a video on LI batteries

[pianotuna]

Hi Folks,

Worth watching I think!

https://youtu.be/WlxBOJrEKAo

[grizzzman]

KJINTF wrote:
Grizz

At the low end Pack Voltage of 12.0Vdc Hi to Low cell difference was 110mv more than I like to see. Got it to <10mv. The High end Pack Voltage of 13.4Vdc Hi to Low cell difference is always < 10mv.

To answer your question "Because I can" and I like to tinker

I like your answer :B It is my understanding that due to the cells not being exactly the same is why you balance the cells? I take it you stay out of the upper knee when charging (cell level)?

[pianotuna]

Ty itnerant1

[time2roll]

Effectively cut-off is zero as determined by the vehicle manufacturer that provides the battery warranty. Pretty sure you are into the knee so going lower does not give much additional power anyway.

[Almot]

time2roll wrote:
I recently ran my EV battery to zero and power was cut off. Charging started at 1.2 kW vs the normal 10 kW charge rate. Ramped up to normal at about 5% charge.

Could it be that cut-off zero was not really zero, but something in the range of 10-15%?

[Itinerant1]

PT here is some info from my 500ah LiFePo4 bank.
These readings are from the 4th morning at 32% (160ah) previous evening starting at 57% (285ah) a few days of poor solar charging.
Batteries 13.03vdc (13.65vdc 100%)
Inverter(3000w) with parasitic draw 2a 12.9vdc
Mr coffee 12 cup 82a 12.7vdc
950w microwave 150a 12.5vdc

When done using appliances returns to initial 13v on batteries or 12.9v fom inverter.

[time2roll]

Almot wrote:
More sophisticated Li chargers start from low amps, increasing it to max current when voltage indicates 40%(?) full, don't remember the exact number.

I recently ran my EV battery to zero and power was cut off. Charging started at 1.2 kW vs the normal 10 kW charge rate. Ramped up to normal at about 5% charge.
This is a 40 kWh battery.

[KJINTF]

PT

A 1Kw Microwave for about 10 minutes
As I recall there was very little voltage drop <500mV

The Li Pack is connected to a 2Kw PSW inverter & switchable to the 8 amp Heater blower motor nothing else. Two Lead Acid GC batteries take care of the other loads

[Almot]

MEXICOWANDERER wrote:
Questions

• 600 actual amp hours of batteries
• 400 amp controlled voltage charging source
• Just start the charging and 400 amps could flow?
• This is in reference to generator charging

They haven't figured Li out yet.
More sophisticated Li chargers start from low amps, increasing it to max current when voltage indicates 40%(?) full, don't remember the exact number.

[MEXICOWANDERER]

Questions

• 600 actual amp hours of batteries
• 400 amp controlled voltage charging source
• Just start the charging and 400 amps could flow?
• This is in reference to generator charging

[pianotuna]

KJINTF,

What is the largest load you have placed on the LI pack (in watts please)

[KJINTF]

Grizz

At the low end Pack Voltage of 12.0Vdc Hi to Low cell difference was 110mv more than I like to see. Got it to <10mv. The High end Pack Voltage of 13.4Vdc Hi to Low cell difference is always < 10mv.

To answer your question "Because I can" and I like to tinker

[grizzzman]

KJINTF wrote:
PT

That guy at WEBER auto knows his stuff!
Well worth looking at what he has to say
Been talking with him for several years now

For me my 200amp/hr Prismatic LiFe battery has been nothing but WONDERFUL
No voltage drops with HEAVY loads and no issues with recharging
Even better I do not use any factory "BMS" I see No Need for that stuff
3 years now and all is good
Just today after three 3 years bottom balanced the Prismatic pack

Why bottom balance in a fractional (low C) use?

[Almot]

The video is about benefits of liquid cooling.

Without liquid cooling you should avoid charging at high ambient temperature, should avoid charging immediately after driving (even if ambient is not too hot), and generally should avoid keeping it in hot temps no matter with or without charging during that time.

These are usual warnings on e-scooters and e-bikes. A bit of hassle, yes. Unfortunately, most of this applies to drop-in batteries in RV. (Also, very cold temps).

[time2roll]

Video illustrates how storage can be an issue with temperature. I tend to only suggest a lithium battery for full time use. This way the temperature can be controlled better.

Heat from charging or discharging should not be a issue as most RVs would not have the sustained high rates as seen in an electric vehicle.