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Post by moonshadow on Nov 4, 2018 20:08:17 GMT
I am not fully up to speed on the “smart” charger/isolation system. I have been wondering if/when the engine battery is dead if the engine can be started with the house batteries. Automatic? Only with a set of jumper cables? There obviously is no “both” battery switch.
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Post by ForGrinsToo on Nov 4, 2018 20:32:57 GMT
Negative lines generally are tied together, so what you need is a "jumper" from one battery bank to the other. Some have installed a battery switch to effect that.
Geoff
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Post by chuckr on Nov 5, 2018 7:10:19 GMT
We have had to do it a couple of times - and yea jumper cables - we also have a little solar and used it too.
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Post by mikebz on Nov 5, 2018 11:29:55 GMT
Our boat has a NASA battery monitor fitted which has a 100A shunt in the -ve line of the domestic batteries. So if we were to just use a +ve jump lead to start the engine from the domestic batteries then all of the current for the starter motor would go through the shunt., which might not be a great idea.
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Post by ForGrinsToo on Nov 5, 2018 18:24:16 GMT
Very good point! A starter can pull 100 - 200 A.
Since I installed my shunt, I know that both sets batteries feed on one side of the shunt from the negative battery switch. The engine/starter is connected to the same side of the shunt. Only the distribution panel draws from the other side of the shunt, so that my battery monitor only looks at consumption from the house bank. I would not assume that every vessel has been similarly wired.
Geoff
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Post by rc sail on Nov 5, 2018 19:41:54 GMT
as others have noted I think you could safely use a jumper cable from house batteries to get engine started.
I am assuming your house bank of batteries is 2 or more batteries. If in a situation where your engine battery
flames out you can always swap in a house battery in place of the dead engine battery to get you started. Been there and done that this summer to get back to home port. Resulting from the factory installed Cistec battery charger staying in
boost mode and frying 3 batteries.
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Post by rdubs on Nov 7, 2018 17:21:40 GMT
I am not fully up to speed on the “smart” charger/isolation system. I have been wondering if/when the engine battery is dead if the engine can be started with the house batteries. Automatic? Only with a set of jumper cables? There obviously is no “both” battery switch. Hi Moonshadow I spent a lot of time studying my SO469 electrical diagrams, back when I was having to wire in an inverter. The ground is common to both the house and the engine start battery. So all you'd need to do is run a jumper from the engine positive battery terminal to the positive of the house bank under the rear mattresses and you should be good to go. Or as RC Sail said, just swap out the physical battery. The isolation system is designed to prevent trying to force a charge into a charging source. So for example if you have the engine running at 13.6 Volts, that is providing charging voltage via the alternator. But if you have an additional charging source, such as the AC-powered battery chargers or solar, running say at 14 Volts, that higher voltage source would try to force charge down the lower voltage charging source. The isolator prevents this and keeps the current coming out of a charging source only flowing out, never in. What it does not do is use a higher voltage from one battery set to replenish a diminished charge in another battery set. This is actually good - let's say you have a bad / vampire battery in the house or engine battery. If you cross-connected the batteries, that vampire battery would suck everything connected with it down. By having the battery systems isolated, even if a battery goes bad and drains the bank, you still have the other bank you can use to get the engine / generator started to replenish the drained bank. By the way, what ever happened to that problem you were having where your boat would pull to one side under power? Did I remember that right? 'dubs |
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Post by moonshadow on Nov 13, 2018 23:07:10 GMT
Thanks for the help
Dubs- yes the boat will still pull to right under power. Slowly at first, then it seems the rudder is following the propwash and turns more aggressively. Maybe my three blade flex fold mated to the saildrive causes this ?
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Post by NZL50505 on Nov 15, 2018 0:16:32 GMT
I am not fully up to speed on the “smart” charger/isolation system. I have been wondering if/when the engine battery is dead if the engine can be started with the house batteries. Automatic? Only with a set of jumper cables? There obviously is no “both” battery switch. There is on my 2006 42DS. It's a parallel switch situated between the House and Start master switches. When I close this switch is joins my House and Start batteries together enabling me to start from my House bank. No jump cables required.
Don't the rest of you all have this???
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Post by allegria on Nov 15, 2018 2:28:16 GMT
Hi All,
I do have a parallel emergency switch on my 2010 SO 36i which I installed myself but this was not standard.
I did hide it, i.e. it is not next the other battery switches, to avoid being turned on "accidentally".
Cheers,
Allegria
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Post by puravida35 on Nov 15, 2018 13:26:49 GMT
I am not fully up to speed on the “smart” charger/isolation system. I have been wondering if/when the engine battery is dead if the engine can be started with the house batteries. Automatic? Only with a set of jumper cables? There obviously is no “both” battery switch. There is on my 2006 42DS. It's a parallel switch situated between the House and Start master switches. When I close this switch is joins my House and Start batteries together enabling me to start from my House bank. No jump cables required.
Don't the rest of you all have this???
Can you provide a photo of this switch? |
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Post by Don Reaves on Nov 15, 2018 21:41:08 GMT
I also added such a switch. You can see a picture in this post. It's the big red switch at the top in the middle.
Don
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Post by NZL50505 on Nov 21, 2018 23:59:43 GMT
There is on my 2006 42DS. It's a parallel switch situated between the House and Start master switches. When I close this switch is joins my House and Start batteries together enabling me to start from my House bank. No jump cables required.
Don't the rest of you all have this???
Can you provide a photo of this switch? It looks like this:
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Post by vasko on Nov 22, 2018 6:15:20 GMT
My suggestion two jumper cables , not only for the + but for the ground also - keep in mind that a starter motor uses about 380amps for the initial seconds and about 180amps while turning.
In my case batteries are pretty close and when I needed to do it after a “pro” servicing the boat has left the engine room cooling fan running ( I specially have a quite one) I just attached the engine battery leads to the house bank.
Also just upgrade to LiFePo4 20AH starting battery - in reality has A LOT more juice to turn the starter (about 8 minute good turning) -then a 120ah standard battery and akso keep higher voltage 14v e.g the starter is a lot happier and power is about 1100CCA - I use it for about 5 years now and extreamly happy.
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