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12v Pb starter/flight-box battery failure


Jonathan M
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12v 7000mAh starter battery failed at patch today - had started Irvine 46 a couple of times but fell off a cliff the third time, glow meter dropped to almost nothing when using the starter.  Had been fully-charged a few days ago, used for starting and glow plug maybe a dozen times since.

 

Back home on the multimeter it read 12.28v.  I'd always previously charged on 1A but found my charger set to 6A from the last time. Have I damaged the plates?!

 

It is a Yasua NP7-12S, about five years old with very light use over that time.

 

Currently re-charging at 1A. If it is damaged would repeated gentle cycling recondition it to health, or time to buy a new one?

 

Edited by Jonathan M
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It would be worth checking that the charger is working properly before buying a new battery!

 

Of course using a Lipo means using a proper Lipo charger and not just any old charger, so factor that cost in if you are not an electric flyer.    I wouldn't expect a Lipo to last any longer than a lead acid gel cell, if as long.....

Shop around for  a new gel cell as prices vary and an online delivered price proved the best buy for me.  A 12v 7 amp will also start your car in an emergency.     The old useless gel cell 12v has some uses as a weight or even a rightangle block whilst building.   

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Having had several of this type of battery over the years, I gave up on them many moons ago.

 

For more or less the same price I purchased a decent leisure battery via an e.bay supplier.

 

I NEVER charge Lipos at home.

 

I also purchased a 100w solar panel second hand (plus control box), and do all the charging etc. up the field.

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The small 12V sealed Gel batteries will not tolerate an incorrect charging regime and cheap wallwart chargers that are often sold with these batteries will kill them stone dead in no time. If handled correctly they should last for ages. i.e correct  initial  charge current , usually 0.1C and correct end voltage - 13.3V is a safe end point for float charging but certainly no more than 14V for an overnight recharge.

Just charging at 1A without taking account of end voltage is not good and likely to cause heating and damage to the battery and destroy its capacity.

I've changed dozens of these batteries in UPSs when I was at work and was surprised at how rubbish the on-board chargers were - made a fortune for my boss though........

Probably better of with a Lipo or similar for your field box - I'll go that route when my ancient Gel battery in my flight box does eventually pack up.

 

 

Edited by Cuban8
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Thanks folks - I realise that I've properly cooked it!

 

Don't want to down the LiPo route, prefer the simplicity and safety of Pb, and weight isn't really an issue (the 7Ah 12v balances the 1/2 gallon tank at the other end of my field-box/stand).

 

This one actually lasted me very well (until I recently attempted batterycide - twice at least! - by charging at 0.85C) and they're not dear, so I'll just order a new one.

 

But one question for Cuban8:  you say charge at 0.1C which my Fusion charger can do (just set it to 0.7A), but I can't change the voltage end-point on it to less than 14v.  Surely this is safe enough for fairly regular overnighters as I did for years?

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54 minutes ago, Keith Berriman said:

Hi Jonathan   there my be two types of battery  one for light use in alarm systems and one for power tools  just seen these on Amazon around £19 and  suitable for drills 

 

That makes sense Keith.  The alarm system type would have thin plates (like a marine leisure battery, for nav and cabin lights, electronics etc), whereas the drill type would have thicker plates (car and boat engine start batteries for cold-cranking).

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I too gave up on Pb`s a long time ago. Max charge for a 7Ah would be about 1 - 1.5A, otherwise it will be destroyed. The charge voltage for a car is 13.8V so this must not be exceeded. If I do use Pb`s for any reason then I use my normal Lipo charger which will cut off when full. I now only use nice, light, old, puffed up Lipos which power the starter, pump and glow for a long time.

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43 minutes ago, Jonathan M said:

I'm hearing all the preferences for switching to LiPos so (as I'd like to fly this weekend) I'm going to try that route - at least as an interim solution!

 

I've got a pair of good but completely redundant 3s 3300mAh LiPos - I assume 3s would be the correct voltage rather than 4s?

3S is indeed a good choice Jon.  I bought a pair of 3S 5000 hard case packs.  One would have done but I can use 2 in series to give me 24 volts for starting my 35 cc petrol.  My starter is a Sullivan Dynatron that will work fine on 12 v for up to 120 4 strokes.  A 180 4 stroke would not turn over but with 24 v the challenge is keeping everything in line when starting!

