Battery Troubles

R

redoctober762

100 µW
Joined
Sep 10, 2015
Messages
7
So I purchased this battery and charger:

52v Samsung 26f 10-ah
http://lunacycle.com/batteries/packs/52v-samsung-26f-10-ah/ the

52v 3amp Ebike Lithium Smart Charger
http://lunacycle.com/chargers/52v-3amp-ebike-lithium-smart-charger/

My primary problem is that the charger won't charge the battery until I have depleted it to the point that the voltage drops below 51 volts.

This is a problem when I ride to work (6.5 miles) try to charge it at work, and then on the return trip home it dies.

The battery itself only has connections for the bike and for the charger. There are not connections for balancing.

What if anything am I doing wrong?

Thank you for your help!
 
This is a typical problem with 48V chargers trying to charge a 14s lipo pack. And that's what this charger is. I don't know if there's an adjustment inside, but a simple workaround is to connect the charger through a pre-charge resistor circuit first so it sees a lower voltage and then connect the direct connection. This pre-charge circuit will work fine.
precharge.jpg
Just put the charger where the controller is. Start charging with connector 2 open, then close it with a switch or whatever you want to use.
 
can you measure the cell voltages of the battery while it is charging? your charger may have a latching output and the BMS on the battery has never had a chance to balance your battery so it is now outa balance. i doubt if you know any of this but there is no other way to isolate the problem. i assume your charger never cycles on and off, it just turns off.
 
I can't measure the voltages of the battery. It's completely enclosed by a plastic cover.

Yea I'm super new to the ebike world :-(

The charger "seems" to be cycling on and off. I only know this by the red light (needs charge) and the green light (full charge) keep alternating and the cooling fan kicks on and off about every other second.
 
The charger cycling on and off is normal during a charge cycle that has cells out of balance. You should leave the pack on the charger until this cycle stops and you are left with a solid green light for a period of time. Then check the pack voltage. It should be ~58.8V, which is fully charged for a 14s pack.
 
For whatever reason, it seems like you are not getting fully charged. That battery should get you the 13 miles, even at a fast speed. Try leaving it on the charger until it fully balances, no longer cycling between red and green.

But I'm confused about one thing. Even if full, and you ride around the block using .1 ah, when you return the charger should turn back on to red, even if very briefly.
 
THANK YOU ALL FOR YOUR HELP!

As you all suggested I left the battery on the charger for 24 hours. The charger is still alternating between red / green and the voltage on the battery is steady at 53.1 volts.


But I'm confused about one thing. Even if full, and you ride around the block using .1 ah, when you return the charger should turn back on to red, even if very briefly.
Click to expand...

I'm also wondering why it doesn't charge after even a short ride. Is that the nature of the Lithium Ion batteries or do I have a bad charger? The seller has offered to send me the 10 amp version of the charger but I'm not sure that will help.

Thoughts?
 
I guess you have a multi meter. Check voltage on charger and report. Check voltage on battery report back. Luna cycle will give support. Just let him know.
 
Lithium batteries without a bms will continue to take a charge until you blow them up. The bms is supposed to limit the per cell charge and bleed the voltage off the ones that are overcharged until they all balance at 4.2V per cell(group). A 14s charger should put out 58.8V ideally. A typical 48V charger designed for a 48V SLA pack will charge to its max voltage which is usually ~60V when connected direct to a lithium pack without a bms. Since you can't measure individual cell group voltages there's no way of telling what the problem is for sure. We can only guess.You can try a new charger and see what happens. If it doesn't change, then it's either the bms, wiring, or the batteries in your pack.
 
I guess you have a multi meter. Check voltage on charger and report. Check voltage on battery report back. Luna cycle will give support. Just let him know.
Click to expand...

The charger is outputting 59.1 volts with the battery detached.

The battery is now at 53.7 volts (with the charge attached or detached).

Luna Cycle has been awesome for customer support. I just want to make sure I check everything before I make contact again.
 
redoctober762 said:
As you all suggested I left the battery on the charger for 24 hours. The charger is still alternating between red / green and the voltage on the battery is steady at 53.1 volts.
Click to expand...
Unless the charger specifies otherwise on it's nameplate/etc., then the alternating colors usually means it is still charging/balancing, and you need to leave it on until it doesn't do that anymore.

On a badly imbalanced battery that can take days, or longer (sometimes much longer) if the BMS is like most and has only a tiny amount of balancing capability (not much is normally needed).

A higher amp charger won't help, AFAICS.

The only thing a different charger would tell you is if there is a problem with the charger itself, assuming the new charger works and the existing one isn't.

The symptoms given so far point more toward a balance problem in the pack than a charger problem, especially since the longer you leave it on there the higher the voltage gets.


To really know what is wrong "right now" without just waiting days (or more) for the results of leaving the pack on the charger, you would need to open up the pack and measure the individual cell voltages at the BMS balance connector.

If you can't do that measurement, you need to leave it on there utnil the lights stop alternating.
 
Those Samsung cells should not be out of balanced. I would say that it's a bms issue or the voltage needs adjusting in the charger. Genuine Samsung cells come out of the factory with the exact same voltage. Unless you have done a serious deep discharge the cells should all be balanced.
 
So after several days of charging the charger has a solid green light! The battery voltage is at 58 volts.

I rode yesterday (around 12 miles) and the battery dropped to 52 volts. When I plugged into the charger I got the same red / green light cycling.

My hope was that after the battery had received a full charge (I'm assuming it was balanced at that point) it would charge to 58 volts whenever it was lower than 58 volts.
 
58V is close, but it's not a full charge on a 14s pack. A full charge is 58.8V. At only 58.0V I doubt the pack ever balanced unless it did balance and then lost voltage just sitting, which is not a good sign..
 
I worked with Luna Cycle, apparently it was a bad batch of 3 amp chargers.


On a completely separate note. When I connect my battery to the bike I get a pretty bad "POP". I'm assuming that I'm getting a spark inside the battery connector.

Will this hurt my battery / electronics?

Is there an easy way to fix this?

I've been reading around the forum and it looks like I can put in a switch (seems easy enough) or build a circuit to stop the spark.
 
You’ll get a lot of disagreement about this topic but for systems under 60-72V I don’t feel pre-charge circuit is worth the trouble. I get years and years and 1000’s of connection cycles from Anderson battery connectors running 67V hot off the charger.

While a spark/pop may seem unsettling to those who’re new to electricity there really isn’t enough resulting damage to make me wanna add more shit to my setup. I’m a KISS type.

But some people gotta load everything and them some on their rides. That’s fine for a hobbyist or retiree but for some this is our lifeline commuting back & forth to work so the less shit that can go wrong, the better.

One thing that may help minimize “arc” is to wash away any oil/grease that may be on the connectors. I use alcohol or contact cleaner if equipped.

If you're convinced must have a switch then you'll need to consider a precharge circuit so that the switch can survive. The parts list just keeps growing...
 
I put this on all the ones I've built from 44.4V to 88.8V nominal. I can't plug in my 88.8V pack without the precharge circuit because the plasma flash and pop is so big and loud it scares the crap out of me every time and the natural reaction is to jump back. It also burns the connectors pretty bad on the tips. I can't imagine should a huge load on the battery and caps in the controller being good even though it's only for a millisecond.
precharge.jpg
 
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