We use the YUASA NP14-12FR 12V, 24Ah sealed rechargeable lead-acid battery on our weather stattions. We have a few batteries that have been in storage for a while and I would like to charge them and test if they are still useable. Can anyone tell me what kind of charger we should buy to do this?
Just be sure to buy a charger designed for 12V sealed lead acid batteries.
Float chargers are cheap. 'Smart' chargers cost more, buy will charge the battery faster.
Before you connect them to a charger, check the voltage on the batteries.
Any battery below 10.5 volts is dead and isn't worth trying to charge.
Between 10.5 and 11.5 volts is a questionable range.
Six months on the shelf is long enough for any lead acid battery to self-discharge enough to be damaged.
My experience with cheap float chargers from discount suppliers has been mixed. I have had some fail in service and they then completely discharged that battery, ruining it.
My next chargers for business and personal (motorcycle) use will come from Yuasa. Check their products at
http://www.yuasabatteries.com/chargers.php
It is also a good website to learn about batteries in general.
The chargers with 'active desulfation' can extend the life of the battery. However, don't have a datalogger connected to the battery at the same time. Desulfation works by injecting electrical noise into the battery.