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Help Solve my problem with charger

R

rl48off

Member
I bought this charger a few month ago and only used it a few times for my Excalibur....with no problem. I went to check the battery pack on the ex cal. and it was way to hot. I checked the out put and this is where I need someones help. I put a volt meter on it and it was putting out 24+ volts. What I need is someone that has this charger to tell me what yours puts out. I think something is wrong. I really don't know what it should be. Critter I took this photo from your post. but it's the same charger bought from Batteries plus.

Ron
 
I haven't checked mine but I would say 14-16 volts, 24 is way too much.....Just checked my Minelab charger and it say 14.3v, my after market charger says 12v but don't know what the actual voltage really is, will check it tomorrow. HH
 
8.4-12v max!!

Throw it away and get a new one!
 
These seem to be good little chargers as I have got some of these for the people around here, but did have one go bad the guy told me as it wouldn't charge his battery, but could be his battery too.
Anyway the voltage you are reading with the volt meter is going to be much higher than what it is charging when connected to the battery as it has no load on it. If you could measure it while the battery was on it you will probably see around 13 volts or slightly higher. These chargers do charge faster then the stock chargers as it put out more current so the batteries do get warm to hot.
Not sure if I have one of those chargers around, but if I do I will check it with no battery connected and feel the voltage will be over 20 volts.

Rick
 
OK we have some mixed information but what I really need before I buy a new one is what is the exact reading (output) after plugged into the wall and the other end checked with a voltmeter. That's what I'm after. Thanks for your replys.

Is anyone using this charger for their Sovereign GT and can you use it.
 
I don't have that charger myself, but I see some Excal guys do. You might try going to a few of the links in the battery sticky where they talk about it and then PM a few of those guys and see if they can take a voltage reading of that charger unplugged from the battery so you'll have a baseline of what the unloaded voltage should be. Under load of the battery the voltage should drop, but that high of a voltage without a load seems rather high to me. I'm guessing you should be seeing an unloaded voltage of around 16 to 18 volts or so maybe.

Then again, just remembered...That charger will do up to how many cells in a pack? Most halfway decent chargers will charge from 1 up to X amount of cells, and will automatically adjust the voltage for the number of cells in the pack. So you might see a very high voltage without a battery plugged in because it's waiting to see how low it should lower the voltage once it senses what the pack is doing.

The voltage of the charger has to be higher than the target voltage of the pack. With around 12V for a 10 cell pack, I'm guessing the output voltage of the charger under load that is only meant to do 10 cell packs and not others (meaning the Minelab wall transformer) should be around 14 volts or so. Voltage has to be higher coming from the charger to charge a nimh or nicad pack or the power won't flow. But if that charger does from 1 up to X amount of cells say 12 cells or more for it's upper limit ability, that voltage looks to be about right that you are reading when not under load.

I need a few bits of info from you-

Up to how many cells will that charger handle, and does it say "up to" or does it say it's only meant for X amount of cell packs?

What is the output amperage the charger says it will put out?

I don't know what capacity pack you are using but let's say it's a 800ma pack. If that charger is charging 800ma (meaning 1C) or more the pack might get hot because that's pushing the cells too fast. Some aftermarket nimhs or nicads will easily handle say 1 to maybe even 5C (5 times the capacity of the pack in terms of a charging amp rate), but a lot of nimhs or nicads out there will get hot at 1C or higher if they aren't meant to handle that fast of a charging rate. For my nimhs or nicads I try to charge them at only about 1/3rd to maybe 1/2C at the most (400ma, or point 4 amps (.4)) in this example). 1/2C would take about two hours to charge a completely dead pack. Only when I'm in a hurry will I charge a nimh or nicad pack at 1C or higher, but that can lead to a shorter life span, loss of capacity, and also getting hot when charging which will slowly destroy a pack.

If that charger says it automatically adjust the charging amp rate based on what it thinks the pack can handle, that can be a problem. I've used chargers like that and they often would make a mistake on what they thought was a decent charging amp rate and would get batteries very hot.

