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Discussion Starter · #1 ·
Right-o, let me start of by saying that I have very little knowledge about electronics, in the realm of batteries/power ratings/power boards/supplies etc.However, I have just ordered an Eken M001 and the only concern I have is the Battery life. That said, I would like to mod the Eken with:a) An extra battery running in parallel to the stock batteryorb) An 'external' battery (though I this would be housed inside the Eken), that would charge the stock one - just like the battery in the Carnivore mod.The battery I have in mind it along these lines (also mentioned in another post) -http://cgi.ebay.co.uk/Li-Po-Lithium-Polymer-Battery-3-7V-3500mAh-SatNav-GPS-/300436835870?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item45f36e4e1e
 

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Discussion Starter · #3 ·
After some research, I have concluded that while safer, Li-Ion are far bigger and unwieldy. Although, Mobile phone batteries (Nokia BL5CT or BL4D) are Li-Ion and a small size. These however have a strange pinout, in that they only have +, Battery status Indicator, and Ground. Knowing nothing about this, would the ground double as the - (negative) pin?
 

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ianae but here's from my experience modding gadgetsA) running battery in parallel generally a bad idea. Parallel batteries have the same voltage but divide the current. If you have one bad battery in the link, the current will be divided among the others and reduce battery life, or worse. This, however, can be handled properly with a balance board.
the external battery mod that carnivore did is, in a way, a parallel battery mod. Instead of having a direct line from one battery pack to the other, it has to go through the board. But the charging process/logic is the same as parallel mod.Again I'm not an expert and I'm talking from experience. The easiest/quick and clean way to do it is to replace the current schema with higher capacity. Most li poli have balance board attached and cut the voltage at 4.2, but some (like for some RC/external dvd player) the balance board is not on the pack but on the mainboard it self. Be careful and good luck.
 

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These fully protected cells simplify usage with their integrated PCB. Perfect for your single cell application these cells are not for pack building as doing so will defeat the PCB protection which is matched to the correct voltage on a single cell.
From battery junction webpage.
 

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Anyway; who is thinking of putting batteries in parallel?That would be not possible:You are going to have 2 batteries of 6 mm that sum 12 mm and it wont fit so lets discuss about serial and this would be the only solution!I check the Li-Po 7.4volts one cell and no one fit in the case for more than 1700 mah.I check too the other possibility of going with Li-Ion safer but there are not much of these arround and take more space.2 batteries of 3.7 volts in serial that give 7.4, there is no other way.This is the way Eken did it and of course you have to take precaution but come on guys; we are going to the moon!2 batteries in serial with a good soldering and circuit protection if you want, thats about it + few hours testing without closing the case (lets say 48 hours charging and discharging).This is not high end electronics.My only problem is : will they fit in the case?
 

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To clarify a lot of confusion here:1.) cell = a single electro-chemical container, in the case of lithium cells considered here = 3.7 volts nominal2.) battery = (properly) multiple cells, in the case of lithium batteries here considered, any multiple of 3.7 volts, for example, a 7.4 v lithium battery3.) series = connecting cells (or batteries) so that the output voltage is additive. Preferably performed only with identical capacity, voltage, and type cells/batteries. Example two 1.5 v 3amp alkaline hour flashlight cells in series yields 3 v. at 3 amp hours.4.) parallel = connecting cells (or batteries) so that the output voltage remains the same as a single unit, but capacity is additive. Again, preferably done only with identical capacity, voltage and type cells. Example two 1.5 v 3amp alkaline hour flashlight cells in parallel yields 1.5 v. at 6 amp hours.5.) The above can also be done together. In other words, serial batteries can be connected in parallel to yield increased voltage and amp hour capacity. So yes @enotar, it is possible to connect batteries in parallel to achieve 7.4 volts. Assuming the batteries are both 7.4 volt batteries. If you are saying additional batteries won't fit in the case, that's something different than saying it's impossible to connect them in parallel. Some people have modded cases, and some are considering external attachment.6.) BUT (big but), being able to do something doesn't necessarily mean you should do it. While the batteries most people are used to are either disposable, or relatively tolerant if rechargeable, lithium batteries and cells are not so casually used. Particularly, Lipo cells (the kind in soft cells found in the Eken) If you wire lithium cells together in combinations that the charge circuitry and protection circuitry are not designed for, you are asking for a damaged cell at the least and possibly an explosion and a house fire.Why is charge protection circuitry essential? Because Lipos can be damaged by either under voltage or over charging, or also over drawing its current limit. Once it is damaged, it is a potential fire bomb. The most common physical sign of damage of a lipo (other than a fire or explosion) is swelling of the cell. Once a cell is damaged it should not be charged again. It should be removed from your house and recycled/disposed of properly. And that doesn't just mean tossing it in the wastebasket.Proper protection circuitry senses when a cell is damaged and refuses to charge it again. That may be why a lot of people's Ekens appear dead, or refuse to charge. It may be that either one cell (of the two in series in the unit) is over-discharged, or is not balanced with the other in voltage beyond acceptable limits, or the charge or protection circuitry senses a charge current problem or cell voltage problem, or the charge sensing circuit is itself damaged.If you add an external battery to an Eken in parallel with the internal (series connected) cells, You may be defeating the internal cell protection circuitry (I say may because no one knows what that is exactly). and you may be overloading the power supply as well. Power supply burnouts appear to be epidemic in Ekens even without user added battery mods. These burnouts themselves can conceivably damage cells or even protection circuitry.In addition, it is unlikely you are adding external cells that match the internal ones in size, type, and even charge level. I suppose if you took the batteries from another same revision Eken and added them this way they would match in type and brand, though the charge levels would also likely be different. You would therefore need to balance charge them, in other words charge the two battery banks separately, not paralleled into the same charger. Most people will not do that unless knowledgeable about lipos, and in possession of a balance charger. The external battery should also have a protection circuit in order to regulate any backfeed from the internal batteries and vice versa if either set gets unbalanced. if you bypass the Eken's charge regulator and solder to the cells, you can conceivably back feed them at too high a rate, unless they have internal regulation. I don't know about that. Nor has anyone here said yet.In none of this am I saying that additional cells and batteries or replacement batteries are absolutely impossible or unsafe to install. I hope to do that myself at some point. What I am saying is that with the current state of a lack of knowledge of the charge circuitry in the Eken, its protection method, and the state of its own internal cells in any individual unit, and the wide range of lithium batteries and cells people are proposing (based often on ebay price alone!) that if this continues I do expect to see some serious mishaps here, just like on the RC group forums I participate in. A house burning or two in these pages might get people a little more serious about this subject, but I'd really like to prevent that by urging caution here.Personally I think any addition of cells in parallel with the the internal cells is potentially more problematic than replacing them. Others may disagree.Ideally, I think replacement of the internal cells with Li-ion rather than Lipo cells of known characteristics, and an appropriate battery protection pcb and/or possibly a 3 wire lead out to a genuine high quality Lithium balance charger set up to work with those characteristics is a safer way to battery mod. Possibly better even would be a removable battery that could be charged outside of the unit in a fire safe container. But all battery mods carry some risk which is very dependent on the abilities, knowledge and care of the builder.To each his own, I just hate to see people with no electrical experience, and no knowledge of the requirements of lithium battery charging proposing or performing modifications to the batteries and charge circuitry of this tablet. Or others saying it is simple. Yes, using Paypal to buy a battery and soldering it in place is simple. What you have, sitting on a nightstand perhaps a month later and smoking is not.
 

