Looking to improve a 48V machine

[Ken Potter]

Looking for advice:

My project is on the road and doing fairly well:  48V Motorcycle using 4 AGM batteries @ 50 AH each, and an identical 5th battery for the 12V needs (the two systems are separate except for the 12V contactor).  The controller is an Alltrax AXE, set to 70% maximum power.  The motor is a Mars ME0708 Brush-Type, Permanent Magnet DC motor, also known as the Etek-R.

Here are the issues:  As usual, extending the range a few more miles is a priority.  At the same time, just a little more power would be welcome for climbing hills at moderate speeds. 

Here are some options:  I have one more identical battery, and I'm tempted to go up to 60V, adding 50 AH at the same time (but exceeding the rating of the motor).  Another possibility is just reprogramming the controller to 80% of max and switching to larger batteries (groan).  A third, and less expensive option, is to add a small DC-DC converter, eliminate the accessory battery, and save about 30 lbs.  By law, the headlight must remain on at all times.  A good LED headlight would improve matters, so the search is on.

Any thoughts?
Ken Potter

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[Jeff Kim-3]

You can usually add additional batteries to increase the voltage without too much risk.  The main reason for this is that the motor does not generally see full pack voltage.  Among other reasons, there is voltage drop during load, particularly as your batteries are depleted.  I know of people that have run more than 50% higher battery voltage than the motor rating, but don't take my word for it.

Jeff Kim

On Sun, Oct 18, 2009 at 12:09 PM, Ken Potter <ken@...> wrote:

Looking for advice:

My project is on the road and doing fairly well:  48V Motorcycle using 4 AGM batteries @ 50 AH each, and an identical 5th battery for the 12V needs (the two systems are separate except for the 12V contactor).  The controller is an Alltrax AXE, set to 70% maximum power.  The motor is a Mars ME0708 Brush-Type, Permanent Magnet DC motor, also known as the Etek-R.

Here are the issues:  As usual, extending the range a few more miles is a priority.  At the same time, just a little more power would be welcome for climbing hills at moderate speeds. 

Here are some options:  I have one more identical battery, and I'm tempted to go up to 60V, adding 50 AH at the same time (but exceeding the rating of the motor).  Another possibility is just reprogramming the controller to 80% of max and switching to larger batteries (groan).  A third, and less expensive option, is to add a small DC-DC converter, eliminate the accessory battery, and save about 30 lbs.  By law, the headlight must remain on at all times.  A good LED headlight would improve matters, so the search is on.

Any thoughts?
Ken Potter

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[Oliver-70]

I have heard the same thing.  When I purchased a CitiCar a couple years ago
that has a 36V motor I was told that didn't necessarily mean it was a 36V
car, and that pretty much all the 48V CitiCars had 36V motors in them.

<disclaimer> I am not an expert </disclaimer>

Cheers!
-Oliver


________________________________________
From: oeva-list-bounces@... [mailto:oeva-list-bounces@...] On
Behalf Of Jeff Kim
Sent: Sunday, October 18, 2009 2:10 PM
To: Ken Potter
Cc: oeva-list@...
Subject: Re: [Oeva-list] Looking to improve a 48V machine

You can usually add additional batteries to increase the voltage without too
much risk.  The main reason for this is that the motor does not generally
see full pack voltage.  Among other reasons, there is voltage drop during
load, particularly as your batteries are depleted.  I know of people that
have run more than 50% higher battery voltage than the motor rating, but
don't take my word for it.

Jeff Kim
On Sun, Oct 18, 2009 at 12:09 PM, Ken Potter <ken@...>
wrote:
Looking for advice:

My project is on the road and doing fairly well:  48V Motorcycle using 4 AGM
batteries @ 50 AH each, and an identical 5th battery for the 12V needs (the
two systems are separate except for the 12V contactor).  The controller is
an Alltrax AXE, set to 70% maximum power.  The motor is a Mars ME0708
Brush-Type, Permanent Magnet DC motor, also known as the Etek-R.

Here are the issues:  As usual, extending the range a few more miles is a
priority.  At the same time, just a little more power would be welcome for
climbing hills at moderate speeds. 

Here are some options:  I have one more identical battery, and I'm tempted
to go up to 60V, adding 50 AH at the same time (but exceeding the rating of
the motor).  Another possibility is just reprogramming the controller to 80%
of max and switching to larger batteries (groan).  A third, and less
expensive option, is to add a small DC-DC converter, eliminate the accessory
battery, and save about 30 lbs.  By law, the headlight must remain on at all
times.  A good LED headlight would improve matters, so the search is on.

Any thoughts?
Ken Potter

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Oeva-list@...
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