My top three guesses are three things- charger is charging at 1C or more, battery is bad and so the charger never knows when to shut off the charging, the charger has a shorted winding in it's transformer and is causing too high of voltage output.

One more thing- Is that charger meant for doing the battery type you are using? If it's a nicad only charger and you are charging a nimh pack there is your problem, because nimhs don't drop as much in voltage when peaked to indicate they are full, so a nicad charger has a high risk of not seeing that the charge is done and will over charge the pack.
 
This is what it says on the back of it. See photo and discription


NiMH/Nicad Peak Charger 7-10 cell 115-240vac input


Click to Enlarge




FEATURES: -Charges 7-10 cell (8.4-12V) Nicad & NiMH battery packs
-Microprocessor controlled negative delta peak detection circuit
-115/240vac input
-Automatically senses pack voltage
-Red/green LED charge indicator lights
-Charge rate 700mA
-Automatic trickle charge mode: 100ma
-Charges packs from 1000ma AAA to 10,000ma D
-Typical charge time for a 3000mah pack 5 hours
-Connector: Male Power Plug 5.5x2.1 (Center +)

Weight: 6.00 ounces
 
It says on the label for nimh packs only. Is your pack a nicad? Really that probably shouldn't matter if it was. Here's why...

When a nimh/nicad is fully charged the voltage will drop from it's peak, so the charger watches for this to tell when the pack is done charging. During the normal charging process there are small dips and rises in the voltage as the pack charges. A nicad pack will drop more in voltage when peaked than a nimh pack will, and the nicad's voltage dips while charging will also be larger. For that reason the charger's m/v threshold setting (which you can set on some chargers) has to be set right for if the pack being charged is nimh or nicad. I usually set my nimhs for around 5 or 6 m/v, or for nicads around 12 or 14 m/v.

If you try to charge a nimh pack on a nicad charger, because the final drop in voltage when the pack is peaked is smaller than it is for nicads, there is a risk that the charger won't see that final dip and over charge the pack.

By the same token, I *think* that if you were to try to charge a nicad pack on a nimh charger, since the dips/rises during charging are much more pronounced for a nicad, the charger will probably shut off early thinking the pack has peaked when it was just dipping a bit up and down while charging as is normal.

So while it's never a good idea to mix packs on chargers they aren't meant for nimh/nicad wise, especially in putting a nimh on a nicad only charger, putting a nicad on a nimh charger *probably* isn't a big risk, other than the charging false terminating thinking the pack is done when it's not.

What kind of pack is it and what capacity? If it's say an 800ma pack charging at a 700ma amp rate is 100ma lower than a 1C charging rate, so I wouldn't think the pack would be getting hot from that, unless those cells are so cheap that they can't even be pushed at near 1C. If the battery is in the POD that might be the issue. Near 1C outside of the POD the pack might only get luke warm (which is fine), but if it's getting more what you'd call "hot" then that's destroying the pack over time for sure. Batteries hate heat when being charged. Some guys in RC charging at say super high rates of 5C with nimh or nicad packs will set the battery in a cooler on an ice pack while it's charging just to keep it cool.

Try charging it outside of the POD and see if it gets very warm. If it still does you are pushing the amp rate too high for what that pack can handle, and probably means it's a rather poor quality pack, because every nimh or nicad pack I've ever charged at around 1C never gets hot. Maybe slightly warm, but not hot.

The 100ma trickle rate after the pack is peaked...If you are using a nimh pack don't let it set on that thing for hours after it's charged. Nimhs I always read do not like being trickle charged once the pack has peaked, where as nicads are fine with that. But even if the pack is a nimh, at a 100ma amp rate that is so low that if the charger has gone into trickle charge I doubt the pack would get hot being over charged, unless maybe it's in a POD, and also if the pack size is on the smaller size (say 800ma), that might be too high of a trickle amp rate to keep a nimh cool to the touch while it's being over charged, especially in a POD.

