Tuesday, 13 July 2010

Rejuvenating rechargable batteries using MH-C204W charger

I bought a Maha MH-C204W charger and one of its big selling points for me is the ability to rejuvenate rechargable batteries that haven't been used in a while. A common problem with rechargeable batteries is that they don't seem to hold enough of a charge if they don't get used frequently. If you Google on "Maha MH-C204W", you'll see it has quite a good reputation with getting these batteries to be quite useable again.

However, when I first started using the charger I was getting behaviour that was not really as described in the 1-page 'manual' for the unit. I put in these 6-yr old Sanyo 2300 Ni-MH batteries to see if they could be made usable again. What follows are my emails to Maha, and the quite helpful responses I got. Hopefully this will be of use to someone experiencing the same issues.

I've reversed the contents of the email thread, so we can start at the beginnning. =)


> -----Original Message-----
> Sent 7/5/2010 5:30:45 AM
> To: xxxxxxxxxxxxx@mahaenergy.com
> Subject: Maha/PowerEx Tech Support Request
> I have a MH-C204W charger, and just inserted 4 AA batteries to recharge.
> On the lower end there are 2 lights, and after charging for 2 hours, only
> the right one is green. The indicator on the left is not lit at all. The
> manual states "Note the two indicators may not turn green at the same time
> due to minor difference in battery status in each bank." What is the
> expected behaviour of the unit? Is each light supposed to be lit as you
> put the batteries into each half of the unit? (red at first, then green
> after charging)


On Tue, Jul 6, 2010 at 3:50 AM, XXXXXXXXXX (MAHA ENERGY COI)
> Thank you for contacting Maha. Here is a brief explanation to what each of
> the four LED lights mean:
> 1.Solid red (Charging)
> 2.Green (Charging complete)
> 3.Flashing red (Battery fault)
> 4.No light (Battery or charger fault)
> To determine whether the charger or the batteries are defective, please
> insert a pair of known "good" battery inside the slot in question. The LED
> should light up as solid red if the slot is working properly. If it gives
> you no signal/light, please provide me with your shipping address so I can
> have this defective unit replaced for you. Thank you and I look forward to
> hearing from you.
> Regards,
> xxxxxxxxxx


-----Original Message-----

Sent: Friday, July 09, 2010 3:39 AM
To: xxxxxxxxx(MAHA ENERGY COI)
Subject: Re: Maha/PowerEx Tech Support Request


It looks like some of my old batteries are at fault. I've inserted 2
sets of recent NiMh batteries and they are charging as expected with
the lights first showing as red for both pairs, and then green.

However, I'm trying to rejuvenate them so following the instructions,
I've charged them til both lights were green, then took them out to
cool down, then put them back and pressed the button between the

The instructions say the lights should then flash yellow. Now in some
cases what I'm seeing is that only one of the lights will flash yellow
and the other one remains green. What does this mean?




From MAHA:

Thank you for the follow-up. To condition both set of batteries, first place two batteries in the middle while leaving the two outer slots empty. After both of the batteries has been firmly secured, place the other two batteries in the two outer slots. Press and hold the conditioning button until you see both LED lights flashes yellow.




Monday, 12 July 2010

Fun with portlets - Vignette Error: "The provided content type, application/octet-stream, is not a valid response content type." (FIXED)


I had a portlet (written using Spring MVC) where I had to download a
CSV file, so in the code, I was making this call


But I kept getting the error below from Vignette.


General Error

The provided content type, application/octet-stream, is not a valid
response content type. Please check the valid response content types
by invoking PortletRequest.getResponseContentTypes().

Please contact your System Administrator for assistance.

class java.lang.IllegalArgumentException


I tried using "text/csv" and "application/octet-stream" and same response.


This was caused by a missing config in portlet.xml

The portlet I was working on had this config:


and to fix the above error, I had to add this: