Announcement

Collapse
No announcement yet.

Battery charger adjustment question.

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • sieg25
    replied
    My Luna advanced 300 watt charger and watt meter arrived today. I set the charger to 2 amps and 100% charge and put it on my partially depleted 52 volt shark pack. I watched it pretty closely the entire time and because it displays charging amps and voltage I was able to see when the amperage started to taper off as it worked down to a finishing charge. It dropped quickly at first and then dropped slower and slower until it finally turned off at .24 amps. It charged the battery to a little over 58.8 volts but dropped a little under 58.8 shortly after it turned off. That is exactly what I was hoping for. I will use my Luna mini charger at a location 15 miles from home to charge my battery back to 80% or 90% before the return ride home. I don't know what I will do with the watt meter I didn't use. I will save it for someday.

    Leave a comment:


  • AZguy
    commented on 's reply
    That's exactly what I was using them for - just monitoring the charging - they never spent time on the bike. Hopefully you'll have better luck than I with them (not too hard ;-} ). They did benefit but they weren't at all accurate. What I found sort of works to see the true end-of-charge is to use a clamp ammeter in line with the charger. I have one that goes down to 10mA and when it drops to 10-20mA, the charge is complete...

    And if I ranted just a little (rereading that sounded a little harsh) =] it's because I see the trust in the DVM's reading the chargers too often and just don't get it since it's pretty obvious folks are looking for more accuracy than their meters have. I've seen more than a few posts that "XXX charger is charging too high/low; my DVM shows a 300mV (or even 1V) discrepancy!" when 300mV on a 200V scale is asking far more than the meter is even specified for, and let's face it, the cheap ones may not meet specs (I've found some that don't and are frankly a lot worse than the spec)...

    Odds are the guys setting the charger have a better meter than a cheap one.... but then again.... you never know!!
    Last edited by AZguy; 02-21-2018, 08:32 AM.

  • sieg25
    replied
    AZguy I agree with everything you are saying. The thing the watt meter is good for (if it doesn't die) is to put in line with the charger so I can watch when the amperage tapers off, and see how long it continues to put a finishing charge on the battery before the charger turns off. I am saying this without any real experience doing this. I will know soon if the watt meter is any benefit to me for this purpose. My understanding of DC electronics is rather limited and appreciate you taking time to point out where I may be getting off track.

    Leave a comment:


  • AZguy
    commented on 's reply
    (58.8-58.4)/58.8 ≈ 0.0068 or 0.68%... Most inexpensive multimeters aren't even 1% and if you are asking for .1 volt out of a 200V scale (worse yet if it's a 300V scale) then you are asking for 0.05% accuracy!!! Only expensive meters are going to get you there.


    Folks really shouldn't put so much faith in their DVM's and it amazes me people don't do the very simple math to figure out their accuracy. I've compared plenty of the cheap ones to the precision calibrated ones I've access to and they simply are not good enough for determining 100% charge on a battery and setting a charger final voltage IMO - I'd think you'd want to be better than 0.1V - I'd shoot for 10-50mV... Find a way to access a good benchmeter - even if you have to rent it... although better to find someone in a business that has one that will give you five minutes with it. ;-}


    Those cheap wattmeters aren't even close to accurate with voltage errors in the few percent and current much worse in the three ebay units I tried (that by the way all died within weeks - same thing on all - display went blank).

    I've got a batt-man (I really like this unit) and out of the box voltage was very close (maybe better than 0.1%?) but current was off more than 5%. It's nice that it's calibratible but the resolution on the current calibration (the offset?) is very rough and I only got to ~1.7% which is "good enough" I guess - I may be able to improve it given more time. The current calibration is much more difficult to do since you need a very high power load - I did it by putting a mid quality DVM with 200A max that had been compared to the lab units and was reasonably close in that range at lower loads on the bench... and then riding, adjusting, riding, adjusting... it's really a pain. To do the current right on a bench would require an enormous bench load and calibrated 4-wire shunts...

  • sieg25
    replied
    The Luna charger and watt meter that I ordered will not be here until the end of the week. I am also getting a better quality multimeter to make sure I am not already charging to 58.8 volts and getting 58.4 from a poor quality multimeter. It doesn't look very hard to open a sharkpack and check the voltage of the 14 cell packs. If nothing changes I think I am going to open it up and see if it is balanced. I will be fine with charging to 58.4 volts as long as I know my bms is balancing my battery. I am not going to continue to charge to 100% every time much longer.

    Leave a comment:


  • sieg25
    replied
    Originally posted by Grendelssen View Post
    Hey buddy. What ever happened with your battery. I've recently experienced my 17.5 triangle Luna battery only charging to 55.1v set at 80%. It should be higher than that for 80%. My question would be is my battery already going bad after owning for 3 months?
    I have never charged to 80%. Have you charged to 80% before and got higher than 55.1 volts? There is a chart in the knowledge base under luna hardcase battery documentation that says 80% charge on 52 volt battery is 55.4 volts, but it says those numbers are only approximate. What voltage does your battery charge to when you charge it to 100%?

    Leave a comment:


  • Grendelssen
    replied
    Hey buddy. What ever happened with your battery. I've recently experienced my 17.5 triangle Luna battery only charging to 55.1v set at 80%. It should be higher than that for 80%. My question would be is my battery already going bad after owning for 3 months?

    Leave a comment:


  • sieg25
    replied
    I watched the video again today and when he talked about setting the voltage on his charger a little higher than 58.8 volts I could read on his watt meter that he had it set to 58.93 volts. The new charger and watt meter I ordered will arrive in a few days and I will charge my battery to 100% with the new charger and see what voltage I end up with.

    Leave a comment:


  • sieg25
    started a topic Battery charger adjustment question.

    Battery charger adjustment question.

    I have a new 52 volt shark pack on a new bbshd build. I have been doing full 100% charges on my battery allowing time for the battery to balance, but my full charge voltage is staying at 58.4 volts. That is what it was after my initial charge. I have done 6 full (100%) charges. My charger is a Luna Mini (no display, just red and green lights). I have never seen the charger come back on by itself after the green light comes on. If (after waiting a short time or a long time) I unplug the charger and plug the charger back in, the batter will start to charge again. If I check the battery voltage the minute it shuts back off I might see 58.5 volts, but after a few minutes it is back at 58.4. After a few hours sitting it may be down to 58.3 volts. I was hoping after some break in with 100% charges and some time for balancing my voltage after charging would be 58.8 volts.

    I read on the knowledge base that if the battery does not charge to a high enough voltage that no balancing can take place. It also explained with a video how to adjust the charger to make it charge the battery to a higher voltage. In order to make the adjustment I need a watt meter on my charger. I ordered a Luna watt meter and a new Luna advanced 300 watt charger. I will see what the new charger does before I make any adjustment to the Luna Mini.

    Finally to my question. In the adjustment video he says he likes to start off by adjusting the initial charging voltage of his charter to slightly above 58.8 volts. My charger is right on 58.8 volts. Does he mean 58.9 volts or 59 volts? Do any of you use a charger that is putting out over 58.8 volts for the initial part of the charge? If so, what voltage?
Working...
X