Here's what I'd do...Drain the pack on a car tail light bulb or something. Then plug it into that charger outside of the POD. If the pack is 800ma it should take about an hour and a half or so at that amp rate to charge. Feel the pack about a half hour into it? Is it hot? If so then I'd stop or you are going to ruin that pack or worse. Feel it at about an hour's time too. Then come back when the pack is done charging and is on trickle and feel it then too. If it's only getting hot on trickle mode then that tells you that the charge rate is fine, and that it's just getting hot when being overcharged at the trickle amp rate. A nicad shouldn't have a problem with this, but a nimh might get hot even at that low trickle rate since I've always read it was bad for nimhs to be put on a trickle after they peaked.

Hope this helps.
 
I have several different one I use on my Sovereigns and Explorers/E-Tracs. As I said in my other post they do run higher voltage than what is said on the chargers as there is no load on them when there is no battery on them as it is a open circuit. My Factory charger for the GT and the Explorer/E-Trac is a 100Ma charger and using my good Fluke digital meter the voltage is 20-5 volts. Now on my Sun Ray SR 12 charger which charges at 350 Ma reads 20.45 volts and feel this one checks the battery voltage before it charges as it is got 9.6-12 volts. Now I had a charger special made to charge my 2600 Ma battery for my Explorers and is rated for 9.6 volts as the Explorers only use 8 batteries, but this charger also works good for my Sovereigns too and it puts out 260 Ma as said on the label and the voltage coming out from it is 25.4 volts. with no battery connected. I did have one of the chargers you were using right now as it is out letting a fellow hunter using it. I do know they do get hot while charging, but don't remember getting so hot you cant touch it. Even when it was fully charged it still puts out 100 Ma in trickle charge, so you can leave the battery on the charger for days and have to check it out and when charged take it off. I would plug mine in at night and take it off in the morning about 6 hours latter.
I know Critter will disagree, but being the charger is putting out 700 Ma which to me is a lot compared to the factory one as 100 Ma the battery is going to get hotter than normal, I have seen this over and over again and seen many batteries get ruined when someone want to charge faster then the battery is made for. I had 2- 9 volts actually blow up when trying to charge them at a higher Ma.
The few I have got this charger for are very happy with them, but know you cant let the batteries sit on the charger much after they are charged and the batteries do get very warm. My 1 hour charger for 8 separate cells I use for my other AA nickle hydride batteries as can charge one or all 8 at one time and when that cell is charged it will shut down charging to that one cell only and still charge the others. This charger the batteries do get hotter than I like to see them. For my Sovereigns and my Explorers/Etracs I like my Sun Ray SR 12 charger which can charge to a safe level and go to a pulse trickle charge plus it can also discharge the batteries to a safe level and recharge to a safe level which is no longer being made and I have never ruined a battery, but saved a lot of the Ni cad with memories in them and woke up the Nickle hydride by charging and discharging a couple of times, so the batteries will hold a full charge.

Rick.
 
I also have a Powerizer Smart Charger which is an auto detecting unit. It will not put out any voltage if it is not hooked up to the batteries. The label says 7.2-12v auto detecting. My regular Minelab charger says it will put out 14.3v but when I checked it with my voltmeter it is putting out 18.7v, hope this helps. John
 
The Minelab charger will charge up my spent battery pack in about 11-12 hours, the Powerizer will charge the same spent battery pack in about 2 1/2 hours, I don't know why the big difference in time but I mostly use the Powerizer and have never had any problems. John
 
John can you check with a voltmeter after you plug it into the wall then check the other side with the meter ??? mine puts out 24 plus volts maybe be bad
 
I guess you can use this charger with the Sovereign gt as long as you have the other connector right ?
 
