VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.






VAF on Twitter:
@VansAirForceNet


Go Back   VAF Forums > Main > RV Ongoing Maintenance Issues
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 07-23-2022, 07:42 AM
dmattmul dmattmul is offline
 
Join Date: Dec 2015
Location: Spring Hill, FL
Posts: 486
Default Warmer battery than desired FWF

Looking for input how anyone reduced the heat of a FWF battery. I made the mistake of putting mine on the side opposite stock location but lower. Seemed to be a good location as my FW is pretty cramped. Yes, takes up just as much room higher than lower but was saving the upper area for equipment I considered less heat tolerant. When installed was early in the kit cycle and did not have the benefit of prior experience. I knew heat could be an issue, so I have a thermocouple in both batteries to monitor the situation. I started flying it Sept in Ohio and took it down to Florida November. It's been in paint since March and now flying it more this time in the South as we are spending more time there now. Situation not going to get better for my airframe. Yes, the internal battery temp alerts are also telling me that after 30 to 45 mins they don't like the temp being operated at. I have tried wrapping the battery with insulated (~1/4 inch) material with reflective tape. Little improvement. Added a blast tube, little improvement. I'm using the standard 5/8 blast tube, if I go a little larger any help? It appears that even using the Earth X box that is designed for higher temps just going to delay the issue. Might help when I shut things off. Anyone have any luck adding some sort of barriers on the exhaust tubes? If so, did that help? Moving the battery would be a major PITA. Any input for the blast tube location considering the battery sit behind the exhaust? Thought maybe might be more effective locating blowing down the top but maybe in front would disperse the radiant heat more efficiently.
__________________
RV-14A QB builds (2017), Lycoming 390 Thunderbolt arrived July 2019, Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 300-72, Earth-X batteries, Beringer wheels and brakes, Parts became real airplane 8/15/2020. Started RV-10 Nov 2020. Empennage arrived (Built) Working on QB kits. Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 3 blade HRT 378, Earth-X batteries, Beringer wheels and brakes, real airplane hopefully early-mid 2024. Paid subscriber
Reply With Quote
  #2  
Old 07-23-2022, 08:25 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 7,690
Default

Two types of heat you are dealing with. One is the air temp in the lower cowl area. Very little you can do about that beyond blast tubes that reduce overall engine cooling performance. Insulation helps in the short term, but over time, the things under them become the same temp as the air outside the insulation if those things can't shed heat some other way.

The other is radiant heat. If the battery is close enough (can't tell you what that is) to a source that is radiating heat, like an exhaust pipe, some of that will be absorbed by the object. Heat shields on the exhaust that reduce radiation can help, as can reflective material on the battery case.

I would try to grab the temp of the air in the cowl and compare to battery temp to see if you are dealing with air temp issues or reflective heat issues. You can't realistically get the battery temp lower than the surrounding air temp without blasting a lot of cooler air around the battery, If this is your only option, I would consider making a diffuser of some sort to get the cooler air to better cool the battery vs just putting a bis @#$% blast tube next to it.

None of these will deal with the extreme temps that battery will see at shut down, where the under cowl temps skyrocket for a period of time. Best option is a lead acid battery that is more tolerant of heat. There is a reason that the automotive industry has not gone to lighter batteries, even though they are working hard to shed weight in their ongoing war with gas mileage regulations. They know they are an option; They just can't make them work reliably with the heat seen under the hood. I suspect they also don't want the liability associated with thermal runaway issues. Recalls are VERY expensive.

Larry

Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 07-23-2022 at 08:33 AM.
Reply With Quote
  #3  
Old 07-23-2022, 08:53 AM
rocketman1988 rocketman1988 is offline
 
Join Date: Jun 2010
Location: Sunman, IN
Posts: 3,178
Default ...and

"...They just can't make them work reliably with the heat seen under the hood. I suspect they also don't want the liability associated with thermal runaway issues. Recalls are VERY expensive..."

Yes, the heat is an issue...also consider that most of the cars out there are liquid cooled; the temps are much lower than in our air-cooled aircraft.

