Electronics question

[Bill Wright]

Why not just use your phone as a wifi hub?

Bill

[Bill Wright]

The trickle charge voltage needs adjusting so that a fully charged battery draws a minute fraction of an amp. Something like 0.001 to

0.003A. Charge the battery fully. Check the battery voltage immediately after you disconnect the charger. Set the charger to that voltage. After 24 hours check the charge rate. Adjust the charger voltage to achieve the above current rates. That works well.

The alternative is to use an intelligent charger. These also work well.

Bill

[Johnny B Good]

The corrosion problem is confined to the positive plates of modern paste filled lead alloy grid construction (presumably there's much less of a problem with the negative plates when the fully charged state is pure lead).

The wikipedia article here:

explains this better than I can.

Incidentally, I've changed my mind about using cheap car batteries now that I've re-read that article. It seems the problem with extremely (and surprisingly) short service life under seemingly the most benign of conditions is not, in this case, the result of excessive float charge voltage so much as a lack of stirring of the electrolyte to prevent stratification.

When used for their intended purpose, the accelerations (due to acceleration, braking and cornering) cause the electrolyte to slosh about and keep it thoroughly mixed. I suppose I could make up a rocking platform to mount the batteries upon, driven by a small electric motor to provide the necessary agitation but that seems an extra complication too far. However, if I can snaffle another bargain set of batteries out of my local car breakers/spares dealer, I might reconsider this option. :-)

It seems my best bet is to find a supplier that doesn't charge the UPS battery pack price premium and invest in a decent set of 25AH Gel SLAs (and reduce the float charge voltage at 20 °C to 53.52 volts as well). A good source of such 'battery bargains' could often be found at major amateur radio (mobile) rallies so I might hang on until the next major rally to try out my luck with the battery specialists.

An alternative to using 25AH or larger capacity SLAs would be to fit

12AH SLAs and invest in a 3KVA inverter based genset featuring eco- throttle control. The last time I looked several years ago, I saw prices as low as 600 quid for some brands of this genset type (four times what I paid for a cheap Aldi 2.8KVA emergency genset several years ago now which proved totally unsuited due to capacitive loading by the SmartUPS2000 causing the genset to overvolt beyond the UPS's line interactive voltage bucking range - the genset overvolting north of the 275vrms mark in this case and a problem common to *all* such gensets).

For anyone contemplating such a genset based emergency power backup solution, I'd *strongly* advise against investing in such a basic genset (the type that drives the AC generator at a fixed 3000/3600rpm to generate the required 50/60Hz mains voltage). The only type that is immune to such capacitive load induced voltage instability is the inverter type where a high efficiency permanent magnet generator is used to feed a mains inverter with a dc voltage, allowing the engine speed to be varied according to power demand.

The Old Skool type gensets whilst ok with resistive loads such as incandescent lamps and able to cope with inductive loads such as pump motors and the less inductive loads from universal AC motors used in vacuum cleaners and washing machines, I suspect the increasing use of capacitively ballasted LED lamps (capacitor volt dropper circuit) might be sufficient to cause problems *before* you even get as far as connecting the more critical and capacitive load from your IT kit.

If you're going for the luxury of a backup power system that can do more than provide you with a 15 to 30 minute margin by which to properly shut down your PCs[1] and allow you to ride out an extended mains outage, you'll need the more expensive inverter type genset. The basic, 'cheap as chips' Aldi bargain gensets simply don't cut the mustard with today's domestic electricity loads.

[1] Indeed, if you are unfortunate enough to be running Windows 10 on your desktop PC, you might well find yourself caught out by an unplanned and protracted update that cannot be interrupted without causing additional out of service time. :-(

[damduck-egg]

Lidl have sold an Inverter type on occasions , I picked one up a couple of months ago. At only 1200 watts peak.1000 continous it would be of limited use for many but about the only situation we could not cover in a long power cut is the loss of the deep freeze contents with the other needs of warmth and cooking provided by the wood burner and lighting by great,great grandparents oil lamps. It was only £99 compared to its normal £129 so just preventing the loss of one freezer load would seen that covered. Would have no hesitation in running a freezer from yonks ago on our old genny which is still available for appropriate loads but this modern freezer with electronics within is probably a bit more delicate than just a hefty compressor and a mechanical thermostat.

Thought I had missed the last one in lidl when I went looking but it is so small someone had covered the last one under a pile of coats.

Probably will come around again.

G.Harman

[charles]

In my case the important use of electricity is to keep the heating system going. The Boiler needs a limited amount of power and so does the pump. It might be good to power a radio, too, to save batteries.

[Johnny B Good]

I knew about these 'cheap as chips' inverter gensets but the ones I saw (in Aldi) lacked the one desirable feature that the use of an inverter allows, "Eco-throttle"[1], so I disregarded it out of hand for that egregious omission alone (quite apart from the fact that its rated output was so ludicrously tiny - a case of "All bluster and no action" - if you're going to put up with all the faff and noise of an emergency genset, at least let it be for a worthwhile benefit).

They're not called "Suitcase Generators" for nothing. :-)

Mind you, this one seems a particularly "Industrial" and noisy example of the breed with a 95dBA SPL rating, assuming it's the PGI 1200 a1 referenced below[1].

And, once again, I'd pass on that offer[2]. Although a 1.2KVA inverter genset would be *just* sufficient to supplement the 2KVA SmartUPS in regard of the load presented by my IT kit, I'd rather be using a

3.5KVA/3KW continuously rated inverter genset with eco-throttle to give me not only additional capacity to run the houselights and fridge/freezer and keep the CH going but also give an extra margin of capacity to reduce the risk of overload induced shutdowns.

In all probability, a 3.5KVA rated eco-throttled inverter is likely to use barely any more fuel, compared to that Aldididdle unit I was checking out some 6 to 12 months back, when powering a 1KW/1.2KVA load (and is more likely to be the quieter of the two under such a partial load).

[1] If it's the PGI 1200 a1 as described here:

then it looks like you got yourself a higher specced version than the ones being sold in (presumably) Aldi stores some 6 to 12 months ago. When I searched for some hard facts (as you inevitably have to with high tech Aldididdle product), I eventually discovered that it lacked "eco- throttle" which put it completely out of the running as far as I was concerned.

[2] Actually, if they do become available at that price (99quid), I think I'd be tempted into buying one to experiment with (especially if it *does* feature eco-throttle as per the PGI 1200 a1). It can act as a reserve backup to a quieter 3.5KVA eco-throttled inverter genset when I eventually do get hold of one at an even more reasonable price than the 599 quid 'bargain' pricepoint I last saw them at a few years back.

[damduck-egg]

It is, I was all set to buy a bigger inverter unit last year and mentioned it to my brother who promptly gave me a cheap open framed

2kw Chinese job he bought to run site tools now spare because he has purchased powerful Honda set and has a changeover switch and socket installed so he can run his house if needed,though when asked if it was an Inverter type I got a blank look so I have advised him to take care what he powers till he knows for sure. I couldn't diplomatically throw it away just yet and TBH with the wood burner and gravity heating and LED lamps we can drop the electrical load to a minimum so the bargain Lidl will be there for sensitive stuff. I did have an 8kw Petter diesel set but that smoked a bit and was very noisy,it would be overkill for what we need now ,it wasn't portable enough for my brother so I got a good price for it rather than move it here.

G.Harman

[Another Dave]

Thanks for your input.

The device you show isn't actually mains powered i.e. you have the problem of supplying