Jump Start.

[Relayer]

Evening All

I have a twin diesel boat and one of the batteries may be flat.....shall find out tomorrow.  Is there a specific procedure to jump start the flat battery from the good battery?|

Many thanks.

 

[CambridgeCabby]

Have you not got a splitter switch ?

[Relayer]

I believe I have just have two isolation switches, one for each engine/battery.....boat is very new to me.

 

[CambridgeCabby]

What type of boat (engines) is it 

[Relayer]

Have also noticed that with both isolators switched off I still seem to have power at the ignition keys. Had assumed that with isolators switch off there would be no power at the ignition keys.

[Relayer]

Cleopatra 850.  Two 1800 Ford diesels.

[CambridgeCabby]

Not a model I’m that familiar with tbh .

I would initially disconnect the starter battery and put on trickle charge. That is presuming you do not have a shore power battery charger fitted  .

If your isolator switches are turned off then you shouldn’t be getting any power to the helm .

mum sure someone far more knowledgeable than myself will be along shortly to help .

In our Ocean which is twin engine, we had a switch on the dash which linked the starter battery with the domestics to start the engine if the starter battery was flat , the starboard engine started on the starter battery the port on the domestics.

[Smoggy]

My princess 30ds has a button at the helm that activates a solenoid between starter and domestic bank for jumping, you could just use a jump lead between isolators or battery banks.

If all isolators are off there should be no power to the helm only fused power to auto bilge pumps and radio memory.

Is there another isolator somewhere that you've not found?

[ranworthbreeze]

3 minutes ago, Smoggy said:

My princess 30ds has a button at the helm that activates a solenoid between starter and domestic bank for jumping, you could just use a jump lead between isolators or battery banks.

If all isolators are off there should be no power to the helm only fused power to auto bilge pumps and radio memory.

Is there another isolator somewhere that you've not found?

We have a similar shorting switch when batteries are low on Ranworth Breeze, but I have only used it once in all the years we have had our share. The boat was managed at the time but the starter battery needed 6 bottles of distilled water to top it up to the correct level. 

[BrundallNavy]

If it has two engine batteries I would think it has an isolated for each and a third for domestic. 

[Relayer]

6 minutes ago, BrundallNavy said:

If it has two engine batteries I would think it has an isolated for each and a third for domestic. 

Correct. isolator for each starter battery and a third for domestic/leisure. 

[Smoggy]

Never worked out the logic behind a starter battery for each engine, once one has started there's an alternator helping the second start, when given some free batteries I did a little test, both engines with 30 seconds pre-heat and cranked simultaneously from winter cold,  both fired up fine, it was a 90ah agm from a 5 year old BMW (manufacture date stamped on battery post).

In normal use you never start both like that and always have a domestic bank to boost from.

[Relayer]

7 hours ago, Smoggy said:

Never worked out the logic behind a starter battery for each engine, once one has started there's an alternator helping the second start, when given some free batteries I did a little test, both engines with 30 seconds pre-heat and cranked simultaneously from winter cold,  both fired up fine, it was a 90ah agm from a 5 year old BMW (manufacture date stamped on battery post).

In normal use you never start both like that and always have a domestic bank to boost from.

That makes sense to me and maybe something I should look at for future.  Any tips on jump starting in the meantime?

[BrundallNavy]

1 hour ago, Relayer said:

That makes sense to me and maybe something I should look at for future.  Any tips on jump starting in the meantime?

Just a regular set of jump leads between both starter batteries.  

[annv]

Hi Relayer YES is the answer first do you just want to start the engine or do you want to check/change the battery. John

[Bikertov]

5 hours ago, BrundallNavy said:

Just a regular set of jump leads between both starter batteries.  

I would say make sure they are reasonably heavy duty, and not too thin. 

[Relayer]

7 hours ago, annv said:

Hi Relayer YES is the answer first do you just want to start the engine or do you want to check/change the battery. John

Start the engine....

[annv]

Hi Relayer ideally you should connect the positive terminal from donor battery to flat battery then negative terminal from donar battery to a bare metal part on flat battery's engine,   then start up doner engine and run for several minitse OR charge battery for 24hrs with battery charger this will prevent any surges/ damage to flat engine circuitry. BUT i guess that the two engines are connected by 100 amp earth wire that connects at the starter motors retainer bolts in which case after making certain there are no fumes by running engine room extractor fans connect positive of flat battery then to positive of donner battery then wait a minute or so then start up engine run for a couple of minutes then remove pos lead in reverse order. I would suggest that you only need one starter battery for both engines A 100 amp 13 plate Automotive lead acid with highest cranking amps this will last forever mine is 12 years old so far with no sign of wear AND get it from a Motor Factors not Halfords or wilco.or domestic/starter battery.    then connect both alternators to a advanced regulator (i use Sterling ones). then chose the highest number of domestic you can fit wired in parallel connected so positive supply cable comes from first/No1 and negative supply cable from last and if not on mains electric get a small solar panel to maintain the battery's voltage when your not there. John

[Bikertov]

If you are a member, Costco are quite good on pricing for automotive batteries, if you say they can be used rather than specific marine ones.

[annv]

Hi I'm advocating QUALITY batteries not the cheapest crap unless you only want it to last a couple of years. i use to fit UNIPART batteries as not only where they very good but gave a life time guarantee to the original purchaser along with a credit card size warranty card this would last in glove box indefinitely as against a paper receipt,  had a customer who had a honda from new he only bought the one battery and as he hardly used it the battery's only lasted four or five years i use to say that a taxi would be cheaper but he wouldn't part with it so every four or five years a new free battery. John

[Bikertov]

Costco sell Bosch batteries IIRC, with either 3 or 5 year guarantees. 

I think if they fail in the timescales, you get back proportionally for the time left on the guarantee.

https://www.costco.co.uk/bosch-battery-guide

 

Edited January 17, 2022 by Bikertov
Edited to add link to Costco

[Smoggy]

At least no-one has suggested a tow start yet or getting out and pushing.

[annv]

Hi Biker you need to be careful when ordering a battery for a car as many  cars today have different needs than older vehicles which just needed to turn engine over. Stop start cars need a different type of battery which won't suit a boat engine when i sorted a battery twelve years ago for my new boat the one that was most suitable ie size, length, height,and cold cranking turned out to be for a Rolls Royce,  that vehicle todays battery would not be suitable for a boat engine today, as engine starting spec's have changed for new cars. John

[Bikertov]

3 minutes ago, Smoggy said:

At least no-one has suggested a tow start yet or getting out and pushing.

That's why Lada's had heated rear screens - to keep your hands warm when you bump started them 

[annv]

If you tow a boat the prop will turn enough to damage some gearboxes so  possible but unlikely. John