Warning: I am an amateur on the learning curve with this stuff.
Steve and I are figuring out how to live with ACR-based charging systems on our boats. He proposed that we start a thread on this topic, so here goes.
My tentative charging/ignition schematic, showing the ACR:
My tentative ignition panel schematic:
The ACR Steve and I are using:
Blue Sea ACR 7610
Combiner battery switch 5511e
(both in kit 7650 http://bluesea.com/category/2/productline/overview/329)
Basic circuit with this kit: http://bluesea.com/files/images/products/7650.jpg. I am not endorsing this kit, it just happened to be available at a good price, and seemed to do what I want. Nor do I have any connection with Blue Sea.
There is an interesting thread on this in the Whaler forum:
For discussion, let's assume a simple system on 20's foot sailboat:
Two batteries, both the same age, type and brand.
One battery in a house circuit, the other battery dedicated to engine start only.
The battery combiner switch is ON-OFF-COMBINE.
The ACR is not in the engine starter circuit. One cable goes to the engine battery (+) post, the other goes to the house battery (+) post. When the battery being charged gets up over 13-something volts, the ACR turns on and parallels the two batteries, allowing the second battery to be charged as well as the first.
The alternator output goes to the engine start battery.
The shore power output goes to the house battery. Shore battery chargers usually have multiple outputs and are smart enough to charge different batteries separately. This is an issue when there is an ACR paralleling the two batteries.
Some issues:
1. Ignitiion panel voltmeter should be set to measure what? If across the (+) Battery terminal on the ignition key and (-) ground, then when the ACR is off it will measure voltage in the engine start battery circuit, but when the ACR is on it will measure the combined voltage of both batteries. That's OK by me, because all I want to know is that the alternator is charging, but not over-volting.
2. Engine start battery dies at anchor for some reason. I can combine the batteries to start the engine using the battery swtich set to COMBINE and then put the switch back to ON when the engine starts. The alternator will then provide electricity to keep the engine running, but if the voltage on the engine start battery remains below 13, the ACR will not parallel the batteries and the house battery will not get a charge. In that situation, should the battery switch be left in COMBINE, continuously paralleling the engine and house circuits?
3. The boat has a dual-output shore power charger to maintain the two batteries independently. Some chargers do not mind having their outputs paralleled, although that defeats the purpose of paying for an expensive multibank charger. Blue Sea has posted two tech papers on their website to provide solutions. I went with using two batteries the same and simply attaching one of the two shore power output cables (to the house battery). My logic is that because both batteries are the same, they can be treated as one battery for all intents and purposes.
4. Measuring current. I took the ammeter out of the ignition panel and now have an ammeter in the cabin. It is easy to interrupt a cable to insert an ammeter shunt in any circuit (just costs money and time), but I decided to put the shunt in the house battery ground cable, following Blue Sea's recommendation. A handheld clamp ammeter is not expensive and can be used to check currents in other circuits as required. I have a set of notes for interpreting the ammeter readings for different ACR states.
5. The ACR will not combine unless the charging system has an output voltage that will get the batteries above the ACR's threshold volts. My old 35 amp alternator only put out 13.1 volts, so I upgraded to the MMI 55 amp alternator which should produce over 14.
There is much to discuss.
Steve and I are figuring out how to live with ACR-based charging systems on our boats. He proposed that we start a thread on this topic, so here goes.
My tentative charging/ignition schematic, showing the ACR:
My tentative ignition panel schematic:
The ACR Steve and I are using:
Blue Sea ACR 7610
Combiner battery switch 5511e
(both in kit 7650 http://bluesea.com/category/2/productline/overview/329)
Basic circuit with this kit: http://bluesea.com/files/images/products/7650.jpg. I am not endorsing this kit, it just happened to be available at a good price, and seemed to do what I want. Nor do I have any connection with Blue Sea.
There is an interesting thread on this in the Whaler forum:
For discussion, let's assume a simple system on 20's foot sailboat:
Two batteries, both the same age, type and brand.
One battery in a house circuit, the other battery dedicated to engine start only.
The battery combiner switch is ON-OFF-COMBINE.
The ACR is not in the engine starter circuit. One cable goes to the engine battery (+) post, the other goes to the house battery (+) post. When the battery being charged gets up over 13-something volts, the ACR turns on and parallels the two batteries, allowing the second battery to be charged as well as the first.
The alternator output goes to the engine start battery.
The shore power output goes to the house battery. Shore battery chargers usually have multiple outputs and are smart enough to charge different batteries separately. This is an issue when there is an ACR paralleling the two batteries.
Some issues:
1. Ignitiion panel voltmeter should be set to measure what? If across the (+) Battery terminal on the ignition key and (-) ground, then when the ACR is off it will measure voltage in the engine start battery circuit, but when the ACR is on it will measure the combined voltage of both batteries. That's OK by me, because all I want to know is that the alternator is charging, but not over-volting.
2. Engine start battery dies at anchor for some reason. I can combine the batteries to start the engine using the battery swtich set to COMBINE and then put the switch back to ON when the engine starts. The alternator will then provide electricity to keep the engine running, but if the voltage on the engine start battery remains below 13, the ACR will not parallel the batteries and the house battery will not get a charge. In that situation, should the battery switch be left in COMBINE, continuously paralleling the engine and house circuits?
3. The boat has a dual-output shore power charger to maintain the two batteries independently. Some chargers do not mind having their outputs paralleled, although that defeats the purpose of paying for an expensive multibank charger. Blue Sea has posted two tech papers on their website to provide solutions. I went with using two batteries the same and simply attaching one of the two shore power output cables (to the house battery). My logic is that because both batteries are the same, they can be treated as one battery for all intents and purposes.
4. Measuring current. I took the ammeter out of the ignition panel and now have an ammeter in the cabin. It is easy to interrupt a cable to insert an ammeter shunt in any circuit (just costs money and time), but I decided to put the shunt in the house battery ground cable, following Blue Sea's recommendation. A handheld clamp ammeter is not expensive and can be used to check currents in other circuits as required. I have a set of notes for interpreting the ammeter readings for different ACR states.
5. The ACR will not combine unless the charging system has an output voltage that will get the batteries above the ACR's threshold volts. My old 35 amp alternator only put out 13.1 volts, so I upgraded to the MMI 55 amp alternator which should produce over 14.
There is much to discuss.
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