This sounds really useful. ?
And I wonder - At the ¡°whole boat scale¡± - since its likely all going to be stationary, couldn¡¯t you just provide a couple of circuits with downconverters or do you have individual loads that are > 60a? ?This is what I¡¯ve done recently when deciding to setup another boat with a single large 48v bank.?
I also considered 80a downconverters, but decided I didn¡¯t need them. ?One place for those is here:??
I did wonder but haven¡¯t tried to figure out if you could run the DCDC converters in parallel, do you know?
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On Apr 29, 2021, at 11:46 AM, Jeff LaCoursiere <
jeff@...> wrote:
We haven't had any bad cells imported yet, knock wood.? We *are*
doing our best to burn down our offices with our BMS experiments
though :)? Also, our latest batch was all EVE 280AH cells, the
Lishen 272AH are apparently "all gone".
Another cool idea we are kicking around... we want our 48v pack
to have a 12v tap, so you can use it as your house battery as well
as your traction battery.? I'm disappointed in the available
downconverters, mostly current limited to 30-60A.? Maybe that
would be enough for your house, but it wouldn't do it for mine.
So we want to try to cycle through internal banks of four cells,
very quickly (like 10khz), connecting them in turn to the 12v
tap.? We believe that this way you will be able to pull the full
1C discharge of the 16 cell pack (280A), but at 12v!? We hope to
maintain balance in discharge by cycling very fast, but the BMS
should pick up the slack.
Cheers,
Jeff LaCoursiere
s/v Angels Quest
On 4/29/21 11:34 AM, Carsten via
wrote:
Hi, Jeff
Did you experience
single/multiple cell dropouts from Lishen batteries so far ?
On Thursday, 29 April 2021, 23:22:13 GMT+8, Jeff
LaCoursiere
<jeff@...>
wrote:
I
wanted to comment on 1) below - we have that same
concept in mind.? We are working on a BMS design that
will basically allow cells to be "dropped out" of
series, the output run through a boost circuit to
maintain steady voltage.? There are of course limits
to how many can drop out and we are very much at the
experimental stage here, but there is some hope :)
Jeff
LaCoursiere
s/v
Angels Quest
First
Draft of Schematic. Using Lishen 202Ah. I decided to
go with the BMS only actively controlling the charge
side of the circuit and opted for passive monitoring
on the load side. Using a victron 712 for monitoring
and hopefully can connect it to a relay to shut off
charge circuit at predetermined voltage. Guys please
tell me what I have missed.
Couple
of points.
1) Passive Load
monitoring. I have decided to go this route as i
understand that the load BMS can turn off for 2
reasons, obviously first is if whole bank drops to
a lower than 20%SOC and secondly if single cells
fail. From my perspective if I have a single cell
failure I would rather still be able to use the
other 15 cells than have no power. If I let my
bank drop to below SOC of 20% that's?on me.
2) Want to keep house bank
separate?for now, mainly as if I have to shut off
my 48v bank for low SOC I don't want to have to
worry about all my electronics being offline.
3) I want a separate?relay
to shut off charge current so that I can set this
manually. When I come back from a sail i want to
be able to top bank up to about a 70% SOC for
storage. Then on the day I want to sail I can top
it off o 90%
--
Jeff LaCoursiere
StratusTalk, Inc.
703 496 4990 x108
815 546 6599 cell
--
Jeff LaCoursiere
s/v Angels Quest
St Thomas USVI
--
 |
Jeff LaCoursiere
STRATUSTALK, INC. / CTO
| Phone: |
+1
703.496.4990 x108 |
| Mobile: |
+1
815.546.6599 |
| Email: |
jeff@...
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Reston, VA 20190 |
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--
Jeff LaCoursiere
s/v Angels Quest
St Thomas USVI
