Charging question - newbie

[DRL]

My battery pack consists of 4 X 15 ah SLA batteries. The charging receptacle is a 2 wire, center positive RCA style plug.
The output receptacle from the pack to the bike is like a computer cord style 3 pin plug.

Could the pack be charged via the 3 pin plug safely?

(I don't see any electronics in the pack and I am thinking polarity is standard for the pins.)

I ask because I need to replace the charger and it would provide a second option for connector style if needed.

Thank you
D

 

[dnmun]

yes, you can charge SLA batteries through the output plug

the battery side has the male pins recessed into a socket and the charger has a plug with the female end. you can show a picture of what you need to know if you want accurate information.

 

[DRL]

Thanks for the rapid response.

Yes the battery side has the male (3 recessed pins) so if the charger has the female socket then this would be a good alternative charging method if the suitable charger has the computer style connector as opposed to the RCA style connector specifically for charging. It seems the RCA connector is not too common for chargers. (please confirm if this sounds reasonable solution.

Another question.

First the bike is a 48V - 15 ah - 350 W motor.

The original charger has a spec label on it saying - Output 59 V, max current 1.8 A. This set up worked well and I was able to ride about 17 - 20 km roughly. The charge time was about 6 hours which was fine.

Subsequently I fried the charger though arc'ing it when plugging it into the bike (DUH)

I tried to get a charger locally, I was sold a charger that has a label spec which reads Output DC 48V, 2.00A.

I was told this would be ok.

It does charge the pack and turns off when charged.

BIG However....

On a fresh pack - The charge time is now only about 2.5 hours and my riding range has been reduced about 50%. It seems to me the pack must not be fully charged using this "slightly" (to the layman) different spec. Is this a reasonable assumption, is it damaging the pack (there is no temp increase when charging)?

Can I get back to original range with a different charger?

Thanks again for the valuable input.

best regards,
D.

 

[dogman dan]

You need to find out what the real world output of the 48v charger is. Like with a voltmeter.

59v is on the high side for charging 4 sla's IMO. 54v is about right for your pack. Since you were possibly overcharging before, that could be a part of why it's less now. 5v less, or more if your current charger is only putting out 48v.

That previous overcharging could have damaged your battery, and that could be the primary problem now.

 

[DRL]

You need to find out what the real world output of the 48v charger is. Like with a voltmeter.

59v is on the high side for charging 4 sla's IMO. 54v is about right for your pack. Since you were possibly overcharging before, that could be a part of why it's less now. 5v less, or more if your current charger is only putting out 48v.

That previous overcharging could have damaged your battery, and that could be the primary problem now.

Ok thanks, I will get a voltmeter and check the new charger output.

Since I changed out the batts when I got the new charger they were never charged with the 59v charger so I don't think the performance of them is related.

I am still trying to understand the apparent loss of range and the now much shorter charge time using the replacement charger, unless the batteries themselves are significantly different.

50% faster charging and 50% range decrease seems extreme???

PS the original 59v charger did charge "warm" on battery feel - so that is probably correct for the too high charge rate.

 

[dogman dan]

Well silly me, I thought only the charger was different.

You could easily be charging to 6v less now. That would likely account for at least 2 mph less top speed.

Sla's can be very very different. Especially if you got a great price on the new ones. They could be completely unsuited for ev use. Or perhaps just slightly less good for that.

50% faster charging would be expected, if there is 50% less capacity. Yes, 15 ah. But a poor choice would go flat in EV use after discharging less of the 15 ah than the other.

The rated capacity is done at a very low rate. Your bike has a very fast rate. So the wrong battery can have much less real capacity at the rate your bike uses.

 

[DRL]

Well silly me, I thought only the charger was different.

You could easily be charging to 6v less now. That would likely account for at least 2 mph less top speed.

Sla's can be very very different. Especially if you got a great price on the new ones. They could be completely unsuited for ev use. Or perhaps just slightly less good for that.

50% faster charging would be expected, if there is 50% less capacity. Yes, 15 ah. But a poor choice would go flat in EV use after discharging less of the 15 ah than the other.

The rated capacity is done at a very low rate. Your bike has a very fast rate. So the wrong battery can have much less real capacity at the rate your bike uses.

Thanks again.

So it seems I need to figure out if the batts are the loss of range difference or the new 48V charger... or a combo of each.

If I get a digital multi-meter and check the battery charge after recharge, what reading should I expect if the pack is fully charged?
Is this a reasonable test for the charger efficiency and battery health?

The batts were not a cheap purchase and I believe (for now) they are a suitable DC type for purpose.

The way fast charging time is bothersome, and I understand too fast of a charge is a symptom of decreased riding range.