Both my Sov. and Excal are Nimh battery packs. I need to know if my charger is Kuput ! Thanks I'll just toss it

Ron
 
Rick, I do agree with you on the point that 700ma might be too much for say an 800ma Excal pack (if that is what it is, as I think the stock ones are 800ma?). I mentioned that I think in the above post. Cheap batteries, especially ones made a while back, might get hot if charged at near 1C, especially if they are in the POD.

All I can say is that all the batteries I've ever charged at 1C never got hot that I can remember, but thats all the loose cells or packs of nimhs or nicads I've owned over the years, but that doesn't mean the stock Minelab pack won't get hot, as we know they aren't exactly using the latest in technology nimh or nicad wise.

Some cells are made to handle higher charge rates and some aren't. Some are even made to handle say 5C charging rates. Every "average" nimh or nicad pack I've ever charged wouldn't get hot at 1C, but as said I don't use the stock GT pack anymore or have ever charged a stock Excal pack, so if they are the cheapest quality cells on the market then even 700ma for a 800ma pack might be too fast. Can't remember off hand what I charged the GT pack at. Probably 500 to 750ma or so at the most maybe.
 
RL48off, yea...the stock GT pack is 1000ma. Provided you charge through the two main battery leads on the pack using alligator clips that charger should work fine with it. You can't charge through the little charging jack because there is a circuit behind that plug, where as the stock wall "charger" is just a DC transformer that feeds that circuit.

I've charged the GT pack through the two main battery leads using alligator clips but don't remember off hand how fast I pushed it. A 700ma charging rate for a 1000ma pack *should* be OK, and should take about just under two hours to charge, but I'd feel that pack while charging off and on and if it's getting hot then those cells in the GT pack can't handle that fast of a rate.

That's one of the reasons why I prefer a charger that lets me set the amp rate. I can play with different rates and always use the one I want for a particular pack. Normally I charge at around 1/3rd to 1/2C for about a 3 hour to a 2 hour charge time. That shouldn't really be pushing a pack to shorten it's life. Around 1C charging all the time and that can shorten a pack's life over time unless it's meant for that high of a rate. Best way to know is heat. If it's luke warm it's OK, but if it's getting much warmer than that then the pack is being pushed and you are punishing the battery. You have to check it say half way through and then also towards the end, because the heat might not show it's self until the battery is nearing full charge or so.

There are nimh cells designed for higher amp rates of say 2 to 4 times C or so. Walmart sells "fast" chargers like that for AAs and such and special AA cells for that, but every time I've looked at the estimated cycle life of the cells they were a good bit less than normal nimhs AAs they also sell. In other words, chances are the "fast charging" cells weren't anything special. Just normal cells with a less expected life span noted on the package.

Bottom line is heat kills. If the pack is getting hot then you know either two things have happened- 1) You are charging too fast, or 2) The charger missed the peak of the pack and it's over charging it.

And one more reminder- From what I've ever read nimhs should not be maintaned with a trickle charge after they picked. That's only OK with Nicads from what I've saw on that. For that reason many chargers have the ability to turn on or off the trickle charge after the pack is peaked. Just a constant 100ma trickle charge on a nimh after it's peaked might be the reason the pack is getting hot if it's a nimh pack.

Minelabs 100ma charge rate for the stock pack is needlessly slow for the health of the pack. For the GT pack around 300ma (roughly 1/3rd C) isn't pushing any nimh or nicad packs I've ever heard of. Around 1/2 C (500ma) should be fine too. I can honestly say I've never ran across any blurbs about a nimh or nicad pack being charged at 1/2C being unheatlhy or pushing any pack. 2/3rds C? Now we are probably getting into a gray area. 1C? Again, gray area. All depends on the cells. Just check the pack. Very luke warm is OK. Warmer or hot and you've got issues IMO.
 
OK Critter I got all that. Thanks good advise. John just told me that when he checked his unit which is the same as mine. He didn't get a reading with his voltmeter and I get 24volts plus So Thanks John that's what I was after. Now I know my charger isn't good anymore.

Thanks Ron
 
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