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Thx Peter.


My starter is a Just Engines one with a 4:1 reduction gearbox and rated for 12 – 15 Volts.  JE add that "under certain conditions the use of LiPo batteries can overpower the starter and cause the switch contacts to weld on.  Many use LiPos without problem..."  but I assume this is where folks are using 4s LiPos?  At full charge my 3s 3300mAh will deliver 12.6v, down to 12.0v at 80%, etc.

 

In the meantime the 7000mAh has accepted a charge of over 1500mAh (20% of its capacity), which doesn't bode well given that a lead-acid is only normally flat when it is approaching down to 50% capacity.

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If you go back to the old lead acid batteries (like the post office used to power the telephones) they were hugely heavy for their capacity but virtually indestructible and could indeed be recovered by a slow 'gassing' charge. Modern ones use a 'matrix' plate filled with a "paste". Once that is damaged in any way there is no recovery. 

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11 hours ago, Simon Chaddock said:

Modern ones use a 'matrix' plate filled with a "paste". Once that is damaged in any way there is no recovery. 

 

I understand.  So even a smart-charger that has a desulfator function won't be able to resuscitate a modern gel-based lead acid that has been physically distorted by massively overcharging at 0.85C.

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15 hours ago, Jonathan M said:

Thanks folks - I realise that I've properly cooked it!

 

Don't want to down the LiPo route, prefer the simplicity and safety of Pb, and weight isn't really an issue (the 7Ah 12v balances the 1/2 gallon tank at the other end of my field-box/stand).

 

This one actually lasted me very well (until I recently attempted batterycide - twice at least! - by charging at 0.85C) and they're not dear, so I'll just order a new one.

 

But one question for Cuban8:  you say charge at 0.1C which my Fusion charger can do (just set it to 0.7A), but I can't change the voltage end-point on it to less than 14v.  Surely this is safe enough for fairly regular overnighters as I did for years?

Yes, 14V will be fine for cycle charging e.g overnight top ups. Use that method myself.

Use one of these on my Bonneville's battery over winter - also suitable for Gel types https://www.sportsbikeshop.co.uk/motorcycle_parts/content_prod/470768?glCountry=GB&gclid=Cj0KCQiAqvaNBhDLARIsAH1Pq52fFbY_vW0WiNjcuVfL4lknNdg1aveF0RwHkiluvXGCPOhRxw3TYngaAuj_EALw_wcB

Edited by Cuban8
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14 hours ago, Jonathan M said:

I'm hearing all the preferences for switching to LiPos so (as I'd like to fly this weekend) I'm going to try that route - at least as an interim solution!

 

I've got a pair of good but completely redundant 3s 3300mAh LiPos - I assume 3s would be the correct voltage rather than 4s?

 

One (probably obvious) point… In this application with a pack of that size you shouldn’t need to charge the Lipo fully. Set your charger to 4V/cell and (due to the far lower IR vs a Pb pack) it will have plenty of grunt for anything you started with your old setup. The advantages of doing this are numerous… It’s quicker to charge before you go to the field, the batteries will last longer as they will never be stored at an elevated state of charge (SOC), and it’s safer too when you store below 4V/cell.

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3s Lipo hotwire hack (didn't want to lose the starter's banana plugs just yet) worked a treat at the patch today!

 

Used 10% capacity of the 3300mAh - as I was doing lots and lots of repeated but short CG and incidence trimming flights on half tank to keep nose light.

 

PXL_20211218_160757179.thumb.jpg.425327f3c564a8efaf3ac1c1e65b27b2.jpg

 

Edited by Jonathan M
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On 17/12/2021 at 15:35, Jonathan M said:

12v 7000mAh starter battery failed at patch today - had started Irvine 46 a couple of times but fell off a cliff the third time, glow meter dropped to almost nothing when using the starter.  Had been fully-charged a few days ago, used for starting and glow plug maybe a dozen times since.

 

Back home on the multimeter it read 12.28v.  I'd always previously charged on 1A but found my charger set to 6A from the last time. Have I damaged the plates?!

 

It is a Yasua NP7-12S, about five years old with very light use over that time.

 

Currently re-charging at 1A. If it is damaged would repeated gentle cycling recondition it to health, or time to buy a new one?

 

5 years old its done very well. Less than a £1 a year. Screw fix have some , just type 12v Alarm batteries

 

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