Luna ga 14 ah shark pack

I would like to thank this forum for all your help.
I just got off the phone with Eric from luna.
He spent a hour on the phone helping me. I couldn't have asked for better customer support. I'm very sorry people used my ES thread to slander luna.
Thank you Luna for your great products and support.

After a few charging cycles, you might have better capacity. New cells sometimes need to be "broken". It could be also, that that the LVC is set conservatively. Otherwise, check every cell group after charge and discharge, to see if they are equal.

Did the sales spec say 14 Ahr "to LVC" ..?
Or did it simply say "14Ahr capacity" ..?
Do you really intend to run a pack down to 100% DOD ?
Remember.. Many 18650s are capacity rated at 0.2C, down to 2.5 volts..so what do you think 2C discharge does to that voltage when its getting near end of its capacity ?

There is no way of getting around this fact about batteries. If you use a slow and even amp-draw, you will get more range. if you use hard acceleration, you will get lower range from the same pack.

This is true for every battery pack, from every vendor.

Oops

What is the voltage that the battery reads out at LVC? What is the voltage it reads out at full change? What charger are you using? Which motor kit are you using (specifically what controller, as it pertains to LVC)?

I apologize if I sound defensive 'in text', I really do want to help.

Oops

Do you know how much current you're drawing when the LVC is hit? Don't forget about IR losses in the pack contributing to the BMS interpreting the cells as being flat.

Grab your multimeter, measure the OCV of the pack after a minute or two. You may find it's around 40V or so, which if you discharged slowly you may find you squeeze that extra 2Ah from.

As others have mentioned, packs are typically rated at say 14Ah based on it being a 3.5Ah cell, and there being 4 in parallel. That's it.

The 3.5Ah cell get's its own 3.5Ah rating by being discharged at a constant 0.2C (or something similar), on your eBike you're likely drawing peaks close to 20-25A, which is more like 1-1.5C.

Go check out what the capacity of your cell is at 2C, and then go find out what the IR of the cell is, then you can do some fun calculations to see if it all makes sense.

If you have 14S4P (ex using the 3.5Ah cell) and the cell resistance is 40mOhm, you'd have 14x(40/4)=140mOhm from the cells. Maybe add 20-30 for leads and mosfets. So lets say 170mOhm when the pack is new.

20A draw, 170mOhm = 3.4V drop, or .243V/Cell. If your particular cell has 2.7V EODV, you'd basically need to add 0.243 to this voltage (2.943), for the low discharge current curve and see what capacity you get. With some cells you may find that this could be 10% of the capacity!

Basically, don't be super discouraged that you're not seeing 14Ah capacity, there are reasons why you're not seeing this.

If you do this little exercise and find that it doesn't make sense, then it's time to see if your pack is balanced

-Robbie

I also have a 14AH battery also that's a month old, bought along with a BBSHD kit.

My 14AH battery has a usable capacity of 11.5AH measured by a CA2, and takes about 12.5AH to fully charge with a Satiator.

Note batteries will always absorb more charge than they release as some is wasted as heat in the charge/discharge process.

I also have discharge tested loose GA and PF cells and found that even at a one amp discharge their capacity is roughly 450mah less than their rating.

The GA's at 2950mah capacity corresponds with 11.5AH in a 4p pack.

The good news is that 11.5AH is good enough to travel 50+ miles, and at that point I'm ready to call it a day.

Perhaps Sanyo/Panasonic rates batteries like lumber companies measure 2x4's?

I have 550 miles on the system and it's very consistent and performs great, so who cares what the exact numbers are.

Oops

I'm using the Luna 48v, 14ah, GA cell, shark pack. The charger is the Luna Advanced charger, settings are: amps set to 3 and voltage max switch set to it's up position, which is supposed to be an 80% charge.

With the 3 amp, 80% settings, the charger charges the pack to 50.8 volts. The Luna Advanced charger indicates 50.8 volts at the end of the charge, and so does my Harbor Freight multi meter when measuring pack voltage at the batteries XT-90 plug, after the battery has been off charge for a while.

A few days ago I rode my ebike 14.9 miles, pedaling more than usual, and riding at a looking for deer speed, average speed was 10.5 mph. This ride had very little climbing, and little wind. Ride time was 1 hour, 25 minutes.

