---------------------------------------------------------- AeroElectric-List Digest Archive --- Total Messages Posted Fri 03/22/19: 6 ---------------------------------------------------------- Today's Message Index: ---------------------- 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 _____________________________________ Time: 04:07:05 AM PST US Subject: AeroElectric-List: Re: Still noisy voltmeter From: "Achille" 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 ________________________________ Message 2 _____________________________________ Time: 06:08:00 AM PST US Subject: AeroElectric-List: Re: Still noisy voltmeter From: "user9253" 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 _____________________________________ Time: 06:53:29 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 07:01:32 AM PST US From: "Robert L. Nuckolls, III" Subject: Re: AeroElectric-List: 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 _____________________________________ Time: 08:42:24 AM PST US From: Eric Page Subject: Re: AeroElectric-List: Re: Battery BMS failures? > On Mar 22, 2019, at 07:00, Robert L. Nuckolls, III 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 _____________________________________ Time: 01:49:36 PM PST US From: "Robert L. Nuckolls, III" Subject: AeroElectric-List: Skip Koss 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 . . . ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message aeroelectric-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/AeroElectric-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/aeroelectric-list Browse Digests http://www.matronics.com/digest/aeroelectric-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.