Batteries Sudden Death

Old batteries can be tempermental.  The MEWP's was playing up just the other day.  Then Pizza's decided to pack in on a cold snowy day.  The load test was showing 20A, when it should be over 400A!

Even when Kendrew's was checked the other day,  it was fine,  but I always worry the batteries over Winter.  In theory they don't like extreme temperatures,  so I should be equally worry in Summer,  but we probably worry more about the prospect of standing in the cold more.  Let's hope for a problem free Winter.