Lead Acid Charger for Li Ion pack

[matthewsx]

Hi,

New here so forgive me it I'm asking something stupid.

I have this really great 48v charger that came with an electric snowblower I had at my shop.

I know the charging profiles for Li Ion are very different from lead acid but this thing has a really advanced control circuit.

I tried reading the patents and I'm not quite good enough to make any judgements based on the components of the board but it does have a "program" switch near the top and also appears to be able to sense what kind of battery is hooked up to it.

Any opinions on whether I can get away with using this on a 13s 48v battery pack?

I do have one of the cheap 2 amp Chinese chargers but if I'm paying attention while charging could I use this US made bad boy?


Thanks,

John

 

[matthewsx]

Here's the pack and BMS I've hooked up to it.

 

[Hillhater]

You are not giving us much info to work with here ..
Make ?
, model ?
, charge rate ?..Adjustable ??
Better photos of the unit
Etc
But, going by the “interactor” web site , it seems that yours is a “special” ( 48v is not standard) , but does have some nice features for a Pb charger....unfortunately a Lithim charge profile does not appear to be one of them !
http://interacter.com/products/lineage-series-features/

 

[matthewsx]

Sorry, it's a Interacter 48v 5 Amp Lineage Series Charger LS4805



Dimensions (LxWxH): 6 x 6.5 x 5.25 in
Weight: 13.0 lb
Shipping Weight: 14.0 lb
Max Current, During Bulk Charge: 5 A
Manufacturer: Interacter

AC Input Volts: 117 V
AC Input Volts Freq.: 60 Hz
Output Banks: 1
Regulatory Approval: UL Listed
Manufacturer Part #: INTLS485
Made In: USA

The only "adjustment" I've found is a small switch (button) at the top right hand corner.

John

 

[Hillhater]

Ok ..more detail here then.
https://www.batterystuff.com/battery-chargers/48-volt/interacter-48v-5-amp-lineage-series-charger-ls4805.html

.....The Interacter Lineage Series battery charger is specifically engineered to meet the demands of the informed consumer who knows that today’s Hi-Tech batteries must be charged c
orrectly, at a competitive price. The Lineage Series features a microprocessor controlled system that out-performs industry standard chargers. The Lineage Series is suitable for charging true Gel-Cell, liquid electrolyte and most (AGM) absorbed glass mat batteries.

The Interacter LS series has a patented three stage constant current, constant voltage charging format. The most important feature of the Interacter is the exclusive proportional timing which automatically adjusts the recharge time in order to achieve optimal performance on old, partially or deeply discharged batteries.

So yes, several good features for charging lead, but not helpful for Lithium.
It is a CC/CV program, but thats all...probably no end of charge auto cut off that you need for Li,,, but you never know ?
You could test it with careful monitoring on a lead pack to see exactly what charge voltage it changes to CV mode, but that may be as high as 54-56 v..not good for a 48v lithium pack !
From their spec sheet..

Voltage limited to 2.4 Volts/Cell
Current limited to AMP rating Mean D.C.
Finish voltage 2.3 Volts/Cell

So on a 48v 24 cell lead pack that means a final voltage of 55.2 v
Even on your 13 cell pack, that would still be 4.25v per cell wich is not good for battery life.

 

[john61ct]

Volts are volts amps are amps

So long as the voltage setpoint - ideally user-custom adjustable

results in the correct finish state of your pack after an hour's rest.

 

[john61ct]

If the charge source finishes a bit too high, cannot be adjusted down

then a separate adjustable HVC circuit could act as the stop-charge

cutting of the chargers' input.

That means CC / bulk stage only, no CV / Absorb time, but that is fine for LI longevity.

For 13S I would calibrate it so the pack ends up between 52.5V and 53.5V

ideally with a BMS failsafe to cutoff earlier if any cell group hits 4.2V.

 

[matthewsx]

Thank you, that's the kind of input I'm looking for. I'll check it on my lead acid pack to see when it changes charge state and voltage cut off.

I was thinking I could buy or make a circuit that would adapt it and a HVC (high voltage cutoff?) sounds like what would be needed.

So, to summarize I should limit the voltage to ~54v and end charging at ~53v. Bulk charging only, no float and check voltage an hour after charging.

The pack is currently at 51.1v but I haven't run the bike yet so I don't know how quickly it'll drain. I do have the cheapo 2 amp charger but I hate to let this one go to waste since it seems to be built really well.

I'm not super worried about the life of this pack since I only paid $70 for it, eventually I'll be building a 52v pack with more modern cells. I really liked the Luna Wolf Cub pack but it seems they aren't making it anymore so maybe something in that form factor. Range isn't that big of an issue, mostly I'm doing this for the experience before I move onto a more complicated motorcycle project.


