Converting POB to Li-ion.

[Parker VH]

"IF" I wanted to convert my POB to some sort of lithium battery what would you guys recommend as far as battery type and size? I know nothing about lithium so any help would be appreciated. Heres a couple of questions.
What would the physical size of a suitable battery be? I want to also upgrade the POB to a 50W ballast so more internal room would be great.

Would I also need a lithium specific battery charger? If so, how much do they cost approx.?

Do lithiums come with any specific terminal/connectors on them that would work with the POB or would I need to mod them?

I'd like to get at least 45 minutes runtime out of whichever battery I end up using. Is this possible without spending a ton?

If you could give me specific battery part numbers or links that would be great.

Thanks in advance.

 

[richardcpf]

I know nothing about lithium so any help would be appreciated.

Before you starting working with this chemistry.. please read about li-ion safety. There are good amount of threads asking for which size to make battery packs. The cells that I know well aren't suitable for this task, for a POB battery replacement you should go with the largest li-ion battery possible, this gives the best power-per-weight.

 

[Patriot]

"IF" I wanted to convert my POB to some sort of lithium battery what would you guys recommend as far as battery type and size? I know nothing about lithium so any help would be appreciated. Heres a couple of questions.
What would the physical size of a suitable battery be? I want to also upgrade the POB to a 50W ballast so more internal room would be great.

Would I also need a lithium specific battery charger? If so, how much do they cost approx.?

Do lithiums come with any specific terminal/connectors on them that would work with the POB or would I need to mod them?

I'd like to get at least 45 minutes runtime out of whichever battery I end up using. Is this possible without spending a ton?

If you could give me specific battery part numbers or links that would be great.

Thanks in advance.

I'd use Li-po since they come in so many sizes and have huge capacity for their size.

You'd probably want a hobby type charge capable of cell balancing. Most hobby chargers will charge every commonly used battery type including Li-po.

You'll need/want to upgrade your connectors to something high quality and low resistance like Dean's or other comparable type.

The cheapest way to get high capacity is to run li-po packs in parallel with something like this:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=7880

A pair of these will give you far more capacity than the current SLA while being quite a bit lighter:
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=6503

Of course double check the battery space dimensions in the POB before ordering and then get what's going to work best for you. If it was me, I'd try to use all of the POB existing battery space.

As far as the expense goes, you're probably looking at about $140 for the battery/batteries and $100 for the charger which can be used for other things too. Not pocket change but it would make one very nice POB. I've been considering this mod myself.

 

[AlexGT]

You need to consider what is the startup current the ballast needs to ignite, I had trouble converting my spotlight to Li-ions and solved it changing the ballast, you can read here

http://www.candlepowerforums.com/vb/showthread.php?t=221303

and here

http://www.candlepowerforums.com/vb/showthread.php?t=221224

I think if I had to do it again I would go with Lipo instead of Li-ion and avoid some of the problems I had, but now the light is ultra light weight and lasts almost 1.5 hours continuous burn.

AlexGT

 

[Patriot]

EDIT,

The OP will need to wire in parallel and I'm posting illustrations of series connections.

Sorry about that.

 

[Fitsbain]

The above harness is series, not parallel.

 

[Patriot]

The above harness is series, not parallel.

ah...yeah. Second time I've done that. I've got one thing in my brain and typing another..

Thanks


Parallel is what he want's though not series.

 

[UnDutchable]

Imo converting to Lipo shouldn't be that hard, I'm only wondering about the start-up currents? If you take a look at this 3S package, it's very small (compared to a 380 brushless rc motor and the iPod classic) and the weight is minimal (approx. 100grams). Is 25C (54A) continues drain enough? The max. burst of this FlightPower 50C (108A)?

I've got a lot of Lipo's (also more Mah) from my hobby, so that would be great!

Ronald
Parker: would you be kind enough to send me the track & trace of the pob? Thanks!

 

[Parker VH]

Thanks much for the replies so far. Keep 'em comin'.

 

[Patriot]

Imo converting to Lipo shouldn't be that hard, I'm only wondering about the start-up currents? If you take a look at this 3S package, it's very small (compared to a 380 brushless rc motor and the iPod classic) and the weight is minimal (approx. 100grams). Is 25C (54A) continues drain enough? The max. burst of this FlightPower 50C (108A)?

I've got a lot of Lipo's (also more Mah) from my hobby, so that would be great!

The 25C is more than enough, but the capacity (2170mah) is way to small. You'll want something in the area of three times that or more. Also, I'd probably go with a 4S pack because I don't know or remember where the cut-off voltage is for the POB. The extra voltage with ensure that you remain above the minimum through it's run-time.

 

[Patriot]

Parker, PM sent.

sorry about the confusion when I suggested and then showed pictures of the series connection. I own about 20 li-po's which I use daily so you'd think I'd be able to articulate my thoughts better. I think I'm loosing what mind I have left.

 

[UnDutchable]

@Patriot: the pic was just for size; I can couple them and also I have some Kokam Lipo's with a capacity of 5000Mah...In al the lipo configs, I use a Voltage Limiter, you can buy the specially for Lipo's. If you connect those, they will cut-off the power when the Voltage is dropping to approx 3V per cell.

Kind regards, Ronald

 

[Patriot]

@Patriot: the pic was just for size;

oh ok, I'm with ya now.

I have a FlightPower 3S 4900mah 50C on the charger right now. They're great batteries but pricey.