Charging AGM batteries (via split charger) in a car

[CompoSimmonite]

I understand AGM batteries need some sort of special battery monitor or whatever when charging so I can't simply use a split charger in a car .
How, therefore, do I charge a AGM battery in a camper conversion ?
Cheers.

 

[hotponyshoes]

Search for DC DC Charger

 

[voipio]

There is very little difference between the recommended charge voltages for AGM and flooded lead acid batteries. AGM are reckoned to need around 0.3V higher for bulk charge, and about the same (13.6-13.8V) for float charge, so really no special charger needed. However, the so called smart charging systems in modern cars can take the main vehicle battery up to 15.5V or thereabouts, at times, in order to dump charge into them faster, which may no sut the AGMs so much, in which case a DC to DC charger would be better.

 

[m_c]

DCDC is nearly always better for split charging, regardless of the battery type.

As has been said, AGM isn't that much different in terms of charging voltages, and will quite happily operate as a direct replacement for conventional batteries, however when they're suitably flat, they will extract every ounce of power possible from the alternator, which is why they're not really recommended as a replacement on older vehicles with basic alternators.
They can also be charged at a higher voltage to get them to charge even quicker.

What vehicle are you converting?
If it's got any kind of smart charging (some vehicles have had Smart Charging for 20years), then you have to consider where it's connected.

Also, for a new conversion, I'd seriously consider LiFePo4 as an alternative, as they give better performance, last longer, and aren't that much more expensive now for comparable Ah. However they don't like sub-zero temperatures.

 

[carbon]

I use a Ctek dc to dc charger in my van to charge an agm battery that runs my night heater and interior lights etc. The agm battery has just been replaced after about seven years