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

[C_Schomer]

I did a search and it's mostly Greek... to me. I'd like to know the key points for, hopefully, a straight across lead/acid to lithium conversion.
My old Flow-Rite watering system just overflowed 2 cells (GRRRR) and I'm thinking this might be the time to convert.
So far I see that SiO2 is better than Li but I don't know why or what the difference is, and charging is much simpler for lithium and not so fussy.
I currently have 2 of the bigger Sams 6gc's that have dimensions and specs similar to T-105s, 2 X 120 watt panels and a Morning Star controller with remote panel/setpoint, that the PO installed.
I don't use an inverter for any 120ac loads. I'm nearly always plugged in to 120. I have no big 12vdc loads... my 5er has full LED lighting but I use a 12vdc bipap for very rare boondocking. The biggest addition might be a 12vdc fridge, someday.
Is there 6v and 12v lithium batteries? I seldom need the capacity I have now but I don't want to give it up, for the times I need the 12vdc bipap. Can I get similar capacity with lithiums and also fit the 2 x 6gc foot print? How much capacity to run a 12vdc fridge? Do I need a different solar controller or just reprogram my existing one? Thanks bunches! Craig

[StirCrazy]

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

[phemens]

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.

[pianotuna]

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)

[phemens]

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.

[steveh27]

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.

[StirCrazy]

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

[phemens]

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.

[steveh27]

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

In my Class B there is no room for insulation. That's why I wrapped the 1/2" neoprene insulation around the outside of the box. My Ultra Heat pad only draws 2 amps from the batteries. And I do not use it unless it is below freezing and I need to charge the batteries. It takes less than 2 hours to warm the batteries up for charging.

[vermilye]

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.

A number of manufacturers are now producing models that have heaters built into the battery. Moving the heater close to the individual cells reduces the amount of power necessary to heat them during charging.

[StirCrazy]

C Schomer wrote:
I'm back and I'm going to keep my lead acid batteries and replace the FlowRite caps. My Duracell egc2's are only 4 y.o. And the plates still look great. Besides that, Online searches don't show any gc2 agms in stock anywhere. Craig

yes, if there still in good shape then there is no point getting rid of them unless they just don't meet your needs. this is the problem I have right now. My 5th wheel needs new batteries but my capmer doesnt. so I am just going to using everything I ordered in the 5th wheel and have over 1000 ah availble, then when the camper batteries are older I take one of the batteries and move it there. the shipping and cost on 16 cells just makes it so price wise it is way cheeper for me to order them all now. who knows I may sell the GC batteries in the camper and switch it over right away...

Steve

[StirCrazy]

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

[steveh27]

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.

[C_Schomer]

I'm back and I'm going to keep my lead acid batteries and replace the FlowRite caps. My Duracell egc2's are only 4 y.o. And the plates still look great. Besides that, Online searches don't show any gc2 agms in stock anywhere. Craig

[EMD360]

Fascinating. I bought Lifepo4 for a trolling motor battery box. Three 20 AH batteries in series. Just did a test and ran a 3 amp load for about 19 hours before the inverter beeped and shut down at 10.9 volts. That jumped up to 11.3 volts when I removed the load. That was pretty close to the 60 AH rated. I’m probably losing some power through wiring. I paid $200 for the three batterie and of course a NAPA 62 AH marine battery costs half of that. But my whole battery box weighs 22 lbs instead of 44 just for the battery. Plus these are guaranteed for 3 years and slated to last far longer. So a decent trade off. I’m going with 2 Lion Safari batteries for the RV that fit the group 24 space and will get 210 AH with a progressive dynamics charger for lithium’s and a dc to dc converter for the alternator side. A bit expensive but a good amount of power to use, compatible with my portable solar panels and hopefully a long life. Since this RV is new to us I’m willing to spend more to not have to switch out the batteries every 3 years or so.