Marathon started struggling to go up a grade

[JohnnieB]

Originally Posted by baymee

See two posts up the page

If you can lay your hands on a 6V charger, charge the 6V battery that was low and then connect the TC-III and run two or three back-to-back charge cycles with it. There might be a little life left in those batteries, but statistically, they are close to the end of their usable lifespan, so start budgeting for new ones.

My Exide batteries turned 7 in November and are still giving me all the speed and range I need, but my needs are modest these days.

[baymee]

I’m happy to report that the pack is 38.3 v this morning after 12 hours of rest. The low battery came up to speed in that recharge. As far as range, I won’t know until it warms up.

[baymee]

Thanks for all the help.

[baymee]

I installed a battery volt meter today and it showed 38.2. Went out for about 5 minutes and drove around. I went up a 25% slope around 10 feet in length and saw the voltage drop below 36v. Parked it and it was showing around 37.5 at rest.

How do I know when the batteries are failing? What signs would I look for as far as voltage drop and recovery? They are almost 5 years old.

[JohnnieB]

Originally Posted by baymee

I installed a battery volt meter today and it showed 38.2. Went out for about 5 minutes and drove around. I went up a 25% slope around 10 feet in length and saw the voltage drop below 36v. Parked it and it was showing around 37.5 at rest.

How do I know when the batteries are failing? What signs would I look for as far as voltage drop and recovery? They are almost 5 years old.

Only dropping 2.2V is better than average.

Voltage recovery after use is pretty slow, so the pack very likely climbed higher the 37.5 after stopping. It take about an hour for full recovery.

Batteries start failing the moment they are installed and reach the end of their usable lifespan when they can no longer provide the performance or range (runtime) you need or desire. In other words, you have to decide when they are no longer doing the job you want them to do.