Upgrading batteries

[eflyguy]

They do exactly that. What is the voltage when driving on the flat, then on a steep hill? My 42V pack drops to around 39V iirc when going up a steep part of our driveway.

This is where having an accurate, *actual* voltmeter wired in comes in handy..
..a

[stellix]

When the batteries voltage drops under a load will that make the bar graph type SOC meter think that the batteries are low? It sure seems week on slight hills now after the Plum Quick motor and no increase in speed.

[scottyb]

The bar graph meters are ballpark accurate. Attach your handheld digital meter to the pack for more realtime information.

[JohnnieB]

Originally Posted by stellix

I'm only running 20" tires. It takes off pretty strong but in the first 1/4 mile there was a little hill for a couple hundred yards and it slowed down a good bit. The bar type SOC meter dropped one bar in the first 1/4 mile. I tested the voltage of the batteries and they were all 6.3 and one was 6.2 the pack voltage was 50.3 but the meter was showing about 40%. Could the batteries be dropping under load but the voltage go back up without a load?

Battery voltage drops while amps are being drawn from it, the more amps drawn, the lower the voltage drops.

Once the discharge ceases, the battery voltage recovers, but it takes a while for it to return to the At-Rest voltage needed for making SoC estimates. When I do battery testing for estimating cart range and other things, I wait about half an hour, the the voltage actually continues to rise (slightly) for at least and hour. To get a rough guesstimate of SoC when out and about, I only wait a few minutes (5-10) since most of the recovery occurs in the first few minutes.

A 48V battery pack is twenty-four 2V cells connected in series, whether they are packaged 3, 4 or 6 cells per box (6V, 8V or 12V batteries). Any one (or more) of the 24 cells could be bad and drop far lower under load than the others and cause poor performance and/or short run-time.

Connect a handheld DVM to single battery and measure & record its voltage while driving cart. Repeat for the other seven batteries.

If any of the batteries are dropping significantly more than the others, they are the bad apples.

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As for the bar graph type SoC meter. They tend to be highly dampened (slow to respond to voltage changes), so they don't flicker up and down during while cart is driven. (The pack voltage is all over the place while driving )

In general terms, that type meter also has some operating characteristics that render them useless as far as I am concerned. However, some people like them.

[stellix]

Starting voltage after charging was 51.5 after my 3 mile run my state of charge meter was 40% but I checked the voltage a few hours later and it was 50.3 and all batteries were 6.3 and one was 6.2 . The state of charge meter was still on 40%.Can one bad battery make it drop like this but still show good voltage after it sits for a while?

[sportcoupe]

Replace your state of charge meter for a digital voltmeter.