Lipo Heater

[Feefo]

I've used the Turnigy lipo heater bag in the past, but been thinking about a heater box instead. Google gave a few hits on lipo heaters available from retailers but £160-£200+ seems a bit OTT really.  I've seen a few pictures where aluminium flight cases have been used, as have ammo boxes but stumbled on this https://www.ebay.co.uk/itm/UK-Portable-12V-Car-Adapter-Plug-Electric-Lunch-Box-Heated-Bento-Food-Warmer/392253901268?hash=item5b542789d4:g:KdQAAOSwBHNdcNX-  and wondered if it could be adapted by using a temperature sensor. The UK F5B blog mentions the use of food warmers so looking for some advice.

[SilentPilot]

Go on, I’ll ask, why?

The only LiPo batteries that I warm are my 1S UMX cells on a cold day. Even then it’s only putting them in my pocket. 

[Feefo]

2 hours ago, SilentPilot said:

Go on, I’ll ask, why?

The only LiPo batteries that I warm are my 1S UMX cells on a cold day. Even then it’s only putting them in my pocket. 

Cold batteries don't perform as well as a warm battery, and seeing as I bought a few high performance planes I should probably start to treat my batteries a bit better. 

https://www.f5b.co.uk/lipo-battery-heater.html

[Brian Taylor]

I have seen a few people using 12v pet bed heater mats fitted into a modified ali case. They are about on eBay for £20 or so.

 

[Feefo]

Cheers Brian, I was struggling to find the name of the flexible elements but eventually found them, that pet bed is definitely an option 

[steveburns]

Hi.

I'll see if I can answer your questions on this.

Why do we heat batteries?

A few reasons for this really, we never used to heat them but the difference in power between the first climb and the fifth climb was around 1 kW with the fifth climb having more power than the first. This isn't good for consistent flying or the health battery.

When you load a battery, the voltage will drop. Just how much this drops is down to the internal resistance of the battery.

The higher the C rate of the battery should mean it has a lower resistance but don’t be fooled by the manufactures claims. A few years back when I was flying 6s we found the blue 30c Turnigy packs to be better than one of the big name and big price 65c packs. The Turnigy packs were £30, the big name ones were over £100 so you don’t always get what you pay for.

If we heat the batteries the internal resistance will drop and as a result of this they will hold a higher voltage when under load.  What doesn’t happen is the voltage of the battery rises with temperature (I did hear a trader telling someone this and that he should buy this heater box or his batteries will explode)

You will have noticed your packs get hot when you use them. This self-heating is a result of the work they are doing and isn’t a good thing for their health. Once we started pre-heating our packs we noticed the temperature rise over a flight was less than when flying a cold pack and our batteries were lasting longer in terms of life, not flight time.

I would recommend you heat your packs to around 30 or 35 deg C. Some of us are heating to a higher temperature than this but we are pushing things quite hard and have been doing it quite a while.

 

What do we use for heaters?

In the early days I used RC car tyre heaters in a cool bag. That worked pretty well. Another option is one of the little 12V fridge/cool boxes that also heats. These are pretty low power and have no temperature control but will get the job done.

I have been making my own heaters for a few years now. I use carbon tows laid into glass to make the heating element. This is also bonded to an Aluminium plate which acts as a thermal mass giving me a nice hot plate to mount in a box. I control the temperature with a cheap temperature controller from eBay.

Another idea for a heater element is a heat bed from a 3D printer. I’ve not tried this yet but coupled up to a temperature controller it should do the job quite well but go careful on how much power it’s pulling. My heat bow runs at about 5A, the 3D printer heat plate I have sat on the shelf pulls 9A on 12V

When I’m making my heaters I size the heater but adjusting the length of the carbon tows to give me just over the temperature a want on 12V and then increase the power by running however many elements I need wired in parallel.

Some where around here should be some pics of one of my heaters. My shinny new heater box that has a flashy epoxy finish to the heat plate and temp controller and charge lead entry all build in. And a 3D printer heater.

