Charging 12V Lithium battery with 24V 5A SLA charger, what's needed to make it happen?

Thread Starter

us202000

Joined Jul 5, 2011
20
All,

I have a 24V 5A SLA battery charger and was wondering whether it can be modified to charge a 12V Lithium battery by purchasing some module. The one I was looking is this one on Amazon: https://www.amazon.com/gp/product/B07CTN2KT7/ref=ox_sc_saved_image_1?smid=A28ZWXW3ZSVNZU&psc=1. It says "Lithium Battery Charging Control Protection Board Charger Switch Module for 12V-24V Storage Batteries" (confusing, not sure what it means).

Will this work? Any suggestions?

Thanks.
 

ericgibbs

Joined Jan 29, 2010
15,697
hi us20,
I read it as settable for 12V or 24V batteries.
Clip from the Amazon specification
Product Description

Features:
This is a battery charging protection switch module that can control charging of 12V-24V storage batteries. The start voltage and stop voltage of this control module can be set according to your need. Support battery voltage detection, automatically stop charging when battery is fully charged.
If you set 10V as start voltage and 14V as stop, then module will charge battery when voltage is lower than 10V, and stop charging when voltage is higher than 14V. Press run and stop button together, the module will display 888 and restore to factory setting.

Specifications:
Input Voltage: DC 10V-30V
Display Accuracy: 0.1V
Control Accuracy: 0.1V
Output Type: Direct output
Voltage Error: +/-0.1V
Used for: 12V-24V storage batteries
Size: 82*58*18mm / 3.22*2.28*0.7"
 

Audioguru again

Joined Oct 21, 2019
4,793
It is not a "balanced" charger that measures the voltage of each cell separately and prevents the weakest cell from an over-voltage explosion.
It does not limit the current to whatever is the maximum charge current for your battery to prevent an explosion.
It seems to be too easy to accidently bump the Chinese language marked keys to the wrong setting that will cause an explosion.
 

MrAl

Joined Jun 17, 2014
9,158
All,

I have a 24V 5A SLA battery charger and was wondering whether it can be modified to charge a 12V Lithium battery by purchasing some module. The one I was looking is this one on Amazon: https://www.amazon.com/gp/product/B07CTN2KT7/ref=ox_sc_saved_image_1?smid=A28ZWXW3ZSVNZU&psc=1. It says "Lithium Battery Charging Control Protection Board Charger Switch Module for 12V-24V Storage Batteries" (confusing, not sure what it means).

Will this work? Any suggestions?

Thanks.
That looks like it only has 2 output wires, so you could only use it on a 12v Li-ion battery that has internal balance and charge limit circuits built in.
If you intend to use a SLA battery charger of any kind to charge Li-ion or similar, it is not a good idea because that kind of charger has no way to balance the cells or limit current to the internal cells that makes up the battery. SLA batteries do not need that so that SLA charger will not have that.
If the Li-ion battery has internal balance and current limits, it may work but it's still taking a chance. They do make chargers that do both but they switch modes.

One other thing Li-ion battery chargers have that SLA battery chargers do not have is very closely regulated top voltage cutoff. The spec for a Li-ion battery is much more strict than for an SLA battery. So although it may appear to work, it may also overcharge it and ruin the battery or even cause it to catch fire or blow up.
Charging is one of the most dangerous modes so you really should have the right charger to be safe.
 

Papabravo

Joined Feb 24, 2006
18,793
All,

I have a 24V 5A SLA battery charger and was wondering whether it can be modified to charge a 12V Lithium battery by purchasing some module. The one I was looking is this one on Amazon: https://www.amazon.com/gp/product/B07CTN2KT7/ref=ox_sc_saved_image_1?smid=A28ZWXW3ZSVNZU&psc=1. It says "Lithium Battery Charging Control Protection Board Charger Switch Module for 12V-24V Storage Batteries" (confusing, not sure what it means).

Will this work? Any suggestions?

Thanks.
Instead of trying to fabricate a cheap shortcut that will be hazardous to your health and wellbeing, save your nickels and BUY the proper equipment. There is literally no substitute for the right tool. Would you try to drive screws with a hammer and nails with a screwdriver? I sure as hell hope not.
 

