an input voltage of 32-70v, so you could supply that with the 10s battery and ouput stable 48v (adjustable)

Add as many as you need in parallel for the required load.

Note, the larger 48/48-8 380 watt model input range is 40-70v so I would not use that one.  I still think its better to just change the battery setup.  I have a bunch of 36v stuff, and I get the struggle.
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#8
Hi Crimp Daddy,

But are they bidirektional? I can't see that exactly.
Regards

cadric
1. Grid-Tie System 09.2017 16,5kWp:  55 x 300Wp BenQ, SMA Tripower 15000-TL30 (18-east/17-south/20-south)
2. Offgrid System 09.2019 7,5 kWp: 25 x 300Wp Solarworld (5x( 3S + 2S )), 2x PIP-5048MS, Batrium WM4, 1st Battery Bank: 840 cells in 14S60P with 80Ah cap in use, 2nd Batterybank 840 cells in14S60P with 90Ah in use, more to be build.
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#9
(09-16-2020, 06:19 PM)cadric Wrote: Hi Crimp Daddy,

But are they bidirektional? I can't see that exactly.
Regards

cadric

They are not bi-directional... most DC converters (at least the one I know of) are directional.
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#10
OK.

Thanks for clarifying.

Regards

cadric
1. Grid-Tie System 09.2017 16,5kWp:  55 x 300Wp BenQ, SMA Tripower 15000-TL30 (18-east/17-south/20-south)
2. Offgrid System 09.2019 7,5 kWp: 25 x 300Wp Solarworld (5x( 3S + 2S )), 2x PIP-5048MS, Batrium WM4, 1st Battery Bank: 840 cells in 14S60P with 80Ah cap in use, 2nd Batterybank 840 cells in14S60P with 90Ah in use, more to be build.
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