Weak Batteries ?

[wayneakp]

Hi

When I try to start Sea Jem neither engine will crank on its own battery - I have to use the link - which seems to suggest that both batteries are weak. The dealer did suggest it might be how they are wired - they told me they did a drop test and the batteries were o.k - . I am now thinking about changing the cranking batteries. There are however three in the box - the other for domestic - all have thick cables to them and they all seem to be linked so I am noit sure which ones to change.

Are there any electrical experts out they that can advise?

thanks

Wayne

[Antares_9]

Truth is it will be almost impossible to do anything other than guess without information on the isolation switches etc, my setup for instance provides for the domestic and cranking battery to be bridged in an emergency but has four separate isolator switches including a master return isolator. Best advice I can offer is trace upstream from the domestic isolation switch (the one with the lighter cable on the isolatable side)

[mbird]

I had to replace two out of the three batteries on Serenity a couple of weeks back. We had three cranking type batteries, of which one is solely for starting the port engine. The other two are linked in paralled and provide all the domestic power as well as starting the starboard engine. The two banks each have their own isolator switch, and it's fairly easy to see what does what.

In the first instance, I would suggest taking all the batteries to be tested (Brian Wards at Brundall did ours) as we have recently learned that what we have been told, and indeed got invoices for, ain't necessarily the case

The other thing we found in the course of replacing the linking solenoid which didn't work, was that the battery charger was not isolating the two banks from each other and was infact joining them together as one big bank. This meant that the two duff batteries we had were constantly trying to be charged by the one good one, meaning that iff shorepower was unplugged for more than 12 hours, they all ended up flat.

The first thing to check would be the voltage on each battery. If they all read the same, the likelyhood is they are all linked somewhere.

[diesel falcon]

hi,

personally i wouldn,t bother which battery does what ,i would just change them all out ,if you have two bad batteries and replace them with new leaving an old one ,you still have a weak link, i,d buy three combined cranking and deep cycle batteries and have done with it.

Trev

[wayneakp]

Another learning experiance today:

With the help of a very nice guy found out that two of the batteries are linked for domestic and the third starts both engines. The batteries are all good, it seems the problem is the cranking battery is a domestic one so it cannot give the engines the whallop they need.

I will be going out to buy a cranking battery and guess keep the domestic as a spare.

Thanks for your help

Wayne

[diesel falcon]

hI,

not heard of that set up before,mine has a craking battery for each engine,and one domestic,with a 3 way split doiode for charging from any engine,when moored overnight ,with no shore power we isolate the starting batteries and use the domestic only for lights/tele ect,that set up is a new one on me?

[wayneakp]

Aparently there are two domestic "leisure" batteries - linked together to give a longer use time. The third battery is a cranking battery which is wired to start either of the engines. There is a solenoid that will link the cranking and the domestics should the cranking battery be low.

regards

Wayne

[diesel falcon]

with you now