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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 Answered

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



8 years ago

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.


Answer 8 years ago


your saying it will take me 62.5 hours to charge ?

so from the math I did it should take 14 hours

I know it takes me 3.5 hours to charge the 4-12 volt - 12 amp battery's
the E-bike is 48 volts well more like 53.8 volts
and the computer sucks some juice wile this go's on
so this slows things up

I've peddled thing thing 2 times

and walked it 2 times
the longest being about 1/2 km
my legs were sore for 2 days after

the peddling sucked garbage on this e-bike

as for getting a higher amp hour changer the highest
that I have access to is 5 amp but I am not shire about
using it since it was built to charger LifePo4 battery
30 amp hour battery

I know the bike can take it but the battery I do not


so if the 12 volt smaller ones are drained out
will the bigger 12 volts have a problem ?

and at the same time will the 12 volts once drained
cause problems ?

I've seen what happens when these 12 volt battery's go bad
the out side plastic shell warps and it's not sealed any more
and the smell is bad

if I had not checked on them the changer and
or the battery's would have caught fire

even after all that Left them sit out side and when I moved one
I got sparks from it


8 years ago

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 !


Answer 8 years ago

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.


Mix BattsMotor.jpg

Answer 8 years ago

48 volts is what it has to be no less as I would speed
the speed is set at 32 km per hour max on level ground
I've been clocked at 30 km per hour

I do not think I can push the motor or the controller computer past that

thanks guys for the input so to speak

i know what I will do from this point onward


8 years ago

since the E-bike is 48 volts
then it would be 48 volt electric motor
as ware that's 90 percent of the power is going

I want to cut weight down ware I can by using only 2
it's less for the bike to push

I want to be able to travel further

I know using this in winter is bad but I do not have a drivers license
and have no plans to get one any time soon if ever

and waiting for the crowed loser slow bus service
is not on my list

I'm starting to think 4 battery's of the same is the only way to go
it will cost me as much as buy a new bike but I will gain so much more distance

just the charge time will be my only thing
more so for the winter months than in summer

I can still do the distance I want to and from work
which is 20.3 km .. well more like 24 km with the hills

but with a second set I can leave one on charge when I go to work
and when I am at work I can change up there just for an extra if I have
to some place after work

7.5 hours of charge time will be enough winter or summer
for the distance I need to cover and I insulate the motor
like I should have last winter the cold that is keep out and the
the heat from the motor is keep in for about 75 percent