Pack voltage was 47.9 at the beginning or recharge and 51.1 volts at the end of recharge. The charger was set to the 3 amp rate, recharge time was 1 hour, 11 minutes, this recharge time included voltage titration at the end of charge, if there was any. If recharge was 3 amps for 1.18 hours, then 3.55 Ah was put into the battery pack. So, the ride used 11.4 Wh/mile, drew 2.5 amps average and the power average was 120 Watts, much of this based on recharge data, average amps is based on ride time, not recharge time. At a nominal voltage of 48 volts, the pack provided 170 Wh for the 14.9 mile ride.

Bike is an old Sterling City Sport 15 MTB style bike, it has 18 speeds, upright bars and an Aotema direct drive, brushless, sensorless, front hub motor. Tires are old 26 x 1.5 Chen Shing City Tires, pressure was 60 psi, the rear had a Slime tube, the front did not have Slime. I weigh 180 lb.

Pack capacity: starting at 80% charge and ending at 20% charge remaining, the middle 60% of the batteries capacity would be used. 14Ah x .60 = 8.4 Ah available for use. As others have stated, at the amp rates we use for ebiking, the actual battery capacity will be less than 14Ah. If we use 12Ah, for our kind of use, then the middle 60% of capacity is about 7.2Ah. Wow, riding on flat bike paths, with little climbing and little wind, my potential range might be 30 miles. That is phenomenal range, especially compared to the 12 miles I was getting from my three tired and abused 12v, 12Ah gel cells, in a 36v gel cell pack. The Luna Shark pack weighs 7.8 lb, the 36v gel cell pack weighs 25.8 lb.

Hope this information helps.

Older now but still riding against the wind,

Mike S

48v charges to 50.8 v? Shouldn't "48v" be 54.6v if it's a 13s pack? Are those shark packs 12s?

I'm just wondering if some of that missing capacity is because the charger is not set to the correct voltage, and it's leaving some ah on the table at the top of charge.

If it's 13s,, 51v will never get it balanced either.

The charger has a three position "charge to xx.x voltage" switch. Switch up is supposed to be 80% charge, mid position = 90% charge and lower position 100% charge.

Switch up charges my pack to 50.8v, mid position charges to 52.2v, I've never used the lower switch position.

From what I've read, 80% charge is 4.05v per cell. The pack is 13s, 4p, so 4.05v/cell times 13 cells in series is 52.65v, a bit more than the mid switch position gives, which is 52.2v.

My plan is to charge to the low switch position, 100% charge, when a long ride is planned, this should balance the pack occasionally.

Normally, I charge to the high switch position, 50.2v, I haven't watched the end of the charge cycle to see if balancing titration is occurring. This is something I need to do.

How are you charging? To what voltage per cell? What charger, etc?

Thanks,

Mike S

I may be wrong because I don't use those cells but:
I would charge to the cells top voltage, and use the 80% charge switch when the bike will not be used for some time. Anyway, I don't see why a charger would have the option to charge lower than full, other than for storage charge level. When in use, most batteries prefer to be on the high side, many are off balance and wearing faster when discharged low.

About charging to less than 100% capacity:

If memory serves (uh huh, sure), the Prius charges to substantially less than 100% and limits discharge to far less than total usable discharge percent. The Prius uses a battery capacity range that is probably centered around 55% of capacity.

Then there is my experience with Lipos, I use a lot of them for RC, but many get used infrequently. I used to charge them to 100% but would get puffed batteries, again the batteries are used infrequently. From what I read, I should have been charging to 60% and then topping up to full charge before use.

So, I decided to limit my use on the 48v, 14Ah, GA cell pack to the mid range of the packs capacity. This type of use still gives me plenty of range for the riding I do.

MikeSSS said:

...., the Prius charges to substantially less than 100% and limits discharge to far less than total usable discharge percent. The Prius uses a battery capacity range that is probably centered around 55% of capacity.
...

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but the Prius is a Hybrid, and it needs battery "headspace" to allow for regen to function, hence the partial charge.
i dont think you can transfer any learnings or operational practices from the Prius NiMh cells to RC lipo or any Lithium cell. their behaviour is very different.
Sure, dont store lithium at max voltage (4.2v) for long periods, but there are many other practices that will affect Lixxx cell life much more dramatically
..such as 100% discharge, excessive charge rates, high temperatures, etc etc

A couple of observations...

Battery capacity should be measured on the discharge side. If only measuring the charge side the measurement should be discounted 5-10%.

