cordless batteries

[p0689109]

I have a Rolson 18v cordless angle grinder. It came with two batteries. It is useless. No torque and if you try to cut say a 8mm bolt a fully charged battery might just about do it! Not much good, but its bought now. Anyway, I went to use it the other day and both batteries were charged . When I went to recharge one of them the battery/charger made a bang, like a fuse blowing, and the battery did not charge. The light stayed green. I tried the other battery to make sure the charger was not the problem. That worked OK. I decided to take the top off the casing (4 screws) to have a look. There was no signs of any distress, (burning or the like). Remembering this was only the second time of using this so it was brand new so unlikely to have worn out the only thing I can think of is the unit fitted on the battery pack connected to the terminal that is not in the feed cables. It is the rectangular cylinder wired to the third terminal in the photos. Does anybody know what this is? Methinks a capacitor but I am not an electrician. It looks replaceable. Just one lead soldered onto the terminal. It is marked with JRMD45.
Other batteries like this I have broken down to scrap did not have anything like this from what I can remember. Why this one? Is it to do with the charger perhaps being multi purpose?
Any comments/knowledge would be most welcome.
Cheers, Michael T

 

[shenion]

It will be a fuse or thermal breaker.

 

[ben8vgte]

Might be a temperature sensor, my Milwaukee packs have one in. Stops them from being charged when they are too hot or cold, infact mine will puts a small charge into them to warm them up before a full charge if they are cold.

 

[p0689109]

The battery had not been used and it popped immediately on switching the charger to charge, My charger for this is the type that when you plug it in and switch the mains on the green light is on. To charge the battery you fit the battery and then press this green light at which time the red light comes on and the battery should start charging. When fully charged the green light then comes on which I assume disconnects the charging circuit. In my case then the battery was stone cold out of the box so temperature was not the trigger. So it looks like this sensor is faulty. Would Maplins supply it?
Cheers, Michael T

Might be a temperature sensor, my Milwaukee packs have one in. Stops them from being charged when they are too hot or cold, infact mine will puts a small charge into them to warm them up before a full charge if they are cold.

 

[matt1978]

If its almost brand new can't you get an exchange?

 

[h3rman]

If its almost brand new can't you get an exchange?

This ^^^^

I wouldn't have opened it just to fix a faulty component. Either get it replaced or replace all the cells with good quality items which will hold charge longer as well as replacing the part in question. That way you migh get decent use out of the tool.

 

[BrokenBiker]

if its new, get repair, replace or refund...simple as that

 

[Hitch]

If its that rubbish, get a refund if possible...

and invest the money in a few decent hacksaw blades

 

[FranV8]

I think it's likely it's a thermal sensor, they're actually a really good control mechanism for charging.

You used to get two(apartfrom timed) fast cchargers for the electric radio controlled cars, that used 6 cell sub C packs (same cells most cordless nicad and nimh stuff has), Peak and thermal.

Peak measured the voltage of the pack while it was being charged, and shut the charger off once the voltage dropped a predetermined amount after the peak.

Thermal used a thermistor, attached to the charger, that you poked into the battery pack As it's name suggests, it turned the charger off when a predetermined temperature was reached.

I think all the cordless stuff I've had or seen seems to use the thermal method. Normally the clue is a third terminal on the pack.

 

[ford34/2]

Battery capacity

I think you will find the Amp Hr rating of the cells to be very low, maybe 1.3Amp Hr, descent stuff is now over 3.0 Amp Hr, the Rolson package, Grinder, charger 2 batteries, case and freebies might have cost £60, says it all really,
The configuration of the battery pack is similar, if not identical to Hilti/Dewalt and the wee blurred image is sure to be a heat sensitive cut out, I`m not convinced this made the charger go bang??
Rolson like everyone else has at least a 12 month Guarantee, get it exchanged or refunded. But before you claim on the guarantee, do run the other battery flat and recharge a few times, so you are sure those two items are still ok.
1.3Amp Hr batteries were on 9.6V tools about 15/20 years ago. And I`m sure the quality of the cells used in the battery pack will be very poor .
Stan

 

