Battery charger issue

GoldenMotor.com

biknut

Well-Known Member
Sep 28, 2010
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Dallas
I wonder if anyone else has noticed this. My charger is 87.6v 6 amp.

I used to always notice that when my battery was fully charged the CA showed exactly 87.6v right when I took it off the charger.

The charger has a cooling fan, and a LED light. When the battery reaches full charge, the LED lights up green, and the cooling fan turns off. The CA would show 87.6v.

Now it only shows 86.6v.

I checked the charger with a volt meter, and the meter also shows 86.6v, same as the CA.

Other then this 1 volt difference, I can't tell any difference in the way the bike runs.

After charging, if the bike sat for about a week the battery would always show about 85v, and that's still about the same as far as I can tell.

I just wonder why the voltage has changed?
 

cannonball2

Well-Known Member
Oct 28, 2010
3,682
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Colonial Coast USA.
My 48v charger puts out 59v under charge, however if read unloaded with a vmeter it only reads 56.6v. I have my Flukemeter in circuit so I can monitor voltage while charging. The voltage is always higher under charge than when removed. When my charger kicks off at 59v, the battery will actually read 58+v as soon as I remove it. Is it the charger, or is the battery capacity beginning to drop? What is the rated voltage of the pack?
 

biknut

Well-Known Member
Sep 28, 2010
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409
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Dallas
My 48v charger puts out 59v under charge, however if read unloaded with a vmeter it only reads 56.6v. I have my Flukemeter in circuit so I can monitor voltage while charging. The voltage is always higher under charge than when removed. When my charger kicks off at 59v, the battery will actually read 58+v as soon as I remove it. Is it the charger, or is the battery capacity beginning to drop? What is the rated voltage of the pack?
I suspect that most chargers work similar to what you describe. Unfortunately I never checked my charger output with a voltmeter before this issue started.

I can however see the charging voltage when it's charging on my CA, but of course the battery is loading it then.

My battery is rated at 72v. It has about 50 cycles on it.

Right now I'm just guessing, but I think it's a charger issue rather than a battery issue, because when charger shuts off, and the green light comes on, it only reads 86.6v on both the CA, or just on a voltmeter.

After sitting overnight my voltage has dropped to 86.2v.
 

paul

Well-Known Member
Dec 23, 2007
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Kalamazoo, MI
48v lifepo is charged to 58.4 volts and and it is very normal for them to drop a volt or 2 after charged. mine will show the 58.4 volts immediately after I take it off the charger but will drop a little soon after.
 

cannonball2

Well-Known Member
Oct 28, 2010
3,682
221
63
Colonial Coast USA.
Cant offer much input on the charger. Opened my 48v unit hoping to find an adjustable pot to up the voltage a few points. Guess thats a thing of the past, its all electronic. Read on the Stealth site that the charge cycle life span is 600cycles:confused:-true?

BTW crazy about the Bomber, considering considering one. I am also drawn to the Zero Stealth Fighter @ $9495.00 also(smaller battery version). Tag and insurance amount to basically nothing/year in Ga., so not concerned about that end. Its light, in the mid 200lbs, and quick, 0-60 in just over 4secs, top of 85. Small battery is only 35 mi in range but I rarely get close just running errands. Still theres something about the Bomber!!
 

biknut

Well-Known Member
Sep 28, 2010
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409
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Dallas
48v lifepo is charged to 58.4 volts and and it is very normal for them to drop a volt or 2 after charged. mine will show the 58.4 volts immediately after I take it off the charger but will drop a little soon after.
Yeah, that's what I'm talking about Paul. The 72v chargers charge to 87.6v. I always used to see 87.6 when the charger cycles off. By off I mean when to cooling fan turns off, and the green light comes on. When I take it off the charger the voltage slowly drops to about 86v in about a week.

Right now all I see is 86.6v when the charger shuts off. This doesn't seem like a big deal, because the battery voltage would fall to 86.6 pretty quickly on it's own anyway.

I just don't understand why it changed.
 
Last edited:

biknut

Well-Known Member
Sep 28, 2010
6,631
409
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Dallas
Cant offer much input on the charger. Opened my 48v unit hoping to find an adjustable pot to up the voltage a few points. Guess thats a thing of the past, its all electronic. Read on the Stealth site that the charge cycle life span is 600cycles:confused:-true?

BTW crazy about the Bomber, considering considering one. I am also drawn to the Zero Stealth Fighter @ $9495.00 also(smaller battery version). Tag and insurance amount to basically nothing/year in Ga., so not concerned about that end. Its light, in the mid 200lbs, and quick, 0-60 in just over 4secs, top of 85. Small battery is only 35 mi in range but I rarely get close just running errands. Still theres something about the Bomber!!
Right now I think a Bomber is the highest high. I thought about getting a Fighter, but now I'm glad I didn't, and there's no doubt about it.

