luna charger?

[jkvt]

Has anyone every used the Luna advanced charger on an NCM battery? It charges, but if you set it to stop at 80% it cycles on and off every few seconds once it hits 80%. I don't think this has anything to do with the battery since it can definitely tell what the battery level is if it shuts off at all in the first place, but figured I'd ask. Thanks.

Edited to note that I am charging at 3A, which is the speed of the charger that came with the bike.

 

[rcdanner]

Has anyone every used the Luna advanced charger on an NCM battery? It charges, but if you set it to stop at 80% it cycles on and off every few seconds once it hits 80%. I don't think this has anything to do with the battery since it can definitely tell what the battery level is if it shuts off at all in the first place, but figured I'd ask. Thanks.

Edited to note that I am charging at 3A, which is the speed of the charger that came with the bike.

The Luna charger did this same cycle on-off on my Aventon Reention Dorado battery (basically the same as NCM). I gave up and just set it to 100% charge. I also only use 1A charge rate. Lower charge rate is supposed to be better for battery.

 

[Mike_V]

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[arcom]

From the FWIW department

This question was asked on the Luna website in August 2020. This was the actual question and their reply a month later:

Hi My 48v Advanced 300w Luna charger does not shut off. I program it at 1 amp 80% and once it reaches that, it cycles on and off and continues the charge. Please advise​

Charles Stoebe 08/15/2020
ANSWER QUESTION
ANSWERS 1
Luna Cycle LLC
Luna Support
09/02/2020
Typically that is the CC/CV it would do at the end of a charge cycle prior to cutting off, which would be normal. If you are saying it goes like that for hours it may be faulty. Email support if need be.

 

[jkvt]

Luna has been really responsive which is nice. I asked them specifically about wear on the relay too. Basically I was told that it's fine and essentially the BMS and the charger fighting (not in those words). I guess the BMS is trying to balance itself requesting more charge to do that and the charger then cuts things off because the battery is over 80%. I mean I guess it kind of makes sense and maybe why they can't guarantee it will work perfect with all batteries (due to differing BMS)? I was also told people leave it going all night and eventually it will stop clicking - I image the balancing just finishes and it's fine for the charger. Another option I was told is to charge to 100% a few times then charge to 80%... which I guess makes sense because the charges to 100% should balance it then there wouldn't be balancing that is really needed at 80%... in theory.

A little weird design, in my opinion, but maybe that's just the nature of how this has to work if you want to tell a battery with any old BMS to stop at a certain percent. I'm still a little concerned that the wear and tear on the relay is excessive, but whatever. As long as it's safe, which it seems like it is... my thinking is it was $99, vs the $300 Satiator and if I get a few years out of it I'll be be happy.

 

[arcom]

According to Luna‘s website, the battery balances after a 100% charge and the battery is removed from the charger. I always thought that leaving the battery on the charger for a few minutes after it reaches 100% will balance the batteries. Not so according to Luna??

Per Luna:
“After a charge, let the battery rest for an hour or two to cool down but also to let the BMS balance the cells.”

 

[jkvt]

According to Luna‘s website, the battery balances after a 100% charge and the battery is removed from the charger. I always thought that leaving the battery on the charger for a few minutes after it reaches 100% will balance the batteries. Not so according to Luna??

Per Luna:
“After a charge, let the battery rest for an hour or two to cool down but also to let the BMS balance the cells.”

Yeah - that's a good point. I always heard the same as you, that the battery needs to be on the charger for the balance charge, although I thought it was for a bunch of hours. Maybe some BMS' do (ie the ones Luna uses) but a lot do not.

 

[arcom]

Once again Luna has answered the question of when and at what charge percentage will cell balancing occur:

Tad Karmesh, Someone answered your question: It Is My Understanding That When Charging To 80%, The Battery’s BMS Will Not Balance When The Charging Is Complete. Is This Correct?

60

Answer: "That Really Depends On The BMS. On BMS Models Older Than A Few Years Ago This Is Generally True That They Required The Battery To Be Fully Charged To Balance. All Batteries Built In-house By Luna Over The Past Few Years Will Balance At Any Level And Do Not Need To Be Fully Charged To Balance As We Use A Pretty Good BMS. If You Bought A Battery Elsewhere It Would Depend Entirely Upon The BMS Chosen By That Manufacturer, How Old That Bms Design Is And What Features It Has. No Doubt There Are Plenty Of Manufacturers That Still Use Older Models Of BMS As They Are Cheaper, But On The Whole I Would Say The More Reputable Companies Are Trending Towards Phasing Out BMS That Requires Full Pack Voltage To Balance."