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[quote name='ripper1;11225]These should work' date='found them on dealexterme #18650 battery 3.7 volt 2800mah built in pcb 16.50 for 2 shipped they are 2.6 inches long and .710 inches rd. What do you think?[/QUOTE']I believe these are for 3.7 v applications only and you cannot series them without defeating the internal pcb. I'm checking on this now. BTW that price isn't a lot better than those available locally (if in US) check out, for instance Battery Junction for Ultrafires. They also have an Ultrfire 3000 mah single cell (though again probably not suitable for a 7.4v application like the Eken). Battery Junction does have a 7.4V 18650 pack with protection, but only 2200 mAh. And again all of these are about 0.7" dia, thus won't fit in an unmodified Eken case.
 

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Can anyone with knowledge in this area tell us if there are industry standards in the area of LiPol battery charging/balancing interfaces, or are these circuits specifically built for each battery pack and device?
 

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awesome post vtpad. very informative.I've been in contact with ebay sellers (hk, mainland) and what not and extended batteries that they have won't fit in eken un-modded case (even those for straight series replacement). I guess the company that makes eken also stuck with battery option like us now? hmm.. shame thou cos it has alot of potential =( .. guess i should just be happy with it connected to the charger all the time.
 

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[quote name='evergleam;11552][URL=http://cgi.ebay.co.uk/New-Replacement-Battery-EKEN-MID-M001-Tablet-PC-/200488604845?cmd=ViewItem&pt=UK_Computing_LaptopsAccessories_LaptopBatteries&hash=item2eae0d54ad]Replacement Batteries now on EBAY![/URL]This is good news' date=' yes?[/QUOTE'] awesome !!! ;)
 

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12v 9800mah 12v 4800mah12v 2800mah nice battery packs for modding....normaly use voltage regulator for convert 12v in 9v
for external use ........i find it to aliexpress too
 

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i thinking this mod for modular external power.normaly min use 9v .... max 32 v but lm7809 go hot!! whit simple deviator use to connect or to external battery or external input.for eternal input use you use direct car power or notebook power supply ;)i looking for high efficent dc dc and find this integrate V7809 is have same pin out and use at lm7809 but have for 11v-32v @ 1A have 95-92% of efficentcapacitor needed is different datasheet request 10uF/50V and 10uF/16VDatasheetNow need help for find it at digi-key 1 piece cost 10.80$
 

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[quote name='evergleam;11552][URL=http://cgi.ebay.co.uk/New-Replacement-Battery-EKEN-MID-M001-Tablet-PC-/200488604845?cmd=ViewItem&pt=UK_Computing_LaptopsAccessories_LaptopBatteries&hash=item2eae0d54ad]Replacement Batteries now on EBAY![/URL]This is good news' date=' yes?[/QUOTE'] UMMM... the auction says 3.7VDCI thought M001 was 7.4VDC???????????????????????????????
 
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