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How do you figure C-Rating of a battery?

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rparigoris

Joined: 24 Nov 2009
Posts: 780

Posted: Fri Sep 11, 2020 11:22 am Post subject: How do you figure C-Rating of a battery?

Hi Group I'm a bit confused how to figure C-rating of a battery. Here's my dilemma, here's a 5,000mA battery that say's it's good for 10C continuous and 15C burst: https://hobbyking.com/en_us/turnigy-sub-c-1-2v-5000mah-high-power-series-nimh-single-cell.html?queryID=3ed79812e155e159b8e96c63dba8378a&objectID=41335&indexName=hbk_live_magento_en_us_products

Initial thoughts is just multiply 5 times 10 or 15. Then I read a review and the battery never made it to 5amp capacity and the capacity goes down the more amps you draw from it. Here's the review: https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html

If I wanted to know what the continuous C rating is for this battery, would you take the unrealistic too high 5aH capacity rating from the Mfg times 10? Take the ~3.5 20 amp discharge capacity rating from the review times 10? Or??

Now for another hard question, how would you figure out burst amp rating? Thx. Ron P.

email(at)jaredyates.com
Guest

Posted: Fri Sep 11, 2020 11:46 am Post subject: How do you figure C-Rating of a battery?

Multiply 5000 by 10 for continuous, which is 50,000 milliamps, or 50 amps.



On Fri, Sep 11, 2020 at 3:38 PM rparigoris <rparigor(at)hotmail.com (rparigor(at)hotmail.com)> wrote:



 	  Quote: 	
		  --> AeroElectric-List message posted by: "rparigoris" <rparigor(at)hotmail.com (rparigor(at)hotmail.com)>

 

 Hi Group I'm a bit confused how to figure C-rating of a battery. Here's my dilemma, here's a 5,000mA battery that say's it's good for 10C continuous and 15C burst: https://hobbyking.com/en_us/turnigy-sub-c-1-2v-5000mah-high-power-series-nimh-single-cell.html?queryID=3ed79812e155e159b8e96c63dba8378a&objectID=41335&indexName=hbk_live_magento_en_us_products

 Initial thoughts is just multiply 5 times 10 or 15. Then I read a review and the battery never made it to 5amp capacity and the capacity goes down the more amps you draw from it. Here's the review: [url=https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html]https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html[/url]

 If I wanted to know what the continuous C rating is for this battery, would you take the unrealistic too high 5aH capacity rating from the Mfg times 10? Take the ~3.5 20 amp discharge capacity rating from the review times 10? Or??

 Now for another hard question, how would you figure out burst amp rating? Thx. Ron P.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=498313#498313

 

 

 

 

 

 

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jluckey(at)pacbell.net
Guest

Posted: Fri Sep 11, 2020 1:58 pm Post subject: How do you figure C-Rating of a battery?

Ron,

The Amp Hour rating for a battery is kind of a theoretical number.  In theory, a 5 Ah rating should deliver 5 amps for one hour but real batteries rarely, if ever, do.  It is more likely to deliver 1 A for 5 hours.  

Theoretically:  Ah = Time (in hours) x Amps

That is a linear equation, but as the current drain increases the length of time decreases in a non-linear fashion.

Those 10C & 15C ratings are typical for batteries used in model aircraft & cars and are usually a little optimistic.

The 10C rating is telling you that the battery supposedly has enough "grunt" to deliver 50 amps, but only for a very short period of time, like a minute or two, if that.  A lesser battery could not deliver 50 A at all, and if you tried to pull that kind of current, the battery voltage would drop-off precipitously.

I fly electric R/C airplanes using Li-po batteries (as opposed to the nickel-metal batts you are referring to) and they can deliver 20C+.  That means, for a 2 Ah battery, it can deliver up to 40 amps in short bursts, like when doing a full-throttle climb for 5-10 seconds.  But the typical total flight time for RC airplanes is less than 10 minutes.  We pull a lot of power for a short (no pun intended) duration.

I'm not sure that answers you questions, but may give you some context.

If we knew more about you application, we might be able to provide more useful information.





-Jeff

                  

                                                                    On Friday, September 11, 2020, 01:02:07 PM PDT, Jared Yates <email(at)jaredyates.com> wrote:                 

                 



                 



                 Multiply 5000 by 10 for continuous, which is 50,000 milliamps, or 50 amps.



