Doing a bit of research during a discussion on another forum where people were trying to work out inconsistent stop start system performance I came across this. It is a small black box on the battery negative terminal and has three thin wires disappearing into a wiring loom on my Jazz. It seems to monitor battery charge level, charge rate, load, and temperature, this information combined with some ECUs seem to make for inconsistent operation of non essential systems.
www.batterypoweronline.com/main/articles/battery-management-with-an-intelligent-battery-sensor-is-vital-to-the-success-of-future-automotive-designs/
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More and more widgets that can leave you stranded at the roadside....
Or let a dealer say "your battery is telling us it needs replacement"
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How does that work if the widget does not let the battery drop to "Stranded at the roadside" levels? My car has restarted itself after an auto engine stop in traffic.
Last edited by: Old Navy on Mon 13 Mar 17 at 18:28
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A basic battery manager isn't that complicated. Current in and current out is measured by passing it through a shunt, measuring the voltage drop across the shunt and calculating the current and time = net Ah.
If you (the monitor) know the battery has 100Ah of usable capacity and is fully charged to start with, then by measuring what goes in and out you can know how much energy there is in there. An efficiency factor is applied usually to charge in, of say 10%, to allow for the fact that 1Ah in will only increase the energy available by 0.9Ah.
There will always be an error and to stop it accumulating the system can reset the charge to 100% when it detects that charging has gone into pulse mode.
The rest is presumably fine tuning as the battery condition (not state of charge) can be inferred from voltage at different known states of charge and temperature so that capacity can be adjusted and ultimately it can tell you when replacement is advisable.
I don't know how or what your Yaris or any other specific car does but that's the basics of it.
I haven't much experience of stop start, but our Kangoo hire car had it. Blower and accessories stayed on while stopped, and on a couple of occasions it restarted early, before the clutch pedal was depressed. My daughter's A6 does mainly short journeys at the moment and often doesn't stop the engine at all.
Unlike a normal car battery, stop start batteries have to cope with deeper discharge. Stop start batteries are different, having to operate at lower levels of charge, with deeper cycles, and higher curent both out and, if there is energy recovery, possibly in too. Replacing your stop start battery with a normal one is likely to result in it having a short life.
I recently replaced my caravan leisure battery with a stop start AGM as it was cheaper and higher capacity that the very expensive and hard to find gel battery that has been in it since 2004. Time will tell if that was a good decision, but I think the usage is fairly similar with deep cycles.
Last edited by: Manatee on Mon 13 Mar 17 at 19:25
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>> Time will tell if that was a good decision, but I think the usage is fairly similar with deep
>> cycles.
The recommended charging regime and voltage is very different (to either gel or conventional lead-acid batteries).
Motorhome forums are full of complaints about AGM batteries not lasting long (.... due to the inbuilt chargers only being designed for gel/standard flooded)
(My current motorhome has two AGM leisure batteries factory fitted, I'm keeping a close eye on them. In the last year, and following the debate, the major supplier of electrical systems to the German motorhome market has added a further, AGM, regime to their charging options).
Last edited by: tyrednemotional on Mon 13 Mar 17 at 20:08
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The onboard charger is a maintenance job (the infamous Scheiber BIP) that is operating all the time the hook up is plugged in. It will not reach full charge, and I am prepared to chance that it will be OK. When I want to top it off I disconnect it and put an intelligent charger on it.
It also gets charged by the car when towing; AGM car batteries are supposed to be OK with standard car alternator charging - maybe you are suggesting that view has come under suspicion? Actually the caravan also has a Schaudt booster that is supposed to manage the charging intelligently when towing - but that was standard with the autonomy pack with a gel battery...I spent some time figuring out what was going on with this years ago and I'm not actaully sure I remember it correctly!
My working hypothesis is that the main destroyer of leisure batteries is deep discharging.
I used to have a 20% share in a boat that had about 400-500 Ah of batteries and a supposedly sophisticated battery monitor. I could never convince the other owners that when the battery monitor said there was 200Ah left it was time to run the engine. Constant almost full discharge meant we had new batteries every other year at some expense.
