Primecell

[Bear]

Bear

Without going thru a long story about my transaction w/Primecell , I was just wondering if anyone else has had trouble with them. I could not get them to reply to 3 e-mail messages or 1 phone call re the status of my batteries.
Is my experience an aberration or are they normally unreliable.

Thanks

Dennis

[gerty]

I used them about 3 years ago the rebuild a 12v battery for my Makita drill and didn't have a problem. And yes, the battery is still good..

[Bigglez]

Greetings (No Name Supplied),

I used them about 3 years ago the rebuild a 12v battery for my Makita drill and didn't have a problem. And yes, the battery is still good..

I have a couple of Makita tools with NiCad batteries.
(9.6V and 12V) and three different Makita chargers.

Some of these battery packs are approaching ten
years old, and certainly don't work "like new".

I'm thinking of rebuilding the packs, do you think
this is worthwhile? Did you do your own work?

I haven't cracked open any cells yet. I see some
have three contacts, while others have four. Any
idea why?

Thanks In Advance!

[gerty]

I just sent them the battery and they rebuilt it. The battery came back with fresh glue at the seams, they must use some sort of heating method to take them apart. I tried to take apart a 9.6 volt battery and broke the case. the battery had my initials engraved in it so I'm sure I got my original battery back.As far as the additional terminals, my only guess is some sort of feedback to the charger so that it doesn't overheat the battery while charging..

[Bigglez]

Greetings (No Name Supplied),

I just sent them the battery and they rebuilt it. The battery came back with fresh glue at the seams, they must use some sort of heating method to take them apart. I tried to take apart a 9.6 volt battery and broke the case. the battery had my initials engraved in it so I'm sure I got my original battery back.As far as the additional terminals, my only guess is some sort of feedback to the charger so that it doesn't overheat the battery while charging..

Thanks for the background. I'll sort out my worst
battery packs and send them in for a rebuild. I'm
leaning towards a capacity upgrade (fresh NiCads)
and not the more expensive upgrade to NiMH.

I've hestitated on this project as I'd like to buy
new power tools as these are showing their age.
(I'm a hobbyist with 10 - 15 years as a "weekend
warrior").

A local store has new battery packs but I suspect
they are NOS (New Old Stock) and not fresh.

One more thing, in my idle moments I've thought
about building a "rechargeable battery meter"
(or more accurately, "a meter for rechargeable
batteries"), to measure the remaining capacity.
Any thoughts on whether this is worth my time?
Does a commercial "meter" exist?

Comments Welcome!

[jwax]

If you look through some recent posts by "MrAl", you'll find he has designed and built just such a device!
It will allow you to monitor 4 channels to observe battery charge or discharge profiles and plot them.
I bought his parts kit, built it, and am very pleased!
John

[haklesup]

The key technology you will want when rebuilding a battery pack would be a spot (tack) welder. Attaching wires to the terminal buttons can't easily be done with solder. Obtaining replacement cells with a tab already welded to the ends eliminates that need but ups the price of the cells. Certainly can be done at home with proper care and planning.

[Bigglez]

Greetings John,

If you look through some recent posts by "MrAl", you'll find he has designed and built just such a device!

I spend ten minutes looking and haven't found it, can
you narrow my search? Do you know the thread title?
I've tried searching for "battery meter"...

Thanks In Advance!

[jwax]

Here's the original post-
http://forum.servomagazine.com/viewtopi ... sc&start=0
PM MrAl for more info.

[Lenp]

Dennis,

To put this back on track, I have used PrimeCell for years. They advertised in N&V years ago, when it was still in large format, as Cunard. ( I think) To date we have had about 8 different battery packs rebuilt and they all still perform without complaints. Two 18volt packs are over three years old and perform as well as the new OEM packs.

As far as communications, I think they do lack in that area. We requested a quote for a special battery and never got one, but, we shipped it using their price chart. It was done, at the published price, and still works well. Usual turn around time is 2 weeks plus shipping.

I don't think self-rebuilding is a bargain unless you can get the pack apart without destroying it, find a good price on the cells, weld the tabs (since sometimes there is no space for soldering or jumpers, and put it all back together again so it doesn't fall apart during use.

