VSR

[ghostlymoron]

I'm in the middle of re-wiring my boat and have a VSR and 2 batteries charged by engine and solar. Is it OK to connect the solar to the VSR as well as the generator (not alternator) as I'm slightly concerned that the start battery will not recharge from the generator within the likely run time. The generator only produces 135W.

 

[VicS]

I'm in the middle of re-wiring my boat and have a VSR and 2 batteries charged by engine and solar. Is it OK to connect the solar to the VSR as well as the generator (not alternator) as I'm slightly concerned that the start battery will not recharge from the generator within the likely run time. The generator only produces 135W.

Yes you can connect the solar to the same battery as the generator.

If you are concerned that the starter battery may not be charged connect the generator output to it and allow the VSR to connect the house battery when it is recharged.

Some VSRs are dual sensing which enables secondary charging to be connected to the other battery.

 

[ghostlymoron]

My VSR is only single sensing so I will connect both sources of power to the start battery and it will then overflow to the leisure when full.

 

[Ruffles]

Do you have to ensure that solar panels are always connected to a battery? I'm thinking it's possible to have equipment connected to a supply charged by a solar panel that then gets disconnected from the battery. Don't they have quite a high open circuit voltage?

 

[Pete7]

My VSR is only single sensing so I will connect both sources of power to the start battery and it will then overflow to the leisure when full.

Which is what I initially did, then found the relay clicking in and out every five minutes. What happens is the solar charges up the engine battery until it reaches 13.7 volts (I think) when the VSR connects to the house bank with a clunk. If the house bank is low then the voltage drops below 12.8v and the VSR disconnects with another clunk. The process then repeats over and over only stopping when the sun goes down. The solution was to connect the solar panels on the house bank.

Pete

 

[ghostlymoron]

Sounds like a good plan. That is how I used did it on my last boat but I'm concerned at the ability of my generator to recharge the start battery. Still, I've got a starting handle (and jump leads). Seriously, I may include a bypass bypass switch.

 

[snooks]

Your engine/generator battery should only be used to start the engine/generator, once that happens the charge in that battery is replaced, then and only then does the vsr kick in and charge go into house batteries. Once the charge falls the engine battery is isolated and should retain it's charge as nothing will be using it.

Your house batteries are the ones in need of the charge from the solar panel, not your engine one.

My wind gen goes straight to the house batteries, the 240v battery charger goes to the engine battery. As soon as shore power goes on, the vsr clicks and all batteries are connected and being charged.

 

[pmagowan]

Your engine/generator battery should only be used to start the engine/generator, once that happens the charge in that battery is replaced, then and only then does the vsr kick in and charge go into house batteries. Once the charge falls the engine battery is isolated and should retain it's charge as nothing will be using it.

Your house batteries are the ones in need of the charge from the solar panel, not your engine one.

My wind gen goes straight to the house batteries, the 240v battery charger goes to the engine battery. As soon as shore power goes on, the vsr clicks and all batteries are connected and being charged.

I always kind of wondered what happens to the 'smart' chargers when the VSR connects the two batteries. There is lots of stuff in their literature about how clever they are at sensing the battery and charging it in 7 or 8 stages but surely suddenly connecting a whole other battery will disrupt this process. I charge my house battery and if I want to charge my start battery also I engage the emergency parallel switch. The charger immediately senses something has changed and changes its 'tune' but whether this is a good idea or not I don't know.

 

[halcyon]

I always kind of wondered what happens to the 'smart' chargers when the VSR connects the two batteries.

As the VSR engages early in the charge cycle, all the charger sees is a small blip as the voltage falls when the service battery comes on line.

Back in 1986 we introduced a multi-stage charger that was interfaced to the VSR. This charged the service battery to 14.2/14.3 volt, then closed the VSR and charge the engine battery to 14.2/14.3 volt. If twin engine banks the second engine battery was charged, then the system dropped to 13.6 volt float/power supply.

Brian

 

[William_H]

I think OP should leave the engine battery on the generator and the VSR then connecting that to the house battery. (As he has it) He should connect the solar panel to the house battery alone. The engine generator will quickly replace the smallamount of discharge from engine start. good luck olewill

 

[ghostlymoron]

The only reason i was considering a change from the norm was the poor output from the generator. When starting i may draw 200a for 30s = 100amin . My generator is 135w or 135/12 = 11a. So in theory the recharge time is 100/11 = 9 min which is ok. In practice the generator output may drop so the recharge time could double. I guess i'll just have to keep an eye on it.

