water for lead/acid batteries

Until recently we,in the UK at least, were told to top up our lead acid car batteries with distilled water. Now we are sold de-ionised   water for the job.    If distilled water was the thing to use then surely water that has passed through a drip coffee maker , or obtained from a dehumidifier would pass muster. What does the panel think ?

Absolutely OK, surely distilled water with a ph of 5 IS deionised water.

The general recommendation for many years have been ordinary tap water - assuming it is god quality (not bore water etc). The reason is that partly that (apparently) modern batteries tolerate the water impurities better, but more so because of economics - it is cheaper (and more reliable) buying a new battery than spending the extra expense buying distilled (or de-ionised) water for turns out to be a mere 3-month life extension (over a 3 year or longer life). I stopped using "open" (6-capped) wet batteries decades ago and have used "low maintenance" types. In theory, low maintenance batteries have enough fluid to cover their expected life (say 3 years, or maybe their warranted 2 years etc) so they never need topping up. Their caps and venting also minimise gas or fluid loss. In practice, I'll open mine up after ~2 years and might then check annually. Small top-ups may be needed. Only if there had be a major loss would I inspect more often - but that would only occur due to over charging (so fix that problem instead) else a collapsed cell which is probably fatal - though a equalisation charging could be tried to reverse sulfation if that is a problem. Low-Maintenance are essentially the same as normally vented/capped wets, but the caps are hidden etc. Their cover-all cover can be removed and individual cells accessed.     Some have a "power-eye" which itself can be unscrewed to check fluid level in that particular cell only. FYI - Low-Maintenance batteries were once sold here as Maintenance Free. But that name was deemed illegal (since they were not maintenance free. Nor are AGM and other batteries - they require maintenance i the form of checking, and maybe occasional equalisation etc charging. [ Trivial: I was going to say the distilled water is de-ionised, but maybe not so. Distilling removes impurities (solids and some chemicals), but maybe not ionisation. Not that water itself is normally ionised. But de-ionisation should remove what is important - ie, things that can conduct. But what if non-distilled remaining solids can become polar or ionised? An interesting subject that I'm surprised I know little about, but the again, IMO it is totally irrelevant - unless I were living off bore water etc, then I'd distill and then use electrolysis for a while... or just buy some bottled water - probably de-ionised or distilled because it's probably cheaper than bottled drinking water!) ]

Thanks for the clear views Oldie, one point especially in the UK, most people never look at their batteries any more or top them up. Come November and freezing nights, when you start the car the next morning you're placing about 40% extra load on the battery. If it isn't topped up, say hello to at least one bent plate, reduced charging, dead battery. I get a lot of diagnostic call-out work at that time of the year, it's always a flat battery.

As I say, a weak battery entering summer may make it thru. A weak battery heading into winter - replace it!

A lttle bit of mission creep here.....but what about these multistage smart chargers that claim to de-sulphate and restore a battery ? I know that a desulphator can be bought or made but they take months to do the job.Are these chargers worth bothering with ? I have a trailer caravan with a 110Ah battery that has a little solar panel on that I thought might benefit from the float charge function.Also some of the batteries for my farm vehicles could be taken off when not in use and kept on an auto maintanance cycle. If these things actually work !

