Testing Leisure battery health? Discharge test?

[da_murphster]

TLR version - how do you get a discharge test on a leisure battery??

Hi, I had a 110AH Xtreme AGM Leisure Battery (XR1750) as recommended by travelvolts and used by many on here.

After a while it struggled to power my fridge for more than a few hours - I mean to do a warranty claim but time slipped by and I'm now past the warranty date.

I have just bought this (as the Xtreme 110ah does not seem to be for sale anymore)

LAGM-110LL

A 12v 110Ah AGM Leisure Battery, perfect for Marine, Canal Boat, Motorhome and Caravan use. ORDER BEFORE 3PM FOR FREE NEXT DAY DELIVERY.

batterystore.co.uk

Which is made by the same people as is near identical specs - apart from being usefully smaller and annoyingly missing the 'feet' so my standard battery clamps do not work!

I have an automotive battery tester that confirmed the old battery was knackered but stated the new battery as only being 66% State of Health.

I contacted the selling company who have been very helpful but stated that the tester is not suitable as it tests for CCA which leisure batterys are not designed to do - they said I need a discharge test.

Google is failing me on where to go for a discharge test - anyone know how to get one?

 

[roadtripper]

Testing company is correct - a starter battery has a large number of closely packed plates to generate a high current as it's job is to fire the starter motor and huge surge of current and then essentially do nothing much - a leisure battery has a smaller number of heavier plates designed to delivery current over hours/days and be more resistant (within limits) to the damage of discharge below 50%

Common leisure battery designs will often just about crank an engine so a reading of around 70% is in that ball park - some vehicles like boats use a common battery bank for both.

The gold standard for a discharge test would be if you had something like a Victron shunt and discharged at a moderate rate of a few amps - the logged capacity can be then compared against the rated capacity.

Failing that a popular choice on the forum is one of the BM2 type bluetooth battery monitors. While not being highly accurate they do continuously log the battery voltage and so under moderate current input or draw can be approximated to capacity. A log over a few days of use will often give you a good idea of how well the battery is performing - or if there are any parasitic loads that may cause it to loose charge.

Remember what ever you do to not let the battery stay drop under 50% much or for any length of time - this is the area on a lead acid battery that irreversible damage will build up and limit the capacity permanently.