OLD ks14c charge port specs please

[UKJ]

As my beloved yet like my getting much older would like to test batterys.

I have read of horror stories of shorts at charge 3 prong

port. I know to be careful with tester probes but would feel a lot better knowing -,+ positions?

Could someone provide this please?

thx ukj

Can submit photo

if needed.

[Chriull]

31 minutes ago, UKJ said:

have read of horror stories of shorts at charge 3 prong

port. I know to be careful with tester probes but would feel a lot better knowing -,+ positions?

One cannot measure battery voltage at the kingsong charge port.

The BMS protects the charge input against shorts. So a voltmeter (with high enough resistance) will show some voltage but not battery voltage.

You can use your charge doctor during charging and some app to look at the wheel reported voltage. Both will differ a bit - you will have to adopt one to another to have comparable results.

As the cd was adjusted once by @hobby16 changes are good that it shows more accurate numbers.

[UKJ]

THX, you are perfectly correct, can not measure voltage at charge plug!

My ks14c is 680, 340 each side bat pack.

Being lazy only cause no need to open,

How many cells each pack please?

And,

I read idea to charge, rest then volt test to compair packs,

good idea?

I have built small eheli lipo packs so would understand how to solder balance leads and use my smart charger to look for weak cells and balance charge.

OR, idea?

Charge backs one at a time, test cell voltage just after green led to detect imbalance before passive resistors kick

in?

Do I miss something?

thx

ukj

 

[Chriull]

43 minutes ago, UKJ said:

THX, you are perfectly correct, can not measure voltage at charge plug!

My ks14c is 680, 340 each side bat pack.

Being lazy only cause no need to open,

How many cells each pack please?

The 67.2V are 16 cells in series (16x4.2V) - with EUC one uses max voltage instead of nominal voltage

This euc used ~2900 or ~3500mAh 18650 cells so this should be a 16s2p pack with the 2900mAh cells?

43 minutes ago, UKJ said:

And,

I read idea to charge, rest then volt test to compair packs,

good idea?

If the packs cannot be charged fully it could be that only one pack is bad and hinders the other. By such comparison one can find the bad pack.

If the wheel charges to around 67.2V there is no need for this test.

43 minutes ago, UKJ said:

I have built small eheli lipo packs so would understand how to solder balance leads and use my smart charger to look for weak cells and balance charge.

OR, idea?

You have weak cells? The packs do not charge orderly?

43 minutes ago, UKJ said:

Charge backs one at a time, test cell voltage just after green led to detect imbalance before passive resistors kick

in?

Passive balancing happens before the green light kicks in.

43 minutes ago, UKJ said:

Do I miss something?

The points from my other post to check the state/health of the cells?

Or you like to tinker? 

[UKJ]

Thx again for Your time and thoughts,

Yes I like to tinker and understand functions, more so on my euc as can hurt me.

I have started testing as suggested, first charge seems to have been ok to 67 v.

Went for long slow ride, opened and tested bat pack sides, both exavtly 62 v so also  seems just fine.

Was considering adding balance leads, to many solder joints.

Also wanted to maybe open pack shrink wrap and test cells one by one but thinking this out. 
 

thx for passive balance info, I thought had read that only starts after pack fully charged?

If passive balance starts before full charge, does this mean using charge doctor to 80% charge is balanced?

I always took, take great care of my heli lipos never had bat problems and they last a long time.

I would like to understand and do the same with my ageing ks14c.

ukj

 

 

[Chriull]

1 hour ago, UKJ said:

Thx again for Your time and thoughts,

Yes I like to tinker and understand functions, more so on my euc as can hurt me.

I have started testing as suggested, first charge seems to have been ok to 67 v.

So the packs seem to be fine?

1 hour ago, UKJ said:

Went for long slow ride, opened and tested bat pack sides, both exavtly 62 v so also  seems just fine.

The are in parallel - so both have the same voltage. ... Just if one packs bms shuts down...

1 hour ago, UKJ said:

Was considering adding balance leads, to many solder joints.

Also wanted to maybe open pack shrink wrap and test cells one by one but thinking this out. 

With opening the wrap and rewrapping the packs and adding 17 solder joints and wires ti each pack one could by accident make the packs more unreliable...

1 hour ago, UKJ said:

thx for passive balance info, I thought had read that only starts after pack fully charged?

No. At about the transition from constant current to constant voltage stage of the charger balancing starts (if needed).

1 hour ago, UKJ said:

If passive balance starts before full charge, does this mean using charge doctor to 80% charge is balanced?

Yes. Afair charging is in such a case stopped at some 4.0V to 4.1V?

Some very unbalanced cells could get the resistor enabled if they manage to already reach 4.2V...

[UKJ]

Used charge doctor to charge, one pack 65.2 other 65.5 cd set to not fully charge.

Is .3 v difference ok please?

thx ukj

[alcatraz]

Usually (99.99%) of bms' don't balance at 80%. By charging partially some people have destroyed their packs.

Even by doing 9/10 to 80% and 1/10 to 100% there's a risk because the imbalance could be too much for the tiny bleed resistors, and so it becomes permanent. The smaller the balancing current (resistors) the more often does the pack need to stay on the charger to 100%.

Ideally charge before a ride, and every couple of weeks do a proper long charge and ensure you're reaching the end voltage 67.2v with the charger disconnected.

Also, a green light on the charger does not mean balancing has completed. 

Edited November 3, 2023 by alcatraz