 

[William_H]

Presumably you have a Dyna starter or old generator and separate starter. I reckon that eventually you will find your self looking at fitting an alternator on the engine. They can provide more charge at idle because the physical design of the rotor means it can be geared for higher speed and still cope with top engine revs. You won't need an especially big alternator to do much better than generator.
I would suggest if you don't have one fit an amp meter to your generator. You may find that charge current into the engine battery is indeed limited by the capacity of the generator. ie at about 10 amps and for a longer period. But if charge current starts to fall off quickly after start then perhaps an alternator will not do so much for engine battery charging. I am sure it will give you a lot better charge of both batteries combined. good luck olewill

 

[VicS]

Presumably you have a Dyna starter or old generator and separate starter. good luck olewill

Yes he has a Dynastarter on a Volvo Penta MD1 in a Mirror Offshore.

Adding an alternator may be an option. It wont be cheap or easily done I suspect. It will need mounting brackets to be made and a pulley added to the flywheel to drive it. Theres not a lot of space for adding bits in a Mirror. I'd not like to speculate on the feasibility.

The Op is obviously worried about recharging the starter battery. For that reason it may be sensible to keep the solar panel connected to the stater battery.
He has a 20 watt solar panel with a basic on/off controller so a reasonable amount of solar power available to top up the 55Ah starter battery if necessary and then put some power into the domestic battery via the VSR

Dunno what his domestic battery is. Couple of months or so ago he decided against fitting one, opting for just a 65 Ah engine battery.

 

[JumbleDuck]

I'm in the middle of re-wiring my boat and have a VSR and 2 batteries charged by engine and solar. Is it OK to connect the solar to the VSR as well as the generator (not alternator) as I'm slightly concerned that the start battery will not recharge from the generator within the likely run time. The generator only produces 135W.

If your starter battery will not recharge within the likely run time, there is something seriously wrong with your system. My 1GM10 has a 1kW/80A starter and a 35A alternator, so each 1s of cranking time needs 80/35 = 2.3 seconds of charging time to replenish. A normal start needs around 5s of cranking, so my battery is recharged after about 11.5s of engine running.

In general you can assume that the engine will take care of its own battery, so you can send the solar power where it's actually needed: the house battery. As others have pointed out, feeding solar into the engine side of a VSR may result in the thing clicking in and out if the house battery is low.

My solution, for what it's worth, was to use a dual battery solar controller and a VSR which only operates when the engine is running. That should take care of self-discharge in the start battery, but mainly feed the house battery. I'll know how well it works in five weeks.

 

[ghostlymoron]

Vics, you've obviously been following my vacillations! You've got my current setup spot on.
Jumbleduck, I would have thought your starter took more than 80a on startup. I can't replace my Dynastart with an alternator much as I'd like to because I'd also have to find room for a starter.

 

[VicS]

If your starter battery will not recharge within the likely run time, there is something seriously wrong with your system. My 1GM10 has a 1kW/80A starter and a 35A alternator, so each 1s of cranking time needs 80/35 = 2.3 seconds of charging time to replenish. A normal start needs around 5s of cranking, so my battery is recharged after about 11.5s of engine running.

I think you are being optimistic. The 1 kWatt starter motor rating is probably its output power. The power consumption is likely to be much greater or at least would be based on a terminal voltage somewhat lower than 12 volts.

You also assume that you will recharge the battery at a steady 35 amps. This is unlikely.

The OP sees his problems as much longer cranking times and a much smaller output from his Dynastarter . Mind you I suspect he is being as pessimistic as you are optimistic.

 

[JumbleDuck]

Jumbleduck, I would have thought your starter took more than 80a on startup. I can't replace my Dynastart with an alternator much as I'd like to because I'd also have to find room for a starter.

It's a 1kW starter motor so, yes, only 80A when running, though there will be a higher transient when it starts. Even though the Dynastart is fairly low output (10A or so, as I recall) it should still be able to replace the charge used for starting very quickly, so you really shouldn't have to worry about anything other than self-discharge in the starter battery.