Stop-start batteries

[srah1953]

When I was in my local motor factors buying a new battery, they had a shelf of special AGM batteries for cars with a stop-start engine.
I was wondering if anybody knew what was particular to a stop-start battery? And whether there was any potential use on a sailboat?
Thanks

 

[pagoda]

When I was in my local motor factors buying a new battery, they had a shelf of special AGM batteries for cars with a stop-start engine.
I was wondering if anybody knew what was particular to a stop-start battery? And whether there was any potential use on a sailboat?
Thanks

Interesting idea.... but does anybody do STOP/START with a boat engine? On a canal with lots of locks or something?? Multiple high loads within a short time does not sound like average engine use while sailing to me?

 

[RichardS]

Interesting idea.... but does anybody do STOP/START with a boat engine? On a canal with lots of locks or something?? Multiple high loads within a short time does not sound like average engine use while sailing to me?

Errrrrr ...... that's got to be a wind-up, right?

Richard

 

[benchmark]

I have 2 Varta Dual purpose AGM batteries on my boat which work fine. The producers website states that it is Alain suitable for start-stop cars but that’s not the reason I bought them.

 

[MikeCC]

They're just AGM batteries and AGM is well-suited to stop-start applications. On a sailboat good for house battery as they function well as deep cycle. But no excuse for not having a good charging regime.

 

[pcatterall]

As I found when replacing my car stop start. The AGM ARE well suited to that use but there is one of those 'mystique' things ( Very special just for your model etc) going on where they are usually overprice the item

 

[srah1953]

Thanks for replies. Answered my curiosity.

 

[Momac]

A stop start system on a boat would be good thing regardless of motorboat or sailing.
It would detect if the gear is in neutral and the battery is in need of a charge - the technology exists I am sure. Do any new boats have this fitted?

 

[AntarcticPilot]

A stop start system on a boat would be good thing regardless of motorboat or sailing.
It would detect if the gear is in neutral and the battery is in need of a charge - the technology exists I am sure. Do any new boats have this fitted?

A friend has a solar powered narrowboat; basically a week's solar gives them a weekend's operation! But they have an auxiliary generator, which cuts in automatically if the charge level drops too low. I guess that's the kind of function you mean? I don't know the details of their system, but as it was fitted by the boatbuilder I guess it uses off the shelf components.

 

[Momac]

A friend has a solar powered narrowboat; basically a week's solar gives them a weekend's operation! But they have an auxiliary generator, which cuts in automatically if the charge level drops too low. I guess that's the kind of function you mean? .

Yes, but applied to the main engine or engines.
My car does the same thing if the traffic doesn't move for several minutes
It makes the battery and starter motor work harder but saves some diesel.

We are river based and do spend time idling in locks but too busy on ropes to be switching engine on and off manually.
A sailing boat sometimes may have the engine idling just in case it is needed.
A few minutes here and there may save a few litres . Probably not worth the expense or retro fitting but perhaps not a big cost to fit as standard if building a new boat.

 

[RichardS]

A stop start system on a boat would be good thing regardless of motorboat or sailing.
It would detect if the gear is in neutral and the battery is in need of a charge - the technology exists I am sure. Do any new boats have this fitted?

I have disabled the stop-start system on my car by reprogramming the CPU and would certainly do the same if the system existed on my boat. :ambivalence:

Richard

 

[Momac]

I have disabled the stop-start system on my car by reprogramming the CPU and would certainly do the same if the system existed on my boat. :ambivalence:

Richard

Why?
Don't you think it saves fuel?

The stop start may be deactivated on my car by pressing a button.

 

[RichardS]

The stop start may be deactivated on my car by pressing a button.

Until you start the engine next time .... probably.

Richard

 

[pagoda]

Yes, but applied to the main engine or engines.
My car does the same thing if the traffic doesn't move for several minutes
It makes the battery and starter motor work harder but saves some diesel.

We are river based and do spend time idling in locks but too busy on ropes to be switching engine on and off manually.
A sailing boat sometimes may have the engine idling just in case it is needed.
A few minutes here and there may save a few litres . Probably not worth the expense or retro fitting but perhaps not a big cost to fit as standard if building a new boat.

