Battery Question for sx350 build

[Brian L]

I'm about to start a 60 watt SX350-based build. I had initially planned on, and ordered a single 18650 battery for it, but now I'm wondering if it might be better to use two 18650's instead of the single. I would like to keep the size down, but more importantly, I want it to be able to go all day on a single charge. This is my first build of this nature so I thought I'd poll the experts here. I'm also wondering if, when using dual batteries, it would be better to run them in series or parallel. I've seen it done both ways, but am unsure if that affects the ability to charge via USB. Any insight would be most appreciated.

 

[Mike H.]

Dual parallel will double your batteries MAh capacity...meaning if you use 2 2500 mah batteries you now have 5000 mah but still a maximum of 4.2 volts...That should last a bit in the day...lol

Running series will double your voltage to 8.4v but still only give you 2500mah with both batteries...you dont need that much voltage at 60w...not even sure if the chip is made for that much voltage input anyway.

I prefer to charge batteries out of my devices but i dont see why you couldnt charge through a USB port in parallel...1 amp might take a while to charge it however.

Id go parallel for the added capacity, myself.

 

[Brian L]

Thanks, Mike! That's just what I needed. I'm not too worried about charging. I installed outlets in my house that have 3.6 amp output usb ports in them. I want to primarily use USB for charging so I can charge it anywhere I happen to be, if need be, and not have to carry around any extra stuff.

 

[Jackson]

You can't use a series stack with that chip.

Input Voltage 3.2 Volts 3.7 Volts 4.5 Volts

 

[Brian L]

Ah - The series-connected setups must have been using the 100 watt boards. No matter - parallel is what I want anyways. Thanks.

 

[Mike H.]

Why not do a build thread on here...Im sure many like seeing those as i do...lots of pics please

 

[Brian L]

I'd be happy to, Mike. I have a picture in my head of what it's going to look like. I have yet to figure out exactly how to make that vision into reality! I ordered another battery and a dual sled, which should be here this week. Other than that, I am waiting on wood and magnets to arrive. I'll log the progress and put up a thread when it's all done.

 

[Mike H.]

I'd be happy to, Mike. I have a picture in my head of what it's going to look like. I have yet to figure out exactly how to make that vision into reality! I ordered another battery and a dual sled, which should be here this week. Other than that, I am waiting on wood and magnets to arrive. I'll log the progress and put up a thread when it's all done.

Do you mean "another battery" as in so you have 2 for the build after its done?

 

[Brian L]

Well I was originally planning on doing a single battery setup, but revised that. I want to run dual batteries, wired in parallel, for longevity between charges.

 

[Mike H.]

I was asking because i strongly recommend both batteries be new and "MARRIED" to the box you build...If one cell goes bad buy 2 more and re marry again..Not good to mix batteries used in other devices...Just a safety and performance thing...Buy in pairs and use in pairs.

 

[Mike H.]

Periodically check voltage of both batteries to see if one is draining faster than the other..if it does replace them.

Within reason of course..if one is 3.8v and the other 4.1v one cell is not a good battery...replace both.

If one is 3.75v and the other 3.80v you have a good pair to work with.

 

[Brian L]

I got ya - I'm not battery expert by any stretch of the imagination, but I did know not to mix and match batteries. I already have one, but it's not even been removed from the box and I bought it specifically for this build. For the second one, I purchased the same exact battery as the first, from the same retailer. No worries there. Thanks for the tip on checking voltage periodically. I'll make sure to do that. I've not used this type of battery before. I'm comfortable with electronics in general and have built several other electronics projects in the past, but those have all been automotive-related. This is my first venture into a hand-held device. I'm doing a lot of reading and knowledge-building before I begin anything.

 

[Jackson]

Periodically check voltage of both batteries to see if one is draining faster than the other..if it does replace them.

Within reason of course..if one is 3.8v and the other 4.1v one cell is not a good battery...replace both.

If one is 3.75v and the other 3.80v you have a good pair to work with.

Being a parallel config that won't work. Between presses the battery voltages will always be self equalizing. If you started with one at 3.8V and put it in the holder with one at 4.1V in less than a minute if you checked them again they would both now be at 3.95V. Basically the 4.1V is charging the 3.8V one. Nor is there any reason to rotate the position of the batteries like in a series config.

That said you wouldn't want to put 2 batteries with a very wide gap in volts into the holder.