So confused, please help (24s 99.6V battery charging/safety)

Batteries, Chargers, and Battery Management Systems.
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alec
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So confused, please help (24s 99.6V battery charging/safety)

Post by alec » Dec 05, 2017 7:58 pm

Hey everybody,

I currently have an ebike with two battery packs running in series. One 16S and another 8S, for a total of 24S. The cells are 4.15V EIG 20Ah. There is no BMS installed on these packs. Every four cells has a 4-pin JST connector for balancing purposes.

Previous owner of the bike would bulk charge with 2x Meanwell 50V supplies in series and then discharge balance with Battery Medic devices.

My question is – leaving these Meanwell series charging unattended will obviously overcharge the cells, correct?

What's the best way to safely charge these packs? Get a 24S BMS and reroute all the balance wires? Somehow find a 24S balance charger?!

Let me know, thanks!
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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by 999zip999 » Dec 05, 2017 8:12 pm

It all depends on the quality of the cells and how hard he has used them in the past . Check all cells to see if the are balanced and if they stay in balance you're fine. Are these 20 ah cells ? What controller and motor are you going to use them with. ? They are good quality cells when new it all depends how they've been used.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by Sunder » Dec 05, 2017 9:47 pm

The overcharge would be negligible. I wouldn't leave it there for weeks, but you shouldn't leave any lithium battery protected or not, on a charger for more than the time it takes to charge it.

You'll get a lot of opinions on best way to manage a battery. A lot of the more experienced members believe there's no substitute for a human BMS. I tend to agree. However, for set and forget, a high quality 24S programmable BMS would be best. Set it to balance and cut charge at 4.10v or even 4.0 volt if you can afford the loss of range, and the battery will last a lot longer.
eBike: Q100H on 16S with Phaserunner FOC Controller
eMotorscooter: Vectrix VX-1 on 36S
eCar: Mitsubishi Outlander PHEV... Waiting for warranty to expire
eHouse: Still on grid, but with LTO batteries and 3kw LF inverter...

After 5 builds, the best advice I can give, is start with high quality products. I prefer http://www.ebikes.ca

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by amberwolf » Dec 06, 2017 3:01 am

On SB Cruiser, I bulk charge the same kind of cells with meanwell HLG's, adjusted so their final voltage is the same as the pack's desired final voltage (different chargers at 4.14v/cell for completely full max range, 4.1v/cell for normal, 4.0v/cell for longer life, etc...but mostly I just use the one I built onto the trike that's set to full final voltage because it's convenient; I rarely use the full range of the pack (40+ miles--I'm using it mostly to support the current the trike pulls at startup). It's a 14s2p pack, no BMS.

On CrazyBike2 I have a 14s1p pack of the same cells, no BMS, and it's been bulk charged to full voltage for the few years I've used it, with only one cell that's ever had a problem in it, and the pack still provides full capacity (since replacing the cell that sagged more at the low-end of the capacity range).

All the cells I have were already well-used before I got them. I just check them for balance every so often, both at the nearly-discharged state and at full, and during recharge, and so far no problems other than the one aged and well-used cell (which is still in use at lower-discharge-rate in my lighting pack, where it still gives full capacity).


I probably wouldn't go without a BMS on most of the other cell types I've seen and used, but I'm comfortable with the EIG cells not having one.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by fechter » Dec 06, 2017 9:43 am

As long as the voltage on the Meanwells is set right and the cells are balanced, nothing will get over charged. If a cell goes out of balance, that's where things could get dangerous. If you run a charge cycle then measure all the individual cell voltages, you can get a good idea for how close the balance is.

There aren't too many 24s BMSs out there, but they do exist. This would probably be the most "idiot resistant" solution.
"One test is worth a thousand opinions"

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by alec » Dec 06, 2017 11:50 am

Thanks for all your answers, everyone. Very appreciative of this forum and all of you.