I would prefer if the problem is the charger $$$ So I would like to nail down that side first.

 

[dogman dan]

13.5v per 12v battery is considered fully charged. So see if your charger puts out 54v. If it's less, then you are getting an undercharge.

 

[DRL]

13.5v per 12v battery is considered fully charged. So see if your charger puts out 54v. If it's less, then you are getting an undercharge.

Thanks dogman.

So after charger cutoff I am measuring 52.5 on the pack which after resting for 12 hours drops to 51.7 v so is it safe to say it is undercharged? or is this too little of a difference to account for the fast charge short range.?

I don't know what the impact is on performance of the 3 or so volts under 54v.

Thanks,
D.

 

[dnmun]

measure each battery, and it doesn't matter anyway since it is lead acid. who really cares if it is lead? why even bother using it. if you have a lithium battery charger then get a lithium battery.

 

[DrkAngel]

13.5v per 12v battery is considered fully charged. So see if your charger puts out 54v. If it's less, then you are getting an undercharge.

Thanks dogman.

So after charger cutoff I am measuring 52.5 on the pack which after resting for 12 hours drops to 51.7 v so is it safe to say it is undercharged? or is this too little of a difference to account for the fast charge short range.?

I don't know what the impact is on performance of the 3 or so volts under 54v.

Thanks,
D.

48V SLA Battery Charging

51.7V is only charging to 12.925V per battery, optimal fully charged maintains ~ 13.5V.
So you are only partially charging your batteries.
This would account for you short range and charge times.

Worse, your batteries are suffering.
For best life and performance, SLA should be kept at full voltage and never deeply discharged!
Charge immediately after any use!
See - ES Wiki Sealed Lead Acid

A 3 Stage dedicated 48V SLA charger is recommended.
Stage 1 - Charges at maximum Amps until charge voltage is attained
Stage 2 - Maintains charge voltage and reduces Amps until minimal current level reached
Stage 3 - Reduces voltage to optimal voltage level and provides a trickle-maintanance-float charge

Optimal charge voltage is between 55.2 - 56.4V
"Full" battery voltage is ~54V ... more voltage (pressure) is required to force electricity into the battery.
Recommended charge period is 8-12 hours ...
So, for a 15Ah battery, a 2Amp charger would be maximum, 1.5-1.6A better ... for battery life.

For a 48V 15Ah SLA, you want to look for a ...
3-Stage 48V (that charges at 56.4V) 1.6A charger

 

[DRL]

drkangel

THANK YOU, this is extremely good information for someone like me who is trying to understand the battery/charging relationship. I had scoured the internet but found so much conflicting/confusing information I was at a loss... but now I am found

Excellent tutorial and rules of thumb, I expect it will help many along the way to get started properly.

Thanks again,
D.

 

[DRL]

This is probably an irrelevant update, but it may be useful to someone somewhere. The replacement sla charger was of unknown pedigree but at the time I needed one and it appeared to charge fine. It dutifully turned green when charge was done- I dutifully unplugged it right away.

During the various tests I noted the charge voltage was 52.5 while the charger was working, lower than the required 54 or so. This led me to think it was not up to spec for 48V 15ah charging, since after resting the pack showed a drop to 51.7V - too low to call a full charge. It was also completing the charge cycle way to fast, usualy about 2.5 hours. I was gearing to replace the charger based on drkangels great guide.

Out of interest I decided to see if the charger was still producing current after the red light went out and the green light came on and the fan stopped.
I was surprised when the "switched off" voltage measured 55V, just about what it should have been while charging.

I reconnected the charger to the pack and measured the pack voltage while it was attached - with the fan off and the green light on the pack was seeing 55V?

This made me think I just needed to leave the charger connected for another 5 or 6 hours so the charge could really complete. I monitored the charger and pack during this time, nothing warmed up although the charger was ever so slightly warm. The pack & charger voltage remained at 55V during this extended time.

I disconnected the charger and measured the pack at 54.7V. After one hour resting the pack voltage went to 53.4V much better than the 51.7V and very close to Full" battery voltage is ~54V.

Since the pack has been run for about a year undercharged and was stored through the winter, I may still have a performance issue and should not expect a full battery performance.

I will road test tomorrow and see if I am gaining on the issue... my hope is I can make it through the season before spending more money.

I will use a timer and do the charging on a timed basis rather than the charger green light signal. Who knows but it is worth a shot.

Thanks again for the great guidance. Best regards,

D.

 

[dogman dan]

Ahh, you did not mention that the lead was just taken out of winter storage. That has an effect as well, and you might see some additional capacity develop after a few cycles, and some longer periods of time on the green of the charger. Just like when brand new, they need a bit of a break in.

