AGM Batteries in Caravans.

[Thingy]

My current AGM battery is perhaps coming to the end of its life based on age, and I have been looking at replacements. I am finding information that didnt seem to be out there at the time I bought the current battery, and there seems to be a lot of discussion as to whether the chargers in caravans are suitable for these.

Apologies if this has already been covered, but what is the general opinion.

Apparently, CAMC stated
The C&MC article states something like :-
"In general, it's probably best to avoid AGM batteries unless you are absolutely sure your charger is suitable, as the otherwise excellent performance counts for little if the performance is compromised through damage by inappropriate charging".

I am not making any personal statements about this because in truth, I simply do not know. There also seems to be some thought as to whether solar panels can damage AGMs. I have been reading the following article
http://www.aandncaravanservices.co.uk/agm-batteries.php
and i have to confess that I am utterly bewildered.

What do you guys use. Perhaps Damian can jump in on this?

I am currently considering this battery.
https://www.alpha-batteries.co.uk/12v-yuasa-100ah-efb-leisure-battery-l36-efb/

The NCC appartently rate batteries as follows
Category A is for batteries with a higher storage capacity for people who frequently use their touring caravan or motorhome away from an electrical hook-up:

• Category B batteries are aimed at those who frequently use sites with hook-up facilities, but require a greater battery capacity to operate devices such as motor movers:

• Category C batteries are for users that require a lower capacity battery to cover basic operation of their habitation equipment for short periods away from an electrical hook-up:

and have provided a chart of their recommended models. See
https://www.thencc.org.uk/downloads/Verified_Battery_Register_03.10.2018.pdf

 

[Damian]

AGM batteries when properly looked after last a lot longer than the flooded wet cell batteries, and provide much better load rates without damage.

They do have specific recharge requirements, and that is the charger must be of the lower amperage range as too many amps input will damage the battery.

It is difficult to say for certainty whether a caravan charger is the right one as there are quite a lot of differences between makers, so one must get the very best information from the charger unit makers.

What category battery one needs is dependent on what is "normal" use for the individual, the more time away from a EHU would tend to favour the A class , the majority of time with EHU, then B or C

 

[Thingy]

You are quite right in what you say about longevity. My current AGM is now into old age.
I am assuming that the charger is a Sargent PX300 the book states that:
For optimum performance and safety it is essential that only a proprietary brand LEISURE battery is used with a typical capacity of 75 to 120 Ah (Ampere / hours). A normal car battery is NOT suitable. This battery should always be connected when the system is in use.The PSU is configured to work with standard lead acid leisure batteries, and in most cases is also compatible with the latest range of Absorbed Glass Matt (AGM) batteries.

The battery category I need is def the Class B, no wild camping for us. Its more for the motor mover.

Am I right in thinking then that the three stage charger
During stage 1 the battery voltage is increased gradually while the current is limited to start the charging process and protect the battery. At stage 2 the voltage rises to 14.4V to deliver the bulk charge to the battery. When the battery is charged, the voltage is decreased at stage 3 to 13.6V to deliver a float charge to maintain the battery in the fully charged state. The charger can be left switched on continuously as required
is fine for an AGM battery that requires
Ideal Charge Voltage 14.1v - 14.6v
Top Up Charge Voltage 13.5 - 13.8V

 

[Damian]

Yes you are right as the charger you describe limits the current whilst increasing the voltage.
Excess current is the AGM killer.

 

[Thingy]

Next task is to find one with post terminals instead of flag at the right side. Most seem to be layout 0 and you guessed it, I need layout 1.

 

[Raywood]

I am afraid I just bought whatever the dealer sold, and it has worked perfectly well for the last few years. It is the wrong type for the mover but it has still survived, although basically we only use the mover for putting it back into storage and the odd time on site to position the caravan accurately.

 

[Thingy]

Pretty much what I did last time, and its been on three caravans. However this caravan is a vastly different animal and I need to be a bit more savvy.

 

[Buckman]

We have an AGM battery in the caravans as it comes standard with the battery. We have a solar panel and found that the solar panel controller needed to be adjusted for the AGM battery. Also we found out that a normal stand alone charger has issues charging an AGM battery and you need to be careful.