Help Needed to Repair a Drill Battery Pack

[clive2016]

Hi

Can anyone out there help me please.

I’ve got a Makita 1834 18v 2.6Ah Drill/Driver and the battery pack wont charge, not realising at the time I left the battery pack too long between charging’s as I’ve always used plug in tools before.
I found out about trying to jump start it but its still not working, anyway I thought I would have a go at trying to fix it, well its either that or bin it.

I’ve taken the plastic casing off the battery pack and can see 15 paper wrapped battery cells; size wise they measure 43mm high x 22.5mm diameter.
On testing each one with a multimeter 14 of them gave a reading of 1.37 volts, the 15th one gave no reading at all, so I assume it’s a dead cell.

I’ve been looking on the internet in the UK and have found paper wrapped cells 1.2 volts 3Ah but not 2.6Ah


Questions:

Will it be ok to replace the 2.6Ah dead cell with a 3Ah one??

ie. will the drill still work??

Will the battery pack still charge in the charger which is CH. P/N 630376B7

Makita DC1804F 7.2-18V, it came with the Drill/Driver??



My thanks to anyone who can help


Clive

 

[ljcox]

It is usual that you have the same cell as the others when you connect them in series. So it may not be successful. But if you can't find a 2.6 Ah cell, then you could risk it & try the 3Ah one.

 

[tvrgeek]

Better to take it to Batteries Plus.

Do NOT mix cells. Good way to get a fire. I doubt the charger would work correctly either.

 

[rjenkinsgb]

You may find you can "zap" the dead cell - eg. a very brief connection to a high current PSU or using a charged capacitor.
NiCd / NiMH cells can often be recovered from that state, unlike lithium - which would likely burst or catch fire with the same treatment...

If it works, charge that cell at 1/10C with a large cap still directly connected, until it has steadied at the correct full charge voltage, then drop the current to under 1/20C and leave it on trickle for a day or so. If it's still at the correct voltage, it should be fine.

Alternatively, make or buy an adapter to allow you to use a standard power tool 18/20V battery pack.
That's what I've done with some of my older tools that were OK other than the batteries; I've made adapters to take the 18V packs Aldi sell in the UK.
This is the 3D printed part of mine, with a converted Bosch NiCd body in the example - I've done the same with others.

You can also buy various ready made commercial ones on ebay and amazon.
eg.

Ecarke Battery Adapter Converter for Makita 18V Ni Cordless Power Tools Compatible with Makita 18V Lithium Battery BL1820 BL1830 BL1840 BL1850 BL1860. : Amazon.co.uk: DIY & Tools

Shop Ecarke Battery Adapter Converter for Makita 18V Ni Cordless Power Tools Compatible with Makita 18V Lithium Battery BL1820 BL1830 BL1840 BL1850 BL1860.. Free delivery on eligible orders of £20 or more.

www.amazon.co.uk

 

[Nigel Goodwin]

Replace ALL the batteries with 15 identical new batteries - don't ever replace just one, and certainly NEVER with a different make or type.

There should be no issues using 3A batteries in place of 2.6A (as long as all are identical and new), and the 3A rating may be fairly imaginary anyway.

One suggestion I would make is to measure the voltages on all the new batteries, and insure they are all pretty well at the same charge. We repair a LOT of battery packs, ordering batteries in hundreds, and often find some are more charged than others, and this leads to premature failure of the new pack. So check them all, and if they are different, then charge each one separately to make them the same.

 

[tvrgeek]

NiCads can also go into run-away and blow up.
Some have suggested freezing to recover them. Never worked for me.

 

[rjenkinsgb]

The short circuit is caused by needle crystals growing across the separator, which short the cell.

If they can be blown by a high current pulse, then the cell can be charged with a cap across it to disrupt the crystal if it reforms.

Once it reaches full charge, a low trickle charge causes the plate surfaces to be continuously reformed and any residual traces of the crystals are destroyed.