[p0689109]

ford34/2 is spot on. I forget where I got it, probably ebay. Rolson don't do it now and don't do any spares back up according to a feedback I read on Amazon! The little blurred item also has another connection casing to casing of the first battery in the link hence the paper removal on that cell compared to the other.
As to getting a replacement, apart from finding one the cost would outweigh the tool! The other battery and charger work ok having flattened the battery and recharged it already. I popped into Maplins but they did not have a clue. They had never seen anything like it. Oh well, it looks like I will have to save up for a Hitachi G18DSL which PPC gave a great report on. They reckon just as good as a mains one. Mind you £298.70 makes the eyes water!!
Cheers, Michael T

 

[ford34/2]

new cells

you can Buy new cells off E bay, pays your money takes your pic, I have rebuilt many Dewalt and Hilti packs, --BUT is the Cut out thingy working??
Cells are easily soldered together using the original links if you prise them off carefully, take a few pics and draw a sketch of the layout. There are s/h batteries on the bay they will have the cut outs in them, I may have hilti ones, but I always put the originals back in.

Stan

 

[p0689109]

Its the cut out thingy that is the problem. The cells are 1 charge off brand new, as is the other battery it came with.

 

[mike 109444]

The "cut out" is found in many devices inc motor over heat cut outs and even in the windings of my mig welder transformer. If you meter it, it should show as a dead short. then heat with a cig lighter and you may hear it click as it goes open as seen on your meter. Then as it cools it should cut back in.
I recon you have one or more dead short cells in the pack. If you meter each cell you should see 0.5 to 1.3 VDC (lower voltage if run down) then you may find one cell showing 0.00 VDC. It is possible to "jump start" a dud cell but is risky. See UTube

 

[Lawnmowerboy]

You can jump start the cell using a car battery. All I'm saying...

The cells are probably of very poor quality. Internal shorts pulling the battery down over time. Possibly resistive connections and resistance inside the cell.

Search sub C Ni-MH cell on E-bay and there's loads to choose from. come up to 5000mAh

 

[Wallace]

Ni-Mh need a different charger to Ni-Cad so not a simple straight swap. I looked into replacing all the batteries in my cordless tools with good quality Ni-Cads and the cost was way above replacing the batteries. What surprised me was replacing the Ni-Cads with Ni-Mh cells and buying the correct charger worked out slightly cheaper than buying factory Ni-Mh but not much.

 

[Flapdisk]

Batteries for power tools are the same kind of scam and rip off as printer cartridges, the profit on those batteries is phenomenal

 

[T0rnado69]

you could get it recelled...

http://www.recellyourbattery.com/

 

[Wallace]

Batteries for power tools are the same kind of scam and rip off as printer cartridges, the profit on those batteries is phenomenal

Not sure the comparison is quite the same but i understand what you mean. A cartridge contains a quantity of ink that will produce a certain amount of pages dependent on the printer settings and the quantity of content on a sheet of paper so it has a finite life. Print a lower case "a" on a sheet of A4 paper and see how long the cartridge last then turn the pages over, replace the cartrdge and print an upper case bold "A", which one will get the most pages?

A rechargeable battery can have a hard or easy life supplying power for the tool performing the occasional cut or drilled hole to multiple holes and aggressive cutting on a daily basis then be left for weeks without being used. The same tool used daily may perform longer in comparison.

Ni-Cads have been around years so you would expect the resale value to now be minimal due to the sheer numbers produced, I spent a lot of time looking for 96 C cells to sort my cordless batteries out and I couldn't beat the manufacturer price for a new batteries. Ni-Mh was the only way I could make a saving on some as the correct charger was available.

you could get it recelled...

http://www.recellyourbattery.com/

I'll look into their prices and see how they compare. Thanks.

Mike

 

[p0689109]

As this appears to be a thermistor(a resistor whose resistance varies with temperature) would it be feasible to put a low value resistor of say 47ohms in its place to "fool" the charger that all is well and allow the batteries to be charged?
I will check each cell later on today to see if any have gone dead, as suggested by an earlier post, before going any further.
Cheers all for your inputs.
Michael T