Start batteries dead with no indication of impending fail

[Simi 60]

Woke up this morning, hits button and engine barely turns over.

Had sounded marginally sluggish on last start but 100amp alt plus a small victron smart charger is connected so barely gave it a seconds thought.

Plus battery voltage monitor reads 25.4 v
Green indicator windows in battery are glowing happily

Checks all terminals, pulls and cleans the already clean starter motor terminals
Nothing.

Hooks them up to a cheap battery load tester and it has them rapidly heading into the bad sector - so don't believe the voltage or green window

July 10 2019 was replacement date so a bit over 4 years.
And symptoms now identical to then so same remedy applied.

Pulls out the spare Victron Skylla 50amp @ 24v hooks it up and plugs it in and ten minutes latter, engine roars to life.

Now, where is that Battery Shop with a pair of N150's that delivers out to the islands.

 

[Simi 60]

I guess what I am asking here is, is it feasibly to think that if I turned the Skylla on for 10 minutes or so before next needing starts, could I do this until a reach a battery shop, six more starts away.

 

[SteveK]

You have a large house bank, is that not an option for starting if you cannot make 6 more starts.

 

[Simi 60]

You have a large house bank, is that not an option for starting if you cannot make 6 more starts.

Not at the moment
Starts and house are 30ft appart

Plus from what I have read, Lifepo4 are no good for starts

 

[mvweebles]

Plus from what I have read, Lifepo4 are no good for starts

My understanding is it's a BMS limitation, not a chemistry issue. For example, here's a LiFePO4 starting battery for automotive applications. 80AH one claims 1800CCA. Depending on your BMS capacity, your house bank may be an option. Or perhaps swing all your charging to the near-dead bank to buoy it a bit.

https://antigravitybatteries.com/products/starter-batteries/automotive/ag-h7-rs/

Sorry to hear this Simi - six starts is a lot. When I've had batteries die, not much of a flicker left. Hope your experience is different.

Peter

 

[Simi 60]

Or perhaps swing all your charging to the near-dead bank to buoy it a bit.

Well that's the 50amp skylla charger option.
Not all our charging by a long shot but plenty for 2x n150

Sorry to hear this Simi - six starts is a lot. When I've had batteries die, not much of a flicker left. Hope your experience is different

.

Well, it's a different beast I know but we have had a failing 12v Genset start battery for 4 years kept alive by a 4 amp trickle charger.

Genset is non critical for us and I have meant to replace it several times but it slips through the cracks every time plus I have a perfectly good slightly bigger one in the tender if needed.
But my point is - THAT - has worked this long, so I'd like to think same principle on bigger battery and bigger charger.
And of course, being mission critical the big starts will be replaced at the earliest opportunity
Might even remember to get that Genset battery this time.

 

[Simi 60]

Well, maybe they ain't dead.

They had 20minutes or so on the 50amp charger and it had throttled back the amps in.

Left it for a couple of hours and hooked up the cheap load tester, let it run until the bars were nice and red and it said that they are good

See what happens tomorrow

 

[Simi 60]

I had been playing around with the 2x35amp B2B chargers the day before trying to get them to play nice together.

One kicks in when the voltage hits 26.4 and starts putting in around 30 amps to house but the second one does not as now, the voltage has dropped.
It seems looking at old online instructions vs actual in box instructions that they changed the startup voltages and I suspect I have two different ones.

As I was not running the engine when doing this and instead using a 240v bench power supply to bring voltage up and start the charger, this has taxed the batteries a bit.

Again, will see tomorrow.

 

[SteveK]

One more thought, disconnect the start battery when not in use or charging. There may be a leak. Can't hurt.