Alternator / Solar Panel Conflict

[ilenart]

Hi everyone,

just had a new alternator installed on my engine and after approx 20 minutes the engine battery warning light and alarm are going off. Have worked out there is some kind of conflict with the solar panel regulator. When I disable the solar panels the alarm stops. Soon as I turn the solar panels back on the alarm sounds. The batteries are full with the solar panels on float at 13.7v When I start the engine the voltage went to 13.9v then slowly drifted down to 13.75v, when the alarm went off.

The new alternator is a Bosch 120amp AL9120N and the solar panel regulator is a Victron MPPT SmartSolar MPPT 100/50 with 400w of panels. The engine is a Volvo Penta D2-55B with the original panel with warning light / alarm.

Turning off the solar panel whilst motoring solves the problem in the short term. However in the long term I suspect I will need to either adjust the voltage set point of the regulator on the alternator (if possible). Alternatively replacing the alternator regulator with a smart regulator maybe another option, which will also improve the charging from the engine.

Comments / thoughts appreciated.

Ilenart

[lateral]

The bosch AL9120N Vset is 14V so I think you are right, but you can confirm that with a DMM. It should be the same as what you have set the Victron. (of course)

Fortunately with that series bosch the internal regulation is part of the brush set assembly on the outside so easy to convert to external regulation with a lot of benefits in terms of configurability.

Vset
Absorbtion time
Float voltage
Belt manager (for times battery is really low and initially alt will be full fielding)
Battery/alt temp management
Soft start
Etc.

[NYSail]

Upgrade to external regulator. You can custom set voltage and charge times and much more to match your set up.

[lateral]

Quick search shows Transpo brushset/reg assembly up to 14.4 Vset on Ebay.
I suspect to 14.7.
They make Delco SI ones over a range of Vsets.
Still dumb though.
Regulatorless brushset here: https://www.aquavolt.com.au/product-...rs-accessories
Gee, I paid 14$ US for them. Ouch.

Do confirm that is a K1 alternator though.
Also if you like value for money:
https://www.240turbo.com/AdjustableVoltage.html#marine

[SVHarmonie]

This really isn't a problem, except for the alarm with is alerting you to a situation that isn't a really a problem.

An engine's alternator warning light and alarm are set up to go off whenever the alternator stops charging. This is measured by comparing the voltage at the outlet of the alternator to the battery. If the battery voltage is higher than the alternator, the alarm goes off because in an alternator only charging system this means the alternator has failed. An internally regulated alternator is never going to run the voltage up as high as a solar system during bulk charging, hence your annoying, and meaningless, alarms.

What you have is not a problem, except for the noise. My alternator system only has a warning light, which comes on all the time on sunny days when the solar system brings the voltage up. It's not a problem, it's not even really a "conflict" everything is working as it should... except for your damn buzzer.

You have a couple ways to deal with this.

Disconnect the buzzer, but if this is the same buzzer as your oil pressure you might want to try something else.

Disconnect the entire alternator alarm circuit. On a boat, you'll have other ways of seeing if the alternator has failed, and other charging systems, so this isn't such a bad idea.

You can set the alternator to run a few tenths of a volt above the solar system. This has the unfortunate effect of overcharging by the alternator, or undercharging with the solar system, but can work if you are aware of the issue and can manage it.

[lateral]

Why charge a battery bank under the manufacturers recommended absorb value?
Also its dumb. It derates as the alt heats up.
Reg is designed for an automobile.
Disconnecting a warning device, is fraught with law of unintended consequences.
But you are right, as a stop gap.

[ilenart]

Thanks everyone for your comments.

lateral where do you find that the voltage set point was 14v? According to this brochure it is 13.5v.

SVHarmonie agree that the main issue is fixing the alarm. Waiting to hear back from my Volvo Penta mechanic on the fault criteria for the alarm, ie what voltage is setting it off. However like lateral is suggesting, I may be able to fix the alarm problem and improve the charging from the alterntor at the same time.

Couple of options I am looking at for an external regulators include:

https://www.mastervolt.com/products/...alpha-pro-iii/

https://www.outbackmarine.com.au/mul...s-harness~2655

Also looks like Balmar has a marine version?

