Simultaneous charging dis-similar batterys..

Don't worry there are a lot of auto elecs living in the dark ages.

With our agreement to sell batterys we have to have a certain type of charger.

I manage to charge 3 x AGM's all the same with 2 Gel Batteries which are different at the same time. I can however disconnect a bank temporarily. Whilst it isn't ideal the gels haven't got long to go, nearly 8 years old now and will replace with AGM's. I use 2 different Ctek 25amp chargers at the same time and engine alternators when going. (Marine App)

Despite all the Marketing hype, must Battery Isolators simply connect the Auxiliary Battery directly in parallel with the Starter Battery - there is simply no regulation of current into either battery.

This works because Lead Acid batteries are self-regulating in normal circumstances - i.e. if they are not heavily discharged, temperatures are in a normal range and they are not left on for days.

You cannot charge batteries in parallel of they have different charge voltages e.g conventional Lead Acid in parallel with Calcium-Calcium batteries.

There is not much problem with charging mixed type batteries in parallel from a vehicle alternator - the big problem is leaving them connected in parallel without the alternator running.

There is nothing new about using one of the older Vane chargers to charge many dissimilar batteries. They operated the batteries in series and controlled the current so as not to charge the lowest capacity too quickly. Whilst charging they monitored the batteries with a hydrometer to check when to disconnect them. You would walk into the local garage and see a few 6 V and 2 V batteries on the charger and occasionally a 12 V one as well. (The 2 V batteries were used to supply the cathodes/heaters in the old console battery radios.)

PeterD