My 03 Alphard 2.4 Hybrid E-four ATH10 campervan has drained the leisure and starter battery even with nothing on and now relies on a noco to start it every time.

I've replaced the leisure battery and that had it's life sucked out within the week. The starter battery is under a captain's seat and I can't see what it is to order a new one. I'm well past my prime and only want one attempt at removing the seat!

It had a new starter battery in 2021 but doesn't state it's details on the receipt.

The hybrid had to be refurbished in 2023, it's costing more in batteries than lpg & petrol 😂

Hi. I am also interested in the answer to this. My starter battery under the drivers seat may need replacing and I want to order it before I send it to the garage. Thanks to whoever can help!

Check with your conversion company to see what battery they installed. It has to be low enough to clear the underside of the seat, I guess it is raised up slightly with a swivel base. If it is a CampervanCo conversion they installed a Red top AGM battery in mine.

Thanks @Jeza - it was indeed done by CamperVan Co and from what I can see through the gap under the seat I have the same battery. Brilliant help, thanks.

Because of its small capacity of 44Ah, it is important to keep it charged up if not regularly using the vehicle, at least once a week. I plug in the AC hook up every week ,with a dehumidifier running inside as well when not using the van after the roads have been gritted or a foot of snow as we have now.

We used Tayna Batteries, excellent delivery and stock age, product support was very good.

Optima red top battery RTR 3.7 product code 8035-255.

Price in August 2025 £155:77

You need to find out what is draining your batteries. If it is just parked up with the fridge turned off, the leisure battery should not be getting drained in a week. Even then, it shouldn't drain the main 12V battery as well.

25 minutes ago, smurf said:

You need to find out what is draining your batteries. If it is just parked up with the fridge turned off, the leisure battery should not be getting drained in a week. Even then, it shouldn't drain the main 12V battery as well.

I agree with Richard,

Your leisure battery should be partially isolated from your starter battery, probably by a split relay circuit.

There are other advanced circuits that do connect the leisure battery bi-directionally to the starter battery, but I doubt you have one of those.

Check your mood lighting, and any other after market gizmos that may have been fitted; ensure they are off or even isolated.

In the extreme weather we have experienced lately many starter batteries will fail to start the engine; and will need a full recharge, even if the battery is fundamentally servicable.

The cold is a battery killer.

How about your alternator, and chance that has failed ?

AND, VERY IMPORTANT, check the condition of your battery terminals, at both ends.

Any 'corrosion' can have a startling (pun intended) effect on the battery's ability to deliver starting current.

Measure the battery voltage across the terminals with a voltmeter.

No engine about 12.6, maybe 12,2v. Any lower will be a problem.

10.5v battery has a dead cell.

With the engine running the voltage output should be well into 13v and maybe even 14v if the battery is fully discharged and being charged by the alternator