Hope this helps.

Len

[k7elp60]

I used to work in a independant electronic distributor that has a value added department. In that department they rebuild battery packs.
One reason that tabs are spot welded to ni-cad and nickle-metal hydride cells is that the soldering temperatures can damage the rubber seals on near the + terminal of the cells. Some battery packs have built in two terminal n/c thermostats that are in series with the cells. It's function is to cut of the current flow if the internal temperature reaches the temperature of the thermostate. This can occur either in the charging or the discharging mode.
Sealed battery cases with seams can be open generally with a edge of a putty knife on the seam and a sharp downward pressure on the handle of the putty knife with a mallet.
When I worked there the individual cells were usually glued together with super glue or in some cases hot glue. The super glue was also use to re glue the battery cases.
While I worked there I built several load banks for them. The load bank was used to discharge charged batteries at a constant current. My circuits were simply power transistors mounted on a heat sink. The emitter resistor had a low value resistor to ground and was used as a current sense. The base of the transistor was driven with an op amp with two inputs, on was the voltage from the current sense resistor and the other input was from a regulated voltage. The current could be adjusted with a pot. I have been using one of the designs at home for a number of years to discharge batteries in testing and to test and adjust current limits for DC power supplies.
I hope this information is useful.
Ned

[Bigglez]

Greetings Ned,

.....
I hope this information is useful.

Enjoyed your detailed post, thanks! As tempting as it
is (to rebuild the pack) I think I'll send one out to
Primecell and let them do it.

As for the battery monitor instrument, I'm thinking of a
similar design to yours for the current drain that
discharges the cells. By adding a DAC between the uC
and the linear constant current load, different loads can
be selected.

I'm going to use a voltmeter (the ADC of the uC)
to determine the initial (no load) voltage and to shut
off the load when the end voltage is reached.

Finally, use a coulomb counter to measure the
discharge energy, and calculate the battery capacity
within the uC.

All battery parameters would be stored in LUTs
(look Up Tables) in the uC so that the instrument
can be used with different battery chemistry and
number of cells in a pack.

Comments Welcome!

[MrAl]

Hi there,

I have rebuilt packs in the past too, and while i cant really recommend
soldering to NiCd's, i have done so in the past myself to rebuild a pack.
The idea is to use a very hot and high powered soldering iron, so
that the solder time is down to 1 second or less.

First you should 'tin' the lead to be soldered *and* the cell itself.
This means covering the end of the wire with solder before you solder
it to the cell, and for the cell this means quickly (one second or less)
heating one end of the cell with the high power iron and applying
a small puddle of solder, but be sure to take only one second or less.
After the cell is tinned like this, let it cool for about 5 minutes,
then holding the tinned wire in one hand and the iron in the other,
heat up the solder on the end of the wire, then move to the cell
and heat up the solder on the cell and place the wire end in the solder,
or else lay the end of the wire right on the cool pool of solder on the
cell and heat from the top of the wire end until all the solder remelts.
Remove the iron and let cool.
It's always a good idea to make sure you dont apply heat to the
cell for too long, regardless of which end you are soldering.

I used this technique to do my Ryobi drill pack and the pack has been
functioning for quite a while now. The drill came with two packs which
both died well within a year of purchase. I got fed up and decided
to rebuild by own pack and had to use soldering to do it.
I have also used this technique on smaller AA cells in the past.

It's also very important not to cover any air holes with solder when
soldering or welding the cells.

Another drawback to soldering the cells is that the manufacturer
will not replace defective cells if they have been soldered.

Another idea is to purchase cells with solder 'tabs' mounted on them
already. The tabs are welded on, and you can readily solder the
tabs to each other or to interconnecting wiring without voiding the
manufacturers guarantee.

OH yeah that's right, my Ryobi cells had tabs on them so it didnt
hurt the cells to solder to them, but the AA packs i have done in the
past still seemed to work for a long enough time even though they
were soldered and didnt have tabs.

[jwax]

Tip- Roughen the battery terminal with a file or sandpaper to prepare the surface for solder first. It will wet better/quicker/cooler that way.