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Killing Lead Acid batteries

7960 Views 23 Replies 12 Participants Last post by  Dave Koller
I've now overcharged my Trojan T-105's at least four times. I usually leave the charger to do its thing overnight, and twice I've come out around noon to find its still trying to charge the batteries, which are smoking, at 180 degrees F, and have dumped battery acid all over my driveway. I've re-filled them with water, but I suspect too much acid is gone. Some cells show no Specific Gravity at all, others show an overcharge.

What happened? Did I have a dead cell that made the charger think I still needed charging? Were the batteries too hot?

The truck is now parked. I'm done.
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Sounds like yu have a shorted cell or two so the voltage never gets high enough trip the charger circuitry to turn off. This is why it is a good idea to also have a timer to prevent such things from happening.
 

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Discussion Starter · #3 ·
I should've used a timer after the first overcharge. I thought I'd have remembered to unplug it before I went to bed. Ha!

I guess I have time to install a timer and a few other goodies before I can go with lithium. You think I'll be smart enough to get a BMS then?
 

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What brand of charger were/are you using??

Yes, you might have a shorted cell before. With the "missing acid", sounds like more than one cell/battery is being vastly overcharged. Check your charging voltage, expecially the finishing/EQ voltage. My EQ amperage is about 4Amps.

Let batteries set for 24hr after charg, then use a good digital voltmeter and check the (resting) voltage of each battery. When batteries bubbled over, you lost acid. You would probably need to check the specific gravity of each cell on each battery (assuming floodies). It's difficult to ADD acid accurately to
reconfigure to the factory specific gravity.

You will probably just have to "write it off" as a learning experience.
A real-time BatteryMonitor on each battery would tell you which battery(s) are showing signs of more/excessive voltage drop under load as you drive.
 

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Discussion Starter · #5 ·
The charger is a Manzanita. I had used the Specific Gravity tool to check the cells charge levels and found 7 bad batteries. Battery voltages were anywhere from 6.2 to 6.8 (6V batteries). I had a Pak-Traker to monitor the batteries, but it ALWAYS went crazy when driving, so its sitting in the garage now. Yes, I did everything except shieiding every wire.

I'm going to try add acid to low batteries in the hopes of bringing them back to life with the help of the battery supplier (SBS). Other than that, its all a write off till I can afford lithiums. Should've gone that way from the begining, but tried to save money!

Maybe I'll throw the Pak-Traker back in and sheild every wire... if I get the batteries back from the dead.
 

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Maybe I'll throw the Pak-Traker back in and sheild every wire... if I get the batteries back from the dead.
Don't waste your breath on shielding Paktrakr, its useless. Noise doesn't come from air, it comes from wires themselves. I did everything there is to fix my PakTrakr. The only fix is to remove it and use something else.

I thought Manzanita has a timer and adjustable voltage? Its a pity when most expensive charger ruins the pack. You could have paid for half the lithium pack with what you spent on Manzanita and Lead.
 

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Discussion Starter · #7 ·
The Manzanita does have a timer, but only starts once the pack is at near full charge. It is also current adjustable, but seems to increase the voltage applied to the pack as the current knob is turned down.

Pak-Tracker is a waste.
 

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It's interesting how many Lead Acid tales of woe seem to relate as much to the charger that the batteries!

Although Lithium is a great technology - it's just as much a can of worms if you don't get the charging and monitoring right.

I've been using PbA batteries every day for 16 Months now and have about 400 charge cycles on them with 50% DOD. My batteries were bought as scrap for £3 each and, if anything have improved through having a proper, managed charge cycle. My range is now 15% greater than it was on day one.

I don't think there is anything wrong with PbA - they are a good solution for many where the range can be low and cost has to be low.

If I were you, I would invest in a better charger. Best of all would be a charger that will charge both PbA and Lithium - at least then you keep your options open.

Si
 

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have an Elcon PFC 1500 which seems OK after about 100 charge cycles. I do, however, find that I need to occasionally charge some of the six batteries individually using my nominal 12V Ctek charger. This keeps the resting voltages much closer to each other, which must be good. My range has fallen after 650 miles. It is as if the Peukert constant has increased. I have also noticed more voltage drop under load now than I had in the early days.

I don't think I did my pack any favours early on by running it down to virtually flat in a number of hour long drives.

I would advise anyone with a new LA pack to be very carefull and never run it down too far.

I'm sure I read this same advice before I was on the road but naturally ignored it!

As for your pack I don't know if you could drain all the acid and replace it completely?????????????

At least you would then have the same SG in each cell.

Andrew.
 

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have an Elcon PFC 1500 which seems OK after about 100 charge cycles. I do, however, find that I need to occasionally charge some of the six batteries individually using my nominal 12V Ctek charger. This keeps the resting voltages much closer to each other, which must be good. My range has fallen after 650 miles. It is as if the Peukert constant has increased. I have also noticed more voltage drop under load now than I had in the early days.

I don't think I did my pack any favours early on by running it down to virtually flat in a number of hour long drives.

I would advise anyone with a new LA pack to be very carefull and never run it down too far.

