small solar panel question. charging an AGM battery

[forresto]

I am going away for a few days fishing and have a 12V 7.5 watt portable charger.
I am charging 2 small 12V AGM batteries.
My device pulls .75A at 12V max.

AGMs are usually charged at a higher voltage so.....
Is this small solar charger going to do anything for charging?
Is hooking up the solar panel to the batteries while running the device a good idea or a bad one?

thanks, hope someone can help.

[SunEagle]

Depends. Most of those small chargers only provide enough to keep a battery at "float" level. They usually do not have enough power to charge a battery from 75% SOC back to 100%.

If you run a device at the same time you are trying to charge your batteries from solar the device will take the lions share of the charging power which usually means the batteries do not get much.

[forresto]

thank you SunEagle. I will leave the solar panel on at the same time.

For increasing a depleted battery charge:
So if the AGM battery usually charges at ~14V@2A my low power 12V @500mA will never be able to charge that battery from 75% to say 90% if I leave it on for even lets say a week?

OK learned more.......sulfation it I am going from dead to full charge....will open another thread about voltage.
thanks.