48v battery only lasting about a mile

Danzkieman said:
Here she isView attachment 133569
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That's the very common silverfish battery. It comes in different lengths, but the common size should hold a max of 65 cells (I have an empty one here to look at), which would make anywhere from a 48V12.5AH to 48v17.5Ah, depending on what capacity cells they put in,
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Avoid the $200 versions that are all over ebay/amazon. They're probably no better than what you had. Generic grade B cells with a 2 year lifetime,.
 
harryS said:
That's the very common silverfish battery. It comes in different lengths, but the common size should hold a max of 65 cells (I have an empty one here to look at), which would make anywhere from a 48V12.5AH to 48v17.5Ah, depending on what capacity cells they put in,
.
Avoid the $200 versions that are all over ebay/amazon. They're probably no better than what you had. Generic grade B cells with a 2 year lifetime,.
Click to expand...
Appreciate the knowledge thank you sir 👍🏼
 
Danzkieman said:
Appreciate the knowledge thank you sir 👍🏼
Click to expand...
Did you see how to rebalance your battery?

Put your battery on your charger and even though it turns green and says full leave it in there for 10-12 hours.

The charger will keep checking the BMS and sending a small charge and over that time the smart BMS if it has one will rebalance the battery.

Now, I recommend you do that outside because it could potentially overcharge a battery with a bad BMS and overheat and start a fire.

If your battery is visibly damaged do not do this,

Then ride your ebike until you drain the battery to vey low and at least 20% and again recharge full and do that when ever you are riding.

Hope that works for you!
 
Last edited by a moderator:
Solarcabin said:
Even your expensive batteries will show that same effect with short charging cycles.

Watch the video and read the article so you understand ebike batteries instead of arguing please.
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nope they won't because your info is faulty, when you have great batteries with a complex BMS you don't worry. my batteries will never need balancing either plus they are UL listed too.
 
Danzkieman said:
So is it just toast?
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No. HarryS gave you great advice. Id do three monitored charges of 8-10 hours. !!!!!!!MONITORED!!!!!!!
The danger of discharging is taking it to low. And killing the batteries that maybe already low. However there are a percentage of budge batteries that will crapbiug and need pro repsir or replacement. Often rrpair can be more expensive than another budget battery or more. I ve been down this road with customers for 7 years of working support.
 
I had a silverfish battery act up just like yours a year ago. I'd charge it full, and it would be flat after six miles, down only about 2 volts,. Clearly an unbalanced battery.
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Took it apart. measured the cell voltages. Found the bad group.. Replaced it with new cells. Also replaced the BMS. Not an easy job and I had to spend $200 on spot welder gear to put it back together. It worked, but it was futile because a second group of cells failed a few months later, or maybe they were already failing and I just didn't know. Anyway, it really failed. It failed so bad that the BMS cut in and wouldn't allow a recharge. I could replace those cells too, but more would eventually fail. The pack was toast.
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FA030153.jpg

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Low cost cells with a service life just good enough to make it past warranty, Then after two years, they're at end of life and start failing. It's just economics. I paid $700 for the ebike. I got a $75 battery.
,
In 2015 I paid $550 for a battery with Samsung cells, and it's still working. You tend to get what you pay for.
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So I don't advise taking it apart to diagnose. It's not easy. It's risky because you got a live pack with lots of electrical energy that can melt wires and start a fire.
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There;s a very slim chance that a long charge will balance it, but your battery needs to have balance capability, which you don't often see in cheap batteries. And it would probably take days to balance, and it's not a good idea to leave a battery with possibly suspect cells on a charger long term. Either monitor it or do it in a place where you wouldn't mind a fire.
 
