R29s battery charging questions

[JohnL]

My efforts to sort out the various battery charging options have raised the following questions:

1. When underway, does the engine alternator charge the engine battery first and then the house and thruster batteries via the two ACR relays? The available schematics don’t make this clear, showing only a connection between the engine battery and the starter.

2. Does the shore powered charger only connect to the house battery bank via the inverter cable and switch? This seems to be the case from the schematic but it surprised me since the cable, switch and fuse are labelled as ‘inverter’ and don’t mention the charger.

3. Which leads to my final question. Can the Kisae inverter/charger be switched off when the boat is plugged into shore power? I can’t find evidence of a switch on the unit or a switch or breaker in the boat’s electrical system.I would like to run a small heater during the winter while leaving battery charging to my two 160 watt solar panels. It seems wasteful to run the inverter/charger when it’s not being used.

 

[Andrew Custis]

Hello John,

At your convenience, please call us at the factory to assist. Better to be on the boat when you call. Office number is (253)-839-5213.

Thank you,

 

[JohnL]

I just finished a very helpful phone conversation with Andrew Custis on the three questions I raised at the start of this thread. I thought it might be helpful to share the answers with other R29s owners.

First, the answer is yes, the alternator does charge the engine battery first via the connection between the starter and the engine battery shown in the schematic. It then shares the charge with the other two battery banks via the ACR relays.

Second, the shore power charger connects to the house battery bank (and through the ACR relays to the other batteries) via the inverter switch and cable found in the port side cockpit locker. There is no separate circuit connecting only the charger to the house battery bank.

And, third, the Kisae charger/inverter cannot be turned off when the boat is connected to shore power. So, if you did not want to use either the charger or inverter when plugged in, the only option is to turn off the inverter switch in the cockpit locker. The charger/inverter will still be on in some form of standby.

I still have questions about how the shore power battery charger, solar panels and alternator work together with the ACRs. The latter are designed to open when the battery bank (one of the two single or the one four battery banks) being charged exceeds 13.2 volts for a couple of minutes. At that point the charging source is presented with a second battery bank that is likely to be at a different state of charge than the first bank. How does the controller or regulator of the three charging source deal with this? Does it carry on the charging cycle that would optimize one or the other battery bank (ie getting one or both banks up to at least 14.4 volts before moving to the absorption and float charging stages? Or does it now see the two battery banks as one bank and respond to the ‘average’ state of charge? Could this lead to the under or overcharging of one of the banks that could be hard on the batteries? And, if this a challenge for the controller or regulator of the charging source, surely the problem is compounded by the addition of the third battery bank to the mix when the second ACR senses that the two battery banks already being charged have reached 13.2 volts. And, what if you have two charging sources (alternator and solar panels, or charger and panels) engaging the batteries at the same time? Finally, dare we even contemplate how the solar panel controller default setting of a 90/10% sharing of charge between the house and engine batteries factors into this mix?

I’ve recently graduated from the sailing world where, in my long experience, well managed, relatively simple house and start battery systems had life spans of 8 years plus. In the Ranger/Cutwater threads that I have been following since joining the fleet I read that a number of skippers seem content if their batteries last more than three years. I’d like to be able to manage my battery banks so that they last a lot longer than that. To do that I need to have a clearer understanding of how the many pieces of our complex charging systems interact with each other. I’m making progress but I would benefit from more discussion of the above questions.



Sent from my iPad

 

[Red Raven]

Hi John,

I like to think of it this way...

Once the ACR requirements are met, the banks affected act as one bank (the adjustment of voltage between banks happens quickly as the batteries can source very high current between each other and the internal battery impedances will cover any voltage difference).

So...just just assume...that during most charging scenarios all batteries are being charged per the charging system in use at that time as follows:

On shore power... the shore power battery charger is in control and all batteries are managed by that profile.

Underway... the a alternator is in control and all batteries are managed by that “albeit basic” profile.

At anchor (if you have a solar panel(s) and controller)...the solar controller is in charge of all batteries as long as the solar voltage is above 13.2 volts.

There are clearly periods of time where this is not “ideal” but those periods are typically relatively short. Depending on your boating habits this may or may not be be an issue.

For most of us who are on shore power greater than 90% of the time it is probably just fine.

If you are running the engine more than 10% of the total hours it may make sense to upgrade the regulator.

If you spend a lot of time time at the dock under shore power with varying loads you may consider disabling the ACRs while under shore power to take advantage of the independent charging provided by your multi bank shore power charger.

If mostly charging under solar the ACRs are really the only option for keeping three battery banks charged though an MPPT controller would provide improved performance for all batteries.

I worry much more about the battery’s state than the particular charging scenario. Try not to ever let any of them get below 12.2 volts or so and they will be happy with all the above charging systems.

Curt