As far as the thermal runaway issue, pretty sure they aren't too afraid of the liability with one small battery when they are trying to shove EVs down our collective throats...
__________________
Bob
EAA Tech Counselor
Aerospace Engineer '88

RV-10-ER
N464RL
Going to Paint at Evoke!
Garmin G3X-T, Barrett EFII S32, CAI, MTV-9B

Dues+ Paid 2021,...Thanks DR+
Reply With Quote
  #4  
Old 07-23-2022, 09:09 AM
PilotjohnS PilotjohnS is offline
 
Join Date: Jan 2016
Location: Southwest, USA
Posts: 2,519
Default Marketing tool

Quote:
Originally Posted by rocketman1988 View Post
"...They just can't make them work reliably with the heat seen under the hood. I suspect they also don't want the liability associated with thermal runaway issues. Recalls are VERY expensive..."

Yes, the heat is an issue...also consider that most of the cars out there are liquid cooled; the temps are much lower than in our air-cooled aircraft.

As far as the thermal runaway issue, pretty sure they aren't too afraid of the liability with one small battery when they are trying to shove EVs down our collective throats...
Remember, EVs are a marketing tool. The li-ion batteries are never going to be the dominant energy source for vehicles. For airplanes, curious if our Li-ion batteries will suffer from the EV vehicle push, either in price or availability.
__________________
John S

WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.

Dues paid 2022, worth every penny

RV9A- Status:
98% done, 2% left to go
To Go: wing mounting, engine baffles, wing tips, move to airport
www.pilotjohnsrv9.blogspot.com
Reply With Quote
  #5  
Old 07-23-2022, 12:45 PM
dmattmul dmattmul is offline
 
Join Date: Dec 2015
Location: Spring Hill, FL
Posts: 486
Default Hope

I was hoping this would not turn into a battery type discussion but after careful review many years ago it was pretty much a fact that lead acid batteries at temps higher than 125 F have ~ 10% lifespan as one that is operated at ~ 70 F. LiFePO4 batteries have been tested at 140 F without degradation of life. I have been using this chemistry for over 20 years and find as long as you take care of the battery. (Not discharging fully, forcing the BMS to open) As part of my conditional I discharged down to 12 volts (3 volts per cell) and both batteries had over 85% of their rated ampacity left. This was one year and 160 hours. I'm trying to keep excursions above 140 F to a minimum and looking for input from this talented group. (Appreciate everyone's input so far) The dreaded thermal runaway is real and every time I have seen or heard about this was because of a crash when someone tried to re-use the battery (Radio control) or something was left on and drained the battery later to be "jumped". If I do run my LiFePO4 battery chemistry down, it will go into my tractor and not back in the air.
__________________
RV-14A QB builds (2017), Lycoming 390 Thunderbolt arrived July 2019, Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 300-72, Earth-X batteries, Beringer wheels and brakes, Parts became real airplane 8/15/2020. Started RV-10 Nov 2020. Empennage arrived (Built) Working on QB kits. Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 3 blade HRT 378, Earth-X batteries, Beringer wheels and brakes, real airplane hopefully early-mid 2024. Paid subscriber
Reply With Quote
  #6  
Old 07-23-2022, 01:04 PM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 7,690
Default

Quote:
Originally Posted by dmattmul View Post
but after careful review many years ago it was pretty much a fact that lead acid batteries at temps higher than 125 F have ~ 10% lifespan as one that is operated at ~ 70 F. .
While I have never measured underhood temps on a car, I simply cannot imagine them being under 125* outside of winter. Heck, I bet a car with a black hood will have temps close to 120 under the hood even without the engine running in the summer. I have had well cared for batteries go 5+ years and 100K miles. The BMW with the battery in the trunk was not a whole bunch better - best was 7 years. Maybe I am looking at this wrong and 5 years is only 10% of useful life. All that said, I do know that high end chargers have battery temp sensors, but thought that was more about limiting current and adjusting voltage to match what the battery can handle or wants. I thought that optimum charging voltage changes with battery temp.

Wish I could provide better guidance for you, but I am in the lead acid camp for my planes.

