Wiring Batteries Together

[frew]

If I wire three 12 volt batteries together in series to get a 36 volt
pack and they are all rated at 10 Ah each, then what is the Ah rating
of the pack? I think it's 10, but I'd like some confirmation.

 

[Tom Biasi]

"frew" <frew@swbell.net> wrote in message
news:bec0ce55-fb7c-45be-8d3e-d14c91e834a9@z31g2000yqd.googlegroups.com...

If I wire three 12 volt batteries together in series to get a 36 volt
pack and they are all rated at 10 Ah each, then what is the Ah rating
of the pack? I think it's 10, but I'd like some confirmation.

Well, in general the current in a series circuit is constant.
But you are not talking about a current flow you are talking about a current
AH rating.
Lets say this, if the batteries are of the same chemistry and in equal
condition you can approximate what you say otherwise all bets are off.
IE 10AH NiCad with 10AH lead acid or what ever would not yield any valid
predictionsions on the face.

Tom

 

[Phil Allison]

"frew"

If I wire three 12 volt batteries together in series to get a 36 volt
pack and they are all rated at 10 Ah each, then what is the Ah rating
of the pack? I think it's 10, but I'd like some confirmation.

** Yep - batteries made from similar cells have the same Ah rating as each
cell. This strikes some as odd because they mentally connect Ah rating with
energy capacity - which is wrong.

The energy capacity of cells and battery packs is rarely ever quoted, but is
given by a watt-hour figure.

The other fact that confounds many is that both the energy capacity and Ah
figure vary with the discharge rate.


...... Phil

 

[stan]

On Aug 11, 10:40 pm, frew <f...@swbell.net> wrote:

If I wire three 12 volt batteries together in series to get a 36 volt
pack and they are all rated at 10 Ah each, then what is the Ah rating
of the pack?  I think it's 10, but I'd like some confirmation.

Yes the combination of your 3 batteries is 10 Ampere hr. at 36 volts.

That's 360 watt hours (Amps times volts).

BTW another way to confirm this in one's mind is this.

Each of your 12 volt batteries is actually 6 cells. Connected in
series.

Each (assuming lead acid batt.) cell has a nominal voltage of 2 volts.

Your 3 12 volt batteries, connected as described, become 18 cells, all
connected in series. Total 36 volts.

Each cell can store enough energy to provided 10 Amp.Hr. (Defined as a
certain number of amps at a defined temperature. for a defined period
of time).
For example;
1 amp for 10 hours = 10 Ahr.
Or, 2 amps for 5 hours
Or, 5 amps for 2 hours
Or 10 amps for 1 hour. Note 1
Or 20 amps for 0.5 hour. Note 1

Note 1: Naturally at higher discharge rates the batteries not only run
down that much quicker they may well have less 'usable' capacity. I
might be possible for example to consider taking 50 amps for only one
fifth of hour (12 minutes!). But in fact one might be lucky to get
just a few minutes at waht is for a 10 Ahr battery, a very high rate
of discharge. But you're probably already familiar with this.

 

[Rich Grise]

On Tue, 11 Aug 2009 17:40:52 -0700, frew wrote:

If I wire three 12 volt batteries together in series to get a 36 volt
pack and they are all rated at 10 Ah each, then what is the Ah rating
of the pack? I think it's 10, but I'd like some confirmation.

Yes.

Cheers!
Rich