Charging rates vs cycle life

Just ordered a battery pack (14s4p PF cells 11.4AmpHour) from em3ev, was looking to get the smaller 2amp charger to help extend life of battery (would manually disconnect at or before 80% also). Unfortunately they are backordered, so I'm thinking of getting their other reasonable priced charger, but it does 5amps. This is still only .45C but worry it would have some affect on cycle life.


Also open to other charger options.
Currently thinking of the Luna with 80,90,100% charge end options which I do value.

More voltage/current options would also be nice but not wanting to spend $300 for Grin's charger.

Any thoughts?

Could always make an "extension" cable with a resistor built in to slow down charging. If you've got plenty of time, charge through the restricting resistor. If you're in a hurry, charge direct.

Best of both worlds.

As these are constant current chargers, my gut reaction is that a series resistor doesn't change the C rate?

ELG-150-54A

that is is charger you should buy. manually set it to 56.7V, set the current to a reasonable level and be done with it.

docw009 said:

As these are constant current chargers, my gut reaction is that a series resistor doesn't change the C rate?

Click to expand...

The police would have to charge them with breaking Ohm's law then

In all seriousness, it depends on whether you pick the right resistor or not. The fundamental unbreakable law is that:

V=IR

If you raise the resistance, either the current must fall, or the voltage must rise.

The voltage *but only as seen at the charger* will rise until it reaches the pre-programmed stop. Then the current will fall.

So you need a resistive enough resistor, to force it out of the CC phase, and straight to the CV phase for this to work.

why woudl you ever do this? you would need a massive resistor and a fan cooling the thing. it makes no sense and doesnt do what you want it do do as it also tanks your charging voltage and it will take forever to reach float voltage if the charger does not cut out before that.

Yeah, the resistor in series is not the correct solution for reason's already touched upon.

>ELG-150-54A

This looks quite interesting: adjustable current (up to 1.4-2.8 Amps) and voltage (49 ~ 58V), relatively low cost, fanless, water resistant, well known manufacturer. Though, it is an LED driver with CC-CV stages. I am hesitant though to hook it up without a very thorough reading of datasheet. Is this a well known solution?

First thing that pops out is that voltage tolerance is: ±2.0% (Tolerance: includes set up tolerance, line regulation, and load regulation) which for 55 Volts is +-1.1 Volts, that's a lot of variance. Though in normal usage/average sample it's going to generally be better, but a bit disconcerting (though setting voltage low would give you head room anyways).

Found another interesting option for stopping dumb chargers early: XH-M604 If it works as described you can set a high (and low) voltage limit. It will disconnect the battery when the battery voltage surpasses a set-point. This does not solve the high current issue though.

Also heard from a friend that uses one of these: MPT-7210A https://smile.amazon.com/DROK-Contr...rd_wg=ZPdvW&psc=1&refRID=6X6WBETFERRKVCWB1D06, driven either off a power supply or solar panel.

using mean well chargers/led drivers is a well used solution and is the default solution for my conversion builds (as a company). i have built in litteraly dozens in the past years in various configurations. they work on exactly the same principle as a regular lipo charger and are basically the highest quality you can buy, usually much higher quality then virturally all chinese chargers.

do NOT use the "charger" you mentioned.

jbwiden said:

Yeah, the resistor in series is not the correct solution for reason's already touched upon.

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It's definitely not an elegant or permanent solution, but in a pinch it is a really cheap solution. Wasn't sure of your budget, but 100w resistors are pretty damn cheap, so I threw my hat in the ring.

I think Flippy might have done some dodgy maths if he thinks it needs a big resistor with a fan though. Remember a resistor in series with a battery only sees the voltage difference, not the whole voltage. So a resistor in series with a 14S pack at dead flat, (3.0v per cell) is only seeing 16.8v, not 58.8v. A one ohm resistor (example only, I'd probably use something like a 1/2 or 1/4 ohm) would only be sinking 16.8w of heat at the start of the charge, fading off to zero. Less if you set the "float" voltage at 80%.

It will really slow down the charge - especially the last few percent, but that's where the batteries are taking most damage from high charge rates, so you want it slow. LiCo at least, not so sure about 18650 chemistries.

The ELGs are a good solution. Previous owner of my eMotorcycle used them and introduced me to them. When one blew, I replaced them with HLGs. Been rock solid since. Mounted in a non-water proof compartment, and going over rough roads at up to 110km/h.

MPT-7210s are also a proven solution, but still leaning more to the "I'm on a tight budget and jerry-rigging". Definitely better than a serial resistor, but it's still not designed for purpose. For the few dollars extra, you're better off going genuine Meanwells.

Sunder said:

I think Flippy might have done some dodgy maths if he thinks it needs a big resistor with a fan though. Remember a resistor in series with a battery only sees the voltage difference, not the whole voltage. So a resistor in series with a 14S pack at dead flat, (3.0v per cell) is only seeing 16.8v, not 58.8v. A one ohm resistor (example only, I'd probably use something like a 1/2 or 1/4 ohm) would only be sinking 16.8w of heat at the start of the charge, fading off to zero. Less if you set the "float" voltage at 80%.

The ELGs are a good solution. Previous owner of my eMotorcycle used them and introduced me to them. When one blew, I replaced them with HLGs. Been rock solid since. Mounted in a non-water proof compartment, and going over rough roads at up to 110km/h.

Click to expand...

i assumed 10A charge current. still, 16W of pure heat is a LOT for those cheap gold resistors from ebay. i used them but always dropped them in a bucket of water to keep them from burning out while loading batteries. the rated specs are VERY generous.


teardown of a ELG for those interested:

https://endless-sphere.com/forums/viewtopic.php?f=14&t=94237

With my Grin Satiator I've been able to charge all my batteries. And with my new Satiator I can range up to 72V and still charge my 48 and 52V.
Those multiple level, single voltage, China chargers have high fail rates and shorter life span. It's easy to spend $300 on crap chargers.