The critical part is getting them to full charge without excess continuous current - that's what could cause permanent damage or failure.

I've used that procedure on a good number of cells over many years, until I pretty much stopped using NiCd / NiMH cells, other than the occasional Eneloop type.

The only way I can see freezing having any effect is if the electrolyte grew ice crystals that disrupted the metal needle crystals?

However that, to me, would also likely cause damage to the separators and other internal structure.

 

[rherber1]

Replacing all cells will be very expensive. I go along with ljcox and suggest you replace the faulty cell. The difference in cell capacity for the new is small in practical terms and it will make no diffference to the charging. Make sure it is Ni-MH and not Ni-Cd.

While most OEM chargers work well I find some chargers don't really charge a battery pack to full capacity. If you have an adjustable bench power supply with current limit you can try this method. Set the voltage to 23V and the current limit to 1 - 1.3A. Connect the PSU to the battery and leave for a few hours. When the battery has charged fully the current will have dropped to an order of around 100mA or thereabouts. You can't harm the battery with this technique.

 

[Nigel Goodwin]

Replacing all cells will be very expensive. I go along with ljcox and suggest you replace the faulty cell. The difference in cell capacity for the new is small in practical terms and it will make no diffference to the charging. Make sure it is Ni-MH and not Ni-Cd.

REALLY bad idea, mixing batteries is fraught with problems, they will charge and discharge at completely different rates, and likely to destroy other batteries, and potentially explode or set on fire.

You also certainly DON'T want NiMh, particularly mixing one cell with the existing NiCd's - but even replacing them all, you should use NiCD, NiMh aren't suitable (too low a current capability) for cordless power tools which is why they were never used.

 

[rherber1]

Nigel,

I certainly agree that mixing battery types is a bad idea... that's why I said make sure it is Ni-MH.

If you look at the photo of the battery pack and you will see that it says Ni-MH.

Not that you mentioned it but as for the small difference in cell capacity, the 0.4Ah is insignificant for practical purposes.

I rest my case.

 

[Nigel Goodwin]

Nigel,

I certainly agree that mixing battery types is a bad idea... that's why I said make sure it is Ni-MH.

If you look at the photo of the battery pack and you will see that it says Ni-MH.

It says that on the plastic case, not on the batteries - which don't specify what type they are. As I said, NiMh don't tend to be used in power tools as they can't provide enough current - they have many advantages over NiCd, but current capability isn't one of them.

Not that you mentioned it but as for the small difference in cell capacity, the 0.4Wh is insignificant for practical purposes.

I rest my case.

You can rest whatever you like, it's a VERY, VERY bad idea to mix batteries, different ages, different types, different capacities - all extremely bad ideas. To make a satisfactory and safe battery pack you should replace all the batteries with identical ones.

 

[rherber1]

NiMh aren't suitable (too low a current capability) for cordless power tools which is why they were never used.

Wrong again... Ni-MH batteries perform extremely well in power tools. Whilst Ni-Cd cells preceded Ni-MH cells and are still used today there are many power tools which use Ni-MH - and have done so for some decades now.

https://batteryspecialists.com.au/collections/power-tool/products/makita-1420-14-4v-3000mah-ni-mh and a simple search will find out just how many there are.

 

[rherber1]

It says that on the plastic case, not on the batteries - which don't specify what type they are. As I said, NiMh don't tend to be used in power tools as they can't provide enough current - they have many advantages over NiCd, but current capability isn't one of them.

So you would disbelieve the manufacturer? The original cells certainly look to be the original ones and I am fairly certain this battery pack has not been rebuilt by the OP previously. So they are Ni-MH and not Ni-Cd cells.

And also see my later post which refutes your claim that Ni-MH were never used for power tools.

Postscript: https://www.datapowertools.co.uk/blog/batteries-for-drills-power-tools-nicd-vs-nimh-vs-li-ion/