The Horrors of Battery Maintenance

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12-07-2009 03:14 PM
Gary

The Horrors of Battery Maintenance

It's been less so long since I've been scootering I've been forced to do test discharges of the battery on my N19 to try and restore the battery capacity. I don't have a auto-cut-off on the discharge so I have to carefully monitor the discharge to stop it before the voltage drops below 21V and over-discharges and ruins the battery.

Yesterday I screwed up and forgot all about it leaving the battery forgotten for over 3 hours. When I remembered I rushed out and found it completely drained. The WATTS-UP meter was BLANK (no voltage to even drive the display).

I knew I'd just completely ruined the battery. The battery that was not 100% anymore anyway after 3 years and trying to maintain with test discharges had just been flushed down the toilet. $600 and all that effort wasted.

cryingxxx cryingxxx

I charged it up again just to see if ANYTHING was left. The first charge barely brought the voltage back up to 21V.

But the second charge got the voltage back up to nominal voltage.

The test discharge (to verify the extent of the destruction) seemed not as horrible as I first expected. Actually as the discharge continued I continued to be surprised each reading that it was still going.

To make a long story short, instead of destroying it it actually completely restored the capacity of the battery. I got 14.4 Ahr terminating the discharge at 21.41V instead of 11.0 Ahr on the last discharge 9 months ago terminating at the same voltage.

Weird and amazing. I lucked out - big time!
12-07-2009 06:41 PM
FW

Hmmm, you might want to let Rodney know about that technique. I knew it sometimes worked on NiCads, but not NiMh.

If you want to be really brave, OFG-1 found a Lithium battery that should fit inside an N-19. It would take some work to get it mounted, weighted, and trimmed, but doable. Not any cheaper, though.
12-07-2009 11:20 PM
Gary

We talked to Rodney about the Li option when Kathleen's scooter battery had a couple cells die. We were planning to replace her's anyway. Resurrecting this one may be temporary or not but it is interesting.
12-08-2009 06:32 AM
OFG-1

While not quite as dramatic as yours Gary, I have been cycling my N-19 battery with a standard 1 1/2 ohm burn tester to see what I could recover. The first time, I ran it from 24.7 volts down to 19 volts, it took 42 minutes. After 3 cycles of 24.7 to 19.5 volts, I am up to 67 minutes. As expected, the curve from 21 volts to 19.5 volts is only about 8 minutes. I don't have the watts up meter. I am not sure how this will actually relate to run time,it seems that no one has a current draw curve for the scooter under actual conditions of say a diver with doubles and a stage at a certain prop setting. If anyone has that information, I would like to see it.

I ran the scooter in Indian for 5400 linear feet, about 36 minutes or so, and it did not cut off. When I bought the thing, I was consistently getting 115 minutes out of it. Last summer it was cutting off at 40. Caver95 charged me $150.00 to tow out of Indian, my AAA card did not cover it.

I know of another person that is completely discharging his pack to 4 volts, and your old one Forrest, and claims to have it back up 60 or so minutes.

This is the replacement battery that I am looking at :

http://www.batteryspace.com/highpowe...fuelgauge.aspx

I believe that 2 of them would fit in the hull, although that would really be expensive.
12-08-2009 07:13 AM
FW

Quote:

Originally Posted by OFG-1

I know of another person that is completely discharging his pack to 4 volts, and your old one Forrest, and claims to have it back up 60 or so minutes.

Darn, I wish I had tried that. I was only getting 40 minutes :(
12-08-2009 07:23 AM
Sludge

Let me semi-hijack this over to lead acids. The UV-26/18 I got this summer was kept indoors and periodically charged by the previous owner. But I was thirty minutes into my first dive on the 26 when it started slowing down. (The audible pitch of the motor had dropped about one step on the diatonic scale. If you don't read music, ignore that.) The 18 had about the same burn time.

After several dives (and charge cycles) it gets a little more, maybe 45 minutes before dropping. It has the cheesy little charger, what, 3 amps? I'm wondering if the whole problem is from not getting a full charge to begin with. Here's why:

With just about any battery charger I've owned over the past ten years (light, scooter, phone) I've done this: after the light comes on to indicate full charge I disconnect and after a few minutes I plug it in again. Most chargers will charge for a few minutes before indicating full charge. I've convinced myself this is giving it a little more juice. But the SS charger's light won't go to red when I do this. It stays green. I can come back a week later, or a month, and when I plug it in it will glow red for about half a second and go to green. I'm thinking the charger is so cheap it won't ever give me a good charge.

