Thread: Which battery charger - dual batteries

Originally Posted by RHS58

I have a Traxide DBS and charge the aux battery through the Anderson plug at the rear. Allows me th charge and still lock the vehicle.
As long as the batteries aren't isolated, both batteries are being charged together, as I understand things.
Same thing I reckon if you charge the main battery, if not isolated from aux then both will charge.

I have a C-Tek which cost about $300 odd a few years ago. Its got various cycles, and hence I am cautious about charging a battery that is connected to another. Also while I understand my vehicle starter battery is an AGM, with probably a larger output for starting, its a different battery in characteristics to the I think smaller capacity yellow top 55AH battery.

The yellow actually is more like 66 AH, due to the way Optima rate their capacities. But the yellow top also charges very quickly. Hence it cannot be treated the same as the main starter battery, which I think is while an AGM, behaves very differently in charge acceptance. While linked batteries equalize to some extent, their characteristics for charging would be very different due to different types, capacities, usage and charging characteristics. IMO at least.

Originally Posted by Melbourne Park

I have a C-Tek which cost about $300 odd a few years ago. Its got various cycles, and hence I am cautious about charging a battery that is connected to another. Also while I understand my vehicle starter battery is an AGM, with probably a larger output for starting, its a different battery in characteristics to the I think smaller capacity yellow top 55AH battery.

The yellow actually is more like 66 AH, due to the way Optima rate their capacities. But the yellow top also charges very quickly. Hence it cannot be treated the same as the main starter battery, which I think is while an AGM, behaves very differently in charge acceptance. While linked batteries equalize to some extent, their characteristics for charging would be very different due to different types, capacities, usage and charging characteristics. IMO at least.

Very good point.i have always wondered about that.Mine are always charged together,both AGM,no issues so far.

Over to Tim.

[QUOTE=Melbourne Park;2393161] the main starter battery, which I think is while an AGM, behaves very differently in charge acceptance. QUOTE]
I have the impression that having an AGM in the engine compartment is not good for the battery as they're not heat tolerant!
Steve

Hi folks, only when charging different types of batteries, and/or batteries at different states of charge, by an alternator, will each battery charge at its now optimum charge rate.

This is the biggest advantage of using an alternator to charge any form of lead acid battery.

When charging mixed forms of lead acid batteries by a battery charger, DC/DC device or by solar, all the batteries will charge at the same voltage level of charge over the entire charge cycle. No one battery will charge faster than another.

But unlike when using an alternator to charge different forms of batteries, when using any of the devices above, you must first determine which battery in the mix, has the lowest maximum voltage tolerance, and then you need to set the charging device so that it does not exceed that voltage during charging.

But note, even when the charge voltage is set to a lower level, all the batteries will still be charged.

Hi Steve and some vehicles will destroy Standby type AGMs but automotive grade AGMs, like Optimas, will tolerate any environmental situation a standard cranking battery will tolerate. Horse for courses!

So DriveSafe I guess what you are saying is that if you want to charge two batteries linked by your device, its best to isolate one and charge them individually?

Originally Posted by Melbourne Park

So DriveSafe I guess what you are saying is that if you want to charge two batteries linked by your device, its best to isolate one and charge them individually?

No, I have just posted that there is no reason to have to separate different types of lead acid batteries when charging, no matter what type of charger you are using.

While on the topic of Batteries, does anybody know which other batteries will fit in the aux location on a D3 with terminal locations that would match the Traxide system?

Originally Posted by austastar

After this experience I intend to wire in an external Anderson plug to the starter battery, and have a convenient switch in the earth wire of the SC80 to force isolation for max charge to the starter battery.

Here's one I prepared earlier. Cut the DBS feed and on the starting battery side installed a Anderson SB50 plus a ground cable to the earth studs then a Anderson PP75 to feed the isolator.
As for the On/Auto switch for the isolator just wired a switch on the brown earth wire.
Way too much time on my hands.