Rebuilding the battery packs

Discussion of Argus4 cameras.

Current users seeking advice from members with a background in thermal imaging welcome here
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Fraser
Posts: 19
Joined: Sun Mar 06, 2016 11:14 pm

Rebuilding the battery packs

Post by Fraser » Sun Apr 17, 2016 10:00 pm

When looking at rebuilding some Argus 4 battery packs I was very pleased to see that they are held together with screws rather than the awful ultrasonic welding used by some companies.

Upon opening the battery casing I found six AA size Ni-Mh cells that were configured as three cells stacked above three others. All cells are connected in series had there is an over temperature fuse in the current path. Temperature monitoring during recharging is provided by a thermistor. Interestingly there are two thermistors present. One in each pack of three cells. In battery packs without the additional charging contacts in the top face, only one is used and the other has its wires cut off. On battery packs with the additional charging contacts for the truck mount charger, the second thermistor is connected to two of the top terminals for truck mount chsrger use.

The Battery 'Gas Gauge' comes in the form of a BQ2010 chip. Unlike laptop lithium batteries, this BQ series chip does not have a faulty cell permanent lock-out. Such is not needed with Ni-Mh cells and so the battery may be rebuilt with ease.

To rebuild the battery you will need six AA cells of 2.1Ah capacity built into two packs of three cells in side by side configuration. Tagged cells are obviously easy to connect to each other but if, like me, you have a battery tag welder, you can use the cheaper nipple ended cells and build the pack with tag welding. There is room for the slightly longer nipple ended cells and, in fact, these are present in some of my battery packs ex OEM. A temperature sensitive fuse is recommended for safety and the original thermistor may be transferred to the new battery pack. Connections to the small PCB within the battery are easily accessed from above and the PCB does not need to be removed from the case.

The Argus 4 reports the battery capacity spec and present capacity in its camera information menu. I do not know what effect, if any would be caused by fitting higher capacity cells in the battery pack. The firmware may just report the higher capacity without incident. The camera provides a maximum capacity indication on the battery meter and this may or may not remain accurate if higher capacity cells are fitted. The maximum capacity line indicates the amount of capacity that the batteries have and so decreases as the cells age and lose capacity. A very neat feature I must say.

Finally ..... I do not recommend rebuilding battery packs when they will be used in Fire Fighting situations as I have no knowledge of any specific specification that the cells must meet for such use. Where lives may depend upon a battery performing, OEM supplied or approved batteries are the safest option.

Fraser

Fraser
Posts: 19
Joined: Sun Mar 06, 2016 11:14 pm

Re: Rebuilding the battery packs

Post by Fraser » Wed Apr 20, 2016 1:42 am

Further to my last......

The BQ2010 battery 'gas gauge' chip can operate in absolute or relative capacity modes. In the ARGUS 4 it operates in Absolute mode so the capacity of the cells when new is programmed into it.
Fortunately the capacity programming is via the states set up on some of the ICs pins and not via software. The BQ2010 data sheet contains full details.

This is why the ARGUS 4 states a specific battery capacity and then current capacity with an indicator of age related capacity reduction. It knows what the battery capacity was when new and checks the capacity with every full discharge and charge cycle. If you wish to use different capacity cells to that set in the BQ2010, just change the programming by following the data sheet guidance. My worn out batteries were configured for 2.3Ah cells. Looking back at old ARGUS 4 specs it appears that 2.0Ah, 2.1Ah and 2.3Ah cells have been used in the battery packs over the years. It is best to buy good quality branded cells of a slightly lower capacity than unknown cells claiming higher capacity at cheaper prices. Such capacity claims are often found to be wildly exaggerated and the cells do not last well. I had some claiming to be 2600mAh and they were really only 600mAh. Cheap Chinese cells with fake capacity markings on their cases. I have even had VAPEX battery packs providing only half their claimed capacity. Be careful in your cell selection.

I have ordered a pile of nice VARTA 2.1Ah long life Ni-Mh AA cells that hold their charge for many months thanks to technology developments. They are also designed to be compatible with standard Ni-Mh chargers. They should be fine for the ARGUS 4.

Fraser

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Re: Rebuilding the battery packs

Post by forum_admin » Wed Apr 20, 2016 1:25 pm

A couple of things to be aware of with BQ2010 and cell swaps:

Firstly there is also a preset value for self discharge on the BQ2010, older PCB cells would probably be set for C/47 to match older cells, but current NiMH are effectively zero discharge. It is a pin on the BQ2010.

Secondly is a problem with any gas gauge, which is aligning the 'logical' capacity of the gas gauge with the 'chemical' capacity of the cells. Your replaced cells will be partly full while the gas gauge will have initialised to empty. You'd need a carefully constructed charge/discharge cycle to do that, or a PC old enough to run the BQ2010 software correctly (DOS 6.2 on a 386 !)

Fraser
Posts: 19
Joined: Sun Mar 06, 2016 11:14 pm

Re: Rebuilding the battery packs

Post by Fraser » Wed Apr 20, 2016 8:36 pm

Many thanks for the info.

I was going to discharge the cells on my battery analyser before connecting it to the PCB. I would then charge the ARGUS battery in its correct charger.
Does this sound reasonable ?

I do have 386, 486 and Pentium II laptops that have DOS on them so I could try the software if needed. I would have to build the 1 wire communications interface as well though.

Thanks again for the advice. Now to hunt down the software for the BQ2010

Fraser

Fraser
Posts: 19
Joined: Sun Mar 06, 2016 11:14 pm

Re: Rebuilding the battery packs

Post by Fraser » Wed Apr 20, 2016 8:52 pm

Fortunately Unitrode cover the issue of new batteries and user calibration in their BQ2010 use guide........

http://www.ti.com/lit/pdf/slua014

The stated procedure is to fully discharge the battery and then fully charge it. The next full discharge will synchronise the batteries to the BQ2010 and all will be well :)

I had a quick look for the software but no obvious source and TI do not list any software for the BQ2010 anymore.

Fraser
Last edited by Fraser on Wed Apr 20, 2016 10:58 pm, edited 1 time in total.

Fraser
Posts: 19
Joined: Sun Mar 06, 2016 11:14 pm

Re: Rebuilding the battery packs

Post by Fraser » Wed Apr 20, 2016 9:26 pm

BQStudio software is to be found here ......

http://www.ti.com/tool/bqstudio

Fraser

forum_admin
Site Admin
Posts: 59
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Re: Rebuilding the battery packs

Post by forum_admin » Thu Apr 21, 2016 10:00 pm

BQ studio is far too modern.......

Files attached, have virus checked etc but all use is at your own risk.

the main limitation is that it uses a serial port as hardware to create a 300 baud data rate in absolute timing. Windows drivers wreck it, hence the need for an old motherboard and DOS to run the nicer EV2010.exe

AP10A.exe runs on more modern machines (up to XP era) booted to DOS but is command line only.
Attachments
ev2010.zip
BQ2010 software 1994
(92.26 KiB) Downloaded 265 times

Fraser
Posts: 19
Joined: Sun Mar 06, 2016 11:14 pm

Re: Rebuilding the battery packs

Post by Fraser » Fri Apr 29, 2016 4:23 pm

Many Thanks for the help

Fraser

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