Does battery size/type make a difference?

Nvreloader

Active Member
Region
USA
Hey Guys
I have a question for those in the know about battery charging, as I am slightly confused,

The Wart Hog MD 750 has a battery size/type of 17200 cells = 48v-15ah-720wh,
I see on this site, that it is best to charge to 80% and then used down to 30%, for the battery cell types of 18650 etc,

Is it safe to use the same percentage when charging these 17200 cells?, or do I need to change the percentage ratio to something better?

I found this charging percentages chart: (there is several listed on the site, which I can't find now.)

I have only charged my batteries twice, this last time was a max of 53.3v and an hour later it was down to 53.1v,
checked via volt meter.
My charger does NOT have scale, just an Idiot light that changes color etc, the spec's are as follows,
F300 Battery charger, input:110/220VAC-50/60hz-6A, Output: 54.6V-5A

The bikes display panel only shows percent scale used. I want to make a percent/scale to tape on the cross bar,
to be safe, so I don't end up pushing the out of the hills...... etc.

Your thoughts and suggestions,
Tia,
Don
 

K PierreR

Well-Known Member
Region
USA
The 80% thing is all good and nice but the cells become imbalanced over time and the battery does not give you as many miles when that happens. I full charge about every 7-10 regular charges and I charge between 80-90% normally. I now have about 40 charges on one of my batteries after 5 years and 15k miles. I have not noticed a huge drop of in miles by doing this.
I have friends who charge their batteries to 80% and have never equalized the cells trying to extend the life of the battery. They currently have about 50 charges after 4 years and they are over 80 years old. I told them charge it to full and enjoy life. Your kids will still inherit a decent battery.
At 80% charge, range is significantly affected regardless of what you read. If all of your rides are short, great but mine never were. I have since mentally gotten over the charging problems.
 

indianajo

Well-Known Member
I charge to 100%, green light, about 3 or 4 times a year, and my battery is 4 years old. It is working fine. I use a timer to stop my charger with one red/green led. I'm stopping charge about 51.5 v on a 48 v liIon battery most of the time. I have a external voltmeter to read the actual battery voltage. I did have a voltage indicator in the throttle but that burnt out in the rain. Battery voltage after full charge sags about .5 to .8 v in the half hour after the charger cuts off. I remove charger to keep it from starting up again.
I charge twice a week in good weather when I commute to summer camp and not at all in freezing weather when the battery lives under a heat pad in the garage. ~300 charges? Life is supposed to be 1000 charges.
 

Nvreloader

Active Member
Region
USA
From what I have been reading and slightly understand, it does NOT appear,
I can reliably use the 18650 battery charging guide, after finding this information.

  • While the 18650 measures 18mm in diameter and 65mm long.
  • 18650 batteries are generally 3.6/3.7 volts and have capacity ratings from 2,300 to 3,600 mAh.

  • 21700 – were designed to be a larger and higher capacity replacement for 18650 batteries.
  • Like the 18650, the 21700 has a nominal voltage of 3.6/3.7V.
  • The 21700 was designed to replace the 18650 in EV battery packs.
  • The capacity of these batteries ranges from about 4,000 to 5,000 mAh.
The 21700 batteries have more mAH than the 18650, with about 75/80% more output,
so I'll have to change the percentage ratio to have approximately the same percentage scale as the 18650,
to have a reliable guide to go by and recharging around the 30% mark,
after using the voltage down from the 80% area maximum setting etc.

This will not change the recharging to the 100% or as close as I can get for balancing the battery pack,
for the 80% charging use for normal riding/charging every 20+30+ cycles.

Your thoughts or suggestion..............
Tia,
Don
 

K PierreR

Well-Known Member
Region
USA
The 21700 batteries have more mAH than the 18650, with about 75/80% more output,
so I'll have to change the percentage ratio to have approximately the same percentage scale as the 18650,
to have a reliable guide to go by and recharging around the 30% mark,
after using the voltage down from the 80% area maximum setting etc.

Your thoughts or suggestion..............
Tia,
Don
I don't follow your reasoning in this paragraph. I don't follow what you are trying to say?
75/80% more output?
percentage Ratio?
30% mark?
The 21700 are the same basic chemistry as the 18650's
80% and 30% are the same for both batteries in terms of voltage and charge percentage.
 

harryS

Well-Known Member
It doesn't matter whether your cells in your battery are 21700 or 18650. That is the size of the container, and the larger size holds more battery material so the AH capacity is higher, The voltage vs percent capacity charts are still the same.
 

Nvreloader

Active Member
Region
USA
Sorry guys, I just don't understand all this yet.

I'll just use this chart and see what happens...........

Thanks all,
Don
 

Nvreloader

Active Member
Region
USA
Thanks Harry
I just don't understand it at all.
I am also attempting to learn on how to charge my 17200 cell battery pack up to 80-90%,
when there is nothing, but an Idiot Light for a meter.

The only way I can think of, is to charge it for 1 hr and then test via volt meter,
and keep repeating the testing, until I get close etc.
The last time I charge it, (I pull the battery as soon as the Idiot light changed color),
the volt reading was 53.7 v, and that took approximately 3hr 15 min.
My charger has these spec's:
F300 Battery charger, input:110/220VAC-50/60hz-6A, Output: 54.6V-5A

Tia,
Don