Larry
__________________
N64LR - RV-6A / IO-320, Flying as of 8/2015
N11LR - RV-10, Flying as of 12/2019

Last edited by lr172 : 07-23-2022 at 01:12 PM.
Reply With Quote
  #7  
Old 07-23-2022, 03:16 PM
dmattmul dmattmul is offline
 
Join Date: Dec 2015
Location: Spring Hill, FL
Posts: 486
Default Agreed

I tend to agree that lead acid batteries seam to last longer. Something about sulfation and for each 10F rise in temperature, the life of a sealed lead acid battery is cut in half. I do think if I could keep my batteries under 140 F I could easily get 3 to 5 years usage from them. I think we all have to admit they swing the prop rather well on start-up and take fairly high amps when needing to charge. My airframe sat for an extended period of time and saw charging rates that I was a little concerned about initially. (Would not want to blow an ANL fuse link) I almost wish there would be a better way or just anyway to limit the charging rate. It's not like I needed them fully topped off in 15 mins. Again, thanks for the input and travel safe.
__________________
RV-14A QB builds (2017), Lycoming 390 Thunderbolt arrived July 2019, Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 300-72, Earth-X batteries, Beringer wheels and brakes, Parts became real airplane 8/15/2020. Started RV-10 Nov 2020. Empennage arrived (Built) Working on QB kits. Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 3 blade HRT 378, Earth-X batteries, Beringer wheels and brakes, real airplane hopefully early-mid 2024. Paid subscriber
Reply With Quote
  #8  
Old 07-24-2022, 05:51 AM
crabandy crabandy is offline
 
Join Date: Jan 2010
Location: Ottawa, Ks
Posts: 2,447
Default

I made my oil door into a cowl flap, it has really helped with my EarthX overtemp alarms and hot quick turn ground cooling.

https://vansairforce.net/community/s...d.php?t=171987
__________________
RV 7 590 hours and counting
21 donation done
Reply With Quote
  #9  
Old 07-25-2022, 12:37 PM
dmattmul dmattmul is offline
 
Join Date: Dec 2015
Location: Spring Hill, FL
Posts: 486
Default Thanks

I'll look into that design. Since it sits on the outside edge of the firewall might be able to look into other options. Just FYI my stock battery location I get temps well within spec for any type of chemistry. It's the one down low and on the other side that has an issue. I'm pretty sure it's the radiant heat coming from the exhausts that is the issue.
__________________
RV-14A QB builds (2017), Lycoming 390 Thunderbolt arrived July 2019, Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 300-72, Earth-X batteries, Beringer wheels and brakes, Parts became real airplane 8/15/2020. Started RV-10 Nov 2020. Empennage arrived (Built) Working on QB kits. Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 3 blade HRT 378, Earth-X batteries, Beringer wheels and brakes, real airplane hopefully early-mid 2024. Paid subscriber
Reply With Quote
  #10  
Old 08-13-2022, 01:46 PM
dmattmul dmattmul is offline
 
Join Date: Dec 2015
Location: Spring Hill, FL
Posts: 486
Default Lowered temps substantially

I installed a Anti-Splat 6 in. heat shield (Nice product, thanks) on the rear exhaust closest to the battery located bottom pilot side of the FWF along with a 3/4 blast tube directed in the front of the battery box (cut a hole in the battery box front plate cover) and this seems to have cured the temperature issue. Went from 155-160 F to 120- 125 F range and no sign of the over temp light coming on (2 sec on and 2 sec off). Even on the ground this seems to have helped but in flight both battery positions are within 5 degrees of each other.
__________________
RV-14A QB builds (2017), Lycoming 390 Thunderbolt arrived July 2019, Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 300-72, Earth-X batteries, Beringer wheels and brakes, Parts became real airplane 8/15/2020. Started RV-10 Nov 2020. Empennage arrived (Built) Working on QB kits. Garmin avionics, Vertical Power, EFII-32 Ignition and Fuel, Whirlwind 3 blade HRT 378, Earth-X batteries, Beringer wheels and brakes, real airplane hopefully early-mid 2024. Paid subscriber
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 02:53 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.