Vax OnePwr battery. Jump from another battery

[Gary Marr]

We have a vax OnePwr system and currently have 3 batteries.
1 is fine however the other 2 will NOT charge.
I have googled this and read you can jump start the dead battery from a working battery so the charger recognises it to start charging.

My only issue is how to recognise the + and the - on the battery to hook them up to do this.
Have included a picture of the battery.
There are 5 prongs in total of which 3 are raised higher than the other 2.
Anybody any ideas of which if the positive and which is the negative?
Are these 2 lower prongs definitely the positive and negative?

 

[flameport]

Use a multimeter set to DC volts on the battery that is working.

 

[SUNRAY]

Use a multimeter set to DC volts on the battery that is working.

If only it we that simple.
I have some radio batteries with 6 contacts to the radio and 5 on the back for drop in charger, 3 appear to be +ve and 3 -ve However within the pack are 2 diodes, 2 thermisters and a resistor, some battery types have 2 resistors. the first time I looked the 7.2v battery had only a couple of volts and testing gave inconclusive results, the only thing I identified for certain was one of each sets of contacts tested zero ohms and appeared to be +ve but so did some of the others.

 

[robinbanks]

May be time to crack one of the duff ones open. I had a dyson battery go the same way - all the cells inside were showing 3.7v apart from one that was considerably lower. Replaced that one..

 

[Wayners]

I would not try jump starting if its a lithium ion..
That could go bang
Better to replace dead cells or just buy another..

 

[SUNRAY]

I would not try jump starting if its a lithium ion..
That could go bang
Better to replace dead cells or just buy another..

Unlike Nicad, LI cells are frequently run in parallel, why should it go bbang

 

[DetlefSchmitz]

It's important to limit Lithium charge and discharge current. This is usually done with dedicated circuitry in the cell package. However when we have 5 connections and don't know the circuitry, some caution is called for.

 

[ericmark]

Lead acid or even NiCad may try, but Lithium forget it, watched videos on recelling car batteries, sand bucket by his side in case one goes on fire, and all cells changed not just faulty ones.

I note Lidi batteries around £25 so not cheap, but when they go faulty that,s it.

 

[SUNRAY]

LI cells in battery pack is totally normal to to have sets of several cells in parallel (say 3) then several of those sets in series (say 4) and the pack will be described as a 4x3 for 14.4V at typically 7.5Ah ish. There may very well be charge control circuitry for every 3.7V parallel block but they are still cells in parallel.