Hello!

I have several DT85 loggers installed to working on batteries. They are equipped with SMSX modem and it is powered by the relay. Somehow the logger do not go to sleep mode every now and then, and it runs the battery flat.

I think that the problem is related to the modem that is scheduled to be on ones a week for two hours. However, I am not sure. Problem does not occur all the time, loggers may be working weeks just fine.

Every time problem happens, battery goes flat fast. My code is:

RB("B:",ALARMS:OV:100KB,DATA:OV:1MB)10M LOGONB GB 
ALARM(4ST><0.8000,1.8000)AND ALARM(3ST><12.0000,14.0000)1RELAY 
'this is for modem 
ALARM(4ST><0.8000,1.8000)AND ALARM(3ST><12.0000,13.0000)AND ALARM(2ST>5.0000)1CV 
'this is for SMS 
RC("B:",ALARMS:OV:100KB,DATA:OV:1MB)1+CV LOGONC GC 
DO"et-sms=0|xxx |nnnn|60^M"

I have powered the logger and the modem by separate batteries. It is always the logger battery that goes flat. My schedule A is driven only ones per hour, so that should not take so much power.

My sensors are powered from the modem's battery. Only thing that could take so much power is that the logger do not go to sleep mode every now and then. Why, that I don't know.

Dear Hessu,

Is the P15 parameters set to its default value? If so (= 0) and the logger is powered by external source (like external batteries) the logger won't sleep. To do so, set P15=1 in order to allow sleeping even if power source is applied to the logger's external power input.

Please give also a look at page 197 of DT8x's user manual.

Regards
teo

Teo:
Thanks for the advice!

Most likely I have the P15 on default. However, I'm not sure is the P15 value the problem that I'm dealing with. I have a DT85 on my desk at the office. It will always sleep after the P17.

The setup is similar like on the field. The problem is that loggers on the field work fine most of the time. Sometimes (let say ones in a three months) logger takes a lot of power and runs it's battery flat. Until that the power consumption has been minimal.

I thought that I found a solution and I installed an external relay and an alarm clock on one logger. The clock makes a hard reset daily. I thought that it would solve the problem, but I found out that this increased power consumption occurs ca. twice a week after a hard reset.

It lasts at least 16 hours (probably 24 hours, until next hard reset). It does not happen every time. Still the problem could be solved with the P15.

I have replaced the original battery with Duracell batteries and my supply voltage is a bit higher than nominal supply voltage. Could that cause an occasional. problem?

Best regards,
Hessu

Good morning Hessu,

P17 is only the Delay to low power mode (How long the logger waits before gong to sleep) P15 controls the conditions under which the logger will go to sleep.
From page 196 of the current DT80 user manual (A9) the allowed values of P15 are:

0 = Allow sleep if battery powered and Ethernet/USB not connected
1 = Allow sleep if Ethernet/ USB not connected
2 = Do not allow sleep
3 = Allow sleep
4 = Allow sleep if battery powered

Please refer to page 227 for more complete description.

DT80 will also wake up if there is incoming data on the RS232 port. Which original battery have you replaced with "Duracell" batteries? How have you connected these batteries to DT80?

Cheers,
Roger

Roger:

I have replaced the lead acid battery with Duracell alkaline batteries. I have connected batteries to either original lead acid battery wires or to the terminal on the left side between pins c and -. I have removed the lead acid battery.

I understand that the communication on serial port will wake up the logger. That is why I guessed that the problem might be related on powering the modem. If the relay stays on, logger doesn't sleep. You can find my code from the first post.

Where can I find the most recent user manual (A9)? Version A8 is on the web.

Thanks
Hessu

Dear Hessu,

In your case P15 to its default value shouldn't affect, as the logger sees 6V voltage on battery connector. In your first post you mentioned schedule A, but the code posted doesn't include it (maybe doesn't have any effect, but please, post the entire code).

Supposing a faulty relay (very unlikely, I don't know if this as never happened yet...) for debugging purpose you may add an acquisition on modem supply voltage every X hours, just to see if the relay is working properly.

Hope this help.

Good afternoon Hessu,

I have just been speaking to our hardware engineer and we DO NOT recommend you connect alkaline batteries to the DT80. Alkaline batteries have very different characteristic to lead acid batteries that the DT80 is designed to take and you may damage the alkaline batteries , DT80 or both.

Please use 6 VDC Lead acid batteries with a maximum capacity of 4 Ahrs. As for the version of the manual. We will be releasing a new firmware version soon and I am working from the new manual (sorry guys)

Cheers,
Roger.

Good very early morning Roger!

I'm sorry about the message that was a phone number included. However, the number wasn't any one voice number, but still traceable. I won't post such things anymore.

I will work on the battery issue. The main reason why I replaced the lead acid battery was that I'm using the loggers on area where temperature may be as low as -40 degC. My concern was the self discharge of lead acid battery. Alkaline battery doesn't have that problem, but the voltage is very sensitive for temperature and load. The latter may be one reason why I have the original problem.

When I built these measuring stations the loggers went to forced sleep mode on cold weather due to low supply voltage. Then I put some more battery cells on the system and they have been working fine. Except that every now and then something drives the battery flat.

One thing that I don't fully understand is that why I cannot use larger capacity lead acid battery than 4 Ah?

Thanks
Hessu

Dear Roger and Hessu,

Interesting, the misunderstanding in use of alkaline batteries may come from this:
In this case an external 6V battery (any type and capacity) is again connected to the C and - terminals (user manual, page 189 on version A8 or page 218 on A9 version).

The paragraph refers to "External Battery with External Charger" but I suppose that is applicable also in case of using batteries without any charger. In my interpretation the 4 Ah limitation is only applicable if the external lead acid is charged by the logger, Roger please confirm.

regards

Good morning Teo and others,

Ok to clarify exactly. You can use other types of batteries as long as you NEVER plug in the 12 VDC supply. If you do the internal battery charger will kick in and try to recharge the batteries as if they were lead acid this can damage your batteries and/ or dataTaker.

Cheers,
Roger

Hi Hessu,

You are aware of the fact that normal alkaline batteries (I think that's what you use and called "Duracell") have indeed much better thermal characteristics concerning very low temperatures than lead acid batteries but will have their capacity reduced drastically with temperatures as low as - 40 degrees Celsius nevertheless.

Do you measure the ambient temperature in your schedule and have you checked the data for any coincidence of your power loss and very low temperatures?

Cheers,
Belibs