Battery charger - cordless drill Ryobi


More of a puzzler, than repair.

Item in question is Ryobi cordless drill 7.2V. Bought it with one battery and charger. Added another 7.2 V battery from home depot. All's fine some far. When I charge the battery, the charger gets somewhat warm, but seems normal.

Later I found batteries on sale at HD and bought two more. These are physically the same and came with short adapter cable for the old charger, which had bigger plug. These batteries have a differnet p/n but according to Ryobi have the same capacity in mAh and clearly the same voltage. When I charge these NEW batteries, the charger gets much hotter.

Called Ryobi and confirmed all numbers, both batteries are 1300mAh. The charger recommended with these new batteries has a different p/n and also has lower current rating (200ma vs 400ma original).

Why would batteries of the same capacity and design, overheat the charger, while others do not. TS at Ryobi is not very helpfull. If anything a higher cap charger should be less likely to overheat, and it's behaving "backwards".


Reply to
Loading thread data ...

Why do you think the charger is "overheating"? In a practical sense, if the charger isn't melting or smoking, then it is probably working as designed.

Why do you think the new batteries are of the same ""? If they were, then they wouldn't draw any more current from the charger (thus making it run hotter) than the old batteries. Seems possible the new battereis are, in fact, not of the same internal design. The cells may use a slightly (or entirely) different chemistry and/or physical construction, even though they have the same voltage and current ratings. Over the past few years, battery technology has changed very substantially, and many of the improvements have been aimed at permitting faster charging. Another fact is that no two manufacturing facilities make "NiCad" or "Ni-Mh" or "Lithium" cells exactly the same way...even when building to the same specs. Finally: If the new batteries require an "adaptor cord" to attach them to the old charger, that is a pretty substantial hint that SOMETHING is rather different.

Bottom line: If the new batteries charge and then power the drill, use them until they fail to do so.

Reply to

----- Original Message ----- From: "webpa"

With the older batteries, the temp of the charger is at a level that I can touch and hold my hand on it during the charge cycle of several hours.

Same charger and new batteries - after 20 min I cannot hold my hand on it. I disconnect it and let it cool. Then plug in again.

Perhaps this is the question - if they are. Both have the same voltage, mAh rating. If Ryobi tech support was better, they would explain the diff. There cleary is some diff, as evidenced by the heating of the charger.


This is why I'm asking the question. Did not think that slight difference in chem or construction would make that much diff. NiCad batteries have been made for ages and used the same chargers.

Only one of these 4 batteries clealry says NiCad on it. All others are missing that info, although they are meant for the same drill.

the old charger,

The adapter is a short piece of wire that changes the plug - no electronics involved. It is sold with these new batteries to all usage with existing chargers.

The mystery is that these apparently "very similar" batteries have such a different characteristics, when it comes to charging.

In a way they do, but I have been babysitting the charging process, being afraid to just leave it on for a long time - fearing a meltdown of the charger.

Would be much nicer if Ryobi provied good info on their products, so I would not have to bother folks here :-) Of course you do not find out these things until after you buy it and a bit later try and observe.


Reply to


Have no idea at all, but thinking out loud....

Wonder if the charger wasn't made to charge either regular or "quick charge" cells. If so, is it possible that there's a current limiting resistor inside the battery packs? (in your case, a different value in each of yours)

Take care.


Reply to
Ken Weitzel

Ryobi (Japan) sold their brand name to Hong Kong based Techtronic Industries in late 1999. Since then Ryobi branded power tools have been made in China and they are not a patch on the original Japanese made tools, especially when compared to the old Ryobi Tradeline series (blue green casing) which were really robust.

I bought a Chinese Ryobi 14.4V drill a couple of years ago and it came with 2 battery packs, all for around AUD100. After a week of use I discovered the batteries would not hold a charge and the charger also ran pretty hot. Opening the battery packs (screws only securing) revealed the NiCd's were of Chinese origin and the battery charger design was woeful. It was such a heap of junk and I ended up complaining about it so much that Ryobi swapped it for one of their new 12V Professional series drills. This was more in keeping with the old Japanese Tradeline series and the Ni-Cd's were Panasonic brand made in Japan and they would hold a charge quite ok. The charger was still a piece of junk and I managed to modify (hacked and plastic welded) and old DeWalt charger to accept the Ryobi battery packs and it now works well.

Reply to
Ross Herbert

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.