Follow below steps:

1) Go to

Settings ‣ Translations ‣ Import / Export ‣ Export Translations

leave the language to the default (new language/empty template) # DO NOT CHANGE THIS

select the PO File format

select your module

click Export and download the file

2) Add your translation terms in the downloaded file. i.e. msgstr "" section depending on your translation language

3) change the filename to language_iso_code.po

e.g. for portugese => pt.po

4) create i18n folder under your module and add po file in it.

5) restart Odoo

6) Go to:

Settings ‣ Translations ‣ Load a Translation

select translation language (in my eg. Portugese)

make sure you check this : Overwrite Existing Terms

click LOAD.

DONE

Hi,

for version6 (perhaps 7 too), to have the translation loaded for you modules with inheritance, you have to add in __openerp__.py line section :

'sequence': 150,

in fact, translations are read by sequence and by alphabetic order (lower to greater). Default value for sequence parameter (which you should not have add) is 100. And if you have a module beginning by a letter < first letter of module inherited, your translation will be read first and your modifications will not be used. Restart openerp server to valid modification naturally.

Bye

Although this is not a solution to your problem, a have chosen a different approach. I have a folder with all the .po files in my language. I have written a script to load all the po files in that folder. Here is the script:

#!/bin/bash

shopt -s nullglob
# Path and the list of files to import. 
FILES=/opt/openerp/mk_MK/*-mk.po
# Database in which to import the files.
DATABASE=openerp_db
# Language you are importing.
LANG=mk_MK

for f in $FILES
do
  echo "Processing $f file..."
  # take action on each file. $f store current file name
./openerp-server -d $DATABASE -l $LANG --i18n-import=$f --i18n-overwrite
done

I'm running my testing server on ubuntu 12.10

I get the same issue. All my updates in po files are not updated even if I restart the server with option -u all.

Did anyone find a solution?

AFAIK, there was a design decision to be made: either to allow users to change translations from the GUI, or to always override user's translations with .po files.

Currently the tradeoff is made in favour of being able to manually change translations from the GUI.

See the corresponding bug report here: bugs.launchpad.net/openobject-server/+bug/1166776

If you don't need the ability to change translations from the GUI (Settings => Translations => Application Terms => Translated Terms), then you could apply the fixes proposed in the bug report and its comments.

Another solution is to manually re-import the changed .po file from Settings => Translations => Import/Export => Import Translation. In some cases the records imported this way may fail to have 'module' value set correctly (it may be empty), which prevents the translation from working properly. This can be fixed by setting the right module value from within PgAdmin.

I tried so many method but i found really easy way to update po files.

First Step : Update your po files at backend.

Second Step : Go to Translations-> Languages and select another language then select activate button and switch the language. 

Last Step: Go again languages, select the language which you update , after all switch the updated  language then all updates will come on your database.   Easy peasy...

For me just do like this and it works fine:
Settings / Languages / Manage Languages
In the language list click "Update" the current language does not update the new text.

try to remove all tranlations like this

delete from public.ir_model_fields where model like 'your_module'

then update your module in odoo

 I am new to odoo and facing the exact same issue. I updated the .po files and I don't know to force odoo to ignore the cached translation/ir_translation and use the ones in po files. I will appreciate your kind help on this as I need to deploy it in many places so I can't just translate it from GUI all from the beginning for every deployment. Thanks!

I removed the rights for the specific module (which translation should be updated) from user, logoff/log in to check if the module removed succefully. 

After, I gave the same module again to the same user, logoff/login. 

Finally, I discovered the module rights just given above is coming with the updated translation. 

Language Translation in OpenERP- Zesty Beanz Technologies Blog

Hello,

I've the same problems, Transalation are finished in .po file and imported in openerp but all fielsd and words are not transale untill now!

any helps please

Several times i recognised to update base module before seeing the results of your modified .po files

1. Go to Settings / Installed Modules
2. In search field enter "base" as a filter
3. Open "base" module in form view
4. Click on upgrade

This should load and update all .po files, because all addons have base as minimum requirement (dependency).