sealed lead acid batteries in series

Quite.

On my MK 8GU1H batteries require:

Charge Voltage @ 77°F (25°C) Cycle 13.8 -14.6 volts Float 13.4 -13.6 volts

1. Bulk charge: a constant current of 1A is delivered until the voltage reaches 14.3V.
2. Charge maintenance: a voltage of 13.6V is delivered for 30 minutes following each voltage retention test, with sufficient current to sustain it against natural self-discharge or drain from permanently active vehicle components or connected accessories (alarm, immobiliser).

Cheers, T i m

Yes, that's fine for a valve regulated wet cell lead acid battery which can be topped up but totally inappropriate for Gel and AGM sealed lead acid batteries which can only tolerate low rates of electrolysis, hence the 13.8v recommendation chosen to limit the gassing rate to a tolerable level for the Gel and AGM types of VRLA.

The data is from a Panasonic LR-RA1212P, which is a non-refillable VRLA with AGM technology...

Thomas Prufer

Similarly, my 2 x 14.5V = 29V figure for cyclic charging came from a Yuasa datasheet for an NP17-12i which is also an AGM/VRLA type. I would be surprised if Bill's battery wasn't essentially the same type ...

I guess, with my concern over standby float charging requirements, that's one interesting 'nugget' that's obviously passed me by. Thanks for that heads up. Next time I'm perusing SLA data sheets, I'll be sure to take a closer look. :-)

AGM ain't the same as gel SLA.

Yep, We know. :-)