ithet
Well-known member
Will do, but think I have checked this in the past. Should I be seeing 14.4v there, and if not always them when?
I took it to mean days outside of marina power and over use of batteries.
MD2030D charging voltage
- Thread starter ithet
- Start date
Daydream believer
Well-known member
My MD2020 would charge into lead acid and AGMs at 14.4 on start up if batteries were down a bit- ie had the instruments or autopilot on for a while etc. Then drop to 13.8 after 40 mins, or so. Sometimes less; rarely longer.
38mess
Well-known member
I have the Perkins equivalent engine. I left all my electrics on last week by mistake and of course I got to the boat a few days later and the batteries were dead, lead acid. I started the engine with a spare battery and noted that the alternator was pushing out 13.8v at the batteries terminal. I took the boat for a run to charge the batts up and after a few hours I was getting 12.9 at the terminals. All fine now. I wouldn't worry
PaulRainbow
Well-known member
Should be between 14.0v and 14.4v. Will vary a little from one alternator to another and the battery SOC. If you've been measuring at the batteries, it doesn't look too far out, but double check at the alternator to make sure you're not getting an excessive voltage drop between the alternator and batteries.
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William_H
Well-known member
The regulated voltage of an alternator is the max it is allowed to produce. Anything above is throttled back. (Assuming regulator voltage is sensed at the alternator output.) If however the load is large as in (large) low batteries then alternator will be running max output for the RPM of the alternator. Ideally max engine RPM should get alternator to optimum output. Any less engine RPM will give less than max output of alternator. So less voltage under load. OP measured 31 amps into batteries. That would represent a significant load on a standard alternator. Then the 31 amps is bound to drop some voltage through the wiring to the battery. (via VSR). So measure voltage at alternator output terminal to alternator case. Then measure and compare voltage at battery terminals. There will be some difference. Caused by resistance in positive or negative wiring. That would be normal but excessive loss may indicate light wires or bad connections switch contacts etc.
The 31 amps is good. Don't worry about voltage until current falls and batteries are near charged when the alternator regulator should start regulating
ol'will
The 31 amps is good. Don't worry about voltage until current falls and batteries are near charged when the alternator regulator should start regulating
ol'will
ithet
Well-known member
So eventually the voltage at the BEP gauge came up to 14.0v at about 12a charging. Note that this was the lowest I have ever allowed these batteries to go. Now had a good run (Lyme bay) and on shorepower.
Will check the alternator output directly sometime.
ithet
Well-known member
BTW, now that I am on shorepower the BEP gauge is reading 14.4, which is what the Victron app gives and it is on absorption. So I think the gauge is accurate for voltage (amps and capacity are a different story).
