View Full Version : Battery For Electric Motor CONFUSION

01-06-2002, 05:28 PM
Gday all,
Well as some of you know I recently purchased a boat that came with an electric motor. The battery that came with it was a marine battery that is rated at 550CCA. This also runs the sounder, nav lights etc The previous owner just got the minn kota and only used it a bit with the electric. So I told my dad that we needed a deep cycle battery for an electric motor.(from hearing advice from others) Seeing he needed to buy a car battery and a ride on mower battery he headed off to a battery store. He asked the guy about deep cycle batteries and that it was needed to run an electric motor etc. Anyways the guy recommended a heavy duty marine battery that was rated 700CCA (cold cranking amps). He had deep cycles there but didn't want to sell dad the cheap ones (around $140) as they were rubbish. (I don't know the brand but he said they were made in Australia.) The guy said the good deep cycles he had that were made in America were around $300, and that you'd need a special charger to charge deep cycle batteries. Seeing Dad didn't want to pay this much and the guy recommended the heavy duty marine battery, dad got that for $120. The cheap deep cycles only had 6 months warranty whereas the one dad got has 12 months. Also the charger dad got (for charging the marine batteries -the one that came with the boat as well as the new one, and the car batteries) was $105, yet its charging rate was 3500mA. I thought chargers were rated in amps? It stops overcharging as well, it is a Projecta Brand. I have heard that batteries rated CCA were not good for constant discharge and recharge, yet the so called battery specialist recommended it to dad, and seeing i wasn't there, dad just believed what the guy told him and took his advice. So whats the deal ?

Robert Russell

01-06-2002, 07:42 PM
:)Hi there Robert
I have a minn kota 55 lb thrust electric motor....Mate i bought an 85amp deep cycle battery for this motor for $150 about 4 years ago and its still going but only just.....If you are using the battery on 50% power it should last for about 5 to 6 hours.
I bought a 14amp charger that will fast charge the battery in approx 16 hours but i also have a 5 amp one that may take 3 days for a full charge....The guy at the shop said the battery will last longer with a slow charge...he also said each time you charge the battery it doesn't quite reach its peak power.
The battery brand i have is CENTURY DURATHON DEEP CYCLE........Mate they weigh a ton but it does a damn good job....hope this helps you with some of those questions.
Don't get cond into spending heaps of money....The battery had 12 months warranty.
Cheers Brent http://www.ausfish.com.au/chat/images/smilies/cwm16.gif

02-06-2002, 06:47 AM
Hey Rob,
Deep cycle would be the best in my opinion as you will draw a lot of power using a electric and will need to recharge quite often. You are supposed to by the right charger for them but you can get away without it the battery just most likely won't last as long. Trickle charging is always better for any battery really not a fast charge but if the guy at the battery shop is any good he should put it on charge for you overnight when needed for free aslong as you aren't there every day. Some guys will anyway. It's worth paying for a good battery as they will last longer as they are made better and thats why they can offer longer warranties.
Cheers Luke

02-06-2002, 03:57 PM
Robert, the battery recomended to me by our Century dealer (work in auto retail store) was the American brand of TROJAN. Reckons they're the ducks guts of deep cycles and s*#ts all over the century deep cycles (coming from the century guy himself too). Also the Projector brand of battery chargers are very good. I also stock them at work cause we have found them to be excelent performers and good value. Chargers are now going under milli amps instead of amps now. Bit confusing but they do that to stop people getting used to something so they have to change it be annoying (thats what I reckon anyway). So when I finally get the cash for my Minnakota I'll be investing in a TROJAN deep cylce for sure. The battery your father got is classed as a deep cycle battery too.

03-06-2002, 06:47 PM

I'm sure if you keep trolling the boards someone will give the answer you want, even if it is wrong.

Be very wary of the type of Trojan recommended as there are many in the range and from what I've seen only a few are available in Australia.

Go to the site www.trojan-battery.com and see if they have the battery for your purpose. I looked and found batteries for lifting platforms, mobility products, solar, and floor machinery. The Marine Batteries are for large power systems on yachts etc.

The Trojan Batteries that are suitable are the "SCS" series. The lightest of these is 23kg and 100AH at he 20hr rate. It will not be cheap! Cheaper types will be the "MT" series which are "MT", "MTX", "MTS" & "MTH". Others in the range are just general Deep Cycle and may not handle the bumps.

You need to confirm the rating for "G" which is the shock to which they are tested. A battery in a boat takes some very nasty and regular shocks which kill the cheaper types and also batteries not made specifically for marine and Offroad applications.

These batteries also supply a "CCA" rating both at 0 degrees and 32 degrees.

Enjoy your search.


05-06-2002, 02:42 PM
You need a deep cycle battery, but as important is the charger. The best type is the switch mode power supply type
like the Baintech ones. I've had several electrics over the years and work as a Instrument/ electric technican. When I bought the most recent one I knew I'd need a better charger. People don't realise that a sealed gel, or a wet cell lead acid or a lead calcium battery need different charging characteristics. A battery that is not stored fully charged and recharged monthly with suffer

I ended up with a Baintech 15 amp. It cost me $500 but I can charge any type of battery by selecting and even do a cell equalisation on a wet cell battery. The main difference between it and a normal transformer type is that while a 25 amp transformer type charger may only be giving about 12-15 amp for most of the charge the switch mode deliver 15amps. I find out on the dams I'm up a re-charged in no-time and my battery will definitely last longer.

06-06-2002, 09:40 AM

I rely mainly on the motor charging loom and travel distances between spots to charge my batteries. I have a standard crank battery and a deep cycle 109amp for the electric. I've never managed to flatten either battery but from reading your post can't help but wonder if I'm doing the deep cycle harm by charging from the motor loom. ??? ??? ???

06-06-2002, 11:36 AM
My view is to "KEEP IT SIMPLE".

I am involved with a charter vessel that has 10 batteries and a racing yacht with wet cell batteries and my own 12 foot tinny. Each vessel has a different priority when it comes to batteries.

Anyway, my 12 foot tinny has a 42 pound Minn cotta fitted, sounder, lights and is a pull start.

I use the old battery from my 4WD for my sounder and lights. It is hooked up to my outboard charging circuit.

For my Minn cotta I have a standard deep cycle battery that cost about $120 3 1/2 years ago. It is charged by a standard Arlec Battery chargers. Works for me.

The battery is only for the electric motor, not for an Aircraft or Deep Cycle Fridge.

13-06-2002, 09:23 AM
Gday Guys,
Thanks for the replies, I called the place where I got the battery and they said that the battery can be discharged and recharged as much as you like even though its not a deep cycle. Also the 12 month warranty should cover any problems, but I shouldn't encounter any. It is about 80 Amp hours and has run my minn kota fine so far. I have a seperate battery to run my sounder, lights etc that charges off the outboard. The reason this battery that runs the kota can be recharged/discharged constantly has something to do with it having thicker cells. So I should be right using this battery for my electric even though its not a deep cycle.

Rob Russell