whats the best way to set up a battery to run a electric starter at the field

ive got a tower hobbies power starter 12v with batterry cable ends on it

Depends, how big is the motor, if it's a small<1 cuin, a pair of bannana jacks are fine it the power panel or small alligator clips, but for big starters, like gassers, I ues a car battery and big deavy-duty alligator clips or even buy repair terminals for cars, the kind you clamp the old cable to, the trick is to find a way to make a good solid connection that's user friendly. Toting a car battery sucks, so I just use my pacific aeromodels starter for the big stuff, it's gear reduced, my sullivan for the stuborn < 1 cuin stuff and the Hornet for 1/2A stuff to prevent engine damage.

I have mine secured inside a field box, and then it's connected to a power panel. I soldered bananna connectors on the wires of the starter and that plugs into the power panel.

Most starters come with clamp style connectors that you can clip directly onto the battery. This works, but you have to be careful that the connectors don't touch and short out. It will make some major sparks.

I got tired of the heavy battery in the flight box. I bought (2) 2400mah nimh packs for R/C cars, wired them together and mounted the pack on the starter. No cords to get caught in the prop too. It starts ever engine I have except the Saito 1.20 and I hand flip that one.

Down side to this setup is you need a charger that will handle the size of pack.


Dru.

Yup the car batteries work great...

I use two 7.4v 3800 NiMH packs, which actually fit in the Hobbico 12v "base" they provide for their whimpy battery.

The whole assembly looks clean and with a normal starter I can turn over a 50CC engine with ease... along with my 1.20's 1.80's, etc.

Can you tell me more about the packs you use? Are they sub-c?

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Can you tell me more about the packs you use? Are they sub-c?
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The lighter starter uses two 3000 Nimh 7cell packs (sub C size) in series for a total of 16.8 volts and this imparts major performance over all the commecial portables I've ever seen. My mondo starter is the same cheap Tower starter with a high capacity switch and two 5000 Nimh 7 cell packs (C size). This combo outperforms even many geared types.

Yup I pretty much did what John said above.

The only difference is I used two "Wolfpack" 3800mAh 7.4v packs from Tower wired in series to produce 14.8 volts.

I cut the existing cable from the starter and wired up two Tamaya style connectors for the batteries.

I charge each battery separately on my charger... so I charge the packs up in 2 hours at 1C.

On a typical weekend of flying I use up about 1000 mA on each pack ( or less! ) and that's over 20+ starts, including hard starts, larger planes, etc.

In other words I could theoretically go 1 month between charges if I wanted to... I tend to charge the packs every 2 weeks though.

I had previously purchased the Hobbico 12v battery and container sold by Tower. But I found that the battery would barely last me a season, and the starter was anemic with the battery sold by Tower.

After starting a larger plane, after borrowing a starter from someone at the field, who had done what John is suggesting, I decided to do likewise... there is NO going back now! It's a huge difference..

I have the battery pack from Tower and I am very unhappy with the performance. I thought You had found something that would fit inside the case. It would be an easy solution with minimal fabrication for me since the case is already attached. If that is not a good way to go I will do what you and John did.

What i did was run a hot and ground wire from my Pickup battery to the back of my pickup. Drilled two holes inside the liscence plate spot and put two bolts with wing nuts on them. Then i just hook my starter straight to 12V works great. Don't think it would crank big gassers but that is the starter itself not being big enough. But will turn a 180 quite well. Where we fly most times my planes are at the back of my truck anyway and if not then I use the panel from my flight box. With using the pickup though I don't even take my field box as i have everything in a bag and small plastic boxes. Most field boxes don't work very well IMO. The drawers fall out or won't close easily. Hard to get to battery also.

Oh use pretty heavy guage wire or you lose power running it that far. But then your battery is always hot. And your truck or car will recharge any time you go anywhere so unless it goes bad you always have a hot battery.

Yes I fit TWO 3800 "Wolfpacks" within the Hobbico case.

I had to cut away part of the flashing, but they fit just fine once done.

For the complete "electrically challenged" guy, can someone validate the proper wiring of this? Looking at the pictures it appears that it goes as follows:

1) Black wire from starter to Black lead from Battery1
2) Red wire from starter to Red lead from Battery2
3) Connect Red lead from Battery1 to Black lead from Battery2

That correct?

-MA

Correct!

However here is something that will make this easier...

