What is a "valve regulated" lead acid battery?

[Turbo DV8]

I acquired two of these 12 volt, 200 Ah lead acid batteries. They are sealed, but am wondering what "valve regulated" means. I have a charger that will charge up to 40 amperes, and when they are fully charged, I want to maintain them with Deltran Battery Tenders, which charge up to 14.1 - 14.4 volts, then lowers voltage to 13.5 - 13.7 volts and negligible current. I have read here that different types of lead acid batteries like to be charged up to different maximum voltages, so I am wondering if "valve regulated" refers to some type of gas recirculation, and if so, what is the maximum voltage I can safely charge such a battery?

I hook these up in parallel with cables thick as my thumb for 400 Ah and use with a 1500/3000 watt inverter... just for fun.

 

[FRANKVZ]

The sealed VRLA battery is a closed system in
which the quantity of electrolyte is limited, but
the gases resulting from energy production are
recombined to be reused instead of being
released to the atmosphere. Because the electrolyte
is recycled, there is no need to add
water to the batteries. Excess gas pressure that
may build up inside the battery is released
through a simple regulating valve to ensure
that structural integrity is not compromised.

From here: http://www1.eere.energy.gov/vehiclesandfuels/pdfs/success/vrla3_28_01.pdf

 

[soffiler]

+1 on FRANKVZ's post.

I'll add this: VRLA acts like a normal "flooded" LA battery for recharging and charge maintenance purposes. Pretty much any Deltran Battery Tender will work just fine.

There are at least two alternate technologies in LA, one called Gel and the other called Absorbed Glass Mat (AGM). Simplifed a bit, the Gel uses a gelled electrolyte and the AGM uses an electrolyte absorbed into a "sponge". AGM also recharges like a flooded LA. Gel is the one that is different. From a deep discharge, Gel requires a relatively high current to recharge correctly, and it also requires a slightly higher voltage to saturate and maintain charge. Deltran offers a tender that works for Gel.

 

[Turbo DV8]

How may I determine if my electrolyte is gel, liquid or other? I have read that liquid electrolyte can suffer from stratification if the battery is left unused but on maintenance charge for a long time. Should LA batteries with liquid electrolye be discharged a littel and recharged from time to time to "mix" up the electrolyte?

Another thing... is it OK to leave the two batteries left in parallel and on a single maintenance charger, or is it better to leave each battery on a separate charger?

 

[soffiler]

How may I determine if my electrolyte is gel, liquid or other? I have read that liquid electrolyte can suffer from stratification if the battery is left unused but on maintenance charge for a long time. Should LA batteries with liquid electrolye be discharged a littel and recharged from time to time to "mix" up the electrolyte?

Another thing... is it OK to leave the two batteries left in parallel and on a single maintenance charger, or is it better to leave each battery on a separate charger?

Let me introduce you to Battery University:

Fundamentals of flooded, SLA, and VRLA:
http://www.batteryuniversity.com/partone-6.htm

Acid stratification:
http://www.batteryuniversity.com/parttwo-42B.htm

There's a LOT more there, too. Surf around.