AC charge controller for lifePO4 battery?

[WRTC928]

I know very little about lifePO4 batteries except that they don't weigh much and they're popular with off-grid preppers who use solar chargers. I understand they're subject to overcharging which can damage the battery. The charger I see recommended most is a "hybrid inverter" charger which is an AC and solar charger with a built-in charge controller, but they're really expensive and I don't need the solar charging feature. I want to put a battery backup on my repeater and keep it charged from the house AC. I'd also like to have a battery I can grab and go if I think I may be using my vehicle radio a lot on a particular day to avoid running down the vehicle battery. Is there a charge controller for the PO4 that will keep it topped off similar to what the "float charger" does for a lead-acid battery? Something that I can just leave hooked up and plugged in without worrying about it? I've done a search for them, but I can't find one that specifically addresses this use case. 

[Lscott]

13 minutes ago, WRTC928 said:

I know very little about lifePO4 batteries except that they don't weigh much and they're popular with off-grid preppers who use solar chargers. I understand they're subject to overcharging which can damage the battery. The charger I see recommended most is a "hybrid inverter" charger which is an AC and solar charger with a built-in charge controller, but they're really expensive and I don't need the solar charging feature. I want to put a battery backup on my repeater and keep it charged from the house AC. I'd also like to have a battery I can grab and go if I think I may be using my vehicle radio a lot on a particular day to avoid running down the vehicle battery. Is there a charge controller for the PO4 that will keep it topped off similar to what the "float charger" does for a lead-acid battery? Something that I can just leave hooked up and plugged in without worrying about it? I've done a search for them, but I can't find one that specifically addresses this use case. 

You can look at some of these.

https://www.bioennopower.com/collections/battery-chargers

[tweiss3]

Yea, all my LiFePO4 batteries are bioenno, and I bought their charger with the battery. They do stop charging (LED goes green from red) when the battery is full.

[Seapup]

Battery Tender markets models that support your LiFePO4 use case. Here are a few of many:

 

https://www.amazon.com/gp/product/B06X9GGNZC/

https://www.amazon.com/Battery-Tender®-Lithium-Selectable-Charger/dp/B09XP77JCS/

 

[SteveShannon]

One week ago I attended a four hour course on safety and lithium batteries.  We saw some very alarming videos that highlighted how dangerous lithium batteries can be. It was chilling. One in particular showed a young man get into an elevator with the battery from a e-bike. It began smoking and flashed quickly into an inferno that killed him before the elevator doors re-opened. You’re right in wanting to incorporate a charger that protects the battery, but you should also consider where you place the battery so that if it fails it doesn’t destroy your house.

[Socalgmrs]

With how horrible lithium is for the environment both when mining and later and how dangerous they are I won’t have them any place near my home or cars.   Even at work we will not carry them in our trucks.  We work with 48v lithium and we let ups deal with that.  We have had many trucks and vans burn to the ground with lithium.  Especially bad while driving on The freeway. 
 

you can get some very nice, however heavy, agm battery’s for much less money.  One of my radios in the house runs off a 100amh agm and a trickle charger and in the truck I have a hard mounted 80amh agm mounted under the hood that is isolated from the truck batteries but charges off the alternator.   

[Lscott]

54 minutes ago, SteveShannon said:

One week ago I attended a four hour course on safety and lithium batteries.  We saw some very alarming videos that highlighted how dangerous lithium batteries can be. It was chilling. One in particular showed a young man get into an elevator with the battery from a e-bike. It began smoking and flashed quickly into an inferno that killed him before the elevator doors re-opened. You’re right in wanting to incorporate a charger that protects the battery, but you should also consider where you place the battery so that if it fails it doesn’t destroy your house.

How stable the battery is depends on the Lithium chemistry used. The worse are Lithium Ion types, followed by Lithium Polymer. The most stable is the Lithium Iron Phosphate type.

[UncleYoda]

38 minutes ago, Lscott said:

The worse are Lithium Ion types

And that's what all (that I've bought or looked at) the HTs use.  I haven't had any smoke or even get hot. (lucky?)  [When talking a lot using a battery eliminator that does get hot but it isn't a battery.]

[Lscott]

51 minutes ago, UncleYoda said:

And that's what all (that I've bought or looked at) the HTs use.  I haven't had any smoke or even get hot. (lucky?)  [When talking a lot using a battery eliminator that does get hot but it isn't a battery.]

All the Lithium battery packs I have, at lest for Kenwood radios, have a protection circuit in them. I don't know if they protect against over charge, fairly sure they do, but they do work to prevent over discharge. When the terminal voltage drops to a bit under 6VDC the output voltage will suddenly drop to zero. I've run into this while testing my packs for usable remaining capacity with an electronic load. Also the radios seem to alarm out and shut down at the 6VDC mark too.

https://forums.mygmrs.com/gallery/image/248-2117323252_batterypacktestingjpg/?context=new

I found a while back a web site where a guy did a tear down of a K2 Energy 7Ah LiFePO4 battery pack. You can see the Chinese protection module inside.

