Dry Lead Acid Batteries

[Harvey Spreckley 2Participant @harveyspreckley2]

Hi I am a newsboy on the forum although I have been modeling 00 gauge rail and boats for eons.

One of my in-hand schemes is to build the Graupner Adolph Bermpohl Life Boat and sister boat and the 2nd is a Fairwind Yacht {deck length is 36" ish inc., plus the stern}. It was/is my purpose to build/finish these boats. I've had them so long that I have forgotten and or lost the instructions as to 'how to' various parts. So as a starter:

I have three Ripmax [dry] lead acid 6V batteries of List No: 0-KM 64 providing 6Volts at 4A/hrs at a 20 hour rate. Instructions on the outer boxing is given as: Charge at 0.5Amps for 30hrs and then recharge at 0.5 Amps for 10hrs. Is this still current thinking please?

Q. What electrolyte/acid should I charge these batteries with prior to electrically charging and where should I obtain that electrolyte? The batteries each measure 90x45x60Hmm the female leads are heavy lead and are on the top all as vehicular batteries.

Thanks,

H. Chris Spreckley

[Harvey Spreckley 2Participant @harveyspreckley2]

How too everything to do with them, pretty well.

[Colin BishopModerator @colinbishop34627]

Harvey,

I think the best advice would be to discard these ancient batteries and use modern NiMH ones instead. Insofar as lead acid batteries are still used in models they are invariably of the sealed gel cell type but are still less efficient than the NiMH types which can be recharged in quite short periods.

You will find a large range of batteries and chargers of all types at Component Shop **LINK**

The electrolyte used in the old batteries was liquid sulphuric acid which is still used in modern car batteries. However the plates in your old batteries may well have degraded over the years so there is a good chance they would never work anyway.

Colin

[Ray Wood 3Participant @raywood3]

Hi Harvey

Colin is correct the only cheap re-chargable batteries in the 60's & 70's were wet lead acid cells, I did keep some mint condition Ripmax for 30 years and took the sulphuric acid from an old car battery and charged them they held a charge and bubbled away merrily giving off sulphuric gas. but they needed topping up etc. They are probably worth money in mint condition to a collector. Things in batteryland have moved on

Regards Ray

[Dodgy Geezer 1Participant @dodgygeezer1]

Q. What electrolyte/acid should I charge these batteries with prior to electrically charging and where should I obtain that electrolyte?

Battery electrolyte is a DILUTE mixture of sulphuric acid and distilled water – around 35% : 65%. Always add acid to water, because adding water to acid may make it boil, and you don't want boiling H2SO4 splashing around. I suspect you can't buy conc H2SO4 nowadays anyway, but you can buy ready-diluted electrolyte, **LINK**

Battery electrolyte is annoying stuff to work with – you end up with spills and vapours which eat through everything. You are much better off following the advice above and buying a new set of batteries which are safer and more efficient…

[Colin BishopModerator @colinbishop34627]

I did use these in one of my models back in the 70s and, as I recall, their performance was pretty weak in terms of power delivery and running time. They didn't last long before they became reluctant to hold a charge either. In those days we all went over to NiCads which are themselves now outlawed!

Colin

[Harvey Spreckley 2Participant @harveyspreckley2]

OK. I get the picture: I am 30 years behind current practise, maybe it was the school boy chemistry/physics thing that made me actually want to try them out.

Cheers & thanks all,

H Chris S.

[Dodgy Geezer 1Participant @dodgygeezer1]

Posted by Harvey Spreckley 2 on 17/01/2017 22:44:39:

OK. I get the picture: I am 30 years behind current practise, maybe it was the school boy chemistry/physics thing that made me actually want to try them out.

Cheers & thanks all,

H Chris S.

You may be tempted to swing to the opposite extreme, and ask for the latest battery technology. This would be Lithium Polymer – better known as LiPo. I would suggest that you avoid these as well, unless you want extra expense and a steep learning curve.

Nickel Metal Hydride (NiMH) are the current batteries which look like the normal cells you are used to, and behave reasonably similarly to 'standard' batteries. They come with the ability to put out varying amounts of current – pick some which put out enough and you will get a sparkling performance. These are commonly used for everyday boat purposes.

If you buy a LiPo it will look like a small, softish and light flat slab. The cells are around 4v each, and are critical to keep within a small range of voltage.You will need a special charger for it, and need to learn how to maintain it properly. Astonishing amounts of power can come out of them, and if you do not look after them properly they can explode or burst into flames. These are commonly used for electric flight, and high-powered racing boats…

[Harvey Spreckley 2Participant @harveyspreckley2]

Thanks for the info DG. I will definitely go with NiMh's which I have on hand. I will also charge up at least one lead acid as I have found throughout my short span of life on earth that in the motor car and sailing yacht that there is no replacement for weight if a comfortable journey is to be had which means I suppose that the only successful racing I can expect using a lead acid will in my Fairwind will be in what is known by sailors as "heavy weather". Cheers and thanks to all. Chris S.

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[Colin BishopModerator @colinbishop34627]

The high capacity NiMH cells will weigh a similar amount to the lead acids – possibly more than the old ones you have when filled and the weight will be much lower in the model.

Colin

[Kev.WParticipant @kev-w]

Posted by Colin Bishop, Website Editor on 19/01/2017 15:56:48:

The high capacity NiMH cells will weigh a similar amount to the lead acids – possibly more than the old ones you have when filled and the weight will be much lower in the model.

Colin

Looking on Comp. Shop site, The high capacity 5000mah NiMh packs in both 6v & 12v only weigh approx. half the weight of the equivalent Gel cell.

[Colin BishopModerator @colinbishop34627]

Yes Kipper, but Chris has the less dense wet cell. You are still correct that the lead acid is heavier but not by as much as you might think. My old Ripmax catalogue quotes 19oz ((532g) for a 6v/4ah wet cell whereas the Component shop 4,300ah NiMH pack weighs 375g. All a bit academic really though.

Colin

Edited By Colin Bishop, Website Editor on 19/01/2017 17:47:19

[Malcolm FraryParticipant @malcolmfrary95515]

Lead acid do supply a goodly amount of weight, but are less energy dense than other types. Unlike almost all of the more modern types they cannot sustain a heavy current without damaging themselves. Heavy in this case means more than 1 amp per amp-hour. A high performance model boat needs more than that to work satisfactorily.

I wouldn't use a lead acid one in a yacht. It might give weight, but it will be in entirely the wrong place. The only place for weight in a windy boat is at the bottom of the fin.

[Dodgy Geezer 1Participant @dodgygeezer1]

There is, of course, the opposite effect of adding too much lightness!

I note that Model Boats did an article on the EeZeBilt Sea Princess and Crash Tender about a year ago. The prototypes were made from Balsa, used NiMH batteries and worked well – Ron Rees built his out of Depron and used Lipos. The resulting boats were so light that when he turned the propeller came right out of the water and the boats lost way and control….

[Colin BishopModerator @colinbishop34627]

In which case Ron's boats presumably weighed less and floated higher out of the water DG? The only other explanation would be if the CofG in Ron's boats was much higher due to the constructional and battery weight distribution.

Colin

[Dodgy Geezer 1Participant @dodgygeezer1]

Posted by Colin Bishop, Website Editor on 21/01/2017 12:33:14:

In which case Ron's boats presumably weighed less and floated higher out of the water DG? The only other explanation would be if the CofG in Ron's boats was much higher due to the constructional and battery weight distribution.

Colin

I haven't spoken to him, but I'm guessing that they floated much higher than designed, and skimmed along the surface. Which is fine for straight-line, but, as he points out, not so good in a turn…

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