LowQCab

Joined Nov 6, 2012
2,171
To dispense with all of the usual speculation .................
How about supplying us with a proper Spec-Sheet for Your Battery ?
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.
.
 

Thread Starter

us202000

Joined Jul 5, 2011
20
Thanks to all. Very helpful. Here is the spec for the small battery (bought on Amazon under 40 bucks):
LiFePO4
Output voltage: 12.8V
Capacity: 8Ah@0.5C (>8Ah@1C)
Internal resistance: <=20mOhm
Charging Voltage: 14.6V
Discharge output Voltage: 9.2V
Continuous charging current: 4A
Continuous discharging current: 10A

So far I have been using a small solar panel battery trickle charger maintainer to charge it very slowly.
 

LowQCab

Joined Nov 6, 2012
2,171
That's a good start ......
Next, does it have a Charge-Balancing-Plug, and/or, built-in Protection/Balancing-Circuitry ?
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.
.
 

Thread Starter

us202000

Joined Jul 5, 2011
20
The battery has two terminals. It looks just like a SLA battery. Here is what it says on Amazon:
https://www.amazon.com/dp/B09SG25HNR?psc=1&ref=ppx_yo2ov_dt_b_product_details

Don't know whether it has any BMS inside.
Wait, actually it says there is BMS:

  • Premium battery cells: PowerUrus 12v lithium battery selects high-grade lithium iron phosphate battery cells, which can assist the 12v battery to achieve more cycles and a long lifespan. It is 8 to 10 times service life of lead-acid battery in the same capacity. Prefer for replacing the traditional SLA battery.
  • Built-in BMS for High-grade Safety: PowerUrus 12V 8AH LiFePO4 battery built-in Battery Management System (named BMS) which protect it from overcharge, over-discharge, over-current, and short circuit. Ensuring high-level safety for using. Moreover extending battery serving life.
  • Flexible Extending Capacity: PowerUrus lithium batteries can be connected in series or parallel to get higher voltage (25.6V / 38.4V / 51.2V) or more capacity (max. 48Ah). Flexibly suitable for various scenarios and feed customer needs.
  • Compact Size and Lightweight: This 12V LifePO4 battery has compact size, 5.9 x 2.6 x 3.7 in, and lightweight 2.2lbs. It is great for your portable needs. Bring convenient electrical power for kid's car, fish finder, camping light and so on.
  • High-Efficiency Performance: The battery capacity is over 80% after 1C charge and discharges under 100% DOD condition for 4000 cycles. PowerUrurs always provides technical support and three-year warranty on this product.
 

Audioguru again

Joined Oct 21, 2019
4,793
Does their ad tell the truth??
It would be a good battery if it was made by a reliable Name-brand company.
It seems that Amazon does not sell it anymore (it was sold for only 3 months) or has run out of replacements.
 

Tonyr1084

Joined Sep 24, 2015
6,883
Given that your battery has BMS:
Charging 12V Lithium battery with 24V 5A SLA charger, what's needed to make it happen?
Nothing. You should be good to go as long as the charger is set for a 12 volt battery. Using it on the 24V setting may over stress the BMS and cause premature failure.

Also, given that your battery is LiFePO4 the danger of explosion is nil. Still, you always want to know you're charging the battery the proper way. No substitute for the correct equipment. Bodging things together in an emergency like MacGyver may work short term, but in the long run it may prove disastrous. Batteries are stored energy. The more energy stored the more potential energy can be suddenly released (explode).
 

Tonyr1084

Joined Sep 24, 2015
6,883
What concerns me is the 102.4 watt hour rating. 12V @ 8Ah suggests 96Wh, not 102.4. If the specs are accurate then 96Wh means you can power (theoretically) a 96 watt lamp for 1 hour. Granted, you may not need that long or that much power. But if you're thinking this can power lamps for hours on end - depending on how many watts you're drawing - you're going to get a corresponding period of time. If you draw 24 watts your lamp will burn for 4 hours continuous. Or whatever equipment you're operating. As for kids ride-on toys? Ones my kids had discharged pretty quickly. Typically about a half hour they had a blast. Then the battery showed signs of weakening.

But your question isn't about usage it's about safety in charging. Like @Audioguru again said
Does their ad tell the truth??
It would be a good battery if it was made by a reliable Name-brand company.
If their ad is truthful (factual and complete information) then you should be OK using the afore mentioned charger. IF their ad is truthful. 102.4Wh puts me in doubt of truth or completeness of information.
 