Any comments?
12-08-2009 07:36 AM
OFG-1

Quote:

Originally Posted by Slüdge

Any comments?

I don't know which charger you have. I have the Interacter with the UV-18 that i have. After a day, it will go back to charging for a short period. Lead Acid batteries store charge better than anything else. Get a burn tester, and cycle the batteries periodically down to say 20 or so volts.

Have a good read here:

http://www.batteryuniversity.com/partone-13.htm
12-08-2009 07:36 AM
RN

There are way too many of you not using your scooters enough. I'll tell you whatm leave al your scooters with me and i will regularly exercise them so this doesn't happen again.
12-08-2009 08:48 AM
sskasser

Quote:

Originally Posted by RN

There are way too many of you not using your scooters enough. I'll tell you whatm leave al your scooters with me and i will regularly exercise them so this doesn't happen again.

Great idea, Rob! I, too, will sacrifice myself to help out my fellow cave divers with this serious problem!
12-08-2009 08:49 AM
FW

Quote:

Originally Posted by RN

There are way too many of you not using your scooters enough. I'll tell you whatm leave al your scooters with me and i will regularly exercise them so this doesn't happen again.

:rollguy
12-08-2009 08:54 AM
FW

Quote:

Originally Posted by Slüdge

....after the light comes on to indicate full charge I disconnect and after a few minutes I plug it in again. ...

Where are you disconecting it? If you leave the charger connected to the wall, and disconnect from the battery for a few minutes, it should work.

If you unplug the charger from the wall, it may not help. Lead acid battery chargers need to be plugged into the wall first.

You might consider investing in an Interacter charger.
12-08-2009 11:12 AM
Sludge

Quote:

Originally Posted by FW

You might consider investing in an Interacter charger.

Absolutely.

I was going to get a burn tester and watt's up meter, but a friend in town said I can borrow his - do I really need to OWN one if I can borrow one every few months? I just need to make a point of going and actually getting it.
12-08-2009 11:47 AM
FW

Quote:

Originally Posted by Slüdge

...do I really need to OWN one if I can borrow one every few months? I....

Nope. Actually, for lead acid batteries, once a year is probably often enough. They don't need to be "exercised" like NiMH.
12-08-2009 02:19 PM
crawford

Quote:

Originally Posted by FW

If you unplug the charger from the wall, it may not help. Lead acid battery chargers need to be plugged into the wall first.

I could swear I read in my manual for my old MLS/MR11 (which I keep as a backup and for my son to OW dive with) that you should never plug into the wall first. I get so confused with all this battery stuff. If you're right Forrest I've been doing it wrong for years.
12-08-2009 02:38 PM
Jason B.

If these chargers have an off/on switch, I can't see where it makes a difference what you plug in first and I'll have a hard time believing otherwise.
12-08-2009 03:31 PM
crawford

Quote:

Originally Posted by Jason B.

If these chargers have an off/on switch, I can't see where it makes a difference what you plug in first and I'll have a hard time believing otherwise.

I've got a charger for a Nimh and a lead acid, neither have an on/off switch.
12-08-2009 03:37 PM
FW

Quote:

Originally Posted by crawford

I could swear I read in my manual for my old MLS/MR11 (which I keep as a backup and for my son to OW dive with) that you should never plug into the wall first. I get so confused with all this battery stuff. If you're right Forrest I've been doing it wrong for years.

Did it have lead acid batteries? NiMH is battery first, wall last. NiCads weren't quite so picky, and Li battery chargers seem to come in both types.
12-08-2009 03:41 PM
FW

Quote:

Originally Posted by Jason B.

If these chargers have an off/on switch, I can't see where it makes a difference what you plug in first and I'll have a hard time believing otherwise.

It depends on how the chargers are designed to work. *Most* lead acid chargers need to "boot" with no battery attached, then connect to the battery to "analyze" the charge requirements.