On Fri, Sep 11, 2020 at 3:38 PM rparigoris <rparigor(at)hotmail.com (rparigor(at)hotmail.com)> wrote:



 	  Quote: 	
		  --> AeroElectric-List message posted by: "rparigoris" <rparigor(at)hotmail.com (rparigor(at)hotmail.com)>

 

 Hi Group I'm a bit confused how to figure C-rating of a battery. Here's my dilemma, here's a 5,000mA battery that say's it's good for 10C continuous and 15C burst: https://hobbyking.com/en_us/turnigy-sub-c-1-2v-5000mah-high-power-series-nimh-single-cell.html?queryID=3ed79812e155e159b8e96c63dba8378a&objectID=41335&indexName=hbk_live_magento_en_us_products

 Initial thoughts is just multiply 5 times 10 or 15. Then I read a review and the battery never made it to 5amp capacity and the capacity goes down the more amps you draw from it. Here's the review: [url=https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html]https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html[/url]

 If I wanted to know what the continuous C rating is for this battery, would you take the unrealistic too high 5aH capacity rating from the Mfg times 10? Take the ~3.5 20 amp discharge capacity rating from the review times 10? Or??

 Now for another hard question, how would you figure out burst amp rating? Thx. Ron P.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=498313#498313

 

 

 

 

 

 

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rparigoris

Joined: 24 Nov 2009
Posts: 780

Posted: Fri Sep 11, 2020 3:51 pm Post subject: Re: How do you figure C-Rating of a battery?

"If we knew more about you application, we might be able to provide more useful information." I have a Europa XS with both long and short wings powered by a Rotax 914. Although true if you have enough altitude you can put the prop in course pitch and air start, but with a cold engine it's hard on the engine and you need enough altitude and a good place to land if restart is unsuccessful to do it safety. Gettin a battery cold soaked can hurt performance for inflight restart or in the middle of nowhere ground start.

I too was an electric model guy 15 years ago when the hottest sub C cell was a GP 2200mA. http://www.europaowners.org/main.php?g2_itemId=27335 I made up a pack that I could wire direct to fuel pump 2 to keep at least 1 fuel pump running if all else failed. So my initial mission was to just run a 2 amp fuel pump with a total loss battery. Since sub C NiMh batteries have been growing in capacity and ability to dump amps I was thinking I could use it for double duty as a jump pack for ships battery in a pinch. I will be using a Earth-X 680. My concern is when connecting NiMh pack to a 680 that is low on charge amperage draw between the 2 could be quite high. Ron P.

jluckey(at)pacbell.net
Guest

Posted: Fri Sep 11, 2020 4:32 pm Post subject: How do you figure C-Rating of a battery?

... so you are looking for some kind of power source to start your Rotax in an emergency?  Is that correct?

The issue of batteries of different type charging each other would be a function of the difference in voltage between them.  I don't know anything about EarthX batts but since you would be building you own pack from individual NiMh cells, you could build a pack that is close in voltage to the EarthX, maybe?

There is also the possibility of isolating the EarthX batt from the NiMh battery using diodes.

I'm not sure but, I think it would take a bunch of NiMh batts to make a pack with enough power to crank an engine.

I believe that the EarthX are lithium based batteries (again, don't know much about them) but that battery chemistry has very high energy density.  Much higher than NiMh, so if you're looking for some kind of backup battery, you're probably better off with the lithium-based batts and their higher energy density and lower weight.

-Jeff

                  

                                                                    On Friday, September 11, 2020, 05:06:43 PM PDT, rparigoris <rparigor(at)hotmail.com> wrote:                 

                 



                 



                 --> AeroElectric-List message posted by: "rparigoris" <rparigor(at)hotmail.com (rparigor(at)hotmail.com)>



"If we knew more about you application, we might be able to provide more useful information." I have a Europa XS with both long and short wings powered by a Rotax 914. Although true if you have enough altitude you can put the prop in course pitch and air start, but with a cold engine it's hard on the engine and you need enough altitude and a good place to land if restart is unsuccessful to do it safety. Gettin a battery cold soaked can hurt performance for inflight restart or in the middle of nowhere ground start.



