# Upgrade batt pack on my mini-vac



## bhds (Sep 20, 2005)

Anyone have any idea if I can upgrade this battery pack to a higher capacity? Its out of my euro-pro mini vac. I really like the thing but it doesnt last very long on a charge. I have "cycled" the batteries a few times with no improvement. A lot of people who have bought the same vac complained about the short runtime also. I think the batteries just arent up to the task of supplying the motor much current.

Any ideas or tips appreciated.


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## Lynx_Arc (Sep 20, 2005)

2000mah for subC is pretty stout. Perhaps the batteries are mediocre quality and not meeting the rated label. I am not sure if there are any nicads much higher than that to warrant upgrading and nimh would require a seperate charger which you may not want to bother with either.


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## bhds (Sep 20, 2005)

Lynx_Arc said:


> 2000mah for subC is pretty stout. Perhaps the batteries are mediocre quality and not meeting the rated label. I am not sure if there are any nicads much higher than that to warrant upgrading and nimh would require a seperate charger which you may not want to bother with either.


 

The runtime was not that great when it was new but it definitely is worse now. How would I go about just replacing the stock batts with equal or higher quality cells?


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## Lurker (Sep 20, 2005)

The easiest thing would be to get it as a replacement part from Euro-Pro. There are also companies that make custom battery packs to order. I think one is a forum sponsor. Or you could source the component cells and wrap them together with tape and solder them together to make your own. But that requires a little experience.

One tip I have is to not leave it on the charger all the time. Charge when necessary, but store it off of the charger. Constant trickle-charging 24/7 is bad for the batteries and you will be more satisfied with your vac if you avoid that.

If you go the custom route, you may be able to change over to higher-capacity Ni-MH batteries without worrying about the charger issue if the charger is a slow trickle charger. I have done that with cordless phones with great success. You can get 3000 mAh or higher sub-C. Keep the charge rate below C/10.


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## bhds (Sep 20, 2005)

Lurker, 


Would like to replace the batts myself. I’m fairly handy with a soldering iron. Also, even if I could get a replacement throught the manufacturer It would probably be not much cheaper than buying a new machine. I’m basing that on experience with other consumer products that I have tried to replace parts on. 

Would love to upgrage to ni-mh but I’m not sure if I have full replacement cost in my home owners insurance package. :devil: 


Interesting about not trickle charging 24/7. I never new that. More info if you have it.

Sub-c. Is that the actual size of my batts or just a general size?


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## Lynx_Arc (Sep 20, 2005)

SubC is a size of battery very common to nicad battery packs found in the majority of high current rechargable devices such as portable vacs, drill motor packs, etc.
If you are unsure about the size grab a C or D cell and hold it up next to one of them. A subC should be shorter and perhaps a little smaller diameter than a C cell. 

If you are decent at soldering you have a few routes to go, buy individual cells from an online vendor, buy a cheap nicad drill motor battery pack and redo it for your vac from a place light harbor freight.

Trickle charging does encourage nicads to die quicker but as they get fairly old I have found they tend to self discharge faster and you nearly have to have them on trickle to be able to use them occasionally it seems. I have a dustbuster I replaced the nicads in from a drill motor pack. It wasn't too hard to fix and if you don't have the tabs you can use some fairly heavy wire to attach them together like 14 gauge or larger.


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## bhds (Sep 20, 2005)

Battery station has 2400mah sub-c on sale. 
What does the "high rate" mean compared to "rapid charge"?
Will the built in charger be able to handle the higher capacity?


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## Lynx_Arc (Sep 20, 2005)

high rate probably means they put out higher amounts of current during shorter time which is attributed to lower internal resistance. Rapid charge means they can accept higher amounts of current with less *damage* or wear in charging.
Your charger should handle the higher output batteries fine but it may take a considerably noticeable amount of extra time to charge them when they are discharged heavily.
Depending on how old your battery pack is you could have a bad cell or two causing it to get weak quickly.. sometimes you can replace the bad cells with similar output ones but a lot of the time it is pointless as the other batteries are worn out also.
I took a battery pack apart that got weak after I discharged it with the drill motor and measured each cell seperately and found 4 bad/weak cells in it.


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## bhds (Oct 17, 2005)

After looking and trying to find a replacement for the vac I decided to go ahead and replace the batts with the 2400scr's from batterystation. A new vac would not be that much more than replacing the batts but I would be stuck with the same problem in a couple of months. 

I was looking at the charger and output is rated at 300ma 18v. Is it common to recharge at a higher voltage than what the battery pack is rated?


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## Wingerr (Oct 23, 2005)

bhds said:


> I was looking at the charger and output is rated at 300ma 18v. Is it common to recharge at a higher voltage than what the battery pack is rated?



Does the owners manual warn against overcharging at all? They may have some kind of charge control circuitry in there to regulate the charging voltage, but that 18V is pretty high. With it hooked up and charging, the voltage may drop lower if it draws more than the rated 300mA, but if they don't have a charge control circuit, leaving it on there 24/7 would definitely be a factor in the problems you have, damaging the cells. 
Have you measured the voltage at the terminals to see if the adapter is indeed simply connected to the battery pack? At the very least I would expect they put a diode inline from the charging jack-


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## bhds (Oct 24, 2005)

Wingerr,

I'm getting 18.2 volts ouput from the charger and 12.97 volts at the input plug to the vac.