NiMH chargers have to have to have battery connected during "boot" to "analyze" the charge requirements.

I have "boot" and "analyze" in quotes because this is an over simlification of how "smart" chargers work.
12-08-2009 04:18 PM
crawford

Quote:

Originally Posted by FW

Did it have lead acid batteries? NiMH is battery first, wall last. NiCads weren't quite so picky, and Li battery chargers seem to come in both types.

Yeah, it's lead acid. I"ll read it again. Luckily I'm doing the NiMH correctly, since the replacement cost on it is 200-300 USD vs. 30 USD for the lead acid.

Oh the irony, I'm posting all this new advanced technology in the Fill Station and can't understand how a battery charger works :roll:
12-08-2009 05:28 PM
saturation

SLA batteries should be charged asap after discharge, this prolongs the life substantially. If you leave it for days, say after the last dive for a weekend, it will not recover very well or at all. The sooner you charge it, the less sulfation becomes a problem. Also, the less you run the battery down, the longer it will provide near virgin amp hours.

http://www.batteryuniversity.com/parttwo-35.htm

See the bottom of the page for the summary.
12-08-2009 06:55 PM
Bob B

Quote:

Originally Posted by FW

Darn, I wish I had tried that. I was only getting 40 minutes :(

Now you know why i bought it from you.. This trick has been around for many years in the RC racing world... So far I have helped at least 8 N-19 batteries "come back to Life" Not counting yours :smt045 (of course I think Edd killed one of his)
12-08-2009 07:08 PM
Bob B

Quote:

Originally Posted by FW

It depends on how the chargers are designed to work. *Most* lead acid chargers need to "boot" with no battery attached, then connect to the battery to "analyze" the charge requirements.

NiMH chargers have to have to have battery connected during "boot" to "analyze" the charge requirements.

I have "boot" and "analyze" in quotes because this is an over simlification of how "smart" chargers work.

I have 1000s of batteries and dozens of battery chargers and testers and matchers and analyzers and crap. (Along with 100s of wins and ET / MPH records, in RC Drag racing ) I can tell you that Most of this stuff (dealing with NIMH and NICAD batteries and chargers) is fluff that comes from people using crappy chargers.. I have heard / seen all kinds of processes that people use to get a "H" charger to charge their HID battery.. Right John.. :)
12-14-2009 07:44 AM
Rodney Nairne

NiMh batts

If your pack is so low it's unusable, there is no real downside to giving this a try...

If that does not work, we have a Xmas special on replacement packs, $495 excluding the spacer/clips and threaded rods.

-Rod
Submerge Scooters

Quote:

Originally Posted by Bob B

Now you know why i bought it from you.. This trick has been around for many years in the RC racing world... So far I have helped at least 8 N-19 batteries "come back to Life" Not counting yours :smt045 (of course I think Edd killed one of his)
12-14-2009 07:51 AM
FW

Quote:

Originally Posted by Rodney Nairne

If your pack is so low it's unusable, there is no real downside to giving this a try...

If that does not work, we have a Xmas special on replacement packs, $495 excluding the spacer/clips and threaded rods.

-Rod
Submerge Scooters

This is the procedure Rodney is referring to:

Quote:

Originally Posted by OFG-1

I know of another person that is completely discharging his pack to 4 volts, and your old one Forrest, and claims to have it back up 60 or so minutes.

Only try it as a last resort, because if it doesn't work, the battery will be totaled :(

Thanks Rodney!
12-14-2009 09:03 PM
GeorgiaDoc

My burn tester from SS cuts off at ?21 volts I think. How do I discharge it lower. Only getting 29 min right now on the burn tester from full charge of N-19 bat.
12-14-2009 10:05 PM
jdh

Quote:

Originally Posted by GeorgiaDoc

My burn tester from SS cuts off at ?21 volts I think. How do I discharge it lower. Only getting 29 min right now on the burn tester from full charge of N-19 bat.

I stick a screwdriver blade between the terminals with the black wires on the low voltage cutoff module.

I recovered some time from my battery pack with this method, but the discharge curve is lower. I also changed the LVC in both the burn tester and the scooter to cut off at just over 20VDC instead of 21.

John