I've decided to be a human BMS instead of going the 24S BMS route. The existing BMS's that would fit my application just seem so dodgy.
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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by 999zip999 » Dec 06, 2017 2:40 pm

I would put four 6s sense wires for EZ hookup of cell meters or a 6s thru the sense wire charger like a bc168 or ? Get used to checking with the cell monitors and not using more than 15 16 amp your hours as you'll find out in time. Are they 20ah cells ?
What controller and motor combo will be using these cells at as Im. Looking into getting some . Please let me know how they work out.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by alec » Dec 06, 2017 4:27 pm

999zip999 wrote:
Dec 06, 2017 2:40 pm
I would put four 6s sense wires for EZ hookup of cell meters or a 6s thru the sense wire charger like a bc168 or ? Get used to checking with the cell monitors and not using more than 15 16 amp your hours as you'll find out in time. Are they 20ah cells ?
What controller and motor combo will be using these cells at as Im. Looking into getting some . Please let me know how they work out.
I'm using a V3 Cromotor and a Greentime 1440 controller right now. About to wire up the MQCON SSC096080 if I can find the darn software for it...
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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by 999zip999 » Dec 07, 2017 3:12 pm

I would like to know how those cells handle that motor and controller and at what amps

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by rojitor » Dec 08, 2017 4:51 am

You can also charge/balance with rc chargers. Very easy and safe.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by flippy » Dec 08, 2017 8:43 am

999zip999 wrote:
Dec 07, 2017 3:12 pm
I would like to know how those cells handle that motor and controller and at what amps
they can do about 100A.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by alec » Dec 08, 2017 10:26 am

rojitor wrote:
Dec 08, 2017 4:51 am
You can also charge/balance with rc chargers. Very easy and safe.
I thought about that, but the way the 24s pack is set up, I’d have to plug the entire 24 cells into the RC charger since many (or all of them?) require the +/- of the pack plus the balance JST. Wouldn’t I blow most chargers up by doing that?
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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by 999zip999 » Dec 08, 2017 12:04 pm

I have a UNA9 for 6s plus 3s. But they have a charge nanny to only be gotten at time of purchase . It can do 8 times 6s for balancing.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by amberwolf » Dec 08, 2017 2:20 pm

alec wrote:
Dec 08, 2017 10:26 am
I thought about that, but the way the 24s pack is set up, I’d have to plug the entire 24 cells into the RC charger since many (or all of them?) require the +/- of the pack plus the balance JST. Wouldn’t I blow most chargers up by doing that?
Don't plug the whole pack in.

Make individual +/- leads with the balance leads that charge only those groups of cells (6 at a time for most RC chargers).

The + of one section will be the same as the - of the next more positive section.

There's lots of batteries charged this way, so there's diagrams and descriptions around the forum.

Or just think of it like RC packs--you can series a bunch of packs, and each one has individual +/- leads plus balance leads. Your pack is exactly the same, except it's "leads" are busbars, so you just have to add external leads at the appropriate busbar screws.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by 999zip999 » Dec 08, 2017 3:15 pm

You can Bluk charge and monitor through the four S's and get the charge nanny or you can put up to eight 6s or eight four 4's to it at one time just to balance this is just for balancing thru the sense wires but I'd only go like 3 amps or so.
Ok reread is a 16s and 8s so 6 - 4s sense wires.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by fechter » Dec 08, 2017 8:13 pm

Just remember that if you charge with more than one RC charger at the same time, they each need their own isolated power supply. You can't run more than one off a single supply or you will have a short (smoke, etc.).
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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by dogman dan » Dec 09, 2017 7:31 am

My two cents.

Nothing really wrong with the existing charging methods, provided the meanwells are set to the right voltage. (not overcharging) You might consider tuning them to very slightly undercharge the pack, if your needs don't require the entire capacity very often.

Using those 4s balance plugs, you can easily balance when you need to, using a very cheap RC 6s charger, or a discharging balancing device. An adapter can be made that plugs into the 4s plug, giving you another 5 pin 4s plug, and additional + and - wires to plug into an RC charger. Set charger to 2 amps, and the tiny wire can handle that fine. If you undercharged a tiny bit, the charger only needs a trickle to finish off and balance, so no need for big fat wires every 4 cells. You'd likely not need to balance all that often, doing it only when your pack has cells more than .05v off from each other.

Check your cells fairly often using a cellog 8, using those balance plugs. That's the human bms part.

If you decide to bms,, well, nothing whatsoever wrong with continuing the manual checks. Just wire it so you still have those plugs to check with a cellog.

