[EVDL] BMS recommendations

[MacWrench via EV]

Hi All,

I've been lurking in the background for some time now,
occasionally responding since my background is that of a mechanic (auto
tech) with extensive experience in electrical and fuel injection systems.
I "retired" about 15 years back and went to work part time for Maine
Organic Farmers and Gardeners Association . MOFGA has
been supportive of my electrical interests and I have converted 2
cultivating tractors (lead acid batteries) and a Chev S-10 (prismatic
lithium cells 100 amp hour) to battery power. And built from scratch a
small, 2 tracked woods vehicle using a powered wheel chair drive system
(4, 7 cell lithium polimer packs in parallel with very basic bms). All
simple dc systems, functional for short trips and farm work.

2
years ago, MOFGA received a donation of a 1940's vintage tractor (Ford
9-N) that had been converted to battery power, again a simple dc
system.  Since that tractor was converted by a friend who, as a
mechanical engineer only made it functional enough to prove the point, it
was too rough and downright dangerous for general use. The family asked
specifically for me to "clean it up". For instance, it had 10, 12v
batteries in series charged by a grid charger consisting of 4 heavy diodes
screwed to a piece of board, 120ac in and 120dc out. Sorry I didn't take
some before pics.

I now have the tractor running on 8 LG Chem
16 cell packs configured to 120v, charging with an Elcon 5000 configured
by Elcon for that battery, and NO BMS. Scares the hell out of me knowing
how quickly that sort of battery can go into "thermal runaway" but again,
needed to prove the concept and get it into public use. I have spent 2
hours (all I could stand) on that machine running a bush hog with no
appreciable drop in battery voltage so I know it is capable of serious
work.

I have looked about for a BMS for this battery pack and
found the following  Is
this the best I can do for this battery pack? Could someone recommend a
better system? Mostly it needs to perform the basics, top balance cells,
monitor temp, provide LVC and HVC for the charger.

Thanks for
your comments and advice.

John
Unity ME
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Re: [EVDL] kWh versus charging temperature

[MacWrench via EV]

Peri,

I'm no chemist but I do know that batteries just do not
perform well when cold and 20F is cold for a battery. That is why my 1994
Solectria came equipped with heaters in the battery boxes. It is true that
Nissan doesn't have a heater for the battery?


On Sun,
April 3, 2022 7:21 pm, Peri Hartman via EV wrote:
> Well, then,
why is the range substantially less in cold weather ? The
>
charger nor the battery don't know the discharge rate while charging.
>
> I understand that charging needs to be slower. But how
does that affect
> capacity ?
>
> As a matter of
example, during 20F weather last december, I was getting
> 20
miles range on the Leaf at full charge. Yesterday, charging while
> 50F, I went 30 miles and still had about 1/3 bars left.
>
> << Annoyed by leaf blowers ?
https://quietcleanseattle.org/ >>
>
> --
Original Message --
>
From: "Cor van de Water"

> To: "Peri Hartman"
; "Electric Vehicle Discussion
> List"

> Sent: 03-Apr-22 16:32:59
>
Subject: Re: [EVDL] kWh versus charging temperature
>
>>Peri,
>>It is the *speed*, not the *capacity* that
suffers in very cold weather.
>>Think of it as ions moving
sluggish through the lattice that makes up
>>the active
material.
>>The colder, the more sluggish.
>>Forcing
too much current into this can even cause faults to develop,
>>which *are* reducing the capacity permanently, not because of
the cold
>>but because of the fault blocking the path of
current in that section
>>of the lattice, taking a little bit
of the total capacity out of the
>>picture.
>>That
is why charging must be slow in the cold, to avoid creating those
>>faults, so that the capacity of the battery remains, albeit at
lower
>>*power* (=speed of current in or out of the
battery).
>>Hope this clarifies,
>>Cor.
>>
>>On Sun, Apr 3, 2022 at 3:50 PM Peri Hartman via EV

>> wrote:
>>>
>>> As I understand, with most Li-ion cells, the colder the
cell, the less
>>> charge it will take on. Correct ?
>>> But what happens if a warm battery is charged and then
cools off ? It
>>> still has all its kWh, right ? And
further, the temperature of the
>>> battery does not affect
how many kWh you can get *out* of it, though
>>> the
>>> rate may change a bit.
>>>
>>>
My 2011 Leaf has abysmal range at this point. I'm wondering if I were
>>> to
>>> charge during the warmest part of the
day, would I get a bit more
>>> range
>>> ?
I'm going to guess it won't make that much difference since the
>>> battery is in the shade (under the car) and won't warm up
much over a
>>> few hours. But I'm still curious if the
theory holds truth.
>>>
>>> Peri
>>>
>>> << Annoyed by leaf blowers ?
https://quietcleanseattle.org/ >>
>>>
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>
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Re: [EVDL] FS: GE ElecTrak Rototiller - Complete

[MacWrench via EV]

Being fairly new (6 mo. or so) to this list, I haven't yet gotten a sense
what is completely inappropriate and what is tolerated. so far, I have
found it to be interesting and occasionally informative. Seeing this
posting reminds me of a co-worker in Portland OR who was very into EVs in
the early 1980's. We used a GE ElectTrak to move disabled ICE vehicles
around the lot. A great little machine in it's day. His name certainly
wasn't Sharkey but if my recollection rings a bell, please let me know.


On Tue, March 15, 2022 9:55 pm, Mr. Sharkey via EV wrote:
> Acknowledging that this might not be the most fruitful place to
list
> this item for sale, offered is a Brinley Hines
electrically-powered
> rototiller with all necessary accessories
to bolt up to a General
> Electric ElecTrak garden tractor.
>
> Includes the tiller, which has few operating hours on it,
the drawbar
> that bolts on the frame of the tractor and the
electric winch to
> raise and lower the implement during use and
transport as well as the
> original factory manual. The tiller has
been kept in covered storage
> for the last 40 years, and aside
from the expected surface rust, is
> in fine condition. It could
probably stand to have the V-belt
> replaced, and new paint if you
are fussy.
>
> First $495.00 takes it. Located in
Portland, Oregon. Local pickup is
> always free, otherwise, can be
palletized and shipped motor freight
> at the purchaser's
expense.
>
> Also available: The carcass of my old
ElecTrak E-12, in case you
> can't turn down the great deal on the
tiller and need a tractor to
> restore to use it with.
>
> Photos upon request.
>
>
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