I think you can trust East Penn for the most part. I also tend to be
on the conservative side along with Stephen and East Penn when it
comes to useful range between charges verses battery life for the Car.
The text that surrounds the chart on the east penn site probably says
"Yes! The harder any battery has to work, the sooner it will fail.
* You may experience longer or shorter life based upon application,
charging regimen, temperature, rest periods, type of equipment, age of
As you can see, the shallower the average discharge, the longer
the life. This is why it's important to size a battery system to
deliver at least twice the average power required, to assure shallow
The need to carry a "unused" reserve capacity in order to get maximum
longevity is, as so often stated, one of the biggest negatives to Pba
batteries. But with that said pushing them hard to get what you need
may be totally acceptable. The big difference isn't between 80 and
100% but in the going over 50%. But no matter what you do they aren't
going to last forever. But mine are still going "strong enough" past
when I thought they would need replacing.
--- In email@example.com, Ken Olum <kdo@...> wrote:
> From: Stephen Taylor <sparrow262@...>
> Date: Thu, 16 Feb 2006 10:47:48 -0800 (PST)
> My opinion is that the Lead Acid Force will do 40 to 50 miles at
> below highway speeds under very good conditions and conservative
> driving, but you don't want to do it often. If asked I generally
> say 20 to 30 miles is a day in and day out range for the car.
> I've driven my Force (1998, 13 Deka 8G27) 48 non-highway miles as a
> test. I did not get into "limp home mode", which is supposed to start
> at 80% discharge. I would not hesitate to drive 40 non-highway miles
> regularly. I don't know whether Deka's specifications are to be
> trusted, but if you look at page 10 of
> http://eastpennunigy.com/products/pdfs/0139.pdf, they give a chart
> of lifecycles vs. depth of discharge. Multipling these numbers gives
> the total amount of charge that you can put into and take out of the
> battery during its lifetime. For 10% discharge they give 5700 cycles,
> or 570 times total capacity. For 80% they give 600 cycles or 480
> times capacity and even for 100% they give 450 cycles. If this is
> right, there's not much reason to avoid deep discharges to increase
> the life of your batteries. Of course the efficiency of the car is
> significantly reduced when the batteries are discharged because the
> voltages less and so each amphour does less work.