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Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery
BMS, load, charger, capacity monitoring would be none-the-wiser.
One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail.
If the failure is a short, it would bring the other cell with it.
?
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel,
but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for
some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel?
I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that?
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On Nov 8, 2023, at 14:40, bobkart <couch45@...> wrote:
?
Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery
BMS, load, charger, capacity monitoring would be none-the-wiser.
One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail.
If the failure is a short, it would bring the other cell with it.
?
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel,
but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for
some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel?
I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
Why not use 500AH cells? Make a single 16s string and keep it simple? Does Victron make a BMS that can communicate with your charger? For my twin 10kW motors. I have a single 16s string with 1,000AH Winston cells. Works well.?
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Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ?
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From: [email protected] [mailto:[email protected]] On Behalf Of ChristopherH via groups.io
Sent: Wednesday, November 8, 2023 11:49 AM
To: [email protected]
Subject: Re: [electricboats] Parallel LiFePO4 Packs? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
Downsides to paralleling two separate strings is you will need two BMSs.
And if the strings are sometimes not in parallel, then separate capacity monitoring is called for.
Charging can happen in parallel, but only when the strings are connected.
Can you help me understand when you'd want parallel versus separate for the two strings?
Once they drift apart significantly voltage-wise, you won't be able to just reconnect them in parallel.
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Reuben, Thanks for the reply. I haven’t given that much consideration yet. Seems like I’ve heard possible reliability issues with the larger cells, maybe not a concern. The other thing for me is the configuration of my battery boxes limits me some in the physical size of the cell I can work with. Also, I was thinking from a reliability standpoint. Having 2 independent banks with each having its own BMS, but that can run in parallel would be more fault tolerant. I have a fear, maybe not legitimate of a BMS leaving “dead in the water”.
Chris
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On Nov 8, 2023, at 14:59, Myles Twete <matwete@...> wrote:
? Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ? ? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
Miles, Thanks for the reply. I currently have 2 X 48V banks of golf cart batteries. Each bank has a Blue Sea 300A rated on/off switch that ties to a common 48V bus. I have ram in parallel, never one bank at a time. It is nice though to be able to take one bank out of service to clean connections, etc. without killing the whole system as the 48V is also my house bank feeding the inverter, DC-DC converters for 12V stuff and to a controller for my 24V windlass. Thoughts?
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On Nov 8, 2023, at 15:08, Chris Hudson <clh5_98@...> wrote:
? Reuben, Thanks for the reply. I haven’t given that much consideration yet. Seems like I’ve heard possible reliability issues with the larger cells, maybe not a concern. The other thing for me is the configuration of my battery boxes limits me some in the physical size of the cell I can work with. Also, I was thinking from a reliability standpoint. Having 2 independent banks with each having its own BMS, but that can run in parallel would be more fault tolerant. I have a fear, maybe not legitimate of a BMS leaving “dead in the water”.
Chris
Chris? Sent from myPhone On Nov 8, 2023, at 14:59, Myles Twete <matwete@...> wrote:
? Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ? ? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
I have had a cell fail. I just removed it from the string making it 15s - I list a bit of AH but the motors run fine.?
if a BMS were to fail leaving you stranded, just disconnect it temporarily and keep a close look on cell voltages while motoring home to prevent a cell discharging too much.?
I originally had two banks of AGM batteries - completely separated with their own panels for loads and their own charging sources. When I went to LFP I chose to make a single battery pack. This makes life much simpler. And as others have noted, combining two batteries in parallel with voltage disparities can lead to disaster.?
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Bobkart, As I mentioned earlier to Reuben, I have a fear of a BMS failure ruining my day. I would like them in parallel for capacity reasons, and separately for failure reasons. I don’t think I’d ever run with them separate. Thoughts?
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On Nov 8, 2023, at 15:08, Chris Hudson <clh5_98@...> wrote:
? Reuben, Thanks for the reply. I haven’t given that much consideration yet. Seems like I’ve heard possible reliability issues with the larger cells, maybe not a concern. The other thing for me is the configuration of my battery boxes limits me some in the physical size of the cell I can work with. Also, I was thinking from a reliability standpoint. Having 2 independent banks with each having its own BMS, but that can run in parallel would be more fault tolerant. I have a fear, maybe not legitimate of a BMS leaving “dead in the water”.
Chris
Chris? Sent from myPhone On Nov 8, 2023, at 14:59, Myles Twete <matwete@...> wrote:
? Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ? ? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
Reuben, Would not the BMS protect the packs if they were inadvertently paralleled when having different states of charge?
Chris
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On Nov 8, 2023, at 15:19, Chris Hudson <clh5_98@...> wrote:
? Bobkart, As I mentioned earlier to Reuben, I have a fear of a BMS failure ruining my day. I would like them in parallel for capacity reasons, and separately for failure reasons. I don’t think I’d ever run with them separate. Thoughts?
Chris Sent from myPhone On Nov 8, 2023, at 15:08, Chris Hudson <clh5_98@...> wrote:
? Reuben, Thanks for the reply. I haven’t given that much consideration yet. Seems like I’ve heard possible reliability issues with the larger cells, maybe not a concern. The other thing for me is the configuration of my battery boxes limits me some in the physical size of the cell I can work with. Also, I was thinking from a reliability standpoint. Having 2 independent banks with each having its own BMS, but that can run in parallel would be more fault tolerant. I have a fear, maybe not legitimate of a BMS leaving “dead in the water”.
