Re: [electricboats] Draft Schematic-Please give input

On Apr 30, 2021, at 9:38 AM, Carsten via groups.io <Carstensemail=yahoo.com@groups.io> wrote:

Another thing, how about making the motor wattage output adjustable, so it is possible to use eg. 96V for a burst mode ? Many 48V motors can be powered by 96V (or higher).

I assume that the wiring can handle that. Making two sets of banks 48V, to be serial connected to 96V.

The short "event" should of course be managed by the BMS/power management system.

This is interesting and something Ive wondered about but from what I've been able to discern it requires dynamically reprogramming the motor controller.  You could imagine a switching setup that let you have 48v traction banks in parallel but then to change them to series.  I wasn't able to figure out a way to use the Seven Gen4 to do this kind of thing, at least from reading the manual.  I fear I am about to venture into the world of the DVT software though and maybe its capable of that. I suppose if a person spent enough on controllers and cables you could have a dual system with two controllers and switch between them but I think you approach the point of diminishing returns. 

However, it points to a possible opportunity or maybe just a future feature that advanced motor controllers will enable.  With EV regen becoming more popular in controllers, I would not be surprised if some battery management features also start to migrate to controllers as well. 

To be true, things made in China is not my cup of tea, but in these days, unfortunately simply unavoidable !

I was a supervisor in China for several years, and know how they make things, and all of QC is not like in the West.

Buy a ME1616 electromotor. Made in China, then sold in the West.

Buy yourself a german or US car. Half of the smaller parts in it are made in China by now.

Company supervisors are not in China now, because of the Made in China virus.

Who wants to spend 2-4 weeks in quarantine to go for an inspection ??

Who's checking the quality now ?

As I spin up my own commercial efforts I have been working with colleagues in CN to understand the quality dynamics and the manufacturing landscape and while I think some of these comments are in a general sense applicable, I think that the demands of growing sophistication in their domestic market, growing domestic regulatory regime, and a drive to differentiate by rising to the QC and supply chain standards of Korea, Japan, US, and Europe is pressuring a lot of CN companies to advance.  I think now it is more a story of doing homework to understand your partners and their processes.

Now, the current chaos of the global shipping / logistics is another story! The Suez Canal incident has cost me several weeks and the knock-on effects will continue for months. 

However, I believe that new, checked, LiFePO4 batteries will last my sailing life out, but the electronics is another concern.

Especially in a marine environment (humid and salty).

Can you provide recommendations where to setup these (rather large) electronic regulators/inverters/BMS'es in the boat ?

I guess IP rating is not relevant, if not encapsuled in IP-rated boxes.

If put into boxes, then there's a cooling issue...

As far from any wet bilge or dripping shaft or outdoor moisture as possible.  In the cabin if you can. If exposed to moist air frequently try running some electric air warmer/dryers or a dehumidifier (when on shore power). 

Working hard on the ultimate solution for my own EMS/Y system conversion design.

Cheers, guys

Carsten

Hint : EMS/Y = Electric Motor Sailing Yacht ;-)

On Friday, 30 April 2021, 02:46:25 GMT+8, Jeff LaCoursiere <jeff@stratustalk.com> 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
www.aquasparc.com

On 4/29/21 11:34 AM, Carsten via groups.io 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@stratustalk.com> 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

www.aquasparc.com

On 4/29/21 10:06 AM, oreillygb@hotmail.com wrote:

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

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Jeff LaCoursiere
s/v Angels Quest
St Thomas USVI

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	Jeff LaCoursiere STRATUSTALK, INC. / CTO Phone: +1 703.496.4990 x108 Mobile: +1 815.546.6599 Email: jeff@stratustalk.com Website: https://www.stratustalk.com Address: One Freedom Square 13th Floor Reston, VA 20190

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Jeff LaCoursiere
s/v Angels Quest
St Thomas USVI