Rechargeable batteries for the flash got HOT in the charger

[fi20100]

I was about to charge the batteries for my flash today, and I noticed after a while that the little status light that usually glows orange (or green, I can’t remember) was not on, but the fan was running. When I touched the batteries they were really hot. Hot enough that I didn’t want to keep them in my hand more than a few seconds. I didn’t let them charge for more than a few minutes.

Is there something wrong with the charger? I can’t remember them becoming so hot before. Do I dare to use it? I tried the batteries in the flash and they worked alright, but I don’t know how much charged they are.

I’ve recharged them tops 15-20 times.

[cdifoto]

Mine get hot too. Too hot to old. I just let 'em cool and don't worry much about it. Maybe I should. ??? Hasn't affected their usefulness so far though.

[In2Photos]

Mine get pretty hot in the 15 minute quick charger but not so hot in the standard charger.

[petrolhead]

mine get hot in a 1hr charger

[fi20100]

I tried putting them back in the charger, and the status light did glow, but only for a a few minutes (it's a 15min charger), so I'm now thinking that the batteries are pretty well charged to begin with. I haven't used them a lot since I last charged them, but that is quite a few weeks ago. I guess I usually haven't paid much attention to the whole charging activity, and perhaps they've always become hot, and I just haven't noticed.

I appreciate your answers :) Thanks!

[olly_k]

you can really knacker nimh & nicad batteries by letting them get too hot - In fact, when there is a change in temperature of the cell this is normally the sign that the battery has reached full capacity.
I wouldn't use any charger that heats my batteries much beyond luke warm.

[Jon]

Batteries will tend to heat up if subjected to rapid charging or discharging.

[the.digital.guy]

You should NOT use Rapid Chargers to charge you batteries.This method should only be used in an emergency. Rapid charging will decrese the life of the batteries.
Here's a GREAT Charger(is also can do rapid charging with a switch of a button)
http://www.thomasdistributing.com/mhc401fs.htm

also in black:
http://www.thomasdistributing.com/mhc401fs_buy_international.php

note that the new MH-C401FS charger from MAHA ENERGY (http://thomas-distributing.com/mhc401fs.htm) uses a new charging technology that helps to keep your batteries much cooler during the charging process.

[nMotion96]

i race rc so i got those special charger that lets you set the capacity, amp and so much more. for r/c racing we want more punch out of the battery so we over charge them with a higher amp. this kills the battery life. but since you want more flash out of each charge. you would charge them at a low amp, also saves the battery life.

[Riff Raff]

The more rapid the charger is, the hotter your batteries will get. That's just how it works. If you want to keep them cool, use a slower charger (or your existing charger on the "slow charge" mode).

[Ronald S. Jr.]

I burned the hell out of my fingers getting my 2500 energizer's out of a 15-minute charger the first time. Stupid me, I had no idea they'd be literally blistering hot.

[fi20100]

Yep, well... I guess I'll have to get a second (slower) charger... at some point :) Until then, I'll be careful with my fingers :)

[Rudy M.]

Overnite trickle chargers are the best for your batteries. Heat will destroy your batteries in short order, so don't use those 15 minute quick chargers unless you don't care about the batteries, and be sure you have good air flow around them. Let them cool before use. I would not leave batteries in a quick charger unattended because of fire hazard. Sterling Teck has a nice overnight wall charger that will charge individual cells, 4 AA's or 2 AAA's independently. It comes with 4 AA cells at 2400 mAh and costs $10.95. Maha also makes a couple of good ones. I like the one that will trickle all night or fast charge at 1000 mAh rate. The get pretty warm if fast charge them, but it takes about 1.5 or 2 hours and you can still touch them. Heat is a battery's worst enemy.

[Headcase650]

I see a lot of bad info given when it comes to this subject. I have the 2500 energizers and the 15 minute charger, bought it over 2 years ago with 4 sets of 4 batteries, havent had to replace a single set and they get charged at least once a week, sometimes more. They have never gotton so hot they would burn me but they do get pretty warm.

