Wednesday, 11 June 2008

Battery Balancing the cheap way

I have installed a zener diode - resistor battery balancer on my 'self balancing scooter'



There are 2 x 6.8V diodes and a 5 ohm resistor across each battery.
(Thanks again for the info from Tuarn)

The Lead Acid batteries at rest are about 13.3V at new and fully charged so no power is lost when the batteries are not in use.

The Zener voltage must be greater than the battery full charge voltage

The idea is that the more voltage there is across a battery, the more current is bypassed that chargers lower batteries.

This worked surprisingly effectively.

The batteries before installing the balancer were from 12.5 to 14 volts at 'full' charge.
After balancing they were all within a few millivolts of each other, even after some discharge.

I was concerned that the bypass current may effect the automatic charger cutoff point as the batteries became fully charged however the charger still functions properly.

Given Zener voltage = 13.6
Maximum charger voltage = 15.2
Bypass resistor = 5 Ohms

The maximum current through the resistor is (15.2-13.6)/5 =.32A
The maximum resistor power dissipation is .32 * (15.2-13.6)=.5W

My ceramic 5W resistors are overkill. I will use 1W resistors in the vehicle system.

Maximum zener power dissipation will be 6.8V * .32A = 2.2W

6 comments:

Sony notebook battery said...
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Kearon said...

Heya Mal, I'll be trying zeners across my #29 battery in the EV Capri tomorrow - the Dilkes BMS module on that one isn't working..... meh. Might chat to you to get your input.

electric_scooter said...

When you mention the means to move, what kind of vehicle do you think of? Vehicles powered by electric power are environmentally friendly, typically electric moped scooter.

Chris_J&T said...

The article is very good, thanks to this blog owner for sharing. I'm not very good at technology. But I think your insights will help many people. I am very concerned about the types of vehicles that operate on electric power. Especially electric scooters for adults.

Kate 'Axemomo said...

Amazing! The blog owner's article is very interesting and interesting. It brings a lot of experience and technical knowledge to me. Thank you for sharing this article. I also often share my knowledge on how to ride a self balance scooter. Not everyone can master hoverboard riding on the first use.

Oliver Mir said...
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