A Fighter tops out at 35 mph. 35 is plenty fast, but if you're cruising at topped out speed, there's no acceleration available, and you're sucking all your battery power up fast. A Bomber is cruising at 35 with lots of acceleration available, but at the same time running well under max power. At that speed it's getting around 2.75 miles, per ah. That's a 50 mile range, going as fast as the fastest electric bicycles can even go. A Bomber is barely breathing hard.

So far the other electric bicycles I've ridden with, some supposedly fast, seemed so overpowered by the Bomber. I feel like a show off asse giving it too much throttle riding with them, riding it like I might normally ride it by myself. Sometimes you can't help it in traffic. I look back, and they're way back there. A Bomber flys like the wind in traffic. One look at the size of a Bombers motor gives any other ebike instant heartburn. It's like the Saturn 5 of hub motors. I don't think they're ever going to get much bigger than this, because it already weighs a ton.

I'll take a Bomber over a Zero too. There's not really any problem with a Zero, but it's not a bicycle, so it's not as free as a Bomber. A lot of versatility is good in the city. There're building a lot of nice bike paths, and I like being able to ride on them, and don't forget the sidewalks.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
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38
Ridin' inSane Diego, CA.
Since the battery is a 72 volt battery, 86 volts is just fine with the charger putting out prolly 90 volts easily with no load. I don't think there is a problem at all as the battery is now conditioned and will gradually deteriorate over it's life expectancy.

You have nothing to worry about as it sounds like you've been charging it properly and the batt should perform for it's life at optimal capacity.

Enjoy the silent ride and relax till it's time for a new power supply, which should be quite a while (2 years or so).

I suspect that most chargers work similar to what you describe. Unfortunately I never checked my charger output with a voltmeter before this issue started.

I can however see the charging voltage when it's charging on my CA, but of course the battery is loading it then.

My battery is rated at 72v. It has about 50 cycles on it.

Right now I'm just guessing, but I think it's a charger issue rather than a battery issue, because when charger shuts off, and the green light comes on, it only reads 86.6v on both the CA, or just on a voltmeter.

After sitting overnight my voltage has dropped to 86.2v.
 

biknut

Well-Known Member
Sep 28, 2010
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409
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Dallas
Thanks Scotto, I kind of felt that way. My bike doesn't seem to notice the difference. I'm just curious why it changed more than anything. A couple other Bomber owners reported their chargers losing a volt too, so mine isn't the only one.

I ordered a second charger as a back up. When it gets here we'll see what happens when I try it.
 

biknut

Well-Known Member
Sep 28, 2010
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Probably just normal. My 48v pack charged up slightly higher when brand new too.
Initially I assumed it must be the battery until I tested the charger and discovered it was only putting out 86.6v.

I'm thinking something changed in the charger.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
24
38
Ridin' inSane Diego, CA.
Thanks Scotto, I kind of felt that way. My bike doesn't seem to notice the difference. I'm just curious why it changed more than anything. A couple other Bomber owners reported their chargers losing a volt too, so mine isn't the only one.

I ordered a second charger as a back up. When it gets here we'll see what happens when I try it.
Be curious to see......keep us posted.
 

biknut

Well-Known Member
Sep 28, 2010
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409
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Dallas
One thing I find interesting is last week I ordered a new charger from a battery factory in China. I was in contact with a sales rep by email, and he wanted to know the specs of my bike. I informed him it has a 72v LiFePo4 battery. He told me they would recommend a 85.5v charger for my battery.

My charger is 87.6v

When I'm riding the bike the voltage quickly droops to about 78-79v, and stays there till the battery is almost empty. By then the voltage has dropped to 72v.
 

biknut

Well-Known Member
Sep 28, 2010
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Somebody snuck in and adjusted your charger when you weren't looking. Sneaky
Something definitely changed. I wish I knew what it means. Is my charger going to crap out? Will it change more?

All I know for sure is I can't tell any difference right now.
 

biknut

Well-Known Member
Sep 28, 2010
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I got my new charger, and I've used it twice. Now when the charger shuts off the battery's at exactly 87.6 v. That tells me the problem was the charger, not the battery. Not that this proves there's anything wrong with the stock charger, but it has lost 1 volt somewhere.
 

biknut

Well-Known Member
Sep 28, 2010
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Dallas
I'm pleased with my new charger. It seems equal to the stock charger, but about $100 less. Charge times are identical. I've noticed it usually shuts off at 87.4v, then trickle charges up to 87.6v, which takes about 1 minute more. You have to be right there when it shuts off or it will already be 87.6 by the time you look.
 

jonsson121

New Member
Apr 8, 2015
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Sweden
Well, thats not a big issue. It happens as I too experienced the same. As bike gets older, a bit deflection i voltage might occur.
 

biknut

Well-Known Member
Sep 28, 2010
6,631
409
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Dallas
Well, thats not a big issue. It happens as I too experienced the same. As bike gets older, a bit deflection i voltage might occur.
I've come to believe it's caused by resistance in the battery that builds up as the battery ages, but I could be wrong. The same thing happens to both my chargers.

What I've taken to doing is once the voltage drops below 87v, I adjust the charger output back up to about 87.3v