Collyn R- Optima Battery- too hot???

Junior.
What you describe is more like masive over charging than engine heat. When you installed the redarc did you wire it correctly. modern vehicles use the bus bar or power distribution point as a sampling voltage for the voltage regulator, if the alternator is charging the optimax but sampling the voltage from the starting battery you will blow up your optimax. Eric

Collyn

I had nearly the exact same problem with a Blue Optima 75AH.

Didn't 'blow a vent' but had a couple of bulges on the top and wouldn't hold a charge for more than a couple of hours.

It came unwrapped, no plastic caps on the aux terminals etc etc so I am now of the belief that it was someone else's return and they tried the old 'pea under the shell ' trick to get rid of it.

The Chit part of it all, was that I was one day into a 3 week trip from Melbourne to Mt Dare, Simpson, Innaminca and home, and had to carry the useles piece of crap back to get a replacement.

Replacement given promptly by battery outlet with these words passed on (allegedly) from the Optima Distributor " we aren't going to replace another one"

So I used the replacement and it wasn't all that much better ($450), so I continued to use the good old Super Thief el cheapo wet cell that I bought in Adelaide and continued to work like a charm.

Later on I had to replace the cranking battery so I replaced both batteries with matching Delkors (Crank & D/cycle) - all okay.

This left me with a great wet cell and the 'gold plated' useless optima sitting on the garage floor, which I just played around with with different charging ideas to see how it all worked.

Mid last year I purchased a readywelder. The USA one that comes in a brief case and is a mig with a spool gun handle.

I picked it because of its versatillity re power sources, in particular 24V using 2 batteries.

When I got around to trying it out The 24V dilema was solved with the aforementioned two deep cycle batteries laying on the floor.

It was very interesing to see how they both stood up to it. The Optima discharges faster than the wetcell when welding, however charges up in an 'instant' compared to the wetcell.

Neither battery runs the welder adequately on its own, however in series will blow a hole clean through 3/16 - 3mm steel if you don't set it right.

So as a wind up - I still look forward to getting some value out of the Optima and most probably will never buy one ever again as there are half the price AGM batteries on the market now with a good as or better performance and no bulging tops.

Regards

Ken Robinson

junior, what has the battery bloke said about it?

We have gone to 34 series yellow optimas in our fleet of 7 ambulances. The mechanic decided to try these out 8 years ago when he got sick of replacing dud wet cells. In the 8 years since we have gone to these batteries there has been one failure, which is a pretty good record. Hope you have luck sorting your problems out.

I run a optima blue top as a cranking battery in my 79 series turbo I also had it in my 75 series ute and have never had a drama with it at all I also run a trojan deep cycle as my second battery because that was all I had handy at the time. I use the blue top for some serious winching activities (I have a warn high mount) and if I'm out camping my car is used for the music and I run an amp I can get 4-5 days runnig the stereo and it recharge's after a fairly short drive. I have had it for almost 1.5 yrs now hopefully I will get about 8-10 out of it if I do its worth ever cent and more. cheers

This sounds like thermal runaway.

It is probable that the prime cause is excess charging voltage. It rarely happens but it is possible for a regulator to fail in this fashion (and if it does an alternator can literally generate 100 plus volts before it blows the output diodes apart).

If this is compounded by the battery being located where it overheats then a battery will almost certainly fail as you describe. (The mode of failure incidentally is why all of my books stress very strongly that ALL batteries must be ventilated).

AGM batteries are generally very rugged but their very characteristic of high charge acceptance and high discharge capability also causes them to be vunerable to 'thermal runaway'.

The warmer a battery the more readily it accepts a charge. If the regulator is faulty, the battery is charged at a higher than acceptable current. This generates internal heat and that allows the battery to accept even higher charge - which in turn heat it up further - and so on. Eventually something gives or goes bang. Or both.

It is just possible this was a crook battery - but if the starter battery too is swollen then it sounds like a serious charging/heat problem.

If you do find the regulator to be crook I would suggest you also replace the alternator. It will have been stressed.

Less probable - but the above can also be caused by a slightly faulty starter battery cable connection. Some voltage regulators take their needed voltage reference from the starter battery - others do it internally. If that cable is slightly intermittant the charging voltage can go very high. This more usually manifests in poor starting - but it can and does happen if the battery connection is clean and normally making good contact but moves sometimes sufficiently to lose contact.

The above is why auto-sparkies will never test an alternator unless there is a battery across it - and why boat master switches always connect the second battery before disconnecting the first (or ground the field connection during changeover).
Trust this helps
Collyn Rivers

Junior

1. Capacity - only meaningful way is to fully charge and then to discharge at a known rate (with an AGM suggest 5%-10% of Ah capacity). and note the time to for voltage to drop to 11.8 volts.

With a good battery the result is will be about 10%-15% bit less than the maker's data: they run the battery to virtually flat - which even with an AGM is not that clever a thing to do. If you do this with a non-AGM use a 5% load.

2. Alternator testing - there's not much you can do except check it using a multimeter across a range of engine speed in situ. If you have any serious concerns take it off and have an auto sparky inspect it internally and check it out on his/her test bench.

3. Re voltage rise from alternators. An alternator's output is determined by the voltage across its field, by the voltage regulator. Its aim is maintain a constant 14.2-14.4 volts (some reduce as temperature rises). To do this it monitors the battery voltage - if that falls then alternator output is increased - and vice versa.

Some regulators have an external battery connection for this purpose, and if that connection becomes loose or is broken then the alternator 'thinks' the battery is dead and winds itself up accordingly (as high as 100 volts).

To reduce this possibility however some other alternators take the battery voltage reference from within the alternator. With these, the problem is rare.

Re underbonnet battery mounting: I don't think this is a major issue as long as the battery is not alongside the exhaust manifold or turbo. There are reported cases of AGMs failing up north but I suspect it is a combination of heat and overcharging that is the cause. Ring Val Rigoli (Fridge & Solar re this - 07 5500 5061) he has a heap of experience re underbonnet mounted AGMs.

I would not bother with heat insulating as such but it might well be worth using a heat-deflector between the side of the battery and any major heat source.

Do note that if using battery chargers - many AGMs including LifeLine specify float voltage of 13.35 at 25 degrees C. and as low as 13.0 at 35-40 degrees C. This is hugely less than the typical 13.8-13.9 volts of most low-priced three-stage chargers - and there is a very real risk of damaging the AGM if left on permanent charge. It is of course also a lot less than the alternator's output, but this is less of a problem unless driving for a long time every day. (My own vehicle has a manual cut-out switch enabling me to stop charging the AGM in such circumstances).

Trust this helps
Collyn Rivers

Thanx for all the replies guys- battery did well over weekend in Portland playing in sand- will test this week with known constant load. PS Collyn- why the 11.8volt figure?- I thought 10.5volts was assumed to be a rough guide to being a 100% flat batt.