I wish I had some other nicad equipment to compare to.


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## Wingerr (Oct 24, 2005)

Okay, then it has some circuitry in there to control the charging voltage and current. That measurement was with the terminals disconnected from the battery, I assume? Otherwise the battery pack would limit the voltage you see.


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## pedalinbob (Oct 24, 2005)

I have a similar issue--even have the smaller Euro Pro vac. My wife has a bad back, so she loves how light it is.

Started out fine, but now the bats just don't have enough oomph, and they die quckly. They look like 6 sub-c's.

But, it will cost me about $4/bat, + $5 to have them soldered together...plus shipping!

This is more than the vac is worth, I think.

I am tempted to make a pack out of 2500mah AA energizers, and charge them once every few weeks on my charger. Not sure how well they would fare with the built-in charger.

Bob


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## bhds (Oct 24, 2005)

Wingerr said:


> Okay, then it has some circuitry in there to control the charging voltage and current. That measurement was with the terminals disconnected from the battery, I assume? Otherwise the battery pack would limit the voltage you see.


 
NO 12.97 volts at the vacuum charging input plug with batts hooked up. I assumed that if there was any electronics in between it would show up. I will take it apart tonight and check it again


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## Wingerr (Oct 24, 2005)

If you're going to have it apart anyway, maybe you can try measuring the current draw of the thing when it's operating. If your meter has a 20A current measurement capability, you just need to unplug one of the connectors, and put the meter in series (connect between the wire and the battery terminal).
This might give you an idea about the suitability of possible substitute batteries.
Nicads can generally put out higher currents than NiMH, even if they're rated at lower capacities.


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## Wingerr (Oct 24, 2005)

pedalinbob said:


> I have a similar issue--even have the smaller Euro Pro vac. My wife has a bad back, so she loves how light it is.
> 
> Started out fine, but now the bats just don't have enough oomph, and they die quckly. They look like 6 sub-c's.
> 
> ...



Do they have any AC powered versions of that vac? I have a small hand vac that's AC powered, don't remember the model, but I think it's a Euro something. It's really light, but don't know if it's the same type you have, this is strictly for small pickups.

The worst rechargeable battery op device I have is an Oreck bug vac; while it works well, I either have to leave it plugged in continually so that it's ready for use, wasting power and killing the batteries, or leave it off and find it discharged when I have a need for it. Rechargeables just don't make sense for things like this. I may open it up and just see if I can put alkalines in it.


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## bhds (Oct 24, 2005)

Wingerr said:


> Do they have any AC powered versions of that vac?


 
bunch of em. The nice thing about the cordless that I have is it comes with a 2 ft flexible hose with attachments and very good suction. Perfect for dusting around the computer room etc. It didnt have an extremely long runtime when it was new but it was very useable. Now the power drops off noticeably within about 15 seconds. A lot of reviewers noticed the same thing. Really good power for a month or so and then almost un-useable.


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## bhds (Oct 24, 2005)

pedalinbob said:


> .
> 
> But, it will cost me about $4/bat, + $5 to have them soldered together...plus shipping!
> 
> This is more than the vac is worth, I think.


 
I considered just buying a new vac for the same reasons but it was pretty evident that I would just have the same problem again. 

I recieved my new batts from batterystation today. Hopefully with the higher capacity replacements and maybe a different re-charge scheme I can get this thing to last for a while.

As a side note I just went through the same thing with my dewalt 9.6 volt cordless drill. 2 new batts would have cost $ 60+ but I was able to buy a brand new drill with batts,charger,case for $99 delivered.


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## pedalinbob (Oct 25, 2005)

Wow, yeah...it stinks when replacing the bats costs nearly as much as replacing the whole unit!

My wife likes the little "Shark Cordless Sweeper" because it is very light and conveinent. We have both short carpet and bare floors, and the little thing works well. We will see if I can resurrect it.
I wonder if nimh bats would charge OK in series via the provided charger? Don't want to kill them. The wall wart reads "9v, 200ma".
Hmmm. Maybe a home-made pack would be ok. Just leave it unplugged, and charge when necessary overnight. anyone know how long it might take to charge 6x2500mah aa bats in series at 200ma?

We also have a Dustbuster, which is very convenient. It had very short runtime, so I replaced the bats with upgraded/higher capacity bats last year--much improved.

Bob


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## bhds (Oct 25, 2005)

Finally able to get back in to cpf.

Looks like there is some electronics in between the charger and batteries. I measured 24.5 volts going to the actual battery pack and and around 7-8 amps peak current draw. Seemed to level out around 4-5 amps but the vacuum was dying pretty fast so it was hard to get a steady reading.


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## Wingerr (Oct 25, 2005)

Well, then you should be careful not to just leave it on charge all the time, since it looks like it probably just routes the DC input pretty much directly to the batteries. Battery longevity is apparently not a priority in that setup.

If you do want to leave it on all the time, maybe you can look into a different adapter that puts out a voltage closer to the full charge voltage of the battery pack, so it'd act like a float charger once charged.
Or put a regulator in line with the input to drop the voltage a bit.

With that kind of current draw, nicads would have a happier time, but NiMH is still worth a try for comparison.


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