Similar, but not quite the same to this Question; "Charging and Using a Li-Po battery simultaneously", I want to have a battery in my camera but also connect an external charger at the same time. Is there a safe way to do this please?

The application is to power my DSLR camera (Olympus OMD EM10) during an overnight timelapse shoot. The camera wakes up every minute and takes a picture. It can take 999 pictures, but the battery only lasts a few hundred..s

The battery is a Li-ion 7.2v 1210mAh unit. This lasts a few hours but isn't enough to do a full night. Because I'm using a tripod, I could have the battery compartment open and fit the battery on top of the terminals, capturing the leads of an external power supply. But I'm worried this might toast the battery or worse, destroy the camera!

(As an aside, the battery - BLS-50 - appears to have four contacts!)

If this is "dangerous" - it is certainly inconvenient away from the house! - , how could I bodge together multiple cells to safely add duration? [EDIT: SO, this isn't thought dangerous. Moving on then, how could I power this from the mains and with a battery at the same time? And could a 5v 10AH USB power bank/battery pack be used or would the voltage difference be too much?]

(Surprisingly, Amazon let us all down and doesn't sell such things...)

Many thanks!



closed as off-topic by Ignacio Vazquez-Abrams, Daniel Grillo, placeholder, duskwuff, Nick Alexeev May 27 '16 at 17:39

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Ignacio Vazquez-Abrams, Daniel Grillo, placeholder, duskwuff, Nick Alexeev
If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ Do you really want the battery in the camera, or is your goal simply to arrange an external/extended power supply for the camera? Also, it isn't completely clear if mains-powered is a goal of this, or if you'd be happy/require with simply an external 5000mAh battery pack. \$\endgroup\$ – Sean Houlihane May 24 '16 at 18:13
  • \$\begingroup\$ 1. Even if Amazon sold stuff like that, you sure as all HELL don't want to buy it there. 2. Use a battery grip made by Olympus if that doesn't exists; 3. Use the optional external adapter made by Olympus if that doesn't exist; 4. You really ought to do better research before buying, as there are $30 cameras with an adapter. 5. Use of appliances, advice for where or what to buy and open-ended 'what shall I do with' are all three reasons for being off-topic and eligible for closing. \$\endgroup\$ – Asmyldof May 24 '16 at 18:16
  • \$\begingroup\$ Hi Sean. That's a good question! Big battery v's mains power for my timelapse goal.. Because I have three batteries and they are quite cheap, a 5000mAh pack isn't necessary - even if it does make me wonder whether I could use my external 10Ah 5v USB pack?! I think the real answer is "external mains supply", leaving the question being "what Amperage does this camera need" rapidly followed by "will the extra terminals cause problems?"! \$\endgroup\$ – Wobbler May 24 '16 at 19:41
  • \$\begingroup\$ the extra terminals are probably for temperature measurement, and can probably be ignored (except when charging). You should edit your question if you have clarifications to make. \$\endgroup\$ – Sean Houlihane May 24 '16 at 19:53
  • \$\begingroup\$ Asmyldof - 1. It's convenient! 2. I checked - they don't make one. 3. I checked - they don't make one. (And I would have already bought one if they did!) 4. My phone has a fantastic camera and a charger - it takes excellent pictures! But not as good as the OMD EM10, which is one of the best in its class. You don't buy a camera for its peripherals after all... 5. That would be wrong, so I've tried to avoid doing that, but thanks for the advice. \$\endgroup\$ – Wobbler May 24 '16 at 19:55

Replace the battery with a dummy (and contacts for the main +/- pins), and wire this to a seperate larger battery. Don't try and include the original battery in the circuit, this should't be necessary. Be very careful to avoid any chance of a short-circuit. Make your contact block out of wood or plastic.

  • \$\begingroup\$ This idea appeals to me a lot - see my comments on my 10Ah USB pack above! Although, I think a mains powered solution may be quicker in this case. \$\endgroup\$ – Wobbler May 24 '16 at 19:48

The only 'safe' way is to parallel multiple batteries of the exact same model, after they have been charged to full capacity. This requires that you do several important task first.

1) Use a DVM or any voltmeter and find out which 2 terminals supply the voltage. The extra 2 terminals are most likely for temperature and charge current.

2) Buy a plastic box the can hold spring contacts (or 'pogo pins')for just the power terminals only, with the battery having a snug fit.

3) Use black 20awg wire to connect all the negative leads from the extra batterie(s). Use red 20awg wire to connect all the positive leads. Use large wire nuts to connect them together, along with the black and red wire going to the camera. Strip back enough insulation so the wires can be taped in place over the + and - battery terminals before you install it in the camera(the tape is on the side of the battery, not over the battery terminals). The camera will not 'see' the extra batteries because it is not charging them, only drawing current from what it sees as one battery.

4) If the connections will not or cannot stay in place at the battery terminals or the battery compartment is too tight of a fit for the wires to pass along side the battery, you will need to find an alternative solution.

5) Do NOT allow the extra wires to short or the insulation could burn. 20awg wire is rated for 5 amps, but a short circuit could allow much more current to flow. Play it safe. If the final results are cumbersome or the wires will not stay over the terminals, stop and find another solution.

  • \$\begingroup\$ I like this a lot, thank you! - but... wouldn't hacking a single pre-made, higher mAh 7.2v pack have the same outcome? (And avoid most of my clumsy build capability). Do we have a potential issue with the extra terminals though? Are these something which need addressing/spoofing please? \$\endgroup\$ – Wobbler May 24 '16 at 19:50
  • \$\begingroup\$ @Wobbler. A higher current battery of the exact same voltage and battery type should be fine. Any batteries in parallel need to have the exact same voltage before connecting them together.) The extra terminals are used by the charger only, because during charging it monitors the battery charge current and temperature for safety reasons, and to insure a full charge but no chance of an overcharge.) The mechanics of doing this could be a show stopper, so I would check for battery fit with the wires attached first, but no extra battery. Be sure the battery will not jam into the camera too tight. \$\endgroup\$ – Sparky256 May 24 '16 at 20:00
  • \$\begingroup\$ Using a piece of wood as a 'dummy' battery that can be trimmed so the wires will fit is a good idea, as long as there is NO chance of arcing at the contacts. This will burn the insulation and the wood and may send smoke into the camera. \$\endgroup\$ – Sparky256 May 24 '16 at 20:18

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