8V battery load-testing, charging-issue diagnosis

[808Pants]

I didn't find much on load-testing for 8V batteries, but that's the core of my question: how to get a sense of their potential.

If there's a better means than loading them, I'd be interested in that, too.

[The sticky "Everything to do with batteries!" could use this info if it's out there.]

Fresh from an aborted charging cycle (that was probably nearly complete or aborted), my batteries range from 8.9 to 9.0V. The total pack voltage is about 53V, which is off the chart (high) and...that can't be right, because these are old and likely tired, much as I'd like to believe my 48V desulfator is going to make them last forever.

I'm writing this because my uprocessor-timer-augmented charger fairly regularly aborts charging...but isn't smart enough to tell me WHY it's done so.

[NoleFan4Ever]

The best load tester is in your cart with a VOM hooked up to the pack and then each individual battery.

The proper voltage for your pack and each battery should be checked 12 hours after the charge completed.

[DaveTM]

Originally Posted by NoleFan4Ever

VOM

What is a VOM? Volt Of Meter???

[NoleFan4Ever]

Originally Posted by DaveTM

What is a VOM? Volt Of Meter???

Voltage-Ohm Meter. (When I tell them to get out their DVM, sometimes I get "I did not install one in my dash yet" Lol!

And it is a Fluke and a Milwaukee!

[DaveTM]

Originally Posted by NoleFan4Ever

Voltage-Ohm Meter. (When I tell them to get out their DVM, sometimes I get "I did not install one in my dash yet" Lol!

And it is a Fluke and a Milwaukee!

OIC!! (Ohm I See )

[Fairtax4me]

ORLY?

The simple answer is either the cables are bad or the voltage is dropping and causing too much amp draw for the cables to handle. (amperage being inverse to voltage: volts go up, amp draw goes down. Volts go down, amp draw goes up)

Like Nole said, you should check battery rest voltage after they have been sitting for 12 hours or so. Then check battery voltage under load by driving the cart with a Voltmeter connected to the pack. Hit the Go pedal and see how far the voltage falls. If it drops under 40V the pack probably needs to be replaced.

[808Pants]

Originally Posted by NoleFan4Ever

The best load tester is in your cart with a VOM hooked up to the pack and then each individual battery.

The proper voltage for your pack and each battery should be checked 12 hours after the charge completed.

I should further explain that, due to current state of topography and project backlog (trust me on that), I have only the option to try to go up a hill that's perhaps too steep to be climbed by my setup. I refitted the cart with mud tires, but on my one and only attempt at this hill, even with a running start, I ended up slowing to the point where the RR tire would slip. That's my way of saying I can't currently take it out for a spin anywhere, but I can put a heavy load on it, almost to the point of stalling. Under those conditions, what's the lowest tolerable voltage without condemnation of pack?

----------------------

During automatic daily charging cycles, no use of the cart, I see
starting charge rate of 7A
finishing rate of maybe 3A

Does that sound normal-ish?

My Lester charger is fitted with an after-market charging controller that is intended to replace a failed OBC by putting key charging controls into the charger itself. It's poorly documented at best, and no one seems to know who makes these, let alone could provide tech support for them. ANyway, charging cycles never 'officially' complete these days; instead it stops, with a red-light indication of "charger problem," despite that it's obviously charging.

Fresh from an aborted charge, I have:
53V pack voltage
8.9 to 9.1V at each of the six batteries.
Those seem to me like high numbers, if anything, and maybe that's what it's trying to tell me by "charger problem," but that would really be a problem with the microprocessing-timer controller itself, if that were the case.

When this happened first a couple of years back, I took all the batteries out and reconnected them on a pallet. Then, using the same charger, I had NO red-light issues, with daily charges ongoing for months without a problem. I finally put the batteries back in the cart. Not immediately, but soon after, the red light issues came back.

Further suggestions/ ideas?

Thanks - Dave

[808Pants]

Originally Posted by Fairtax4me

ORLY?

The simple answer is either the cables are bad or the voltage is dropping and causing too much amp draw for the cables to handle. (amperage being inverse to voltage: volts go up, amp draw goes down. Volts go down, amp draw goes up)

Like Nole said, you should check battery rest voltage after they have been sitting for 12 hours or so. Then check battery voltage under load by driving the cart with a Voltmeter connected to the pack. Hit the Go pedal and see how far the voltage falls. If it drops under 40V the pack probably needs to be replaced.

Thanks - I don't have a 'driving' problem so much as I have an ongoing charging problem. See my reply to NoleFan4Ever... also should note my cables are fine: clean, and oversized. IIRC I saw my dash-mounted VM drop to below 40, but that was under the 'can't-quite-get-up-it' hill-climb I described in the other post.

[808Pants]

side note: isn't there a setting in the user CP to automatically subscribe to any thread I post? (FFS!?) I'd think that would be the default setting.