Audioguru again

Joined Oct 21, 2019
4,793
The battery is not 12.0V, instead they say, "PowerUrus 12V lithium batteries flat discharge curve hold above 12.8V for up to 95% of its capacity usage, transferring a strong boost for its working time." Then 12.8V x 8A= 102.4Wh.

My "3.7V" older lithium batteries all charge to 4.2V.
 

MrAl

Joined Jun 17, 2014
9,158
Thanks to all. Very helpful. Here is the spec for the small battery (bought on Amazon under 40 bucks):
LiFePO4
Output voltage: 12.8V
Capacity: 8Ah@0.5C (>8Ah@1C)
Internal resistance: <=20mOhm
Charging Voltage: 14.6V
Discharge output Voltage: 9.2V
Continuous charging current: 4A
Continuous discharging current: 10A

So far I have been using a small solar panel battery trickle charger maintainer to charge it very slowly.
Hi,

Since the max charge current is 4 amps and you have a 5 amp charger, you have to find a way to reduce the maximum current.
The internal circuitry can only take so much heat before things get too hot, so you have to stay within specs. I think i would start with 1 amp and go from there to see how things go. But on the other hand, i would just use a charger made for charging lithium batteries.

It's interesting they say 12.8v but that's probably not correct. It is probably 12.6 at the maximum voltage right after a full charge and no drain current.
After a load is applied, it will drop down slowly to about 9v maybe a little less, then you have to charge it again.
(Note that 4.2*3=12.6 not 12.8, and they say charge voltage is 12.6 not 12.8 i think).

Trickle charge is not recommended for Li-ion because it causes electroplating of one of the electrodes inside. That causes cell degradation.
Yours isnt really Li-ion so you should look up the exact type and see if that applies to yours too.
Also when you charge at a decent level the charging efficiency goes up.
 

Audioguru again

Joined Oct 21, 2019
4,793
This thread is all mixed up.
The title says a Lithium battery and a completely different SLA (Sealed Lead Acid) charger.
But the link to the Chinesium battery says it is LiFeP04 type which has lower voltages than older 4.2V per cell Li-Ion type.
The charger needs to be setup for the battery voltage.
The Chinesium charger/protection circuit might take weeks to charge the battery because its charging current is not listed.
 

LowQCab

Joined Nov 6, 2012
2,171
There are some things that You just shouldn't buy from China .........
In fact, most things.
As long as the purchaser understands the risks involved, it's on him.
.
.
.
 

MisterBill2

Joined Jan 23, 2018
12,401
hi us20,
I read it as settable for 12V or 24V batteries.
Clip from the Amazon specification
Product Description

Features:
This is a battery charging protection switch module that can control charging of 12V-24V storage batteries. The start voltage and stop voltage of this control module can be set according to your need. Support battery voltage detection, automatically stop charging when battery is fully charged.
If you set 10V as start voltage and 14V as stop, then module will charge battery when voltage is lower than 10V, and stop charging when voltage is higher than 14V. Press run and stop button together, the module will display 888 and restore to factory setting.

Specifications:
Input Voltage: DC 10V-30V
Display Accuracy: 0.1V
Control Accuracy: 0.1V
Output Type: Direct output
Voltage Error: +/-0.1V
Used for: 12V-24V storage batteries
Size: 82*58*18mm / 3.22*2.28*0.7"
the specification does not explicitly state the adjustment range for either voltage or current, and both are important for charging lithium batteries of any variety. Also it does not seem to mention the maximum current capability of the board. so the board module might be ok, or not. How lucky do you feel??
 

MrAl

Joined Jun 17, 2014
9,158
the specification does not explicitly state the adjustment range for either voltage or current, and both are important for charging lithium batteries of any variety. Also it does not seem to mention the maximum current capability of the board. so the board module might be ok, or not. How lucky do you feel??
I am guessing that the right thing to do is buy a charger meant for these kinds of batteries, and i think you can find chargers that do both SLA and Lithium.
If something goes wrong and the Joulies decide to expel in one second, it could be like 350000 watts for one second. That's enough to cause a LOT of damage to the surrounding area. It would be better to stick to dynamite for the Fourth Of July :)
 
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