Starter box with Dewalt LiFe battery.

[Paul Traufler]

Good deal, I was thinking the DC to DC unit would do the job, but I'm not 100% sure the unit will be "hardy" enough for a long term or not. Use it, see what happens now I say. Good job BTW.

 

[Dan_Cousin]

Were you able to get 5A from it for your cold plugs?

 

[Terry Keeley]

Were you able to get 5A from it for your cold plugs?

Didn't have the guts to try yet, gotta work my courage up, don't wanna let that magic smoke out yet! :lol:

 

[Dan_Cousin]

Looks like a pretty good sized module so they might have enough output capacitance to deal with the output current pulses. DC-DC switcher is the way to go anyway so you don't generate so much heat.

Good luck.

 

[Terry Keeley]

Were you able to get 5A from it for your cold plugs?

Should clarify, it only takes 3A or so to light a K&B HP, MC9, OD89 etc. Guess you'd only need 5A for something with coat hanger wire in it. :lol:

 

[Dan_Cousin]

Yup 3A usually gets it for most plugs. Didn't know if you were running some ultra cold plugs that would need 4+a to glow hot.

One last test is to fill an old plug with some water and see if it can burn off the water. When the plug is not lit it looks like a much smaller resistor than 0.5 ohms (measure the resistance with a meter to see that its almost a dead short). You need some OOMph to get it up to glow. If the plug is flooded with fuel/water or you're trying to start a rich motor, this is a tough condition for the plug starter.

If the water boils off the water quickly (like a second or so) then you should be good. If it sits there an sizzles and the output voltage of the dc-dc converter drops, you may need to address that.

I suspect it would be fine but better to find that out now than at the pond.

Nothing worse than a weak plug starter when you're on the clock and trying to crank a rich running engine. :angry:

 

[Terry Keeley]

Here's what I ended up with for now, I'm not completely happy with the wiring but until i figure out a better way it'll do. I used it at our race last weekend and it has every bit as much cranking power as my big (30 lb) 28v aircraft nicad, lasted all weekend too.

Here's the guts of the DW 28v pack showing the BMS (battery management system) or balancer for short.

Also the 8 x A123 cells:

All wired up, I came off the main terminals to the plugs (car stuff) and out the back to the converter, didn't end up using the interface:

Used a Plano pistol case, fits great:

Oh, it'll put 5A to the plug no problem, HP's don't take that long...

 

[tnrcboatracer]

Did you wind up using the scooter interface card, or just wire it direct?

 

[Terry Keeley]

Did you wind up using the scooter interface card, or just wire it direct?

Nope, didn't use it. Going through the interface and BMS would "soft start" the starter to protect the cells I guess, not the way you wanna crank a 90.

It also didn't like the "noise" from the converter, had to wire up a choke to make it work:

Would have been nice as it'll shut the pack down when the cells reach 3.4v each or 27.2 total, it was getting complicated tho.

BTW, anyone wanting to try this, don't plug your starter directly into the outer terminals on the DeWalt pack, the BMS has an internal 15A fuse that'll blow making it useless.

Ask me how I know...x2! :blink:

 

[Chris Wood]

man i wish i had your brain power keeley

 

[Terry Keeley]

man i wish i had your brain power keeley

I didn't know anything about this stuff, trust me! :unsure:

I'm the guy that lets out the magic smoke, remember... :lol:

 

[Chris Wood]

ya well magic smoke or not.. if i could do half the stuff you or dad does i would be dangerous..

chris

 

[Tony Jacuzzi]

ya well magic smoke or not.. if i could do half the stuff you or dad does i would be dangerous..

chris

I couldnt agree with that brain power statement more on TK and SW. ... geez If only I would have known back in my high school days, I was supposed to let the magic smoke out instead of holding it in ..LOL

 

[Terry Keeley]

Checked the voltage on the DW pack after the weekend and it had dropped to 3.4v!

The charger didn't like that and would just error out. I was able to charge the cells by by-passing the BMS but the problem is current is drawn by the dc-dc converter somehow pulling the pack way too low. Didn't really like how it came out either...

Sooooo, I re-wired it with a Dean's Ultra plug and 14ga silicone wire so it can be un-plugged at the end of the day:

Also wanted to plug the starter into the power panel so I "bypassed" the panel for 28v to the starter:

Nice neat package:

and I can just un-plug the pack, stick it on the charger and forget about it:

Thanks for all the help!

 

[TEMPUS]

Been starting 67 scales for the past three week ends-

with the Boris Starter and 4500 mah battery, no problems

never need to go back to a stater box- My 2 cents!!!!!!!