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I'm working largely on the empirical evidence from motorhome forums, particularly German ones, where there is a weight of opinion that the switch from factory-fit gel batteries, to AGM, has been disastrous.
There are simply too many complaints of premature failure (< 2 years) to dismiss. Certainly deep discharge (below 50% for a good few times) may well contribute (which is why I double-up my capacity), but many of the complainants are long-term users who haven't changed their practice, and haven't suffered problems with previous technology.
The battery manufacturers' advice seems to indicate a minimum AGM charge voltage of 14.7V to avoid sulphation, and in general fitted onboard chargers and/or vehicle alternators have not been able to deliver that.
In response to the issues, about 18 months ago Schaudt amended their charger line, deleting the 'flooded' setting and replacing it with an AGM one. This has a "full" charging stage of 14.7V; higher than the setting it replaces or the remaining and alternative "gel" setting, and a (significantly) different length of charging cycle.
The jury is still out (since less than two years have passed since it started being fitted) as to whether this has improved things.
I suspect that, if there is mileage in the charging voltage theory, then there will also be a knock-on effect from the vehicle alternator output not reaching this voltage during running, and thus "on-road" charging being deficient as well (most motorhomes are not stop/start, and have a standard vehicle battery and associated charging).
I now have two vehicles with stop-start technology (and I believe AGM batteries), but I haven't measured the alternator output as yet (note to self....). In passing, however, I had gained the opinion that those vehicles so fitted as standard have had the alternator voltage and charging regime set to suit them.
I do know that there are dire warnings about replacing such a battery in an "intelligent" system as it generally needs the car electronics re-synchronising with the new battery.
(we could discuss the potential issues in caravan and motorhome charging that arise from "smart alternators" which may switch to zero output if the vehicle battery is sensed as full, but I think I'd rather leave it there ;-) )
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Interesting. The received wisdom used to be that, as gel need a lower voltage than AGM then a gel setting would not hurt an AGM; the theory you report being that too low is also damaging!
It must be a massive generalisation, because both types can be designed for different applications, but gel are supposed to handle >50% discharge better than AGM. Knowing how some people use leisure batteries that could be a factor.
My old gel battery did well, at 60Ah a bit weedy for the motor mover but still working at 12 years. I have kept it but I think it was starting to lose its virtue and wanted something with more Ah that would fit and the AGM stop-start battery has higher cranking amps and 80Ah. It does seem to have more punch, life of course is another matter.
It's one of these, which was about £20 cheaper last August - must be Brexit;)
www.tayna.co.uk/F21-Varta-Start-Stop-Plus-AGM-Car-Battery-580901080-P8720.html
Last edited by: Manatee on Mon 13 Mar 17 at 21:59
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Re the OP - intelligent battery monitoring/charging has been around for a good while. As with most mid noughties onwards BMWs our 2005 120i (pre stop-start) has some clever battery monitoring features and will apparently charge the battery at different rates as it determines what is required, it also puts more load on the alternator on the overrun and less under acceleration, early efficient dynamics I guess. The downside is that you cannot simply swap a battery as the new one needs to be coded/programmed to the car, the plus side being that it has not needed a new battery, the original is going strong.
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My car has an IBS, the battery change procedure is a one for one swap. The user manual only states the new battery must be the same type (EFB in my car) and gives instructions for re-activating the radio / phone / tablet gadget. Using an external battery charger is the same procedure as any "dumb" system.
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>>My car has an IBS
My sisters boy has that too, quite serious at one time and had to have 'the bag' at one point.
He's more-or-less ok nowadays, 20 years on, but still has to watch what he eats etc. etc. etc..
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>> My sisters boy has that too,
Don't be daft Dog, IBS was The Secretary of State for Work and Pensions from 2010 to 2016.
:-)
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S'funny, I thought it stood for Industrial Boiler Supplies :)
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I initiated a project a few years ago for a piece of software I called IBS, for intelligent broker system. The name was the first thing that was changed.
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You are all wrong, it is Irritating Battery System. :-)
Last edited by: Old Navy on Tue 14 Mar 17 at 12:16
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Institute for Brewing Studies ...
... reckon I might be an honorary member ;-)
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Intelligent battery sensor. - martint123
