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Old 01-08-2013, 12:43 AM
Matter45 Matter45 is offline
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Default Estimate BMS cost per lithium battery?

I think the title sums it up.

lets say you wana use 3.2v 40ah batteries with a total pack of 20kwh.

thats 156 batteries.

All yo experienced converts please stand up

P.S it has to be a realistic figure.
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Old 01-08-2013, 01:33 AM
TEV TEV is offline
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Default Re: Estimate BMS cost per lithium battery?

You have to specify the voltage of your battery,configuration and so , you're mentioning 156 cells * 3.2V = 499.2V if this is what you want , it would be expensive, because it's depend of the number of the cells in series.

http://liionbms.com/php/bms_options.php


http://liionbms.com/php/bms-selector.php
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Old 01-08-2013, 06:47 AM
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Default Re: Estimate BMS cost per lithium battery?

You need to define your request--Do you want Battery Management or Battery Monitoring ?
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Old 01-08-2013, 10:07 AM
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Default Re: Estimate BMS cost per lithium battery?

Quote:
Originally Posted by Matter45 View Post
[Let's] say you [want to] use 3.2v 40ah [cells] with a total pack of 20 [kWh]. [That's] 156 [cells]. All [you] experienced converts please stand up.
I assume that all the cells are in series.

I looked it up in the BMS selector:
  • Cheapest analog BMS, centralized or distributed: CleanPower MiniBMS: $ 1926*
  • Cheapest digital BMS, distributed: Elithion Lithiumate Lite: $ 1763
  • Cheapest digital BMS, centralized: Ewert Orion BMS: $ 1490*
*) Wiring harnesses not included (for 156 cells, for the Orion BMS, about $ 154)



In order of ease of installation and configuration:
  1. MiniBMS, distributed
  2. MiniBMS, centralized
  3. Lithiumate Lite, distributed
  4. Orion BMS, centralized
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Last edited by Elithion; 01-08-2013 at 11:53 AM.
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Old 01-08-2013, 03:43 PM
Matter45 Matter45 is offline
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Default Re: Estimate BMS cost per lithium battery?

wow, over $1000?

Ok lets be a little more specific. 3.2v 40ah batteries. say 125v battery pack in series of 4. 39 batteries per series.

you want the BMS to do balance charging, cut off power if voltage is to high when charging and cut off power if voltages gets too low. and whatever extra the system may come with.

Would this still be over $1000? does anyone have experience installing a BMS system?
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Old 01-08-2013, 03:57 PM
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Default Re: Estimate BMS cost per lithium battery?

You can be as specific as you want.... Go to the links above.... you have everything you need to make all sorts of different configurations. Play around with it.

And you should parallel the batteries FIRST, then series.... If you have 4 series packs of 39 cells and 4 of those in parallel, you still need 156 BMS channels because each cell could have a different voltage. If you parallel first, you get all 4 cells on the same channel at the same voltage, and would only need 39 channels of BMS.

Since you want Balancing, choose "YES" under "SOC Balancing"

I have experience with both Elithion and Orion BMS systems and own an Elithion myself.... but all of the things I've learned are on the web (www.elithion.com and www.orionbms.com).
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Old 01-08-2013, 06:54 PM
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Default Re: Estimate BMS cost per lithium battery?

Quote:
Originally Posted by Matter45 View Post
wow, over $1000?

Ok lets be a little more specific. 3.2v 40ah batteries. say 125v battery pack in series of 4. 39 batteries per series.

you want the BMS to do balance charging, cut off power if voltage is to high when charging and cut off power if voltages gets too low. and whatever extra the system may come with.

Would this still be over $1000? does anyone have experience installing a BMS system?

why not simplify number of connections with bigger ah prismatics? and.... a BMS is *not* an absolute requirement; there are a number of us that subscribe to the top-balance and 'go commando' let the charger do its thing at end of charge without any BMS or cell level monitoring. If you do a good initial parallel balance, then good final tweak in series before buttoning up, and have no parasitic loads on partial pack to unbalance, Li cells seem to stay remarkably balanced.... so far, in my experience.
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Old 01-08-2013, 07:20 PM
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Lightbulb Re: Estimate BMS cost per lithium battery?

I have been thinking about designing a BMS which would consist of one PCB per cell. It would incorporate a shunt MOSFET which would offload charge current above a specified limit, such as 4.2 volts, and send a signal which could be used to reduce or stop the charging at that point. It would also send a signal if the cell voltage dropped below a minimum level, such as 2.5 volts. I think such a device can be made for about $5 each, or less in quantity. So a 150V (50 battery) pack BMS would cost $250, and a 600V BMS would be $1000. I'm assuming a 10 amp maximum charge current so that the offloading device would be limited to about 40 watts of dissipation. But if the BMS can control the charger it could allow much higher initial rates and then start bypassing cell charging current toward the end of charge when the first cell reaches its peak level.

It's possible that a device such as this could be made for much less, or perhaps designed for groups of 4 (12V), 8 (24V), or 12 (36V). My idea is to have this device always connected to the battery pack and constantly sampling the SOC, while drawing no more than about 100 uA average, which would take 50,000 hours to take a 10 Ah cell to 50%.

The same basic design could be used to perform a full load capacity test by discharging the cell through a load at a specified rate and tracking the voltage over time. The information could e stored in EEPROM or dumped continuously to a PC over a USB port. There are USB PICs that sell for less than $1.30 each in 100 pc quantity.

If you think this is a project worth pursuing, please give me your "wish list" of specifications and actual charging and discharging parameters so I can see what it would take.
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Old 01-08-2013, 08:32 PM
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Default Re: Estimate BMS cost per lithium battery?

Quote:
Originally Posted by PStechPaul View Post
I have been thinking about designing a BMS which would consist of one PCB per cell. It would incorporate a shunt MOSFET which would offload charge current above a specified limit, such as 4.2 volts,
you obviously don't understand *much* and hide it behind technobabble. waiting till 4.2v would certainly be too late for any cell ... the rest of your proposal thus loses all credibility.
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Old 01-08-2013, 09:15 PM
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Thumbs down Re: Estimate BMS cost per lithium battery?

Quote:
Originally Posted by dtbaker View Post
you obviously don't understand *much* and hide it behind technobabble. waiting till 4.2v would certainly be too late for any cell ... the rest of your proposal thus loses all credibility.
I don't appreciate the tone of your response. I'm trying to present an idea that may help people, and my 4.2 volt cutoff is merely a representative number. I think it is YOU who don't understand much, as evidenced by your "technobabble" quip. And you also ASSUME this is for LiFePO4, which are nominal 3.2V, but I am also looking at LiPo cells with a nominal 3.7V and a 4.2V cutoff. Look at this picture of some cells I am considering:



Would you care to apologize, or are you not "man enough" to admit your own lack of credibility (and manners, for what that may be worth).
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