I'm sure I read this same advice before I was on the road but naturally ignored it!

As for your pack I don't know if you could drain all the acid and replace it completely?????????????

At least you would then have the same SG in each cell.

Andrew.
It's my understanding that FLA sinks about 20% per year of age, which might be the effect you're seeing. That's just what I've read, not personal experience.
 

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Something doesn't add up somewhere, the PFC is a great charger. How many batteries, what was the voltage setpoint at, what is the dipswitch configuration, etc. Which model PFC?

Sorry 'bout your problems...

Frank
 

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I read a thread on a different EV forum where someone was having exactly the same experience as me with Numax CVX batteries after about 600 miles. I don't know if my batteries will stabalise at this point or whether it will be all down hill from here.

I have six batteries and the charger is set to go up to 86.4V (which it does). My problem is the voltage drop under use. It doesn't take many miles before the voltage under a battery current of 60 amps is down to mid 60's in volts. The resting voltage seems to spring back up to 72V quickly enough. I've checked individual battery voltages under load and they are pretty even until I've discharged deeply. I must say I'm losing faith with LA, but lithium is still expensive and I'd hate to spend £2000 on a 72V pack and BMS only to find problems in use. If money was no object I'd get straight on with it.

Is there any thing I could do to reverse the apparent decliune?

Andrew.
 

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Andrew,

I tried to find specs on your batteries but could not. Do you have a very lightweight vehicle? Generally, 12 volt batteries are not recommended for EV use as the current draw can easily overwhelm them (as a percentage of C.) How many amps to do you draw when accelerating? What kind of range are you getting? Mid-60's under load is just about as low as you want to go.
 

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Frank,

My Trike weighs 330Kg and I weigh about 75Kg. My maximum motor ampage set on the Alltrax controller is 180 Amps. So even without an ammeter (too difficult to fit) I know that my draw on the batteries at 30mph or 36V is not going to be significantly greater than 90 Amps. The batteries claim 3 hours at 25 amps to 100%DOD. The range is down to about 15 miles at modest cruising speeds in the low 30's.I will soon be borrowing an ammeter to check this but I can't see the figures being wrong. My driving consumes about 140 Wh/mile. I simply don't get the batteries to give me as much energy out as I did at first.

Andrew.
 

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I agree, I suspect the manzanita is not configured correctly.

You need to set the pack voltage using the 10 turn pot. This setting is where the charger to switches from CC to CV. If you are cooking your batteries, this is likely what you need to adjust.

The CC to CV transition also starts the count down timer which eventually shuts the charger off based on the time set with the 16 position rotary switch.

You also need to set the dip switches correctly.






Something doesn't add up somewhere, the PFC is a great charger. How many batteries, what was the voltage setpoint at, what is the dipswitch configuration, etc. Which model PFC?

Sorry 'bout your problems...

Frank
 

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I hate to hijack, but has anyone ever tried installing a low pass filter on a pak tracker? Id love to try it, but cant afford the tracker...

just something at like 100hz. That should kill all the ~16khz of a controller, and leave the DC it wants.
 

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I've now overcharged my Trojan T-105's at least four times. I usually leave the charger to do its thing overnight, and twice I've come out around noon to find its still trying to charge the batteries, which are smoking, at 180 degrees F, and have dumped battery acid all over my driveway. I've re-filled them with water, but I suspect too much acid is gone. Some cells show no Specific Gravity at all, others show an overcharge.

What happened?
bummer.... lead-acid is pretty forgiving, but the last third of life are prone to death by cooking because the voltage may not get up high enough to reach the trigger voltage in the charger. As the plates sulfate, the charge cycle takes longer, self-discharges faster, and doesn't get as high. I know MINE ( a 96v pack of usbattery 8vgchcx ) stopped triggering the auto-off voltage after about 400 cycles or so.

I am still limping along on the floodies for now... and what I do is keep track of miles on trip odo, and set a timer on my charger to charge only for miles/2 hours. When new the pack would do a full charge including over-voltage gassing cycle on about (miles*.4) hours.

with your now empty and unbalanced SG pack, you MIGHT be able to revive them by draining completely and using some new acid, but I would NOT fill 100% with new acid as there is probably some still in your plates. Maybe fill just to top of plates with acid, then top with water. put a timer on charger power!
 

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Discussion Starter · #20 ·
bummer.... lead-acid is pretty forgiving, ...!
These batteries are shot. I opened one up, aint pretty!

On the good side, I found a web site that has a 6V battery BMS? that uses two doides, light bulbs and resistors to bypass the current once the battery is fully charged.

I used it on my 8 good batteries, and placed two on dead ones (all in my 144V pack). Turned the charger on and the good batteries lit up at various levels and eventually were fully lit up, while the killed batteries never lit up.

The charger, Manzanita, which is a very good charger, started timing countdown shortly after the good batteries lit up. The bad batteries must be shorted, though they do read varying voltages. specific Gravity of those batteries is mostly nothing with a few low and one or two good.

I'll fing the web site and create another post asking if this might be a good design.
 
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