But also, they may have lost some capacity in storage. They were stored fully charged? If not, that was a huge mistake. Even stored fully charged, there is a bit of a time clock ticking with any battery, and especially with sla's. As they age, they may still take a full charge, but capacity continuous to diminish over time.

 

[DrkAngel]

48V SLA Battery Charging

51.7V is only charging to 12.925V per battery, optimal fully charged maintains ~ 13.5V.
So you are only partially charging your batteries.
This would account for you short range and charge times.

Worse, your batteries are suffering.
For best life and performance, SLA should be kept at full voltage and never deeply discharged!
Charge immediately after any use!
See - ES Wiki Sealed Lead Acid

A 3 Stage dedicated 48V SLA charger is recommended.
Stage 1 - Charges at maximum Amps until charge voltage is attained
Stage 2 - Maintains charge voltage and reduces Amps until minimal current level reached
Stage 3 - Reduces voltage to optimal voltage level and provides a trickle-maintenance-float charge

Optimal charge voltage is between 55.2 - 56.4V
"Full" battery voltage is ~54V ... more voltage (pressure) is required to force electricity into the battery.
Recommended charge period is 8-12 hours ...
So, for a 15Ah battery, a 2Amp charger would be maximum, 1.5-1.6A better ... for battery life.

For a 48V 15Ah SLA, you want to look for a ...
3-Stage 48V (that charges at 56.4V) 1.6A charger

I edited this a bit for an ES Wiki page - Charging SLA Batteries

Added a bit of info on "heat" ...
Heat
Charging produces heat (warmth), hot-heat indicates a problem!
Heat is normal ... and necessary.
SLA operate by a chemical reaction, producing heat during charge and discharge.

This process actually helps balance the individual cells inside the 12V "battery". When a cell reaches "full" it dissipates excessive charge as heat, allowing the remaining cells to continue charging till, also, "full".

Interesting fact - Battery does not directly refer to an electrical storage cell. "Battery" is a collection of items working together, as in a gun, (artillery), battery.
Initially electric cell usage required multiple cells in series, (for higher voltage), or in parallel, (for higher capacity) ... leading to electrical cells being referred to as a battery of cells, then, more simply, a "battery".
So, while a 12V SLA, with 6 internal cells, is accurately called a battery, a single AA, C or D Alkaline cell is not!

 

[DRL]

Ahh, you did not mention that the lead was just taken out of winter storage. That has an effect as well, and you might see some additional capacity develop after a few cycles, and some longer periods of time on the green of the charger. Just like when brand new, they need a bit of a break in.

But also, they may have lost some capacity in storage. They were stored fully charged? If not, that was a huge mistake. Even stored fully charged, there is a bit of a time clock ticking with any battery, and especially with sla's. As they age, they may still take a full charge, but capacity continuous to diminish over time.

Yes, I had them indoors and put the charger on them for a few hours every couple of weeks although the charger always popped up the green light and didn't go into charge mode. However since I found out yesterday it is producing 55V when "not running" that was probably maintaining them. Anyway, I will put theory to the test on my next few rides and take readings before and after as well as monitor distances traveled. Doing this sort of thing adds interest to the hobby. I had expected to get at least two seasons from each replacement pack. I will try not to take them to the bottom and try the timer charging method. Nothing ventured - nothing gained

I should have mentioned the batt type is AGM, apparently they have specific needs.

D.

 

[dogman dan]

That sounds like a proper storage then, you tried to keep them topped up. But even sitting properly stored, there is a bit of a capacity leaking away thing, that's there in use or in storage.

But after storage, they tend to need a cycle or two to develop full charge holding capacity again.

 

[DRL]

Optimal charge voltage is between 55.2 - 56.4V
"Full" battery voltage is ~54V ... more voltage (pressure) is required to force electricity into the battery.
Recommended charge period is 8-12 hours ...
So, for a 15Ah battery, a 2Amp charger would be maximum, 1.5-1.6A better ... for battery life.

Ok, so with a close to spec charger doing about 56.9V @ 1.7A things appear well and good. Starting with a "fully discharged" condition (51V where the low voltage switch kicks in), the charger again completes the charge in only about an hour??? Way too fast.

The charged voltage looks ok at 55.9 V without standing time when the green light comes on and the fan stops.

However, the discharge rate under light load is as fast as the short charge time.

Conclusion: now isolated to the batteries.
----------------------------------------------------------------------------------------------------------------
For the sake of the education (and future avoidance) can anyone explain what battery condition causes a "too fast" charge time??? Even though the finished result looks ok.

Thanks in advance, best regards
D.