Click on this link:

[link=http://www3.towerhobbies.com/cgi-bin/WTI0095P?FVSEARCH=LXMTZ3+&search=Go]Connector[/link]

Using one of those, you only have to cut the existing starter wires and attach one new connector.

It also makes the batteries easier to disconnect to recharge...

Awesome!! That's exactly what I needed. Thanks Opjose! [8D]

BTW: I also kept the cut piece of cable and placed a corresponding connector on it.

That way I could always go back to hooking the starter up to a field box.

I have yet to use this however...

Just for a little clarification:

I'm unclear about the 'amperage' here. In other threads people were saying that the hobbico power core was weak due to the amperage - 1.2 amps. Is this different than having a 12v 1200mah battery?

I just got the heavy duty starter. There seems to be little difference between that and the regular '90' starter. I tried both with the power core 1.2 amp battery, and then with my car batter.

I then tried my '90' starter with my 14.4v power drill battery, and WOW! I think it's a 3amp battery. This is different than 3000mah?

I want to get two of the 7.2v rc car battery packs and wire them together with the above connector. Will there be a difference in cranking amps with different capacity batteries, or is the capacity strictly the length of time the battery will run?

Also, if my charger can charge up to 16 cells, can I just charge the packs while still connected in series?

I was not looking forward to taking my EE classes, but I'm so sick and tired of not knowing this stuff! Next semester hopefully I will be able to give advice and not have to ask

gaRCfield


I'm no EE.

But a 3000 Mah battery will give you
3 amps for 1 hour.

As for charging, charge each pac seperate.

Also 1.2 Amps is 1200 mAhs.

Bob

Go to Walmart and buy a $30 Black&Decker Jumper battery, you will use it to start, charge, all kinds of things, it comes with 2 or 3 chargers from the house or car, will jump off your miata or the honda thats been sitting in the basement for 3 years (yes it will) and anything you need 12 volts for at the field without ruining your car battery (had that happen too)...its a great investment,I saw a guy at the field with one charging his lipo's and I was having trouble (redoing a 91 miata) with a car and BOING it hit me , what a great idea...so I got one, very useful so far and after 2 days of carb cleaning I DID get my 95 Honda Magna running!!!...course the tank is shot but thats another story......Rog

Do not increase the voltage if you expect to keep your starter with your stuff and not have to go looking for it all the time. Its as simple as that. No matter how much you agonize and anylyze. Mine all operate at 16.8 volts seven cell packs and various capacitys the all work great the small half A unit I charge all fourteen cells together and the two larger units each seven cell pack is wired to charge with separte dedicated peak chargers. Bottom line all the starters operate at 16.8 volts regardless. The commercial portable starters that operate at 12 volts are in My Opinion a complete waste of money.


After some years now thankfully a number of the other locals are copying this set up and I finally do not have to go looking for my starters, well at least not as much.

John

Thanks guys. I can get a couple of 7.2v, 1800mah batts for $13 ea. Sounds like that will be enough then

The power available to turn the starter depends on the voltage available. What many people don't consider is the internal resistance of the battery. About the worst setup to use is the gelcel, which has a fairly high resistance, plus a pretty short life. They do work well as doorstops, so not a total loss.

I built my first cordless starter over 25 years ago. Just a couple RC car packs in series of only 1200 mAh which was plenty for a weekend. I would select batteries today based on what you have on hand to charge with or what you want to buy. Some chemistries tend to self discharge.

Regardless, keep the voltage high, the internal resistance (# cells x mOhm/cell) low, and the wiring heavy duty, short and clean.

i use one of these 7.4v batt's (hobbico yellow starter like above) to start my .47 gms.
http://www.all-battery.com/72v4200ma...umorobots.aspx
with a 40 amp drain rate (4200 mah) these can turn a starter well w/ 7.4v, let alone 14.8 if i were to add another pack

or you could make a pack w/ these (way overdoing it) and power your starter(and everything else) for a month or so (being sarcastic)
http://www.all-battery.com/4pcsfsize...batteries.aspx

Perhaps I was not clear enough on the relation between voltage and power.
When you double the voltage, in effect you get 4 times the power. (It's actually a little short of that, because with the higher voltage, you also have higher losses due to higher current.)

But if you ever plan on running bigger engines, more power (grunt, grunt, grunt).

I've got a 1.20 two stroke and a 1.10 four stroke so I need the power. Thanks for all the input.