Battery heat ?

[X]

I am putting a CF4 into my MHS and using a 4AA pack that I made using a battery pack and Nimh AAs. When I first charged the pack it got warm almost hot to the touch. If I glue the CF to the pack and I charge it will it get hot enough to melt the glue again? Will it screw with the CF?

[Novastar]

Let's see...

* If you are "mixing" battery technologies (i.e. alkalines with ni-mh)... that is a big no-no. Granted, I don't THINK you said this... but... I thought you might be alluding to that...

* When you charge rechargeables... most chargers (MOST) tend to give the batteries a little "push", and feed a few amps into them while also "topping off" with a bit of over-voltage. In other words, for a 3.6v battery, the charger is likely giving 4.2v--which is NORMAL.

This causes the cells to get warm to hot... and again--is fairly normal (when at full charge)

* If the batteries aren't problematic, they shouldn't melt the hot glue you'll be using over them. However... I would still protect the CF board with some insulation layer in between the cells and the glue.

As it is, I *ALWAYS* shy away from hot glue since it just makes a mess in my opinion and can also leads to "pulling parts off" of a board or pull a wire, etc.

[Onli-Won Kanomi]

So if you shy away from hot glue Novastar how DO you mount the boards in your sabers???

Good idea about the insulation...I figured just using a PVC plastic chassis to mount everything would insulate my ultrasound and MR circuit boards from grounding out but didnt think of any more insulation would be needed between it and a TCSS battery pack what with its shrink wrap [I have one of those flat packs now but havent mounted a board on top yet...just been using tandem configs so far]...what in your experience works best for that?

[vortextwist]

On my last mhs I mounted the board in the ribbed section towards the emitter and most of the hilt section is battery. The board seems to react the same as when I had it near the butt.

[SWAT Strachan]

If you want to prevent the cells from getting hot during charging, use a charger with a lower mAh rating.

I have several (OK, about a dozen ) airsoft gun batteries here, and with the charger I use I have the option of a slow or fast charge. The fast charge dumps about 1.5 amps in to the cells, and although they charge in about a tenth of the time a slow charge would take, the battery does get exceedingly hot! The slow charge uses a 130mAh trickle feed, which can take up to 48 hours to fully charge a battery, but they'll barely get warm.

If you're not going to be using a 'smart' charger that cuts off automatically, remember the formula for charging times for empty cells...

(mAh rating of battery / mAh rating of charger) x 1.4

Also make sure you're using NiMH batteries as these don't develop a memory. To be on the safe side when charging, it's good practice to run the cells down completely (I use an 80mm PC fan as a discharger) before recharging them.

[X]

Thanks guys. NOVA I would never mix types, I used Erv's tutorial on making a battery pack and what would you suggest to use for mounting the CF?

Vortex how did you mount your board cuz I'm having a space issue and think I need to add another section to my MHS.

[vortextwist]

well since the new cf 4.0 is smaller i had an old mr fx maul bladeholder and fit awesomein the ribbed section and then I split it down one side and trimmed about 1/8th inch (thickness of the board) and it fit perfect. I also mounted it so the sd card was toward the emitter. The battery I used was the 7.2 6 cell AA pack from the store. it goes from the bottom of the ribbed section to the first screw in the switch box.

[Novastar]

If you want to prevent the cells from getting hot during charging, use a charger with a lower mAh rating.

I have several (OK, about a dozen ) airsoft gun batteries here, and with the charger I use I have the option of a slow or fast charge. The fast charge dumps about 1.5 amps in to the cells, and although they charge in about a tenth of the time a slow charge would take, the battery does get exceedingly hot! The slow charge uses a 130mAh trickle feed, which can take up to 48 hours to fully charge a battery, but they'll barely get warm.

If you're not going to be using a 'smart' charger that cuts off automatically, remember the formula for charging times for empty cells...

(mAh rating of battery / mAh rating of charger) x 1.4

Also make sure you're using NiMH batteries as these don't develop a memory. To be on the safe side when charging, it's good practice to run the cells down completely (I use an 80mm PC fan as a discharger) before recharging them.

SWAT's 100% right... basically, think of it like this... the harder you push a battery... the hotter it gets. What does that mean? Well, it means how much CURRENT you draw from it all at once... usually measured in current per hour, hence "milli-ampere-hour" (mah).

When you're driving at 1A... you're sucking 1000ma over a period of an hour. "I've just sucked one year off of your life. I one day may go as high as five, but... I really don't know what that would do. So... let's just start with what we have."

Sorry... had to do it. Count Rugen.

Ok... so when you CHARGE a saber... it's the same idea. If you're giving it back 1000ma over a period of an hour... that can get the cells hot...

...but they'll charge quicker.

If you trickle charge (as SWAT mentions)... they probably won't heat up even a bit...

...but they'll charge slower.

My chargers tend to take about 4-5 hours to charge a COMPLETELY sucked dry (yet protected) 18650 setup. But... normally I don't wait so long, and so it takes something like 2.5 to 3 hours. And again, there is absolutely no effect on Li-Ions regarding when to charge them. You can completely discharge them, charge in the middle, use it for 5 minutes, recharge... won't affect the cell's individual charge duration.

The Flange III sabers get about 3.5 to 3.75 hours of runtime, given the flicker options and that the cells are rated somewhere in 2200mah to 2600mah (can't remember which is what anymore).

Also, since the packs are 7.2v or 7.4v... they will "cut out" LONG before CF would need to "quit" due to under-voltage. Under-voltage would be something like 3.2v. And... there ain't no way a 7.2 pack would ever go that low. If it did... sayonara to the UN-protected pack!!

[SWAT Strachan]

"I've just sucked one year off of your life. I one day may go as high as five, but... I really don't know what that would do. So... let's just start with what we have."

The Princess Bride, a cracking film .