Thanks,

John

 

[john61ct]

Unlikely to be a problem IRL but note that some powerful chargers designed for lead may not have great current limiting since lead chemistry does not draw that much current at least past the first 10-20min.

While a large LI bank will (try to) pull **huge** amps nearly the full charge cycle

which can release the magic smoke, most commonly with power supplies and alternator circuits.

So ight be a good idea when testing, to put an ammeter in the circuit and if you see current getting past what the charger's rated to put out, be vigilant for heat buildup or other signals

or just shut the session down out of caution.

Current **protection** (as opposed to limiting) features may (should) kick in for you

read the data sheet if you can find it

Worst case put in a fuse

 

[john61ct]

Just as a side note, many/most chargers that do have a LI profile

are set way higher than they should be, for cell longevity, completely unnecessary for no benefit.

Adjustability to get the custom setpoint **you** want is much more valuable than just a label claiming "lithium ready".

For LFP my Full target is 3.41-3.48Vpc

for li-ion 4.05-4.15Vpc

depending on the charge source current rate.

And as stated, CV/Absorb should be very brief, or just do "charge to a V and stop" CC only profile even better, easy to implement with a HVC circuit.

 

[matthewsx]

Seems like the charger wants to put out ~57.2v so maybe it's a 52v pack charger?

I have an electronics store just up the road and there are plenty of circuit diagrams on the internet. Breadboard here I come....

 

[amberwolf]

Seems like the charger wants to put out ~57.2v so maybe it's a 52v pack charger?

Around 56-58v-ish is about right for a "48v" lead-acid pack's float voltage (trickle charging to keep it topped off), if the SLA used are 14.4v cyclic use types (14 x 4 = 56v; 14.4v x 4 = 57.6v).

But if the voltage you read is with no SLA battery attached, that could just be the open-circuit voltage, which it may never reach in actual use.

 

[matthewsx]

That's actually what it was reading connected to the lithium pack (only for a short time for testing).

 

[matthewsx]

On my previous build, a three wheel tandem recumbent I used four cheap SLA batteries. It went great but had almost no range. I've moved the 1000w hub motor to a Boss Cruiser modified with disk brakes and a 27.5" front wheel.

The 48v pack I bought from Battery Hookup just to get it going but later I want to switch to a smaller 52v pack (would like something like a WolfPup) since I don't need huge range.

John

 

[john61ct]

Seems like the charger wants to put out ~57.2v so maybe it's a 52v pack charger?

No, that's only 14.30V per 6-cell lead, nominal 12V

in fact quite low for many Pb chemistries.

Deep cycle 6V FLA GCs like Trojan, are very often fast charged at 14.6V even close to 15V

depending on battery temperature.

It would be a bit high for GEL units though. . .

 

[john61ct]

That's actually what it was reading connected to the lithium pack (only for a short time for testing).

Whoa Nellie!

Don't do that anymore, good way to start a fire if you got distracted

boom bad!

 

[amberwolf]

That's actually what it was reading connected to the lithium pack (only for a short time for testing).

Was there still current flowing at this point?

Or had the battery's BMS shutoff it's charge input, so that was really just the floating (disconnected) voltage on the charger?

If the latter, then the only worry is whether the charge port FETs in the BMS are rated for that high a voltage (probably).

If the former, then it's overcharging the 13s 48v lithium battery, 57.2v - 54.6v = 2.6V too high. That could be either across all the cells or just some of them. Worst case if it's only on one group of cells it could be 4.2v + 2.6v = 6.8v on those cells. Best case it's 2.6v / 13S = 4.4V/cell.

 

[999zip999]

What is the exact end charge voltage of that charger ?

 

[matthewsx]

Unfortunately there aren't really good specs for this charger that I've found, with the help here though I have a good idea of what to measure and how I might modify it to work well.

The pack never got above 51.1v so I don't think there's any chance of damage. Only had it hooked up briefly to test a theory, definitely not UN-attended.

John

 

[john61ct]

Hooked up to 48V lead for 5-7 hours will be the way to tell, but have to catch the CV peak while in Absorb stage

before it drops to Float.

What is the exact end charge voltage of that charger ?

 

[999zip999]

If it stops at 54volts your ok if you stop it at that voltage and stop the charge not leaving it in float.
Best if stops at 53v and then use your 2a charger for the balance stage of your BMS to act.

 

[Hillhater]

As previously posted...
The Manufacturers spec says “2.4v per cell”. for a 24cell , 48v, lead acid pack.
So that suggests a 57.6 v peak charge.

 

[john61ct]

Which is way too high for 13S li-ion

but could be made to work fine with an adjustable HVC

set between 53 and 54V depending on the C-rate.