Today's Message Index:
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1. 04:07 AM - Re: Still noisy voltmeter (Achille)
2. 06:08 AM - Re: Still noisy voltmeter (user9253)
3. 06:53 AM - Re: Re: Battery BMS failures? (Robert L. Nuckolls, III)
4. 07:01 AM - Re: Re: Battery BMS failures? (Robert L. Nuckolls, III)
5. 08:42 AM - Re: Re: Battery BMS failures? (Eric Page)
6. 01:49 PM - Skip Koss (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Still noisy voltmeter |
It's grounded on the ground bus were all my items are coming. Same ground like
voltmeter 2.
I will try thank you ;)
When you tell "loop wire around the switch" it's around the connection ?
Thank you.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488183#488183
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| Subject: | Re: Still noisy voltmeter |
No, I did not mean to connect the ground wire to the switch. What I meant was
to run the positive and negative wires as a twisted pair all of the way from the
source to the voltmeter (as much as possible). Try to avoid a single wire.
If the wires are twisted together, radiated energy will be minimized.
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=488184#488184
Message 3
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| Subject: | Re: Battery BMS failures? |
>An aircraft of that size and vintage may have had a battery charger
>that monitored temperature and could limit charging current??
>It seems like the Lithium "BMS" strategies are moving in that direction.
Don't think so. The 'charger' was not much
different than what we have in our airplanes:
An engine driven power source regulated to
idealized charging levels for the battery.
Some airplanes had two engine driven sources
like starter generators. These would parallel
for delivering up to 800A. The larger
aircraft would also have a auxiliary power
unit good for perhaps 200-300 amps that could
be operated in parallel with ships generators.
None of the generator controls were fitted with
any way to monitor either battery temperature or
current.
>Limiting the alternator size as per Earth-X recommendations is a
>small step in that direction which I applaud. Even with VRLA
>batteries I tossed my 100+ amp alternator in favor of a 40 amp unit.
But suppose your running loads call for more
current? Heated seats maybe? Electric cockpit
heat a la LongEz? A B400 has electric
de=ice on the tail feathers . . . lots
of amps needed there.
Virtually every rechargeable battery's maintenance
instructions call for constant-current/constant-voltage
recharge profiles. I.e. limit current into the
battery to some friendly level until the desired
bus-voltage set point is reached whereupon you
change to constant voltage operation.
All it takes is a current sensor on the battery
feeder to monitor the battery's recharge
current and adjust bus voltage to maintain
fast recharge at the recommended current
until the battery is topped off whereupon
the controller reverts to constant voltage.
Not difficult to do for any combination of
battery and engine driven power sources.
Bob . . .
Message 4
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| Subject: | Re: Battery BMS failures? |
>Don't quote me on this (it's been awhile...) but
>as I recall, the temperature monitoring was
>separate from the charger. I think the
>charger's only data inputs=9D were
>weight-on-wheels and where its AC Power was
>coming from (external or engine-driven generator).
If the aircraft had 3-phase alternators
and separate starters, then DC power was
derived from transformer/rectifiers to
run DC systems and recharge batteries.
These aircraft were generally large enough
to carry an APU which was used to start
engines thus reducing demands on the battery.
These systems could easily include features
for battery management.
But for twin-jets up through ships like
the Hawker 800 series, batteries were
connected to a bus powered by generators
with a LOT of output capability. Any
necessary monitoring of battery temperatures
was a simple thermometer gage with warning
and danger lights.
It was up to crew to notice and then
take an overheated battery off line until
it cooled.
Bob . . .
Message 5
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| Subject: | Re: Battery BMS failures? |
> On Mar 22, 2019, at 07:00, Robert L. Nuckolls, III <nuckolls.bob@aeroelectric.com>
wrote:
> If the aircraft had 3-phase alternators and separate starters, then DC power
was derived from transformer/rectifiers to run DC systems and recharge batteries.
>
> These aircraft were generally large enough to carry an APU which was used to
start engines thus reducing demands on the battery.
The Dash-8s of this vintage had Pratt & Whitney PW123Ds (2,150 shp/side) with starter/generators.
There were also AC generators (thats what they called them!)
and TRUs. It was a complex electrical system, to put it mildly.
The planes were available with APUs, but the airline chose not to install them.
The reasons for that remained a mystery to most of us who flew them, as the
plane was an overpowered beast that had no trouble hauling a full cabin and bulked-out
cargo bins. The extra couple hundred pounds would have made zero difference
in performance, but would have improved interior comfort and reduced battery
demands enormously. As it was, all of our engine starts were battery powered
for #2, then tie the DC buses to start #1 assisted by the #2 generator.
Eric
Message 6
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I learned today that Skip Koss passed away
last Tuesday.
Skip was indeed an aviation legend. Generous
of his time and resources, he was eager to share
his vast knowledge in all matters aircraft but
especially batteries.
You can read more here . . .
https://tinyurl.com/y5guu4gc
I met Skip while employed at Gates-Learjet on the
GP-180 program in 1985. I was privileged to enjoy
Skip's friendship for more than 33 years.
He will be missed.
Bob . . .
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