When you are going to discharge 100%, figure out which cell is the lowest capacity by checking voltage when they are close to empty, like 10% or less left. ( like about 3.55v)Then put a cheap low voltage alarm on the plug that has that cell in it. Stop when the alarm goes off, and won't stop when you slow, or stop. You only need one on the worst cell. it will be the one that tells you when to stop, the others will still have some juice in them.

Use this alarm only when you need it, when the pack is nearly empty, leaving them in place all the time just makes their draw unbalance the pack. The alarm is just for limp home. Watching voltage of the whole pack will tell you when to start for home before you reach that limp home point.

As for safety, well, a "safe" battery with bms burned my house. Garage destroyed, house all smoked. It was a 9 month nightmare getting it all repaired.

So my shit, its never coming inside again, ever. The old kitchen stove that got ruined in the fire is now my battery storage place, in the back yard.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by alec » Dec 09, 2017 11:11 am

dogman dan wrote:
Dec 09, 2017 7:31 am
My two cents.

Nothing really wrong with the existing charging methods, provided the meanwells are set to the right voltage. (not overcharging) You might consider tuning them to very slightly undercharge the pack, if your needs don't require the entire capacity very often.

Using those 4s balance plugs, you can easily balance when you need to, using a very cheap RC 6s charger, or a discharging balancing device. An adapter can be made that plugs into the 4s plug, giving you another 5 pin 4s plug, and additional + and - wires to plug into an RC charger. Set charger to 2 amps, and the tiny wire can handle that fine. If you undercharged a tiny bit, the charger only needs a trickle to finish off and balance, so no need for big fat wires every 4 cells. You'd likely not need to balance all that often, doing it only when your pack has cells more than .05v off from each other.

Check your cells fairly often using a cellog 8, using those balance plugs. That's the human bms part.

If you decide to bms,, well, nothing whatsoever wrong with continuing the manual checks. Just wire it so you still have those plugs to check with a cellog.

When you are going to discharge 100%, figure out which cell is the lowest capacity by checking voltage when they are close to empty, like 10% or less left. ( like about 3.55v)Then put a cheap low voltage alarm on the plug that has that cell in it. Stop when the alarm goes off, and won't stop when you slow, or stop. You only need one on the worst cell. it will be the one that tells you when to stop, the others will still have some juice in them.

Use this alarm only when you need it, when the pack is nearly empty, leaving them in place all the time just makes their draw unbalance the pack. The alarm is just for limp home. Watching voltage of the whole pack will tell you when to start for home before you reach that limp home point.

As for safety, well, a "safe" battery with bms burned my house. Garage destroyed, house all smoked. It was a 9 month nightmare getting it all repaired.

So my shit, its never coming inside again, ever. The old kitchen stove that got ruined in the fire is now my battery storage place, in the back yard.
Wonderful advice, with first hand safety experience to boot. I believe I saw your disaster thread. What a nightmare; I’m very sorry that happened to you, but must admit – the kitchen stove comment made me chuckle. It’s almost like you’re operating a bomb squad’s safe detonation. Remind me to get renter’s insurance...
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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by 999zip999 » Dec 09, 2017 1:13 pm

UNA9 Plus+ Intelligent Parallel Charger Set With Charging Nanny Protection

$116.22 $149.00
Check it out. It's interesting
I bulk charge for 1,082 times and have balanced them 8 times over 4.5years. High quality cells make it ez. Yes I slightly under charge.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by dogman dan » Dec 10, 2017 7:36 am

Just happen to have a spare, unusable, kitchen stove around now.

Makes a good weatherproof, rat proof box is all. Perfect outdoor storage. Easier to use an old barbeque grill for most. Glass top, so the surface makes a good non conductive table top.

For a colder climate, use old tiny fridge, or ice chest to keep the cells unfrozen.

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Re: So confused, please help (24s 99.6V battery charging/safety)

Post by 999zip999 » Dec 10, 2017 2:18 pm

I'm interested in how the buss bar is. As didn't these come from a zero and there buss bar and packs are set up as 2p. Did he make new buss bars for 1p ? I heard eig is very safe ? Still NMC.

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