Battery chargers acting strange

[Crowz]

This one may be all in my head and just a bunch of coincidences.

I'm trying to charge my 12V lifepo4 batteries (weize 12v and chins 12v in parallel) and every battery charger I put on them has issues.

Clouds rolled in and I won't have any real sunshine for 2 days so I wanted to use 12v battery charges I had laying around to top them off some.

1st charge is a schumacher battery charger old school battery charge (dial showing amps going in and a switch for normal/deep cycle and 2, 6 and 50 amps).
This charger works fine but overheats after 10 minutes set on 6amp charge kicking out the breaker inside and after cooling it goes back to charging. Never had this problem with anything else I have charged.

2nd charger is a 3.6amp axtro charger from amazon. Fancy but still no lithium setting. It runs fine but gets VERY hot so I figure it might mess up if I left it going and stopped it from charging after 30 minutes or so.

3rd charger is an old black and decker fancy charger (one of the first "automatic" models they had). It works fine on other batteries but on the lifepo4's it flashes "full" on the display and stops after I tell it to start.

4th charger is Schumacher SSC-1500A-CA Ship 'N' Shore 15 Amp SpeedCharge Charger. It works fine except seems to get hot faster than normal and its fan has long since bit the dust so not risking frying it.


So is something weird going on? Do lead acid chargers just hate charging lifepo4 and I never notice it before heat wise?

Solar charging works fine with it but again solid clouds for 2 days at least.

 

[Samsonite801]

They are likely getting hotter due to the low internal resistance of LFP batteries, they are drawing the chargers up to their highest current while on automatic mode (perhaps is static calculated, and not a CC regulated max current). I might look at a charger that has an LFP charge profile. That first charger you have is probably the heavy kind with transformer, so its current is likely static calculated and engineered based on for a typical lead acid battery internal resistance.

I know some guys burn up alternators on cars charging LFP batteries, due to their low internal resistance... A good solid state charger made with LFP charge profile can charge up to the max regulated CC amps (bulk) not go over, and switch to CV when it reaches absorption voltage, then taper off to float...

 

[Crowz]

I'll probably pull my noco 5amp charger off of another project tomorrow since its the only one I have that has a lithium setting.

 

[pollenface]

My best chargers are a couple of adjustable bench power supplies. I would normally pair them with a 24hr timer switch as needed.

 

[Solarcabin Channel]

You can charge LIFEPO4 with a standard charger however the batteries will not get fully charged because LFEPO4 charge at a higher voltage.

I don't recommend mixing battery brands and the BMS may not be set for same charge rates per cell. This can cause problems with chargers and solar controllers.

Make sure both batteries are at same charge level before connecting and in general most manufacturers recommend no more than 3 LIFEPO4 batteries in series or parallel though some say they can have more. LIFEPO4 batteries take time to balance as they reach full charge and will trickle charge at a lower rate than some chargers can handle causing the overheat issue.

Make sure the amp output on all batteries is the same and they are within the same specs and age of battery.

Once the battery is fully charged remove the charger and you don't need to trickle charge a LIFEPO4 in storage. Just check level about every 4 months and charge if needed. For storage keep them at about 50% of full for best life.

 

[Crowz]

You can charge LIFEPO4 with a standard charger however the batteries will not get fully charged because LFEPO4 charge at a higher voltage.

I don't recommend mixing battery brands and the BMS may not be set for same charge rates per cell. This can cause problems with chargers and solar controllers.

Make sure both batteries are at same charge level before connecting and in general most manufacturers recommend no more than 3 LIFEPO4 batteries in series or parallel though some say they can have more. LIFEPO4 batteries take time to balance as they reach full charge and will trickle charge at a lower rate than some chargers can handle causing the overheat issue.

Make sure the amp output on all batteries is the same and they are within the same specs and age of battery.

Once the battery is fully charged remove the charger and you don't need to trickle charge a LIFEPO4 in storage. Just check level about every 4 months and charge if needed. For storage keep them at about 50% of full for best life.

I think at 200ah I don't have much to worry about other than just getting thru till the sun's back out with these chargers because they won't see anything near a full charge

Again this is just to get a fully working mini system thru bad weather. Sure would be nice is there was a 12v version of the chargeverter.

My house runs on 48volt this stuff just runs my security cameras, pi monitoring computers and network routers.

 

[Crowz]

I put the noco 5amp charger on it and set it to lithium and its charging great so far. No excess heat and working nicely. It's not like its going to recharge all that much but it does cover the power usage and lets the solar charger actually charge the batteries even with rain and clouds till the sun comes back out in a few days.

When I get a few more 450 watt panels for my 48v stuff I will add the old 255w panels on the 12v stuff and that should make it charge even in pouring rain

 

[Quattrohead]

I wonder if putting an automotive bulb of either 15/21 or 50/55 watts in line between the charger and battery may help to not overheat the charger.

 

[Crowz]

I wonder if putting an automotive bulb of either 15/21 or 50/55 watts in line between the charger and battery may help to not overheat the charger.

I can try it if you want me to.

It's sure strange how the lead acid chargers heat up like they do.

 

[Samsonite801]

It's sure strange how the lead acid chargers heat up like they do.

It has a lot to do with ohms law... Now most decent quality lead acid battery chargers of some moderate quality range should be able to withstand connecting to a low resistance battery, when they are on CC they 'shouldn't' go over their max current rating. I would think an electronic solid state charger wouldn't (or shouldn't), but depends on their design I guess, I can see how an older 'heavy' charger (not electronic), could draw overcurrent. But it is the excessive current that is making them get hot.

If any of your chargers might have a manual CC amperage setting, where you could set it to a lower amps value, then check it with an amp-clamp probe to confirm actual vs setting, that might help.

But this is why LFP have a round-trip-efficiency so high like 92% and higher (vs 80% with lead acid), because they have a low internal resistance so they don't waste as much energy in charging / discharging...


More info about LFP internal resistance:

How to Test the Lifepo4 battery Internal Resistance?

Detecting the lifepo4 battery internal resistance is an important part of maintaining and extending its life. And we will teach you to understand what internal resistance is and how to test it properly.

harveypoweress.com

What Is A Good Internal Resistance For A Lifepo4 Battery?​

The internal resistance of common lithium iron phosphate batteries is usually in the range of 0.6Ω-1Ω, but for batteries, the smaller the internal resistance, the better, because it is impossible to achieve zero internal resistance due to the manufacturing process and other factors. Therefore, the internal resistance of a good lifepo4 battery is usually in the range of 0.15Ω-0.3Ω.

 

[Quattrohead]

I think it's worth a try. People just don't understand what a brilliant electronic component an incandescent bulb is.

 

[Crowz]

I think it's worth a try. People just don't understand what a brilliant electronic component an incandescent bulb is.

Oh I'm all for testing to reference since this could come in handy helping others later on but I'm having a minor problem doing the test right now that just shows how the world has changed.....

I can't find an incandescent bulb

All of my stuff has been switched over to led so far but I'm still hunting.

 

[Quattrohead]

Fortunately efficiency ratings haven't hit car bulbs yet.
People are investing in Bitcoin and gold bars but I am investing in tungsten and halogen ?

 

[Young power]

230ah liffepo4 cell