Ilenart

[facciatosta]

I am on the market for the solar panels and wonder myself about compatibility between alternator and solar panel controller.
1) Alternator may not putting out pure DC current and it rather fluctuates and creates AC harmonics that may affect solar panel controller. When alarm goes off did you check if solar panels still charges the battery?
2) More likely electrical impedances of alternator and solar panel controller are different and incompatible. That means that one of them sinks another and likely none of them works properly. In this case there got to be some external steering device allowing to charge the battery simultaneously( or one at the time) or built in circuitry in each of them. I doubt that either manufacturer had each other in mind when they designed their products

Why would you want solar panels to charge the battery while engine is running anyway? To me it is little gain with too much troubles. Connecting two power sources in parallel is never a good idea. Better keep it simple.

[hlev00]

We had the same problem with our Balmar alternator that is externally regulated and our solar panels that use Victron MPPT controllers. I don't recall whether we lowered the MPPT setting or increased the regulator / alternator, but we ultimately accomplished SVHarmonie's suggestion #3 - have the Solar set to charge a few tenths of a volt below the alternator. Maybe someday the alternator folks will get together with the solar folks and come up with an integrated controller that will sort all this out behind the scenes.

[Jack C]

Charging batteries from two charging systems at the same time is not advisable. You can mess with the settings but when the chargers are at different phases of charging it wont help. Chargers use time and voltage as inputs. It gets worse. A solar charger with low wattage panels can fool the alternator charger that the batteries are full. You motor all day then at night you find that the batteries are only partially charged. My simple solution is to disconnect the panels when the engine is running because the alternator typically provides more charge than the panels, although it slightly adds to fuel consumption. This can be done manually or via a relay driven by the boat ignition.

[stormalong]

I have a similar issue. I have two alternators on my engine, two battery banks and a battery combiner (ACR - Automatic charging relay). The original engine alternator charges the engine start battery and the high output alternator charges the house bank.

When the batteries get combined by the ACR and motoring for a long time the battery voltage rises above the cut out voltage of the original engine alternator and the tachometer stops working. The solution has been to disable the ACR. On top of this I have 290 watts of solar. I am not too concerned about the different charge profiles since anytime the battery voltage is that high I don't need all the charging sources. It is just an annoyance to loose the tachometer. When that happens it is usually during a long motor run. I just hit the disable switch on the ACR and I am happy. Some automated disable when the engine is running would be nice but not worth it for the few times this happens.

The primary purpose of the ACR on this setup is to keep the engine start battery fully charged when not running the engine for long intervals. The shore power charger and the solar go to the house bank.

[smac999]

13.7 is really high for. float. The default setting of the victrons is crazy. Lower to something realistic. Under the alt voltage.

[kenbo]

Originally Posted by smac999

13.7 is really high for. float. The default setting of the victrons is crazy. Lower to something realistic. Under the alt voltage.

I agree it's a bit high but not outrageous. Trojan calls for 13.5vdc for float.

Dual charge sources is not a problem as long as the regulator/controller are sensing the voltage at the battery.

[hlev00]

My simple solution is to disconnect the panels when the engine is running because the alternator typically provides more charge than the panels, although it slightly adds to fuel consumption. This can be done manually or via a relay driven by the boat ignition.

Interesting thought of using a relay to disable the solar charging. We did have an instance during our cruise last winter where our alternator failed and had to rely exclusively on solar charging for a week while we waited for a spare that we did not have. Including an override / disabling jumper for the relay would let us override in this case.

[Dsanduril]

The Volvo alarms are notorious for going off when the voltage gets "too high". On our D2-40s that is somewhere between 13.8 and 13.9V. The internal regulator on our default alternators is set for 13.8V (newer/other models might have different setpoints). Our solar is set to bulk at 14.2-14.4V, so if motoring and the batteries are full then the Volvo engine alarm will go off.

One solution (which is what we have) is to put a diode in-line with the voltage sensing wire to the Volvo panel. That will drop the voltage the engine panels sees by the diode's forward voltage, for a standard silicon diode that's about 0.6V. Gives you a low battery alarm sooner, which I don't really mind. If you want to get really fancy you can put a switch or relay (tied to the ignition circuit) around the diode so you can run with/without as you choose. Putting in the diode allows all the alarms, including the battery alarm, to still function but "adjusts" the battery voltage alarm hard-coded by Volvo.

[Edit]
Note that this is separate from any changes to the alternator/regulator setpoint. The voltage sensing for the alarm is in the engine control panel. If you install an external regulator that allows you to get a higher voltage from the alternator then you'll also get the high voltage alarm when charging by alternator. Hence the diode.

Nordkyn Design also makes an external controller for the stock alternator that does all of this for a few more $$$$ and keeps the alarm from going off. Not sure how/whether it would work with the new alternator.