Zoom Gear & Home Recording Forum

Yes, their info is confliciting. They don't consider that charger as fast either. Look at the others they have:

http://www.batteryspace.com/index.asp?P ... egory=1021

What I can tell you is this: they take about 5 hours to charge my 9.6v/2000mA batteries. If there's a compromise to depart from the usual 10% of total capacity for charging current and still not being really fast, I can accept that.

Working at a tangent to this, does anyone know what voltage external power the H4 will work down to?

EDIT: found the answer. That's what I get for not searching properly...

I just wanted to add a little warning: Some RC _lithium_ batteries are sold without an internal protector circuit - this is because RC folks will sometimes stack the batteries themselves and do other mods, they'll also handle the electronics themselves. I have a couple of such batteries, these had to get circuitry installed before I could use them safely.

Here's what I whipped up today:


Despite the poor quality of these photos, primarily I'm a photographer and I have lots of "7.4V" Li-Ion batteries for my cameras. I went to the local retail camera store and spent AU$10 on a charging plate (for their generic Li-Ion charger) to match the Canon BP-511/A batteries I have. I then opened it up (takes a screwdriver), replaced the internal cables (takes a soldering iron, but it's just wires: no electronics), and reshaped the back of the plate with a knife.
The plug was cut from the end of the AC adaptor that came with the H4 (no point in keeping it as it only handles 120V AC which we don't use around here).


The battery clips into the plate, and the whole thing is held onto the back of the H4's tripod mount by the mount's velcro strap. The strap fits snugly along the back of the battery (you might notice in the first photo that there's a despression along there between two bulges).



I'll probably replace the DC connector with a lower-profile right-angle connector later, and am looking at putting a low-voltage warning LED into the battery mount. For now I'll just cycle fresh batteries into it without letting them run too low.

As for power, the batteries are typically rated at 1100-1600 mAh, with a nominal voltage of 7.4V (although I measure over 8V).
A 7.4V 1400 mAh battery theoretically has twice the capacity of a pair of 2300 mAh AA NiMH batteries but only about 2/3rds the capacity of the 9.6V 1600mAh battery shown at the start of this thread (although the voltage/current/time behaviour of Li-Ion vs NiMH means that the comparison isn't that simple).
So the run-time will be longer than with the internal batteries, although obviously there's another benefit: the hiss and beeping produced by internal batteries with an un-modded H4 are completely gone.

A low-battery alarm is in order for you to better care of your battery. I am trying to get some help and find a server where I can send the battery alarm circuit for all here to see.

If I am not wrong, which means you should investigate it, the lower point that Li-Ion battery should get to is 6v. As you soldered a cable from battery to supply, you could measure what's the current consumption for your usual setups, using a DMM meter. Then you can compute how many hours you can use them.

I'm not exactly an electronics guru, so this question may seem dumb but....

does more mAh equal more battery running time?

I've found some 9.6v NiMH battery packs with chargers on eBay, but they list them as 2200mAh

is this okay to use on the H4?

Just made one up using Sam's formula. Added a velcro strap to the battery pack so I can zelcro strap it on the tri-pod.

sam rules

Yes, more mA means more capacity = more running time.



Yes, they should do fine. Charge them after every day you use them; or count the hours you use them and charge them after 12 hours.

My Radio Shack solution power pack was charging this evening and, as usual, the battery pack was warm during the process. I unplugged the pack before the charger light went out and as I was strapping it to the H-4 it seemed to get hotter. Actually, it did get so hot I could not hold it in my hand and I believe some of the clear plastic outer wrapping was starting to melt!

I have done several successful charges previously. Could this mean a short in the battery pack? Some defect? Ouch!

Replying to my own post...

Yes, looks like a short - but not in the pack, in the cable/connector I made for the H-4. Makes sense because I noticed the pack getting hotter once I plugged it into the H-4 via my connector. Ok, I can whip up another, perhaps more carefully. Just hope I didn't damage the battery pack by shorting...?

Yes, it did sound as if it was a short somewhere. Batteries are so simple, that only current going through them can get some sort of external reaction, like heat.

It's quite likely that all the battery or some of the elements were permanently damaged. NiMHs are not prepared for high currents. But it may not have.

My advice would be to use a short cable adaptor, that you can disengage from the battery, to solder the H4 connector. Then you can unplug it if you feel the battery gets hot. It will be bulky, but it may save you from losing a battery.

Do you know what caused the short? Do look into that before soldering another one.

It may be a good idea to simply cut a 4" end of the H4 original supply cable terminal, and solder that into the adaptor/battery cable. Then carefully wrapping each wire joint with heatshrink tubing. But when you end do check the voltage at the H4 connector is correctly polarized, or you may blow the H4.

Me too... 20D My Photo Site


Is the 7.4V (some are actually 7.2v) enough to properly drive the H4 and drive it without the beep?

Got a battery pack (same parts as the first post in this thread)

I tried to solder the wires in good, but it's obvious thats I'm HORRIBLE at soldering.... so instead, I found an old power transformer that had a size M plug on the end of it and cut it off.
I used crimp connectors and some electrical tape to connect the wires together, and so far everything seems good!

I did a 6 hour test record with the battery before fully charging it, but i accidentally wiggled the plug out of the H4, so it never saved the file.

But it runs good and strong!
More live music to be taped soon!!!

(rig: Schoeps CMC4 > Sonosax SX-M2 > Zoom H4)

Looking for an external battery solution that's more manageable (by hand) than 8AAs..and doesn't have to provide 12 hours of record time...I found this:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2644

Apparently it's got internal safety circuitry.

FWIW.

Could you wire several of these in parallel to extend the recording time?

It is not a good idea to parallel rechargeable batteries. It's alright for alkalines though.