 

[DrkAngel]

Sulfation
See - ES Wiki Sealed Lead Acid (SLA)

 

[dogman dan]

Looks like your last season, before you stored them, was enough wear on them to do in a lot of your capacity. You had crystals forming, and over the winter they grew bigger.

Lead, even stored properly is aging, and the damn dendrites are growing between the plates. So your capacity is just not there now. You might consider trying one of the deslufinating devices for lead batteries. Some say they work, some say they don't. I think they can be somewhat effective, but once the sulfite crystals grow, they grow back fast. Such a device might work best to prevent the crystals from growing as fast in another set of batteries, rather than for fixing the batts you have now.

My advice, save up and go buy a pingbattery lifepo4. That should get you about 3-4 years use, weigh a lot less, and have much better ability to take a 100% discharge.

Lowest cost per mile of any battery I ever owned was a ping lifepo4. Worst was lead, next worst NiCad. I flogged the lead though, and could have done better.

 

[DrkAngel]

Sulfation
See - ES Wiki Sealed Lead Acid (SLA)

The Wiki article is my brief summation of my SLA learning.
If genuinely interested in learning, the Battery University article is an excellent tutorial.
See - BU Sealed Lead Acid
Also,
See the link to - BU Charging Lead Acid

 

[DRL]

Thanks everyone for the great info. It is much appreciated.

The closest match I have found to my issue is this....

"False" Capacity

A battery can meet the voltage tests for being at full charge, yet be much lower than it's original capacity. If plates are damaged, sulfated, or partially gone from long use, the battery may give the appearance of being fully charged, but in reality acts like a battery of much smaller size. This same thing can occur in gelled cells if they are overcharged and gaps or bubbles occur in the gel. What is left of the plates may be fully functional, but with only 20% of the plates left... Batteries usually go bad for other reasons before reaching this point, but it is something to be aware of if your batteries seem to test OK but lack capacity and go dead very quickly under load.

Although not chronic... I seem to be where the pack is operating at 50% for range and charging quickly as though the pack is 50% smaller than it is. Readings after charge are (deceptively) good.

Best regards,
D.

 

[DrkAngel]

Although not chronic... I seem to be where the pack is operating at 50% for range and charging quickly as though the pack is 50% smaller than it is. Readings after charge are (deceptively) good.

Best regards,
D.

Seems typical of sulfation.

Symptoms:
Charges fast
Empty fast
voltage sags deeply under throttle

Confirmation:
Voltage sags deeply under throttle ... to LVC ~41V, but rebounds to well above (empty) 46.8V when throttle released.
Charged voltage ~56V
Empty (static) voltage ~46.8V
Empty under load ~42V
LVC is typically ~41V

 

[dogman dan]

It's those damned sulfphite dendrites. They just keep a growing, even when you do all correctly.

Even though it weighs like, well lead, if it weren't for the dendrites you'd see a lot more lead users left.

 

[DRL]

It's those damned sulfphite dendrites. They just keep a growing, even when you do all correctly.

Even though it weighs like, well lead, if it weren't for the dendrites you'd see a lot more lead users left.

I know, the plumbum is the bottom of the pit of despair .

I got the bike 5 years ago after extensive surgery, chemo & rad treatments, I called it freedom 70 I am somewhat N of retirement age but not ready to succumb to a rascal yet. Anyway I must say for my mobility need, recreation and some peddling as I am able--I have enormously enjoyed my chino el-cheapo lead burning steed.

I did get 2 seasons of very active riding from the original 12V 12 ah 6-DZM-12's, often round tripping 23-30km and almost daily use through the riding season. I am fortunate to be located a few minutes from extensive paved bike paths along the shores of Lake Ontario.

If I had to rely on the electric bike for primary transport I would of course be shaving off my pension cheque to afford the litheePO4LiOnsuperWizzBang fuels... BUT!

4 X 12V 15ah at $180 pack price guarantees me a full season ride and perhaps, if the tail winds are right and the sulphate gods smile kindly, possibly 2 seasons. False economy, perhaps... BUT...

The marvelous thing about EV is the range and depth of options possible which can only encourage diverse participation as needs dictate. After learning from you guys about giving even lead a sporting chance I am determined to squeeze every ounce from my next 40lb of lead. I will water and feed them as though they were gold.

Now... if only the throttle didn't twist so easy--and my shaking hand didn't encourage as many snaps, pops and flashes when I am doing diagnostics... I would be golden
--------------------------------------------------
Final conclusion
Seems my #3/#4 year pack sulphated excessively through the riding season & winter storage due to an undercharging charger... something to be aware of going forward. Have new charger and next week new lead.... So here is hoping I recapture the year 1 and 2 performance.
--------------------------------------------------

Kindest regards to all who have helped....
D.

My Ebike Heaven - or short run on it.