OT Car batteries going flat.

[T i m]

Of course, that's what 'can' implies. ;-)

Ok.

I have found under those conditions they all pretty well delivered what was advertised or even a bit more.

For the right size of panel to battery they don't need a regulator. Further, in many cases where the gains are marginal, many regulators (especially PWM) will negate any gains you do make when everything is working at best. ;-(

Again, if you match the overall charge from the panel to the worst case losses, the chances are you aren't going to be able to overcharge any car battery with an existing (continuous) parasitic drain.

Quite, but that's quite a large panel and unlikely to fit on your dashboard. ;-)

Even if the roof of your RV was covered in solar panels and you were in a very sunny place, your overall load could possibly outstrip your battery capacity and at night, that's all you have (excluding your genny / mains hookup etc).

Walking along the towpath in the early evening and you often see (hear / smell) 'Boat people' running their onboard engines or generators to top up the batteries but I don't think they are allowed to run them at night (when you might need most power etc).

Of those I've spoken to, most suggest that even a reasonable array of as large a panel as will fit across the roof of a narrow boat is only enough for some very light loads.

Talking to the chap at a boat rally that built a battery powered narrow boat, he calculated the use of solar panels to charge the main traction batteries as non viable, relying on a built in generator or shore hookups. I think he may have had a small panel or two for topping up the aux battery (but wasn't replacing those panels as / when they failed).

We have successfully used a 5W SP when cycle camping to charge a pack of SS's in the trailer (behind the solo / tandem). The SP is on the trailer so picks up any sunlight when we are on the road and we prop it up outside then tent, facing the sun when in the tent. Given a reasonably sunny week we can usually stay self sufficient for nighttime lamps and the GPS etc.

Cheers, T i m

[Steve Walker]

If there are heavy loads (diesel electric auxiliary heater, heated front scree, low battery) the ECU will increase the idle speed to provide more power as well.

SteveW

[Steve Walker]

And they are IP68, so can be exposed to the weather while charging.

SteveW

[tabbypurr]

Nah, not enough voltage. Lead acids aren't capacitors.

A variable regulated psu would be fine if you happen to have one. Lead acids are not hard to please when you're just home charging them once per blue moon.

Even ancient chargers with nothing remotely like any voltage regulation work, and are ok if not used often.

NT

[tabbypurr]

I don't understand why you want to play the prat.

[tabbypurr]

Well it's not, but hey.

[tabbypurr]

Old iron transformer types go for a couple of quid.

[tabbypurr]

There are folk building new valves now. It's a long process though.

NT

[Paul Cummins]

Says the idiot who can't understand that a Lead-Acid and Calcium-Lead-Acid battery are two different things which need different treatment.

[T i m]

<snip>

And we all do don't we? ;-)

Or even at home charging them quite a bit.

Agreed ... and depending on the 'modern charger', can still serve a purpose.

One of the reasons I prefer the Optimates over the C-Tech clones as with the Optimates you don't have to press a button to get them to start charging. So, no good if you put them on a time switch or you get a power cut down the shed and don't realise for a fair time?

Had the former with daughters van the other day. Battery very flat (left unused for a few months) and the Lidl C-Tech close wouldn't even start. Luckily Dads old linear charger was on-hand and brought the battery voltage up enough for the intelligent charger to start. ;-)

Unfortunately, I think we had a brownout locally so there is a good chance the charger on the van dropped out and I'll have to go round there and press the button again. ;-(

It *may* resort into a very low / trickle charge if you don't press the button?

Cheers, T i m

[tabbypurr]

some here do

If charging often, something more complex than a dumb unregulated charger is wise

NT

[RJH]

JOOI, I put my car's battery on one of those chargers yesterday after 3 weeks standing (but it was charged for a few hours then), and not much use over the past 6 months. Started at 1/5 bars, 12.2V. Ended 5 bars filled, 14.4V after 12 hours, but flashing, indicating still charging. I would have left it longer but the manual car lock doesn't work and I didn't fancy leaving it unlocked overnight.

It's a 6 month old 65Ah battery. Anything to be concerned about?

[fred]

Detach both terminals. We used to detach only the positive terminal on the boat over the winter but it still ran flat. Since we started detaching both terminals this problem has not reccured.

[Steve Walker]

I would think that it was close to switching over to maintenance charging, but it still had a very small way to go. A little longer would likely have done it.

I'd get that lock fixed quick though. What are you going to do if the battery goes flat at some point while the car is locked?

SteveW

[T i m]

<snip>

Ok.

As indicated by the charger (once charging) or a DMM etc?

One test of the likely chance of recovery of a lead acid battery is the off load, off charge terminal voltage. Much less than 12V and I would start keeping an eye on it.

Ok, two good things there, the voltage and the 12 hours (and the flashing for that matter, three good things) ;-)

The fact that it took that long to get to that level of charge, that would suggest to me that the battery still had a reasonable capacity (depending on the charge rate etc).

OK.

I wouldn't say so from what you have said so far, assuming it can still start the car ok. ;-)

Cheers, T i m

[T i m]

Quite, an array of Optimate chargers. ;-)

I also have a charger multiplier that works with 2 to 4 12V LA batteries.

Basically it looks to see around 12V on port one and if it's there, it applies the input (one Optimate charger) to that output. After a preset time (6-12-24 hours) it switches to the next port. If there is no 12V it steps to the next and so on. So if you had 4 batteries connected and the time set to 24 hours it would take 4 days to go though all 4 batteries (irrespective of if they were charged or not).

Cheers, T i m.

[AnthonyL]

OK so I've got a 19v power brick from an old laptop. Would that likely work?

[bert]

And air con

[Steve Walker]

Yes, but not to keep the alternator output high for it, as air-con is almost always belt driven.

SteveW

[T i m]

On Mon, 06 Apr 2020 11:36:01 GMT, [e-mail] (AnthonyL) wrote: <snip>

No mate.

You could use such a thing as the basis of a variable PSU / battery charger but with dedicated 'Intelligent chargers so cheap, it's not worth the fuss / risk, other than for the fun of it etc.

You could hook it up though something like:

eBay item number:

312565786982

(Not checked it out in detail).

The idea is that if you can set the maximum output current (say 2A) and maximum output voltage (say 14V) and the laptop PSU is greater than 2A, then it could work. ;-)

Cheers, T i m