Surefire B90 test results

[ToddM]

First 2 week test of the surefire -vs- custom radio shack nicad 2000mah packs is in, and well it's not pretty for the surefire packs.

Basically I charged 4 packs, 2 made from a 2000mah radioshack RC car battery and two new B90's that came with my 9AN. All 4 were new, and put though 3 charge/discharge cycles before the test. They are of the lot #CK43 that is not supposed to have any problems. I then took voltage measurements at 15 min off the charger, then at one week and then at two weeks with no load.

Then I put them on load for 5 minutes making measurements of voltage starting and finishing.

The load was a maglite 3 cell bulb kyrpton star bulb. Not nearly the load as a surefire but it did the job.

Then I put them on load for 20 minutes making the same measurements. Tests were stopped if the pack went below 1 volt per cell (3 volts) in order to keep from damaging the battery.

Here are the results of the 4 batteries I tested at 2 weeks of sitting around. They sat around in my basement which is pretty consistantly 70 deg.

# 1 & 2 are surefire B90's
# 5 & 6 are radio shack custom packs

Initial voltage (no load) taken 15min after being taken off charger)

1) 4.22
2) 4.23
5) 4.20
6) 4.20

Voltage after one week (no load)

1) 3.82
2) 3.78
5) 3.89
6) 3.88

Voltage after 2 weeks (no load)

1) 3.59
2) 3.73
5) 3.84
6) 3.82

2 Week runtime voltage testing


#1 (surefire)
Starting: 3.30 volts
5 min: 1.5 minutes in dropped below 3 volts stopped test. Bad pack, one cell failed.

#2 (surefire)
Starting: 3.59 volts
5 Min: 3.51 volts

#5 (RS pack)
Starting: 3.64 volts
5 min: 3.59 volts

#6 (RS Pack)
Starting: 3.63 volts
5 Min: 3.57 volts

20 minute runtime test

#1(surefire)
unable to run due to pack failure

#2(surefire)
Starting: 3.57 volts
20 Min: 3.43 volts

#5(RS pack)
Starting: 3.59 volts
20 Min: 3.55 volts

#6 (RS Pack)
Starting: 3.61 volts
20 Min: 3.56 volts

The one surefire pack did very badly. In fact I put it back on the charger and in like 15 minutes it had a green light and only the last cell in the pack was VERY hot. This leads me to believe that the last cell in the pack is defective in some way. Loosing it's charge much sooner than the others. This would explain why it fully charged the pack so quickly it only had to really charge the one cell. The voltage when taken off the charger was similar to starting no load voltage.

Neither surefire pack compared to the RS, even the pack that seems "good" lost twice the voltage over the 20 min load test than either RS pack. Granted the RS packs have a slight advantage in capacity.

I can certainly see how a surefire pack would not be reliable to have in storeage more than a few days or a week with this data. Along with as many bad b90's get reported. I'll be getting a couple more RS packs and converting them for use in surefires. I've had 6 of these RS converted batteries for 3-4 years now and never had one go bad.

I'll have to contact surefire about replacing the first pack that has a bad cell in it. From now on I'll be using custom packs only.

Todd

 

[Tombeis]

ToddM:

I am having the same trouble with B90 batteries which Surefire replaced. The lot number is also CK43.

What did you have to do to the RS batteries to convert them to run in the Surefire flashlight?

Will they recharge in a Surefire charger?

I am also thinking about having some batteries made from 2400mah. Nicad sub C cells.

 

[ToddM]

Yep, surefire replaced my bad B90 with two new B90's also from the CK43 lot and it looks like at least one of them is bad as well.

It's good customer service on the one hand cause surefire is so good about replacing/making things right.

On the other hand there have been so many problems with the B90 batteries that I cannot believe surefire has not pulled the entire lot of them and held production until reliable batteries are made. I would go so far as to suggest a recall. The one battery I had fail got SO hot in the charger it melted the blue shrink wrap off. That's a fire hazard, and far from the first report I've read of it.

I personally will not rely on their batteries. I will either gut RC car packs or have custom packs made I can rely on.

Here's what you do to the RS batteries to use them in your surefire (9N/9AN only, the 8series is much harder).

The 2000mah RC car pack from RS is about $25. You cut the connector off and cut the shrink wrap off. You will see two 3 cell cardboard tubes that are connected at the bottom by a strip of metal soldered across. Basically you remove the wires, remove the peice of metal bridging the bottom of the battery. Then you have two battery packs the same size as the B90.

At that time I will take and scuff up the positive terminal, put a little flux on it, and put a drop of solder on it to use as the raised terminal (since the cells are flattop they won't contact the lamp right without the raised contact). I've heard of a 9 volt connector being used as well but the solder blob works fine for me. I also like to remove the cardboard tube and use a 1" heat shrink tubing it's just more secure and doesn't slide around.

That's about all there is to it. Takes a few minutes and are much more reliable than surefire's B90s, and slightly larger capacity.

The stock surefire rapid/smart chargers will charge them just fine. They will also charge the 2400mah packs as well but that is about the limit of their charging. Due to a shut off safety timer the max capacity that could be properly charged is around 2500mah.
If you have a older timed overnight charger it may not fully charge the larger batteries if they are put in near dead.

Why surefire isn't using 2400mah sanyo cells I cannot think of why aside they are getting those 1800mah cells really really cheap. They sure aren't getting any quality control from whoever is making them.

Todd

 

[pdobard]

I see this is an old post, but maybe someone is linked who posted the original thread. Purchased an L7 with B90s in about 2000. Purchased a NOS L7 on eBay, but had UK Plug easy to change since it was the newer model charger. Long story short does anyone know of a reliable replacement for the B90.
thanks

 

[yellow]

Homebuilt from 7.2 v racing Packs.

There should be a few threads to be found w. search