IMO not a mission creep (hijack) but a good question. Sulfation occurs whenever a battery is not fully charged - ie, is not on a float charge (which is usually up to 1 or 2A at about 13.6V - enough to stop the battery self discharging - not that self-discharge current is as high as the float current). Hence yes, ideally when a battery is not in use, it should be on a float charger. But that may be uneconomical - ie, the energy/cost "fulltime" when sulfation is minimal near full charge (sulfation rate increases the more discharged a battery is). And there are 2 stages - the initial "soft" sulfation which can be reversed (maybe with an absorbtion charge - higher than 13.6V; say 14.4V to 14.8V - but see re BatteryFAQ below) and "hard" sulfation which is what the soft stuff becomes. That hard sulfation can only be fixed physically - ie, physical removal of the sulfates. But (as I understand) this can be via a HIGH charge current that may knock of the sulfates - probably through bubbling, plate vibration etc. (My local battery supplier once said that 20A or more is needed to "recondition" a battery after a good flattening. I took this to mean to ensure that the soft was reversed, but maybe also help knock off any hard that may have formed. (I think soft -> hard is mainly a time factor (say a week?) but maybe it is a severity issue as well?)    So, hence to your question.... Yes, there are multistage chargers that can "recondition" batteries which is AFAIK mainly the reversal of (soft) sulfation. I should check my terminology & definitions (ie, refer to batteryfaq.org - namely its Car and Deep Cycle Battery Frequently Asked Questions (FAQ) 2011 - oops, that gets into the BIG section 9 - but 9.1 sums it up. [ Damn you (LOL!) - now I've had to correct my earlier term "equalisation" to "absorbtion", but I added 14.8V as the upper range instead on my "14.1V - but can it be higher?". You'd think I'd know that stuff! ] But that's worth reading (s9.1) - at least I was correct about Equalisation for de-sulfation, but that is a "controlled 5% to 10% absorption overcharge "... not merely 14.1V or so... Yeah - get it from the Master - not a second-rater like me. But those special reconditioning stages should be used sparingly - they are for occasional maintenance, not daily use. Battery care or maintenance (as with their use) tends to be a compromise. EG - a solar floater is itself one charge-discharge per day (or maybe more with clouds and shade etc). Now if the number of charge-discharge cycles effects battery life, is that a negative? Or is it better than NOT having the battery self discharge for that period?      And I could give dozens of similar but common examples/dilemnas. Then there is theory, specifications, and reality. The Specs are usually "minimum guaranteed performance" type documents. They might rate a car battery for (I dunno, but say) 500 cycles. Yet a daily use car probably has 2 cranks with recharges per day, plus the interim discharges during idle, and how many "short" discharged during alternator shortfalls (like the instant brakes or headlights are applied, or during flasher indicator pulses?) {though "surface charge" may also look after those instances...}. The point is, shouldn't a car battery therefore only last a max of 500/2 = 250 days? Yet they can last years... But Specs are a "minimum", and subject to "based on whatever" - eg, a cycle might be from 100% to 80% capacity (the normal Spec extremes for a cranking battery). Alas I ramble with the stuff that makes a "universal battery solution" or answer so difficult. (Well, at least as a definitive simple solution!). How would I treat my solar setup (once I start to use it properly)? My solar regulator charges at approx 14.4V (I think - maybe it's 14.4V, but it is certainly not 13.xV). Hence it should be keeping the battery at a good voltage even if not fully charged. Certainly if the battery needed extra charging to power the loads (through the night etc), I would charge it, else rely on my LVCO (low voltage cut out - aka battery protector) and the sun;s recharge the next day. If the battery were full and to NOT to be used for a week etc, I'd leave it. If it were fairly discharged, then I'd recharge before storing (leaving idle for days or a week etc). If only a little bit discharged... well, recharging would be nice, but a little discharge means little sulfation which should(?) be reversed in a weeks time etc... Even for me it will be a "suck it & see" approach. I might determine some things - like that needs a minimum of 14.6V to absorb or equalise hence my solar output is too low. (Hence more urgency to recharge after a discharge, else rig a voltage booster for the regulator - eg, insert a diode in the sensing line to increase voltage output by ~0.6V for a while...) But I might find that despite <whatever> specs, leaving idle for a week etc causes no noticeable or serious battery degrading. I should point out that although initially intending to use AGM for solar, I now intend using ~100AH cranking-cum-deepcycle wet-cell batteries - one as main (vehicle) battery and the other as spare cum camping. I still have 2 AGMs that I was intending to use, albethey only 38AH and $670 UPS batteries. But they are now being used as my main cranking battery (just one, the other is in-house pending alternator replacement since its charge-lamp circuit isn't working - hence my (UIBI) battery isolator isn't working), and in theory theory should not last long (as I warned my brother 3 years ago - his is still going strong). But the 100 - 130AH version of the same battery is a "mere" $500 (which is cheaper than our RRP for an Optima yellow ~75AH) so maybe my next AGM will be that instead. But the $220 flooded 110AH should be good. Anyhow, the 2 batteries means different strategies. EG - equalisation charging is generally not used on AGMs - at least not by multistage charges - eg, a 4-stage charger only uses 3-stages if it's an AGM or gel cel. The AGM can sit longer idle, and probably be okay partially discharged for a while, but needs to be quickly recharged after a heavy discharge because its "sulfation" cannot be reversed. (Though AGMs can be given equalisation charges - with appropriate knowledge!) And both will have different voltage specs for charge stages etc (though for normal use, both can be paralleled when (the array is) charging).    Geez - did I answer anything? FYI - next time Aldi have their $25 4-stage SMPS charger ($A or 8A?), I'm grabbing one of a few. I've been rapt with my $30 2A/8A 6V/12V charger, but there is nothing automated about that, I have to switch manually when battery voltage gets too high. Plus it's linear (transformer). And while cTeks etc may be good, in my case I think $25 will beat the $200-$400 of the cTeks.

Now THATS what a call a reply ! Im going to have to print that lot off to study. I was just going off to see a guy who runs a shop that sells all the 12v stuff for RVs and caravans,etc as I have some stuff for him on waste veg oil fuel. I mention that as I was going to buy a £35 c-tek 6 stage-r from him....now I may give that a miss and wait on aldi and lidl....bless those germans ! I also mean to pick this guys brains on fuel cells,the methanol ones.

If the ctek is only £35, I'd be tempted... That's about AUD$55 - not that >$200 they seem to be here. Not that I know that ctek's specs, but rather than wait - if I was desperate.    (Besides, when will the Aldi be re-released? The week after you buy the ctek!)