Any energy consumed by your starter motor is replaced by the alternator as it re-charges the battery. It increases fuel consumption above normal to achieve this. Repeated starts with limited running (charging) time are hard on batteries. Where the breakover point for fuel saved idling is balanced by fuel consumed re-charging batteries is not remotely clear and would take some serious investigation involving shunts and battery monitoring. Never heard it quoted anywhere?

 

[black mercury]

These start stop batteries have virtually zero internal resistance, which means that they charge up extremely quickly. You know when you put a normal lead acid battery on a 10amp battery charger the ohm meter would show roughly 5 to 6 amps which will slowly decrease as the battery approaches full charge. With a start stop battery it will take the full 10 amp charge rate. They are designed so they can be recharged extremely quickly by the alternator from one start to the next when in traffic. I can see a few advantages on a boat were the engine is only used for short amount of time, say when only used to motor out of marina and back in again, or were you need to charge the batteries quickly. They do have a huge starting amp rating when comparing size with a normal lead acid, but one thing to be aware of is the amp hour rating of these batteries is lower compared to same size of lead acid, so not much use as the house battery. They are also much more expensive.

 

[RupertW]

Until you start the engine next time .... probably.

Richard

Yes, my new (to me) car is the first one I've had with stop/start and every time I press the ignition button I press deactivate button next. Forgot to do it a couple of days ago and nearly got rammed on a roundabout as the extra unexpected couple of seconds really mattered.

 

[benchmark]

They do have a huge starting amp rating when comparing size with a normal lead acid, but one thing to be aware of is the amp hour rating of these batteries is lower compared to same size of lead acid, so not much use as the house battery. They are also much more expensive.

Not really, this is the AGM battery i use also recommended for start-stop cars
https://www.varta-automotive.com/en-gb/products/varta-professional-dual-purpose-agm/840-105-095

105 ah for those dimensions , it’s capacity in amp hours very much like other conventional wet batteries of that size.
With its capacity to outlive more charge cycles than a normal battery ,not to mention its better ability tolerate deep discharges without getting damaged and then quick charge faster than a conventional battery after that. If you claim it’s not much use as a house battery then I do not know what is.

 

[black mercury]

Yes the agm battery you refer to is ideal for a domestic battery, but it is not a stop start agm battery. The varta stop start range are blue or silver dynamics. Modern cars have a battery management system that is regulated by the car's ECU, the alternator has no built in regulator. Many marine chargers won't charge a stop start agm properly. You can now buy a automotive charger that has an Agm stop start charging mode, if you charge it with an ordinary charger set to gel you will ruin a stop start battery.

 

[srah1953]

Not really, this is the AGM battery i use also recommended for start-stop cars
https://www.varta-automotive.com/en-gb/products/varta-professional-dual-purpose-agm/840-105-095

105 ah for those dimensions , it’s capacity in amp hours very much like other conventional wet batteries of that size.
With its capacity to outlive more charge cycles than a normal battery ,not to mention its better ability tolerate deep discharges without getting damaged and then quick charge faster than a conventional battery after that. If you claim it’s not much use as a house battery then I do not know what is.

When I asked the question originally about the usefulness of stop start batteries on a boat I wasn't thinking in terms of stop starting the engine but whether the nature of these batteries was such that they might be good (or better) for deep discharge or repeated charging, as commented upon in this post. Or possibly a bow thruster where there could be a number of hard bursts if mooring in difficult conditions.

 

[PaulRainbow]

When I asked the question originally about the usefulness of stop start batteries on a boat I wasn't thinking in terms of stop starting the engine but whether the nature of these batteries was such that they might be good (or better) for deep discharge or repeated charging, as commented upon in this post. Or possibly a bow thruster where there could be a number of hard bursts if mooring in difficult conditions.

AGM or well suited to bow thrusters and are fitted as standard in many installations. They also make good engine batteries.

For domestic use, i'd have to question the use of the likes of the Varta battery above. For many, the pattern of use and cost of batteries still makes normal lead acid batteries well suited and cost effective. If that isn't the case, then i suspect you'd be better off with true deep cycle domestic batteries.