I too was an electric model guy 15 years ago when the hottest sub C cell was a GP 2200mA. [url=http://www.europaowners.org/main.php?g2_itemId=27335 ]http://www.europaowners.org/main.php?g2_itemId=27335 [/url]I made up a pack that I could wire direct to fuel pump 2 to keep at least 1 fuel pump running if all else failed. So my initial mission was to just run a 2 amp fuel pump with a total loss battery. Since sub C NiMh batteries have been growing in capacity and ability to dump amps I was thinking I could use it for double duty as a jump pack for ships battery in a pinch. I will be using a Earth-X 680. My concern is when connecting NiMh pack to a 680 that is low on charge amperage draw between the 2 could be quite high. Ron P.



Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=498320#498320



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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Sep 12, 2020 8:29 am Post subject: How do you figure C-Rating of a battery?

At 02:22 PM 9/11/2020, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "rparigoris" <rparigor(at)hotmail.com>



 Hi Group I'm a bit confused how to figure C-rating of a battery. Here's my dilemma, here's a 5,000mA battery that say's it's good for 10C continuous and 15C burst:  https://hobbyking.com/en_us/turnigy-sub-c-1-2v-5000mah-high-power-series-nimh-single-cell.html?queryID=3ed79812e155e159b8e96c63dba8378a&objectID=41335&indexName=hbk_live_magento_en_us_products 

 Initial thoughts is just multiply 5 times 10 or 15. Then I read a review and the battery never made it to 5amp capacity and the capacity goes down the more amps you draw from it. Here's the review: [url=https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html] https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html[/url] 

 If I wanted to know what the continuous C rating is for this battery, would you take the unrealistic too high 5aH capacity rating from the Mfg times 10? Take the ~3.5 20 amp discharge capacity rating from the review times 10? Or??

 Now for another hard question, how would you figure out burst amp rating? Thx. Ron P. 	
    

    One generally doesn't 'figure' any of that stuff.



    I'm pleasantly surprised when bench tests echo

    the nameplate ratings on any consumer production

    cell. Incorporation of any particular

    device into a project requires good DATA.

    Brands like A123, Samsung, Panasonic, Enersys, 

    et. als. will publish data sheets with realistic

    performance metrics.



    Here are some sample engineering data sheets

    on products offered by reputable manufacturers.



  https://tinyurl.com/y425k3x6



    Note that they offer detailed information, particularly

    discharge data that allows the system integrator

    to incorporate the device with confidence.



    No way in this universe are these cells

    capable of 6000 mAH . . .

    

  https://tinyurl.com/yyf64qe6



    Another example of 'blue smoke' merchandising



  https://tinyurl.com/y2j9dkoh



    Note the 12v, 2A power input jack . . . 200

    watts? Gimme a break. Now, I've used numerous

    examples of these amplifiers over the past 20

    years . . . and they're quite capable of the

    2-3 watts per channel called out in the spec

    sheets for the integrated circuits from which

    they are built.



    Attached are data plots on some 18650 cells

    marketed as '5500 mAH' devices with '10A

    pulse capability'.



    I was considering these cells for modifying

    a 20+ year old Makita drill from MiMh to

    Lithium.  Tests on the drill demonstrated

    peak loads on the order of 10A.



    Based on some 'marketing' assertions I purchased

    some cells for consideration. The cells clearly

    tested at MUCH less capacity and sagged by 25%

    voltage under just a 5 Amps load. Clearly

    incapable of practical service at 10A.



    Note the difference in stored energy for having

    been charged to 3.7 versus 4.2 Volts. If you

    charged these cells in a charger optimized

    for LiFePO4, you would achieve about 1/2 the

    chemical capacity of the cell.



    Sorry Ron, the short answer is, "Lacking

    engineering performance data on the proposed

    device, you're searching around in a coal

    mine for a black cat with no flashlight."



    I'm not implying that ALL marketing hype is

    suspect . . . I've purchased many products that met

    their nameplate performance ratings quite

    well. But lacking hard data from the manufacturer

    or your own measurements, then it's a bit of

    a crap shoot.



    If you have exemplar cells you're considering

    for the task, mail them to me and I'll suck

    out their precious bodily fluids to MEASURE

    from what stuff they are made.



    By the way, the performance benchmark "Ampere-Hour"

    is useful only when comparing one device with 

    a competing device. It has no definition in the

    science of energy measurement. The scientific

    description for energy will be in units

    like Watt-Hours, Joules, Ergs, etc.



    Definition of an Erg: "The energy required to lift

    a postage stamp to a height equal to its thickness"

    == Robert A. Heinlein, "Rocket Ship Galileo" 1947 ==

 

   Bob . . .