 

K2 Energy K2B12V7EB LiFePO4 Internals.pdf

[UncleYoda]

Lithium ion batteries do drop quick near the low end.  But I don't see the connection to over-heating.

[Lscott]

11 minutes ago, UncleYoda said:

Lithium ion batteries do drop quick near the low end.  But I don't see the connection to over-heating.

The attached paper, from my personal electronic technical library, goes into some detail on the various failure conditions for Lithium cells. Worth the read.

Safety of lithium-ion batteries.pdf

[WRTC928]

5 hours ago, SteveShannon said:

One week ago I attended a four hour course on safety and lithium batteries.  We saw some very alarming videos that highlighted how dangerous lithium batteries can be. It was chilling. One in particular showed a young man get into an elevator with the battery from a e-bike. It began smoking and flashed quickly into an inferno that killed him before the elevator doors re-opened. You’re right in wanting to incorporate a charger that protects the battery, but you should also consider where you place the battery so that if it fails it doesn’t destroy your house.

That's good to know. I was not aware of that.

[WRYZ926]

Fire departments pretty much have to let electric vehicles burn themselves out because of the lithium batteries. Lithium is like white phosphorus in that it will keep burning when you try to put it out. 

I'm not super familiar with putting out lithium fires.  I do know the only way to stop white phosphorus from burning is to bury it so that there is no oxygen. And it will reignite if exposed to the open air.

Willy Pete grenades are fun to play with and the white phosphorus will burn straight through even some of the thickest armor plate. White phosphorus grenades are great for when you have to destroy equipment and vehicles.

[WRTC928]

21 hours ago, WRYZ926 said:

Willy Pete grenades are fun to play with and the white phosphorus will burn straight through even some of the thickest armor plate. White phosphorus grenades are great for when you have to destroy equipment and vehicles.

My father had burn scars on his chest from a bit of WP spray he got in the Korean War. I never thought to ask him if the grenade was Chinese or American. 

Speaking of destroying equipment, in 1978, US troops on the listening posts in Iran had to pull out in a hurry and leave their highly classified comm equipment behind. They applied something that looked like fruit roll-ups and lit it. In fairly short order, it reduced millions of dollars' worth of equipment to slag. I don't know what that stuff was, but I'll bet I could have some fun with it.

[WRTC928]

As I said, I don't know much about these batteries, and it gets confusing to read the info on the sales sites. They never say whether the thing will safely act like a trickle charger or not. 

[WRTC928]

And a follow up question... Is there any reason I can't hook two 50 Ah lifePO4 batteries in parallel to provide 100 Ah like you can with lead-acid batteries? I think some solar charging systems do something similar, but I'm not sure. I can't think of a reason why it would be a problem, but this is uncharted territory for me.

[SteveShannon]

2 minutes ago, WRTC928 said:

And a follow up question... Is there any reason I can't hook two 50 Ah lifePO4 batteries in parallel to provide 100 Ah like you can with lead-acid batteries? I think some solar charging systems do something similar, but I'm not sure. I can't think of a reason why it would be a problem, but this is uncharted territory for me.

Lead-acid batteries have measurable internal resistance that will limit the current flow between them. LiFePo batteries have very little internal resistance so connecting two batteries together that have different voltage levels could be exciting when the current between them spikes. I can only assume that some kind of balancing circuit would be necessary to parallel them. 

[WRYZ926]

You can safely connect LiPo4 batteries in series or parallel or both.  LiPo4 batteries do have a BMS (battery control module) that protects them. Always use the exact same size and capacity batteries when connecting multiple LiPo4 batteries together. It is also advisable to make sure they are the same age. IE you don't want to connect a brand new inline with an old battery

I run 4 10AH LiPo4 batteries hooked in parallel in my small battery box and two 50 AH LiPo4 batteries connected in parallel in my big go box. I also have an Apache case with two 10 AH LiPo4 batteries and a spot for my Xiegu G90. I can run those two batteries separately or in parallel if I want.

[tweiss3]

From Bioenno

 

Long story, you can but you probably shouldn't.

 

 

[WRYZ926]

Each manufacturer is going to have different instructions when it comes to using their batteries. I use Redodo brand batteries and they do not have any warnings on their website that I could fine.

How to Connect Batteries in Series and Parallel?

As always, consult the manual that comes with your batteries or consult the manufacturer directly.

Make sure that what ever charger you use is designed for lipo4 batteries. I use a Bioenno 5 amp charger for my 10 AH batteries and a Redodo 10 amp charger for the 50 ah batteries.