Replacement Lithium Magnum batteries

Got my VB torch open, ive no idea if its the battery or LED, but i tried charging the battery straight from the charger and the load isnt holding. So im presuming the Battery is fried.

Which means i have to get a replacement battery or somehow find a way to test the LED!!!

The Battery is a BMZ (see picture) but they dont appear to respond to emails, so any suggestions on an alternative battery supplier / repairer here in Germany????

Neil

I don't see a picture. There are two ways to post one, and both require that you have a link to the picture on some other hosting site.

If you paste the link directly into your post, the link will appear and people can click on it to see the picture.

If you click the 'insert image' button, you can paste your link in the dialog box that appears and the picture will appear in the thread without people having to click the link. If you do this, remember that forum rules require the picture to be no more than 800x800 pixels. Also, if your hosting site is dropbox, you have to edit the URL they give you. If you need help with this, I'll look it up (I can never remember exactly what to do).

In diagnosing something like this, it's really helpful to have a multimeter. Even a super cheap one from the bargain store (do you have those in Germany?) would do. I'm thinking something like this: https://www.harborfreight.com/7-function-digital-multimeter-63759.html

There are other possible failure points than the battery or the LED. There are switches, charger, connectors, battery protection circuit, LED driver, to name some of the most obvious. Granted the most likely is the battery, but with a meter and access to the battery terminals, you could tell for sure in a jiffy, and might also help in finding other problems if it's not the battery

let me try this.


And yep, tried a multimeter, tried sending a charge through, and there is nothing. The connection points record that their is a charge, but the batteries are just not holding it.

[/URL][/IMG]

BBcode, not html

you got it.

Yeah, most likely the cells are dead. In fact, if they are dead and have been sitting a while, they are more dangerous if charged. Please be careful.

Is there a circuit board connected to the pack? If so it's possible that the board is bad. If that discharged the cells and they sat a while that way, the cells are dead and dangerous if charged.

nothing attached to the batteries, just two cables which go up to the head!!! so okay, what i think i hear you saying is the torch is then dead dead... unfixeable.

I also got an email from BMZ, the battery manufacturer, whom advised they no longer make these batteries..

Any suggestions other than use this as a paperweight??

I wouldn't say unfixable. If it was mine, and it was just the batteries, I would definitely figure a way to make it work again.

But they look like unprotected cells, and they are in a pack, in a closed container, charged with no balancing. That sounds like a hand grenade. The general rule is that if charging two or more LiIon Cells in series, there must be balancing or cell-by-cell protection. I'd consider rebuilding the pack with a protection or protection/balancing board included.

Can you give us a better pic of the writing on the cells, or just post what it says? I wonder if we're missing something.

In the US we can buy cells with tabs already attached. Soldering to the tabs or soldering them together is both safe and much easier than soldering directly to cells. We also have batteryspace.com that makes custom packs. Is either of those options available to you?

I've also been thinking strongly about building a battery tab welder. The only thing that's stopped me so far is that I don't have much call to build battery packs. It's not really that hard to make a passable spot welder.

As a last resort you could buy an off-the-shelf pack of the same voltage but maybe lower capacity that would fit in the canister.

neil_richardson said:

let me try this.

And yep, tried a multimeter, tried sending a charge through, and there is nothing. The connection points record that their is a charge, but the batteries are just not holding it.

[/URL][/IMG]

Click to expand...

From the image and what can be read from the label, the battery has 6 parallel sets of 3 series cells, total 18; 103.6 watt-hours which at 10.8v (3.6v per cell compared to usualy 3.7v) works out to 1600mAh per cell. This is fairly low cell capacity. If the pack were to be rebuilt, number of parallel sets could be reduced; but does not eliminate the need for proper cell management. Using 2600mAh in place of 1600mAh reduces to 4 parallel sets; 12 cells v. 18. Just before COVID struck I saw a neat live demo from a guy who made his own tab welder using a car jump-start pack which contained a (guess what...) Li-ion battery. I didn't get much detail and I don't know the guy well nor how to get ahold of him easily. I am guessing it delivers a very high current accurately-timed pulse to its output. This may be worth considering. Dave

There are many DIY tab welder videos on youtube. Some use microwave oven transformers, car batteries, capacitor banks, etc.

Only what you need is amount same voltage and bigger battery capacity . Measure your battery tank and buy batteries .
I have made 2 packs for 160€ BMS included , 13.8V@18Ah

https://www.ebay.de/itm/363038381927 LiFePO4 pack 25

https://www.ebay.de/itm/4S-BMS-Li-ion-LiFePo4-30A-3-2V-3-6V-Board-18650-Balance-PCB-Battery-Protection/254099203219 BMS 4S/ 30A

hot stacking 25€ per pack ( Ni strips , plastic heatfoil , connectors included XT60(60A/12awg/4mm2))

Can do that by myself , but it is important to have here some skills not to destroy packs and I would made them bigger for sure and I dont want that !