harryS said:
I had a silverfish battery act up just like yours a year ago. I'd charge it full, and it would be flat after six miles, down only about 2 volts,. Clearly an unbalanced battery.
.
Took it apart. measured the cell voltages. Found the bad group.. Replaced it with new cells. Also replaced the BMS. Not an easy job and I had to spend $200 on spot welder gear to put it back together. It worked, but it was futile because a second group of cells failed a few months later, or maybe they were already failing and I just didn't know. Anyway, it really failed. It failed so bad that the BMS cut in and wouldn't allow a recharge. I could replace those cells too, but more would eventually fail. The pack was toast.
.
View attachment 133613
.
Low cost cells with a service life just good enough to make it past warranty, Then after two years, they're at end of life and start failing. It's just economics. I paid $700 for the ebike. I got a $75 battery.
,
In 2015 I paid $550 for a battery with Samsung cells, and it's still working. You tend to get what you pay for.
.
So I don't advise taking it apart to diagnose. It's not easy. It's risky because you got a live pack with lots of electrical energy that can melt wires and start a fire.
.
There;s a very slim chance that a long charge will balance it, but your battery needs to have balance capability, which you don't often see in cheap batteries. And it would probably take days to balance, and it's not a good idea to leave a battery with possibly suspect cells on a charger long term. Either monitor it or do it in a place where you wouldn't mind a fire.
Click to expand...
I appreciate the information. Where did you buy your battery with the Samsung coils?
 
Those batteries I had were a different style, and also sold by a US vendor.

I'm not aware of a 48V Silverfish battery that uses premium cells, except for a UPP 17.5AH model with Sanyo cells that's like $680.

Some of you other guys have a lead to good battery makers? Someone that will put good cells in a Silverfish?
 
Yeah, herbert@dtbattery as long as they have the Silverfish case which as popular as it is they probably do. You could even get one with 21700 cells if you ask.
 
harryS said:
Those batteries I had were a different style, and also sold by a US vendor.

I'm not aware of a 48V Silverfish battery that uses premium cells, except for a UPP 17.5AH model with Sanyo cells that's like $680.

Some of you other guys have a lead to good battery makers? Someone that will put good cells in a Silverfish?
Click to expand...
Perhaps a shrink wrap pack sized to fit?
 
tomjasz said:
Perhaps a shrink wrap pack sized to fit?
Click to expand...
The cells in my Silverfish were in the plastic cell form shown a few posts above above. The dimensions are around 67 x 82 x 260 mm. I onlu had 50 cells in mine to make a 36V battery, Fylly populated, that form could hold a 5x13 array of 65 cells. The resulting capacity could be 48x12.5AH up to 48V17.5AH depending on the AH of the cells used.
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The inside dimensions of the white metal shell are 71 x 93 x 285 mm. This pic shows the original cells in a green shrink wrap.

W7210120.JPG


If you went to buy a shrinkwrapped pack, most of them quote 70 x 110 x 268, probably because they put the BMS on the top of the cells to make it 110 instead of 90. They usually have a fiberboard shell around the cells too.
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One could still buy one of them,. take it apart. move the BMS. and re-wrap it. However, most of the shrink wraps on ebay aren't any better than buying an inexpensive 48V silverfish,
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I’m not a UPP fan but if given specs and parameters Rechie can build a proper shrink wrap. Jenny Mao also. She’d be slower since her company focus is OEMs’ and bulk orders, but patience could result in a decent pack. I’m highly critical of UPP but I have a recent pack with a better BMS, pure nickel connectors and decent cell separation.
 
Maybe the bms is damaged, as it was with me after the battery got wet. It can be understood by connecting the charger and opening the battery and shunting the minus of the bms. If the battery starts charging, then the bms is damaged
 
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Danzkieman said:
Yeah that makes sense because I ride it to work and I only live about 1/2 mile away and top up when I get home. My battery doesn’t have a USB port. Is their another way to completely drain the battery?
Click to expand...
Depending on the BMS, a simple way to discharge is to buy a cheap 2 prong extension cord and cut the plug in half. The prongs will fit into your battery terminals.

P1080654b.jpg
P1080655b.jpg


Be careful NOT TO SHORT THEM! Turn the battery switch off first if you have one.

Wire the other end to a bulb socket like this one and use a low voltage LED bulb:

411wHbdsdcL._AC_.jpg
51tt0t-7kRL._AC_SL1200_.jpg


It takes time to discharge and hopefully, the BMS won't shut down with the low drain. Using multiple sockets or different bulbs can shorten discharge time if necessary.
 
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