Battery keeps going flat


Ex. Club Member
Battery keeps going flat (abit of back story)

A reconditioned Alternator was purchased in June 2020

A new battery was purchased in October (the same day I started to pull the 1.0L out). Did the engine swap and the car started first time with no issues every day up until the 29th December

Ever since then its been hit and miss with starting. The cold weather at the beginning of 2021 certainly didn't help.

I swapped the battery under warranty in March and it was fine for a few weeks then it started to play up again.

I've recleaned all of the earth points in the engine bay including the battery posts and battery terminals.

I've done a parasitic draw test. The negative battery post/earth strap test came back as 0.25mA

I recharged the battery and it was fine for a week or so. Left the car unused over a weekend and monday morning it was flat.

Last week I mounted a 1.5W solar trickle charger to the dash but that hasnt really helped.

With the car running, the alternator postitive terminal reads 14.1v where as the power lead from the alternator on the battery side shows 13.8/9v

When the car gets jump started, I drive approx 4 miles (city) to/from work. Perhaps this isnt long enough but doesnt explain why it died a week after I bench charged it.

Ive got a spare used alternator I can try while I contact the seller for the current unit

Any other ideas?


Ex. Club Member
Fitted a battery isolator switch which seemed to have cured the issue so there is a draw somewhere.

I then disconnected the gauges and left the switch on and it has been fine ever since. I've now fitted a switch for the gauges so thats 2 birds with 1 stone
When I did my engine conversion I used a Suzuki alternator, I originally wired it up as for the micra but found the alternator was a little warm and the battery draining, it seems the Suzuki alternator wanted a switched power feed rather than what the micra wiring loom had, it was a while ago now so I may not have remembered correctly, perhaps something similar with your new alternator?