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Old 05-31-2020, 01:11 PM   #1
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Quick Battery Equalizing Question

Hey everyone.

We went and anchored out last weekend for the first time in several years... three I think... (donít ask... North Carolina hurricanes and other stuff) Anyway, our eight, 6V lead acid batteries are about five years old and have really never been off charge for very long, nor have they been depleted more than a few percent over a single night at anchor. We have a 60A Sterling charger with a temp sensor and it mostly keeps a float charge on it as we are only weekend warriors.

As I said, we anchored out last week and we had an issue with the davit crane dropping the voltage so low that the breaker popped as we were lifting the dinghy back in place. The Victron shows only 12.2 (60% SOC) with only a few lights on, so I think the batteries need replacing.

My question is this: I was going to head to the boat tomorrow-ish and was going to do a 12-hour resting voltage test. Can I equalize the batteries BEFORE the test? If I opt to equalize, do I need to wait longer before I do a test or do I need to let them rest longer than overnight?

Honestly, I donít mind replacing them, there are only 8 and I have an inexpensive golfcart store on the way to New Bern where I can replace them for about $1000. Still, I donít want to replace them if I donít have to... it just seems weird that they have lived such a sheltered life and are now bad for no specific reason.

Thanks!
Tom-
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Old 05-31-2020, 01:17 PM   #2
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I'd follow the instructions in the Sterling manual and equalize them first. Make sure they are topped up with water. Have you measured them with a hydrometer? Measured the amp draw of the davit (could be a motor or wiring issue).?
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Old 05-31-2020, 01:22 PM   #3
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How has the water use been over the years?
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Old 05-31-2020, 01:23 PM   #4
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Quick Battery Equalizing Question

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Originally Posted by caltexflanc View Post
I'd follow the instructions in the Sterling manual and equalize them first. Make sure they are topped up with water. Have you measured them with a hydrometer? Measured the amp draw of the davit (could be a motor or wiring issue).?


I have not measured the draw of the davit motor, but if it matters, it does work fine when we are plugged into shore power.

Good idea about the hydrometer. I have one down there and will see what it reads.
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Old 05-31-2020, 03:13 PM   #5
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I no longer have wet cells but when I did one of the first things I would do is use that hydrometer, not the mickey mouse floating ball type but a good one.
Last time it was used was to help a dockmate figure out why he was having trouble starting his engines. Made him go down and check all cells of both starting batteries.
Both had 1 dead cell. Voltage showed fine with just the DMM but under load they failed.
THe dead cells were the last straw.

The other way is to test for Vdrop under a serious load.
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Old 05-31-2020, 04:24 PM   #6
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I would equalize them and wait the prescribed time and check them with a good hydrometer. Then you will likely go buy new ones... hope not though.
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Old 05-31-2020, 07:14 PM   #7
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Part of most equalization processes is checking with a hydrometer as you go. See page 20 of Trojan's excellent user guide:
https://www.trojanbattery.com/pdf/Tr...UsersGuide.pdf
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Old 05-31-2020, 07:17 PM   #8
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Quote:
Originally Posted by C lectric View Post
I no longer have wet cells but when I did one of the first things I would do is use that hydrometer, not the mickey mouse floating ball type but a good one.
Last time it was used was to help a dockmate figure out why he was having trouble starting his engines. Made him go down and check all cells of both starting batteries.
Both had 1 dead cell. Voltage showed fine with just the DMM but under load they failed.
THe dead cells were the last straw.

The other way is to test for Vdrop under a serious load.
What is a good-quality hydrometer? I'd like to ditch my floating ball hydrometer and upgrade.
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Old 05-31-2020, 08:14 PM   #9
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Quote:
Originally Posted by caltexflanc View Post
Part of most equalization processes is checking with a hydrometer as you go. See page 20 of Trojan's excellent user guide:
https://www.trojanbattery.com/pdf/Tr...UsersGuide.pdf


Nice. Thanks.

Yaí think I should I disconnect the VSR (voltage sensing relay) before equalization?
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Old 05-31-2020, 08:16 PM   #10
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Nice. Thanks.

Yaí think I should I disconnect the VSR (voltage sensing relay) before equalization?
I take it the VSR goes over to a start bank? then yes it would be a good idea to disconnect it.
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Old 06-01-2020, 05:33 AM   #11
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"The other way is to test for Vdrop under a serious load."


Its a simple wiring job to use an installed V meter wired to the starter motor to have a check of the start system with every engine start.
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