RV.Net Open Roads Forum: Tech Issues: Basics of Lithium conversion... I'm lost!

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Basics of Lithium conversion... I'm lost!

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 9  
Prev
Sponsored By:
phemens

Montreal, Canada

Senior Member

Joined: 09/18/2006

View Profile


Offline
Posted: 04/27/21 06:17am Link  |  Quote  |  Print  |  Notify Moderator

StirCrazy wrote:

steveh27 wrote:

https://diysolarforum.com/threads/lifepo4-battery-warmer-install.14485/

This thread shows how to install warming pads and a thermostat controller for LiFePo4 batteries. Mine is shown on page 5 for my Class B. Works great.


thats interesting, a lot of them seam to wrap the batteries in insulation tight, then have the pad stuck to the side. wouldnt it make more sence to have that insulation an inch or two away from the battery so you could get a bit of air movment and use less pads to heat more batteries? just thinking here so if it has been done and didnt work I would be curious as to why.

seams to me if you have the space to put say 2 or 3" of good insulation with sy a 2" air gap between the batteries and the inside of the insulated box and say a tiny ultra low draw fan to cirulate the air, you could probably heat several batteries with one heating pad and cut the amp draw for that purpose. of course this would depend on the space you have also I guess.

Steve


That's exactly what I do. I have a single waste tank heater placed under 6 LiFePo batteries (with a thin sheet of aluminum to spread the base), with 4 inches of foam insulation cased around the battery box. There's about 3 inches of gap between the batteries and the foam. I checked this weekend and the temp at the battery terminal according to the Victron shunt was 8C, ambient outside temp was -3C. Works well for my purposes, we don't camp in extreme cold weather but do in the fringe seasons.


2012 Dutchman Denali 324LBS behind a 2006 Ford F-250 V10 out of Montreal
1 DW, 1 DD, 1 DS, 2 HD (Hyper Dogs)
1200w solar, 600AH LIFePO4, Yamaha EF2000 gen, Samlex 3000w Inverter

StirCrazy

Kamloops, BC, Canada

Senior Member

Joined: 07/16/2003

View Profile



Posted: 04/27/21 06:34am Link  |  Quote  |  Print  |  Notify Moderator

phemens wrote:

StirCrazy wrote:

steveh27 wrote:

https://diysolarforum.com/threads/lifepo4-battery-warmer-install.14485/

This thread shows how to install warming pads and a thermostat controller for LiFePo4 batteries. Mine is shown on page 5 for my Class B. Works great.


thats interesting, a lot of them seam to wrap the batteries in insulation tight, then have the pad stuck to the side. wouldnt it make more sence to have that insulation an inch or two away from the battery so you could get a bit of air movment and use less pads to heat more batteries? just thinking here so if it has been done and didnt work I would be curious as to why.

seams to me if you have the space to put say 2 or 3" of good insulation with sy a 2" air gap between the batteries and the inside of the insulated box and say a tiny ultra low draw fan to cirulate the air, you could probably heat several batteries with one heating pad and cut the amp draw for that purpose. of course this would depend on the space you have also I guess.

Steve


That's exactly what I do. I have a single waste tank heater placed under 6 LiFePo batteries (with a thin sheet of aluminum to spread the base), with 4 inches of foam insulation cased around the battery box. There's about 3 inches of gap between the batteries and the foam. I checked this weekend and the temp at the battery terminal according to the Victron shunt was 8C, ambient outside temp was -3C. Works well for my purposes, we don't camp in extreme cold weather but do in the fringe seasons.


do you use a tiny computer fan or anything to blow the heat around or are you just using the heat radiating off the alumium base?

Steve


2014 F350 6.7 Platinum
2016 Cougar 330RBK

steveh27

Grosse Pointe Woods, MI

Senior Member

Joined: 08/21/2004

View Profile



Good Sam RV Club Member


Posted: 04/27/21 08:01am Link  |  Quote  |  Print  |  Notify Moderator

StirCrazy wrote:


do you use a tiny computer fan or anything to blow the heat around or are you just using the heat radiating off the alumium base?