Links to a couple of the temperature controllers I use…

Temp controller 1

Temp Controller 2

(You can get those at better prices but that's just the first links I found)

I think that pretty much covers it.

Steve

[steveburns]

Another option for a heater is a 12v mirror heater...

Mirror Heaters

[Feefo]

Cheers Steve.

Heated motorcycle grips are another option I saw on YT video.

Thanks for the detailed explanation on the why to warm batteries, I probably read about it years ago and only bits have stuck with me tbh.

I haven't flown much the last couple of years and found the lipo heater bag from HK to be ok, but could now do with something bigger really. I think I'll have a go at using a case and assembling my own, cheers for the links. 

I've also considered making a variable discharger a few times over the years to cycle batteries from new, some seem to think it helps but one picture I saw of a piece of board with dozens of halogen lights on put me off due to cost and storage. Is it worth using a discharger like that and are there any better options than using bulbs?

 

[steveburns]

I don’t bother cycling packs from new, just get on and fly them. For storage voltage I find they are pretty close to that after flying so just leave them as they are.  If I do find I have fully charged packs left at the end of a flying session I use my charger to return them back to storage voltage.

[f3fman]

1 hour ago, steveburns said:

I don’t bother cycling packs from new, just get on and fly them. For storage voltage I find they are pretty close to that after flying so just leave them as they are.  If I do find I have fully charged packs left at the end of a flying session I use my charger to return them back to storage voltage.

I don't cycle packs when new either, but ....     I treat them a little more gently for the first five-ish flights and don't discharge them anywhere near an esc cut-out for instance, they do improve over the first few flights.  Demonstrated in the last week with 5 new 1s drone batteries which at first would hardly let the drone climb, and now are working much better :-)

[wixy]

Rick Loyd makes a nice lipo heater . 

not sure if he is a barcs member , but should be able to contact through FB.

G

[DaveH]

The difference in the first climb on my 2M F5J gliders between a pre-heated battery and a cold (thinking typical spring/autumn day of 15c) is easy to see.    I started to prewarm them in warm pocket and began to do the same for my sports plane batteries.   I now carry them in a padded camera bag with one or two of those rechargable hand warmers.   The hand warmers only do about an hour each, so a few might help.      

[wixy]

[Feefo]

11 hours ago, DaveH said:

The difference in the first climb on my 2M F5J gliders between a pre-heated battery and a cold (thinking typical spring/autumn day of 15c) is easy to see.    I started to prewarm them in warm pocket and began to do the same for my sports plane batteries.   I now carry them in a padded camera bag with one or two of those rechargable hand warmers.   The hand warmers only do about an hour each, so a few might help.      

Cheers, hand warmers would work if I was only going to use a few packs, but with 1 of my planes running a 2 pack setup I think I need a case to warm them up really. I've used the stick it in your pocket technique too but I'm now using bullet connectors and don't fancy an accidental short in my pocket 

[Feefo]

29 minutes ago, wixy said:

Yeah both that one and the Steve's version both look ideal and pretty much what I'm after. There was a thread on RCG but the images have disappeared, I guess deleted as the thread is a few years old now.

[Rick Lloyd]

Hi all 

if anyone is interested I still make them to order. 

here is a video review of a custom made box I did a few years ago ..

 

 

 

[Baldyslapnut]

Steve's post shows his home made box. A fair amount of work has gone into that. 

You can get heater boxes that are made commercially. If that is beyond you or time is short. Or you could ask Steve to make one for you.

This a top of the range from our Germany friends.:

https://www.hoelleinshop.com/zubehoer-lipo-heizkoffer-355-255l-profi.htm?shop=hoellein&SessionId=&a=article&ProdNr=LZHK-PL&t=49302&c=25745&p=25745

They do different versions  which are priced depending on power and size.

 

[Feefo]

I'd seen that box here http://www.hadi-rc.de/HBKofferPL , it's nice but  more than I wanted to spend. After looking  at different options and pricing parts up I ordered 1 from Rick.