Go to this site and get the facts about nickle based batteries and the proper way to charge them.

http://www.batteryuniversity.com/

[rklepper]

Another reason to only use a rapid charger in case of emergency is that they do not completely charge the battery. I have a pair of 24 hour chargers and after using a 15 minute charger they will still charge for a good 10 hours.

[Headcase650]

Straight from the link in my above post.

Nickel-based chargers are grouped into three categories:

* Slow Charger - Also known as 'overnight charger', the slow charger applies a fixed charge of about 0.1C* (one-tenth of the rated capacity) for as long as the battery is connected. Charge time is 14-16 hours. Slow chargers are found in cord-less phones, portable CD players and other consumer goods.
* Quick Charger - Also knows as rapid charger, this charger serves the middle range, both in terms of charging time and price. Charging time is 3-6 hours. The charger switches the battery to trickle charge when ready. Quick-chargers are used for cell phones, laptops and camcorders.
* Fast Charger - Designed for nickel-based battery, the fast charger fills a pack in about one hour. Fast charging is preferred because of reduced crystalline formation (memory). Accurate full-charge detection is important. When full, the charger switches to topping and then trickle charge. Fast chargers are used for industrial devices such as two-way radios, medical devices and power tools.

[Samgoit]

From the same site as quoted above:

Simple Guidelines

* Do not leave a nickel-based battery in a charger for more than a few days, even on trickle charge.
* Exercise nickel-cadmium every 1 to 2 months and nickel-metal-hydride every 3 months. Running the battery down in the equipment may do this also.
* Do not discharge the battery before each recharge. This puts undue stress on the battery.
* Avoid getting the battery too hot during charge. The temperature should only rise for a short moment at full charge, then cool off.

My Energizer 15 minute charger kept my batteries (Energizer as well) as hot as embers during the entire charge. Firing the batteries with the 15 minute charger destroyed their usable time for me.

Nickel-cadmium in regular use and on standby mode (sitting in a charger for operational readiness) should be exercised once per month. Between these monthly exercise cycles, no further service is needed. No scientific research is available on the optimal exercise requirements of nickel-metal-hydride. Based on the reduced crystalline buildup, applying a full discharge once every three months appears right. Because of the shorter cycle life compared to nickel-cadmium, over-exercising is not recommended.

I, unfortunately, didn't make it to three months before my batteries were shot. I bought the Le Crosse SC-900; it succeeded in bringing life back to my batteries (as measured by the SC-900 and a B+K 5370 multimeter; more simply, the batteries just lasted much longer) using its refresh mode, which discharges then recharges the batteries until no further gain is measured.

I have found the maximum charging current that keeps the batteries cool during charging - something that is possible with the Le Crosse.

[Headcase650]

* Avoid getting the battery too hot during charge. The temperature should only rise for a short moment at full charge, then cool off.

Define too hot please. Mine get warm but never to hot to hold, maybe as warm as one of those desposable hand warmers you get in the sporting goods department. If I leave them in the charger after the light turns green the fan has them cooled off in less than 5 minutes. Ive got 4 sets that are over 2 years old and have up to 150 - 15 minute charges on them and they are still going strong.

[Samgoit]

Define too hot please.

This is too hot:
I burned the hell out of my fingers getting my 2500 energizer's out of a 15-minute charger the first time. Stupid me, I had no idea they'd be literally blistering hot.

This is too hot:

My Energizer 15 minute charger kept my batteries (Energizer as well) as hot as embers during the entire charge.

A charger that needs a fan for cooling is too hot. ;) I can't be sure, but I have a feeling the author of that site would agree with the above.

It's good your batteries still work fine, but mine sucked (3 sets of 4 2500 and 1 set of 2200) until I got the Le Crosse. A pair of 2500mAh Energizers on the 15 minute charger would run my cordless mouse for a week - Pitiful. Putting them in my 430EX or A510 was an even bigger joke.

They shouldn't call it a battery charger; they should call it a battery kiln.

As always YMMV.


A warning about self-discharge from the same site:
Factors that accelerate self-discharge are damaged separators induced by crystalline formation, allowing the packs to cook while charging, and high cycle count, which promotes swelling in the cell