Optima red top starter battery - probably dead, but anything else I should check?

[Northwards]

Hi folks, 

It's a 1994 300Tdi 110SW. 240k miles, but a recent engine rebuild (Turners) and (April 2018) a dual battery/split charge system professionally installed. With the engine rebuild I fitted a new and bigger alternator (120Amps I think, rather than the standard 65A).

Over the last few months it's been harder to start the car. This morning (and not for the first time) a turn of the key led to a few declining cranks of the starter, and no start. Thankfully, because I've had a bit of warning, I'd bought a Noco starter and stashed it in the battery box. First time I'd used it in anger, and it was simple and effective.

Voltage, when I first turned on the ignition was 10.7V, but once the glowplugs had clicked off, and I turned the key it dropped away down to 5v or so. When I got it started, and drove to work, the voltage was 12.7V but dropping steadily. I think it would likely start this afternoon, and probably tomorrow morning, and if I were to use it daily, would be OK... but it's not as reliable as it was.

So, the Redtop Optima is an '8002-250'. It's still in place, so I don't have all the CCA or the like to hand.

Would a 4 year failure on this battery be 'normal', or at least 'not unusual'? Probably, because of COVID the car hasn't been used as it normally would - fewer long runs, more time in the garage. 

Because it fired up instantly on the booster, I'm inclined to think it is the battery, and not any kind of fuelling issue (that and the fact that so much was renewed at the time of the rebuild in Jan 2020) but just in case, is there anything else I should check? When this started happening, a few months ago, I did a check for any residual current/draw and there was nothing. 

What do we think? Any suggestions always appreciated.

Cheers

Donald 

[simonb]

Simple check, voltmeter across battery, engine running, headlights on. Do you get 14V or more on the voltmeter? If not your alternator isn't charging.

Was your 12.7V measured with the engine running - if so then the alternator is definitely not working properly. 

[TSD]

Before you condemn the alternator, don't ignore the wiring, earthing and possibly the split charge setup. If you don't get a decent charging voltage directly across the battery terminals, check at the alternator, measured alt terminal to alt body, and possibly at the split charge (depending on type).

But that sounds a fairly typical failure for an Optima. Because of the high cranking current capability, it's easy to not notice the battery failing, especially if you have a fresh engine that starts easily. I've had the situation where it can easily crank and start my tdi daily, but one day it didn't catch  for some reason, and there wasn't enough left to even crank the engine a second time. Before that I didn't have any inkling the battery was failing. The (normally 55Ah) Optima was only capable of something like 15Ah when I tested it.

Edited March 1, 2022 by TSD
Forgot stuff

[Northwards]

Thanks Simon, sorry I thought I’d got it all in there. 

With the engine running I’m getting 14.4v (I’ve maybe seen 14.6v on occasion)

The 12.7v reading I mentioned was with the engine off, but ignition on. I’m taking the voltage off my ‘Madman’ gauge and the ignition needs to be on to power it up.

As I suspected, when I left work, ‘brrp’ started instantly. Did a couple of stops on the way home, started instantly. 

I’m pretty convinced the alternator is working OK, but yeah, in order to get proper advice I do need to make that simple check. I’ll see if I can do that tomorrow. 

Also checked, and it seems Optima do a 3 year warranty, so if it’s dead, it’s a replacement.

Hoping my P38 can get MOT’d next week which will make it easier to pull the battery out and charge/test it.
 

 

[Northwards]

Thanks TSD - When the car was redone, it was a new Autosparks loom. The split charge was professionally and well installed though I agree, never assume. 

How did you check the Ah of your battery, is that special equipment, or just a voltmeter?

Edit to say that’s interesting about your battery failure story. Not at all dissimilar.

Edited March 1, 2022 by Northwards

[TSD]

I've seen more than one Optima fail like that. I used to work with some mobile equipment where the batteries were run to exhaustion almost daily, and batteries replaced whenever the 'off grid' life dropped too low. Optimas seemed a good compromise then as they were relatively cheap and easy to buy, compared to some of the more exotic options, and could be replaced with halfords finest as a 'field expedient' repair. I don't think Optima are as good as they once were, but I suspect this effect is more due to the high cranking current available from them and other 'similar' batteries (AGMs for Stop/Start use). It's not so much the failure thats the problem, it's that the cranking ability doesn't give any warning. If starts got slower/weaker over 6 months or more (as you might expect from older wet cell battery designs), most people just say 'well, the battery was getting weak anyway' and just replace it without question after a few no-starts.

The Ah check was done with a testing rig and some software that has its beginnings back with that same equipment. It's not a clever 'answer in 10 seconds' device, instead it loads the battery in a similar way to the 'official' standard tests for measuring Ah capacity. For that reason it's also slightly destructive, in that it takes the battery to that 'end point' in order to measure it, something that shouldn't be done to any lead acid battery you care about, as it inevitably shortens the life slightly. Fridgefreezer posted a pic of the output from his version of the same rig in this thread

Split charge setups generally like to have well matched pairs of batteries. How is your secondary battery holding up? Can you swap them over for a few days?

[Northwards]

Thanks again. The second battery is an Optima yellow top. Because of how they’re located, half tucked away under the passenger seat it’s hard to see precisely what model, but I probably could swap them over.

Today (because the car was used yesterday) it started fine. I took a slightly long way home just to give it a better run. 12.6v, switched off, shortly after getting home. 14.4v with the engine running. I’d expect that 12.6v to drop overnight to below 11v, but I’ll check again in the morning.

It does make me think, if it’s a trait of these batteries that they just suddenly drop off the edge, then what’s the benefit? I’ve never really had any problems with lead acid ones? Is is size? Do the gel batteries give more CCA from a smaller package? I used to use mahoosive truck batteries in there - but they’d be too big to accommodate the split charging stuff, the second battery and the aux fuse box.

Edited March 2, 2022 by Northwards

[smallfry]

I had an Optima a few years ago, and it failed in around three years. An ex colleague runs a couple of modified BMW cars on them, because they are lighter ?

Anyway, he seems to have hassle with them quite a lot.

IMO they are just gimmicky garbage. Buy a decent lead acid battery, unless you insist on turning it upside down.

[Troll Hunter]

I had brand new Optima Red Top and Yellow top installed together in a twin battery set up and they both failed in just over three years.  Basically expensive junk!  Until well proved, stick with good old lead/acid before embracing expensive, new technology!

Mike

[Northwards]

Thanks guys. You’re making the decision easier.

I’ve had it confirmed that I can ‘mix and match’ lead acid and gel in my twin battery set up; and I’ve no intention of turning it upside down….managed not to achieve that so far in 21 years of ownership!

so the next thing will be finding a lead acid that packs enough punch in a smaller battery.