Geoff, it looks like you might have been creating something there..a bit of fun with VB or something perhaps? Very nice.

By for now, must go, need to see how my batteries are charging!!!

That will be pretty interesting for SLAs.

we have a number of old equipment using NiCd batteries and we use the Triton 2 to cycle the batteries.

From the manual of the Triton 2 (can be downloaded from the above link) :

Cell manufacturers note three main benefits of cycling NiCd and NiMH batteries:
1. Battery maintenance: NiCd batteries benefit the most from regular cycling to help keep them in good operating condition, and is recommended once monthly. NiMH batteries do not require as much cycling.
2. Determining battery condition: NiCd and NiMH batteries are rated by how much charge energy or “capacity” they can store compared to their rated capacity. A battery that can supply only a small fraction of its rated capacity is likely reaching the end of its useful life and may need to be replaced.
3. Breaking-in batteries: new NiCd and NiMH batteries may need to be broken-in before they will perform to their specifications. Older batteries which have been unused for an extended length of time may require to be broken-in again to regain their usefulness. Repeated cycling is the best way to revive such batteries.

We use page 2 of the Triton 2 Battery Memory Charts in setting up the proper charge current settings.

Tony. Visual Foxpro (as usual). And the DOS version in FoxPro 2.6 (naturally). Both freely available for anyone who wants them.

Do you use the Optimizer ... or some other bit of kit?

Alan. Yes the C/20 calculation is only necessary for SLA's (as far as I am aware).

Thanks for that information on the Triton. I'll take a look at it later (I'm up to my ears in floppy disk controllers and other "interesting" stuff at the moment)!

How do you get on with SLA's. Do you consider the C/20 aspect?

Hi Geoff,

Thankfully, we don't have that much SLAs to warrant getting a dedicated charger. We replace the batteries after 2 years or if the machine doesn't pass the recommended time for battery operation (done during PM). With some of the "not so smart" SLAs which fail the time test, we discharge it and then charge using the Triton. Most of the time, we can verify that the battery needs to be replaced as it'll charge halfway or wont charge at all.

We are looking into dedicated charger though as we would go for one or two brands in our upcoming hospital building.

Regards,
Alan

Check out the download (and, if you like, the DOS version).

In addition to rated voltage and Ah capacity, Sealed Lead Acid batteries have a "C" rating designed to meet specific load applications, such as C/5, C/10 and C/20. The vast majority of SLA batteries are rated C/20, which means they are designed to provide 1/20th of the stated Ah capacity for 20 hours. For example, 7 Ah/20 = 350 mA load for 20 hours.

So SLA are typically rated using a C/20 discharge rate and because the Optimizer discharges at 600 mAh, it is necessary to apply a calculation when using a Discharge Only or Analyze cycle capacity reading on the Optimizer 2000.

The formula to use is:-

Cap C/20 = (Cf(CapOpt-0.225))+Offset

Cap C/20 is the capacity the battery should read if discharged over 20 hours (ie, at the C/20 rate).

Cf is the correction factor for the nominal capacity of the battery according to the Correction Factors chart.

CapOpt is the capacity result given by the Optimizer.

Offset is also according to the Correction Factors chart against the nominal capacity of the battery under test.

Example:- Nominal battery capacity 2.3 Ah. This would be the expected result at a 20 hour discharge. Say that the result from the Optimizer was 1.75 Ah. First, we would need to refer to the Correction Factors chart supplied by the manufacturer of the Optimizer, where we would find that the correction factor Cf for a 2.3 Ah SLA battery is 1.29. We would note also that the Offset figure for this battery is 258 mAH (note that the C/20 Calculator program refers to this chart in the form of the database file C20.dbf). So, by applying the formula:-

(1.29x(1.75-0.225))+0.258 we get 2.225 Ah

and (2.225/2.3)x100 gives 97%

The C/20 Calculator program saves you the effort of applying the formula, as it is embedded into the program. Note that the 80/85/90/95/100% radio buttons simply change the initial (target) value given in the Opt field (that is, the hoped for result given at the end of the Optimizer test run). Many biomedical engineering departments take 80% as an acceptable "pass" mark. Although they do not alter the C/20 calculation in any way, these values are also stored in the C20.dbf database file.