Is 90VDC output normal on the EMS 68V (per label) battery charger for Lithium?

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GreenBiker
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Is 90VDC output normal on the EMS 68V (per label) battery charger for Lithium?

Our multimeter shows 90V open circuit voltage on the Electric Motor Sport's 68V lithium battery charger. What does yours indicate on a multimeter? (Be careful that you don't short the XLR male pins when connected to AC -- use a multimeter on a Ohms-connection test mode before checking for high voltage DC. Also, such high voltages can potentially kill a person -- be careful.)

antiscab
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Re: Is 90VDC output normal on the EMS 68V (per label) ...

90v isn't that scary, just don't put yourself in the circuit :)

68v nominal indicates ~22 cells lifepo4 or 19 cells LiCo,

90v = 4.1v average for 22 cells, or 4.7v for 19 cells.

the voltage is too high for both sets.

how many cells are actually in your battery pack?

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

GreenBiker
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Re: Is 90VDC output normal on the EMS 68V (per label) ...

There are 16 Thundersky yellow 40AH cells.

antiscab
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Re: Is 90VDC output normal on the EMS 68V (per label) ...

There are 16 Thundersky yellow 40AH cells.

then yes, the charge to voltage is way to high.....

for 16 cells it should be around 58.4v

what BMS, are you using?

If you use this charger without a BMS, it will overcharge 16 cells.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

GreenBiker
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Re: Is 90VDC output normal on the EMS 68V (per label) ...

Matt - the BMS in the one you were commenting on under Blogs.

colin9876
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Re: Is 90VDC output normal - YES

@Mat I dont agree with what you said that voltage was too high.
The charger gets pulled down to the cells voltage when its connected.
The higher voltage is what effectively pushes the amps through

The voltage the charger stops charging at will not be the same as 'the open voltage' in a working charger.

Edit - Ive realised that this was an old post thats been bumped by having than rouge airline post!!

antiscab
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Re: Is 90VDC output normal - YES

The charger gets pulled down to the cells voltage when its connected.
The higher voltage is what effectively pushes the amps through

The voltage the charger stops charging at will not be the same as 'the open voltage' in a working charger.

Hi Colin,

spam is annoying isn't it :)

the open voltage measured on the majority of chargers is equal to the voltage on the CV stage of charge.
ie, its not the max the charger is capable of, merely, its the max the charger will charge to.

They are setup up this way for testing purposes, if you put a variable load on the output, you can trace the whole charge profile.

The deviation from this is if the charger outputs nothing unless a voltage is present (ie connected to a battery).

The max output voltage of the charger can be measured by opening it up and measuring the voltage on the dc bus immediately before the buck stage (all chargers have a buck stage).

given the charger was rated 68v nominal, and there were only 16 cells, it was almost certainly the wrong charger.

Matt

Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah
Vectrix 60Ah Lithium Tyres Fuel Registration Insurance cycle analyst 2 x TC Charger & MC
conversion

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