5500_mAH_18650_Not!.png

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rv8iator

Joined: 11 Apr 2006
Posts: 143
Location: Newberg, OR

Posted: Sat Sep 12, 2020 9:17 am Post subject: How do you figure C-Rating of a battery?

RegardingÂ 18650 cells... etc.



I purchased a few samples from different suppliers with ratings up to 4500 mAh.Â  Â The ones rated at 4500 mah felt lighter in weight than the similar cells rated at 3000 mAh.Â  A friend designs medical x-ray machines so I asked if he would x-ray one of the light weight cells and one "normal" cell.Â  UnfortunatelyÂ I don't have an image to share.Â  A description will suffice.Â  The light weight cell housed a much smaller cell.Â  Hmmm!

Simerly I was replacing the output transistorÂ in a regulated bench power supply.Â  I recall it was a 2N3055.Â  I found a "deal" on Ebay.Â  Five for $5...Â  Upon receiptÂ I noticed the marking on the case didn't appear quite right.Â  It was labeled STM... lightly scratchingÂ the marking it readily came off.Â  Hmmm.Â  Â Using a DremelÂ tool with a cut-off wheel I removed the top of the case.Â  Voila!Â  A tiny junction with .002" bond wires!Â  That someone can make a living going to the troubleÂ of counterfeitingÂ transistors!

Caveat Emptor

Chris Stone





On Sat, Sep 12, 2020 at 9:36 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:



 	  Quote: 	
		    At 02:22 PM 9/11/2020, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "rparigoris" <rparigor(at)hotmail.com (rparigor(at)hotmail.com)>



 Hi Group I'm a bit confused how to figure C-rating of a battery. Here's my dilemma, here's a 5,000mA battery that say's it's good for 10C continuous and 15C burst:  https://hobbyking.com/en_us/turnigy-sub-c-1-2v-5000mah-high-power-series-nimh-single-cell.html?queryID=3ed79812e155e159b8e96c63dba8378a&objectID=41335&indexName=hbk_live_magento_en_us_products 

 Initial thoughts is just multiply 5 times 10 or 15. Then I read a review and the battery never made it to 5amp capacity and the capacity goes down the more amps you draw from it. Here's the review: [url=https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html] https://lygte-info.dk/review/batteries2012/Turnigy%20Sub-C%205000mAh%20(Gray)%20UK.html[/url] 

 If I wanted to know what the continuous C rating is for this battery, would you take the unrealistic too high 5aH capacity rating from the Mfg times 10? Take the ~3.5 20 amp discharge capacity rating from the review times 10? Or??

 Now for another hard question, how would you figure out burst amp rating? Thx. Ron P. 	
Â Â Â  

 Â Â  One generally doesn't 'figure' any of that stuff.



 Â Â  I'm pleasantly surprised when bench tests echo

 Â Â  the nameplate ratings on any consumer production

 Â Â  cell. Incorporation of any particular

 Â Â  device into a project requires good DATA.

 Â Â  Brands like A123, Samsung, Panasonic, Enersys, 

 Â Â  et. als. will publish data sheets with realistic

 Â Â  performance metrics.



 Â Â  Here are some sample engineering data sheets

 Â Â  on products offered by reputable manufacturers.



  https://tinyurl.com/y425k3x6



 Â Â  Note that they offer detailed information, particularly

 Â Â  discharge data that allows the system integrator

 Â Â  to incorporate the device with confidence.



 Â Â  No way in this universe are these cells

 Â Â  capable of 6000 mAH . . .

 Â Â  

  https://tinyurl.com/yyf64qe6



 Â Â  Another example of 'blue smoke' merchandising



  https://tinyurl.com/y2j9dkoh



 Â Â  Note the 12v, 2A power input jack . . . 200

 Â Â  watts? Gimme a break. Now, I've used numerous

 Â Â  examples of these amplifiers over the past 20

 Â Â  years . . . and they're quite capable of the

 Â Â  2-3 watts per channel called out in the spec

 Â Â  sheets for the integrated circuits from which

 Â Â  they are built.



 Â Â  Attached are data plots on some 18650 cells

 Â Â  marketed as '5500 mAH' devices with '10A

 Â Â  pulse capability'.



