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I want to combine 2 - 12 volt 12 amp hour sealed lead acid battery's with 2 - 12 volt 50 sealed lead acid battery's

I want to extend my driving distance

I know if I got with 4 - 12 volt 50 sealed lead acid battery's

it will take 14 hours to charge the set of 4 and I do not know even
if I bought a new 2 amp hour charger that it the charger will last very long being run for that long of time

I wan to combine 2 - 12 volt 12 amp hour sealed lead acid battery's with 2 - 12 volt 50 sealed lead acid battery's

is this a safe thing to do will the higher amp lead acid battery's do damage to the lesser one's ?

this set up is for a E-bike which takes just under 25 amp hour draw
I've seen the draw get into the first bar of red but only in winter when it's rile cold
say about - 47 Celsius

6 answers
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Jun 9, 2011. 8:01 PMfrollard says:
You need to convert your units - it's like saying "The distance between chicago and new york is 600 miles per hour".

A volt is how much potential an electron has - how far it is willing to jump, essentially.

An Ampere (amp) is a quantity of electrons going from A to B as a count similar to 'electrons per second'...a flowrate if you will.

A WATT is a measure of energy transmittal. Volts times amps-- how much the electrons want to go from A to B, multiplied by how many there are flowing.

Adding 'hour' to the end of something is like saying 'how many hours you can run 1 amp' or 'how many amps you can run for 1 hour' -- or any other fraction that divides out to the same number.

An amp hour is 1 amp for 1 hour, or for example, 60 amps for 1 minute (1/60th an hour) at whatever voltage.

A watt hour is 1 watt for 1 hour...or say 60 watts for 1 minute.

NOW, you have 4 batteries, each 12 volts
2x 12 Amp Hour = 24 Amp hours *12v = 288 Watt Hours
2x 50 Amp Hour = 100 Amp hours * 12v = 1200 Watt hours

Totalled that's 1488 Watt Hours.

If you have a 25 Amp draw @ 12 volts, That's 300 watts.

1488 watt hours / 300 watts = 4.96 hours.

Remembering, pedaling a bike with 1500watt hours of lead battery on board is gonna suck when you run out of juice. Lead acid also sucks at cold temperatures...electric bikes suck at -50...most vehicles do.

1500 watt hours @ 12v*2a (24 watt charger) will take 1500/24 62.5 hours to charge...or a little over 2.6 days. Not awesome. You need a bigger charger.

Hooking all the 12 volts batteries in parallel will be fine - they won't hurt each other because they should all be at the same voltage.
Jun 9, 2011. 8:40 PMiceng says:
If you have different amp hour capacity batteries in parallel, the lower
capacity batteries will discharge first and then be reverse charged by
the bigger capacity batteries.

This is very bad ( Lead Acid Murder ) for the lower capacity batteries.

Attached are the first two ways of handling the Problem.
  • A) Using power diodes protects the batteries but wastes 10% of the power at 12 VDC motor. ( What is the Motor Voltage ? )
  • B) A power relay is more efficient but needs a controller You !


Jun 9, 2011. 9:46 PMiceng says:
Just read your text.
If you put identical batteries in series that is a higher voltage ( 24VDC ),
the diodes now only take 5% and make sense to use.

The third way to handle the problem is a controller that uses PWM
( Pulse Width Modulation ) to vary the power to the motor and
ultimately the speed of your vehicle.

The most desirable condition would be five identical batteries in series
and a regenerative PWM controller to run and slow it collecting stopping
energy too.

A

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