Steve


If using a thermostat controller like mine it must be placed to measure the heat in the batteries, not the surrounding air which would heat up quickly and perhaps shut down the heater before the batteries reach a good temp. If you look at my diagram and read the text, I placed the temp sensor between the 2 batteries which are tight together and below the top.

phemens

Montreal, Canada

Senior Member

Joined: 09/18/2006

View Profile


Offline
Posted: 04/27/21 01:00pm Link  |  Quote  |  Print  |  Notify Moderator

steveh27 wrote:

StirCrazy wrote:


do you use a tiny computer fan or anything to blow the heat around or are you just using the heat radiating off the alumium base?

Steve


If using a thermostat controller like mine it must be placed to measure the heat in the batteries, not the surrounding air which would heat up quickly and perhaps shut down the heater before the batteries reach a good temp. If you look at my diagram and read the text, I placed the temp sensor between the 2 batteries which are tight together and below the top.


I use a Victron shunt connected directly to one of the battery terminals. No fan, aluminum dissapates heat for all of the batteries.

pianotuna

Regina, SK, Canada

Senior Member

Joined: 12/18/2004

View Profile


Offline
Posted: 04/27/21 01:58pm Link  |  Quote  |  Print  |  Notify Moderator

phemens,

Nice post on aluminum heat sink dissipation.

I think the trust of the recent posts is how to keep the batteries warm in cold weather. (which is what keeps me from using them)


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

phemens

Montreal, Canada

Senior Member

Joined: 09/18/2006

View Profile


Offline
Posted: 04/27/21 06:06pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

phemens,

Nice post on aluminum heat sink dissipation.

I think the trust of the recent posts is how to keep the batteries warm in cold weather. (which is what keeps me from using them)


Yes, but I think that's largely overstated as an issue for 95% of people that are the potential target market. Your use case evidently is extreme, which means that chemistry isn't for you!
In my case we camp on a remote piece of property without any services and need the batteries & solar to function continuously to keep the residential fridge going 24/7. We're also not there for several days at a time, so I need something that is relatively fool proof.
There are a few weeks in the spring and fall where the temperature drops enough that if I didn't warm the batteries, the Victron sensor would prevent the MPPTs from charging (I set the cutoff for 5C, which is conservative). The warming mat and insulation see me through but I can't speculate on whether it would be sufficient for much colder temparatures. Were that the case I would probably opt to add a beefier heater and fan.

StirCrazy

Kamloops, BC, Canada

Senior Member

Joined: 07/16/2003

View Profile



Posted: 04/28/21 06:39pm Link  |  Quote  |  Print  |  Notify Moderator

steveh27 wrote:

StirCrazy wrote:


do you use a tiny computer fan or anything to blow the heat around or are you just using the heat radiating off the alumium base?

Steve


If using a thermostat controller like mine it must be placed to measure the heat in the batteries, not the surrounding air which would heat up quickly and perhaps shut down the heater before the batteries reach a good temp. If you look at my diagram and read the text, I placed the temp sensor between the 2 batteries which are tight together and below the top.


ok I have my case for the small cells I have set up a little different to play with this winter. like you I did place the temp probe between the cells but I set it up so no direct heat can just move between the cells. it has to propagate from the 6 outside surfaces inwords. the discharge and charging also adds heat from the inside so who knows actualy how long the heater will be on. I am starting out with a heat pad that uses 0.2A and I like the idea of some sort of alumium heat sink. with a small fan (0.05a) i could make a heat tube to transfer the heat to the air more efficently..

guess Ill see how it works this winter, I dont mind screwing up my 30ah prismatic cells to find out what works and doesnt for setting up the big ones in the rv's

Steve

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 9  
Prev

Open Roads Forum  >  Tech Issues

 > Basics of Lithium conversion... I'm lost!
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:




© 2021 CWI, Inc. © 2021 Good Sam Enterprises, LLC. All Rights Reserved.