 Â Â  I was considering these cells for modifying

 Â Â  a 20+ year old Makita drill from MiMh to

 Â Â  Lithium.Â  Tests on the drill demonstrated

 Â Â  peak loads on the order of 10A.



 Â Â  Based on some 'marketing' assertions I purchased

 Â Â  some cells for consideration. The cells clearly

 Â Â  tested at MUCH less capacity and sagged by 25%

 Â Â  voltage under just a 5 Amps load. Clearly

 Â Â  incapable of practical service at 10A.



 Â Â  Note the difference in stored energy for having

 Â Â  been charged to 3.7 versus 4.2 Volts. If you

 Â Â  charged these cells in a charger optimized

 Â Â  for LiFePO4, you would achieve about 1/2 the

 Â Â  chemical capacity of the cell.



 Â Â  Sorry Ron, the short answer is, "Lacking

 Â Â  engineering performance data on the proposed

 Â Â  device, you're searching around in a coal

 Â Â  mine for a black cat with no flashlight."



 Â Â  I'm not implying that ALL marketing hype is

 Â Â  suspect . . . I've purchased many products that met

 Â Â  their nameplate performance ratings quite

 Â Â  well. But lacking hard data from the manufacturer

 Â Â  or your own measurements, then it's a bit of

 Â Â  a crap shoot.



 Â Â  If you have exemplar cells you're considering

 Â Â  for the task, mail them to me and I'll suck

 Â Â  out their precious bodily fluids to MEASURE

 Â Â  from what stuff they are made.



 Â Â  By the way, the performance benchmark "Ampere-Hour"

 Â Â  is useful only when comparing one device with 

 Â Â  a competing device. It has no definition in the

 Â Â  science of energy measurement. The scientific

 Â Â  description for energy will be in units

 Â Â  like Watt-Hours, Joules, Ergs, etc.



 Â Â  Definition of an Erg: "The energy required to lift

 Â Â  a postage stamp to a height equal to its thickness"

 Â Â  == Robert A. Heinlein, "Rocket Ship Galileo" 1947 ==

 

 Â  Bob . . .

_________________
C. Stone (RV8iator)

rparigoris

Joined: 24 Nov 2009
Posts: 780

Posted: Sun Sep 13, 2020 6:53 am Post subject: Re: How do you figure C-Rating of a battery?

Hi Group Thank you for replies. Again I want a dual mission total loss battery, one to run a Rotax 914 fuel pump which I'm certain the 5,000mA cells are up to the task and two is to jump start main battery in a pinch. My dilemma is if I hook up NiMh pack to a flattened Earth-X battery the amp draw can be quite high. Not sure just how high and not sure how many amps the NiMh cells can dump. OK let's take a different tact for in a pinch jump starting. I posted a link to discharge table up to 20 amps for NiMh cells. I feel confident those cells can handle a discharge rate of 30 amps. What's thoughts of using this to limit amperage draw on NiMh cells when using them to jump?: http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=184069714833&category=117000&pm=1&ds=0&t=1596298535000&ver=0

I have EZ pilot access on passenger headrest where I could make a series converter with red and black Anderson Power Pole connectors.  Ron P.

rparigoris

Joined: 24 Nov 2009
Posts: 780

Posted: Sun Sep 13, 2020 6:53 am Post subject: Re: How do you figure C-Rating of a battery?

Hi Group Thank you for replies. Again I want a dual mission total loss battery, one to run a Rotax 914 fuel pump which I'm certain the 5,000mA cells are up to the task and two is to jump start main battery in a pinch. My dilemma is if I hook up NiMh pack to a flattened Earth-X battery the amp draw can be quite high. Not sure just how high and not sure how many amps the NiMh cells can dump. OK let's take a different tact for in a pinch jump starting. I posted a link to discharge table up to 20 amps for NiMh cells. I feel confident those cells can handle a discharge rate of 30 amps. What's thoughts of using this to limit amperage draw on NiMh cells when using them to jump?: http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=184069714833&category=117000&pm=1&ds=0&t=1596298535000&ver=0

I have EZ pilot access on passenger headrest where I could make a series converter with red and black Anderson Power Pole connectors.  Ron P.

ceengland7(at)gmail.com
Guest

Posted: Sun Sep 13, 2020 7:40 am Post subject: How do you figure C-Rating of a battery?

