DIY Electric Car Forums banner
1 - 1 of 1 Posts

· Registered
72,624 Posts
Discussion Starter · #1 ·
Re: [EVDL] Buddy pairs AGM & Floodie


I am just guessing here as I have no experience etc. with this. I think
that two batteries of different chemistry or built differently would
charge / discharge each other at the different voltages and power use
rates or charge rates that they would be subject to. In certain
situations wouldn't the batteries fight each other, or lose efficiency
as one discharges into the other, then back and forth over the range of
operation. When you charge or discharge a battery you lose a little due
to the system not being 100% efficient. Enough small partial cycles
back and forth and there is some loss. Is this significant? Does the
benefit of having another battery choice between AGM and flooded
outweigh any loss?

It would be interesting to set up a test with three battery systems.

2 flodded batteries in parallel.

2 AGM batteries in parallel.

1 flooded and 1 AGM in parallel.

The batteries should be as close in capacity as possible or practical or

Charge and discharge each set similarly and keep data on everything.

Is the "1 flooded 1 AGM" set better at something? What does it do best?

What does the 2 flooded set do best?

What does the 2 AGM do best?

I would think that if the "1 flooded 1 AGM" did turn out to work well,
that you would have a battery with a little of both attributes of
flooded and AGM. Someone needing a tad more range than AGM alone, and a
tad more available power that flooded alone would be pleased to have
another option.

How would you know if the "1 flooded 1 AGM" combination did not work?
Could you average the results from the other two battery sets, and
expect at least that much performance from the "1 & 1"? If you noticed
a 1 percent loss in performance or a 1 percent extra need for charging
in the "1 & 1" could you say that was acceptable, and use this system to
meet your unique needs between speed and range? If you noticed a 25
percent loss in performance between the "1 & 1" and the average of the
other two systems, could you chalk that up to the flooded battery and
the AGM battery in the mixed set fighting each other, or charging and
discharging each other during a range of use and the resulting
inefficiency of charge / discharge cycles?

I wish I had the time and equipment to check this out, but do not.


-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of Marty Hewes
Sent: Wednesday, August 22, 2007 6:41 AM
To: Electric Vehicle Discussion List
Subject: [EVDL] Buddy pairs AGM & Floodie

Hi All,

I'm no battery chemist or charging expert. But I've been thinking of
running two strings in parallel, an AGM string and a floodie string,
figuring the AGM's would get me some acceleration, the floodies would
get me
more range. But I haven't found much data on how the two strings would
interact with each other.

Now I'm wondering if it would work better if I paired a 12 volt AGM and
a 12
volt (or two 6 volt) floodies as a buddie pair, and then charged them
AGM type battery management? If a 12 volt floodie were paralleled with
a 12
volt AGM, and charged as one battery like an AGM, what would be the
on the floodie?


For subscription options, see

For subscription options, see
1 - 1 of 1 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.