Hope someone can guide me :-)
We are in a professionally built expedition truck with Victron systems. Over the last two days we have been smelling rotten eggs. I started with the toilet but ended up at the starter batteries :-(
Both starter batteries are leaking (2 x 12v series).
Q1 Is it usual for both starter batteries to fail together or is this symptomatic of an external issue ( overcharging issue or something else)?
We are parked up (Corona 19) with a shore supply feeding a Pheonix Multiplus that charges our leisure batteries and starter via a Cyrix-i 12/24-120 bidirectional voltage sensitive relay. A Victron MPPT solar charger is a second charging source (added a month ago to replace a PWM unit).
About two days ago the inverter displayed a Bulk Protection alarm. And I reset it. I didn't know what this was, but the community has told me that it means the max bulk charging time of 10 hours was exceeded. I suppose this is associated with my problem.
I noticed yesterday that my MPPT was generating 17A, but the BMV indicated only a few amps charging the onboard leisure batteries and I wondered where the rest was going as I had not much load switched on. I guess it was going into the started batteries.
Q2 Can anyone through some light on what is going on? Have the batteries failed as a result of a system issue or of their own accord and just need replacing?
Many thanks in advance to responders.
Multiplus & MPPT have identical charge settings (bar current limit):
Vab = 28.8v
Vfl = 27.6v
Current limits are 45A and 30A respectively.
Voltage across starter battery terminals (chargers off): 24.8v
Voltage across leisure batteries (from BMV) (chargers off): 25.5v
Voltage across starter battery terminals (MP charger on): 27.6v and climbing slowly
Voltage across leisure batteries (from BMV) (MP chargers on): 27.7 and climbing slowly
The starter batteries are fully sealed maintenance free units.
The leisure batteries are Victron AGM 220AH (2 in series for 24v)
Starter batteries last replaced in May 2016.
1 = Starter Battries
6 = Cyrix-i 12/24-120
9 = BMV 602s shunt
8 = Leisure batteries
11 = Inverter 24/3000/70 Phoenix MultiPlus
I measured the voltage across each of my series 12v starter batteries: 13.35v and 11.25v.
The latter seems low given they have been on charge for 24hrs +.
Does this mean that the starter battery voltage is low overall 24.6 and this would mean battery voltage does not reach Vab and stays in bulk or just make absorbtion and draws lots of current. This causing both batteries to overcharge and leak?
Have I answered my own question? I don't want to rush out and buy two new starter batteries until I understand the problem. They cost $$$.
As suggested by respondents, I charged the under-voltage battery overnight on a 12V charger. This morning the on charge voltage was 12.1v and this fell back to 11.4v within 20 mins after being taken off charge.
The other battery was at 13.06V this morning.
Q1 I guess this means this battery is toast and needs to be replaced?
Q2 I intend to replace the pair (they are 4 years old) - any reason not to?
FINAL UPDATE 7
I replaced my starter batteries and everything is fine. I have ordered two battery balancers, one for my starters and one for my house batteries.
Thank you all respondents for helping me out.