I do think the GA cells are a good match for the BBSHD. My pack barely gets warm when pushed and after a normal ride is very close to ambient temperature.

I've measured the capacity of the GA cells on a PL8 and the result was 2950 mah at one amp down to 3.15 volts.

I suspect the rest of the capacity might be there but at an amperage and voltage that really is not useful on an ebike.

Kind of like the C170B I used to fly that had a fuel capacity of 42 gallons but only 37 was officially usable.

Here's a question, is it wrong for car companies to advertise the official government fuel economy numbers if they know that the real world numbers are less?

RickM39 said:

..........
I've measured the capacity of the GA cells on a PL8 and the result wbas 2950 mah at one amp down to 3.15 volts.
I suspect the rest of the capacity might be there but at an amperage and voltage that really is not useful on an ebike.
.............
Here's a question, is it wrong for car companies to advertise the official government fuel economy numbers if they know that the real world numbers are less?

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There are several independent "test" or review sites that have shown the GA capacity to be ~~3.4Ahr even at a constant 8 amp discharge.
.....but that is taking the cell down to 2.5 volts. ..which as you say is not really very useful on an Ebike.

"Official" fuel consumption test figures are necessary to standardise the test criteria and proceedure since those "real world" numbers will be different for every user with different usage profiles.

Interesting how some few people want vendors to understate pack specs to make up for these users' lack of accurate measuring equipment.

I think the satiator is a great charger.

terminus said:

Interesting how some few people want vendors to understate pack specs to make up for these users' lack of accurate measuring equipment.

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That's not the point at all. This assembled pack will never deliver 14Ah.
So advertising it as 14Ah causes confusion.
That's not the end users fault, and something a quality vendor could address in their sales listing.

We test that pack all the time at 14ah .... honestly i was amazed at how closely name brand cells test to their actual capacity. I cannot believe what i am hearing in this thread.... accusing luna the most forthright and honest dealer of overblown advertising? ARE YOU KIDDING ME? compared to who????

We run them down at 20 amps ontinous and they test at 14ah all the time.

Can you please name me one vendor who sales GA packs and rates them for under their actual capacity?

Who does that?

I dont know many vendors who sale packs with top shelf authentic grade A GA cells.... if their is a vendor out their who not only makes their packs with top shelf GA cells and also for some reason under rates the expected capacity of the pack??? please tell me who that vendor is i would like to massage his feet and worship him every day and twice on Sunday.

We have made packs out of the best cells we can find.... in our short 1 year in business.... we have constructed cells from the best 18650s available.... 30qs, hg2s. GAs, 25rs, he4s, PFs and NCrbs...... all grade a authentic cells from korea and japan. and yes we base our capacity on the ratings of these top name cells....and guess what....when we test they always test at the capacity they are rated for.

when we came into the market very few vendors would even advertise what cells were in the packs and every pack was over priced. Now there is a major adjustment being made...and its because of luna. That was my goal...now i can just stop i guess and all the ebike vendors i hope will be happy again.

Also all the other stuff..... the quality of the bms...does your bms even have temp control? how many temp sensors? did the bms in your pack cost the manufacturer 15 dollars or 60 dollars becuause trust me there is a big difference...... xt90s (spark resistsant) connectors, stencils in between the cells spacing them out (not glued together) proper pack padding.... 50 amp continous bms?

i am sorry... but luna is a new player....1 year old.... we havent been doing this for 6 or 7 years.....we ship our packs legally although we have been turned in by competing dealers for supposedly shipping illegally....ironically most of our competitors ship illigeally..... but you gotta hand it to us for raising the bar in this game......

And now we are raising it even further in ways you will see very soon. If you are not a competing dealer you have no reason to hate on us.

Oops

broke said:

Great so if I charge my pack to 58.6 volts and run tell bms lvc. why can't I ever put more then 12.5 ah in the pack? Most of the time it's 12.25 with my satiator. I'm just trying to figure out before my warenty runs out.

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no worries...

we take care of our customers more than anyone....and if you arent getting your 14ah for some reason we will take care of you and its your right to test and make sure.

My problem is not with you.

Green Machine said:

Can you please name me one vendor who sales GA packs and rates them for under their actual capacity?

Who does that?

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Luna does it here. Advertised as an 18650GA 10Ah pack, presumably 3P, so nameplate 10.5Ah.

But seriously, I'd love to see some data showing a 14Ah @ 20A discharge.