Chris
Chris? Sent from myPhone On Nov 8, 2023, at 14:59, Myles Twete <matwete@...> wrote:
? Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ? ? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
It is my understanding that the BMS only protects the battery cells from over or under voltages - there may be some out there that can handle connecting/disconnecting a pair of battery packs safely - I have never researched this.?
my guess is you can find a Victron BMS that can communicate with your Victron charger/inverter. This would be a good thing.?
if space requires use of pairs of smaller cells, I’d suggest you build the pack with pairs of cells. As mentioned, each pair would be treated like a single cell by the BMS. If a pair is out of spec, you’ll have to unwire and test the cells to see which one is faulty. I’d suggest you buy a couple of extra cells to have handy for replacement or just take the pair out of the string and run 15s until you can get replacement(s).?
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I don't have a LOT of experience with this, but am now running my electric dinghy with two separate 48V ebike batteries.
I like keeping them separate so that if one gets accidentally discharged (or any other failure), I still have a second battery to get home on.
On Wednesday, November 8, 2023 at 01:59:35 PM CST, Myles Twete <matwete@...> wrote:
Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ?
From: [email protected] [mailto:[email protected]] On Behalf Of ChristopherH via groups.io
Sent: Wednesday, November 8, 2023 11:49 AM
To: [email protected]
Subject: Re: [electricboats] Parallel LiFePO4 Packs ? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
John, Thanks for your input and good point about having an ace in the hole! Chris?
Sent from myPhone
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On Nov 8, 2023, at 16:22, john via groups.io <oak_box@...> wrote:
?
I don't have a LOT of experience with this, but am now running my electric dinghy with two separate 48V ebike batteries.
I like keeping them separate so that if one gets accidentally discharged (or any other failure), I still have a second battery to get home on.
On Wednesday, November 8, 2023 at 01:59:35 PM CST, Myles Twete <matwete@...> wrote:
Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ? ? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
Reuben, From what I’ve seen, Victron only have BMS for their line of packaged batteries in the 12 and 24 volt ranges.
Chris? Sent from myPhone
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On Nov 8, 2023, at 16:55, Chris Hudson <clh5_98@...> wrote:
? John, Thanks for your input and good point about having an ace in the hole! Chris?
Sent from myPhone On Nov 8, 2023, at 16:22, john via groups.io <oak_box@...> wrote:
?
I don't have a LOT of experience with this, but am now running my electric dinghy with two separate 48V ebike batteries.
I like keeping them separate so that if one gets accidentally discharged (or any other failure), I still have a second battery to get home on.
On Wednesday, November 8, 2023 at 01:59:35 PM CST, Myles Twete <matwete@...> wrote:
Thought: Dangerous for the switch unless it’s a break-before-make or other exclusive-or arrangement. ? Why: You’ve been running for hours on one string, then decide to switch to the other.? If you thought that you’d just use a standard marine battery combiner switch, you could accidentally switch to “ALL” position, which would then put both strings in parallel thru the switch, quickly shorting it and possibly melting the housing.? Might also have a problem with that type of switch switching between each string. ? With Lithium-Ion there’s something to be said for having separate strings---ability to switch and get a higher pack voltage again for a time giving higher power/speed than if the strings were paralleled and slowly going down together.? But really, a slowly dropping voltage is better than one that drops much faster due to not paralleling.? Not as much of a big deal with LiFePo, but still, I’d tend to think paralleling is better. ? Just a thought. -MT ? ? Bobkart, Thanks for the reply. Actually I’m proposing to have 2 independent 16 cell strings with the ability to parallel them at the 48V level with switches, not at the cell level. Thoughts on that? Chris? ? Connecting two 230Ah cells together in parallel (sixteen times) would allow you to treat the 32 cells as one large 16S 48V x 460Ah battery BMS, load, charger, capacity monitoring would be none-the-wiser. One concern of that configuration that wouldn't otherwise come up is if one cell in a two-cell pair were to fail. If the failure is a short, it would bring the other cell with it.
Hi Group,
My Morgan Out Island 41 is ready for new batteries. I’m ready to embrace LiFePO4. When I originally converted to electric I built and glassed in 2 battery boxes to hold 2 banks of 8 (16 batteries) golf cart batteries. I always run with both banks in parallel, but have the ability to run on just 1 and this has worked well. Unfortunately this size battery box doesn’t make efficient use of most individual LiFePO4 cells. I would however be able to use 32 X 230Ah EVE cells in 1 battery box, leaving the other box for some other purpose. My questions: I’d like to be able to run the 2 X 16S strings in parallel. Is this possible with LiFePO4? Is it safe to do this? Any precautions? Would I have 2 separate BMS units? How about capacity monitoring for the 2 banks in parallel? I have a Victron 48V/5KVA Victron Quattro charger inverter.?
Thanks in advance for any assistance/suggestions.
Regards,
Chris Hudson
Sent from myPhone
|
I found this great article by Orion BMS that discusses parallel strings. Reading this really makes me lean toward parallel cells as you wise gents previously suggested.
Thanks again for all the valuable input.
Chris? |
bobkart
Reuben Trane