On 9/13/2020 9:53 AM, rparigoris wrote:

 	  Quote: 	
		   



 Hi Group Thank you for replies. Again I want a dual mission total loss battery, one to run a Rotax 914 fuel pump which I'm certain the 5,000mA cells are up to the task and two is to jump start main battery in a pinch. My dilemma is if I hook up NiMh pack to a flattened Earth-X battery the amp draw can be quite high. Not sure just how high and not sure how many amps the NiMh cells can dump. OK let's take a different tact for in a pinch jump starting. I posted a link to discharge table up to 20 amps for NiMh cells. I feel confident those cells can handle a discharge rate of 30 amps. What's thoughts of using this to limit amperage draw on NiMh cells when using them to jump?: http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=184069714833&category=117000&pm=1&ds=0&t=1596298535000&ver=0

 I have EZ pilot access on passenger headrest where I could make a series converter with red and black Anderson Power Pole connectors.  Ron P.



I think we still don't have enough detail on your hypothetical 
	


'situation' needs. On the one hand, you're talking about powering just a 

fuel pump (implying a total electrical failure), and the other about 

either jump-starting the engine, or recharging a dead battery, but we 

don't know if that means a failed charging system or just a run-down 

battery.



We do know that NiMh cells have much lower energy density than any of 

the lithium tech. Transferring energy to a lithium tech battery from 

NiMh cells just doesn't sound like a reasonable path to me, for a 

variety of reasons.



I'm pretty 'cheap'; I've been known to expend prodigious effort to save 

a few $. But from what I think I understand about your goals, I'd find 

it hard to resist just picking up one of the dozens of lithium 'jump 

start' packs. They have high current cables for jump starting, and 

almost all of them now include smaller terminals, adapters, etc that 

allow connection of devices with lower current demands. $55-$75 will get 

you pre-packaged cells, cables, a handful of adapters, etc, very close 

to 'plug&play'. I'll bet that by the time you gather up all the stuff 

you need to make your idea work, you'll have close to that much money 

tied up, and a *lot* more work. Way more starting current than you'd 

ever need, and even the cheapest versions will have more total energy to 

run the fuel pump than the NiMh cells.



Charlie



-- 

This email has been checked for viruses by Avast antivirus software.

https://www.avast.com/antivirus

ceengland7(at)gmail.com
Guest

Posted: Sun Sep 13, 2020 9:57 am Post subject: How do you figure C-Rating of a battery?

On 9/13/2020 11:06 AM, Robert L.       Nuckolls, III wrote:

     

      	  Quote: 	
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		  I'm           pretty 'cheap';           I've been known to expend prodigious effort to save a few $.           But from           what I think I understand about your goals, I'd find it hard           to resist           just picking up one of the dozens of lithium 'jump start'           packs. They           have high current cables for jump starting, and almost all of           them now           include smaller terminals, adapters, etc that allow connection           of devices           with lower current demands. $55-$75 will get you pre-packaged           cells,           cables, a handful of adapters, etc, very close to           'plug&play'. I'll           bet that by the time you gather up all the stuff you need to           make your           idea work, you'll have close to that much money tied up, and a           *lot* more           work. Way more starting current than you'd ever need, and even           the           cheapest versions will have more total energy to run the fuel           pump than           the NiMh cells.

           

           Charlie

         	
       

         

           Sure. If he drops the 'jump start' requirement

           but has an FMEA driven justification for a

           stand-by battery on the fuel pump, these batteries

           connected in series would run the pump for a very

           long time . . . probably duration of fuel aboard.

         

                    https://tinyurl.com/y4oulfy9

           

           Down side is the legacy stand-by-battery-cost-

           of-ownership for insuring continued air worthiness.

           I'd like to understand what conditions would drive

           the need in the first place.

           

         

         

                

             Bob . . .            	
     As I said in the earlier section of that post, we don't know his     actual needs. But if 'jump start' or 'recharge' involves being stuck     out in the boonies with no access to service or a charger (which     could easily happen at a paved, government-run airport in some parts     of the country), then I can see having a 'jump start' pack in my     emergency kit.

     

     There may be no reason to have a dead battery, but unfortunately,     *we* have to be figured into the equation. I managed to kill a     fairly expensive 'certified' SLA battery by leaving the 'mag switch'     controlling the electronic ignition turned on for about a week. No     excuses; my stupidity, but that didn't keep the battery from being     dead. Fortunately the plane was in my hangar at home.

     

     Charlie

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