24 volt Bow Mount setup.

[Feral]

How to set up your battery bank to run a 24 volt bow mount electric motor. - My way!

Ok Thanks to Ray's generosity (ie giving me a cheap deal) with his old bow mount motor, I had a new little project to put together. After Nads won that small watersnake bow mount in the ABT at Bribie a few weeks ago, he put it up for sale on the site. After a bit of negotiation Ray bought it for his boat. The one he had he reckoned was to big for his boat, and at 24 volt, needed to many batteries! which weighed down the nose of his boat to much. So I bought the big un off him and fitted it to the Yak! This is the story.

Ok get up off the floor. I fitted it to the silver bullet not the Yak, just having a lend of ya's! ; har har:

Anyway 65lb, autopilot, cable remote, 24 volts.

Fitted the motor itself last weekend, but I had to wait for some cable and plugs before changing the batteries over, which I started today.

I had 2 x 35 kilo 6 volt 160 amp batteries under the front seat, I swapped them out for 2 100amp hour 12 volt batteries run in series to give me the 24 volt power. I've had the big units in there for 3 years, powering a second electric on the back. (Will still have another 2 x 35 kilo 6 volt 160 amp batteries under the rear seat for powering the 54lb electrics on the back.)

Mount was done using a piece of ally box section dredged out of Rays shed, combined with a bit of marine ply.

View of bolts down ally section

Exposed bolts through top of section (love 3/4 inch drill bits!)

Front view

side views

Unfortunately Maxi it obscures the north coast fishing sticker!

This week I removed the existing batteries and replaced them with a lighter pair of batteries capable of delivering the required 24 volts at the front of the boat, About 17 kilo's each. Ironically whilst the batteries were to heavy for the front of Rays boat, putting them in mine will drop the weight in the front of my boat by 20 kilo's!. (after allowing for the weight of the motor)

Those of you who been around long enough to have seen the original project where we rebuilt the silver bullet in to a dam boat will remember that I had 2 x 160 amp 6 volt batteries in series (Ie wired to deliver 12 volts at 160 amps) at each end of the boat, I also have cabling running under the floor of the boat which allows me to deliver power from either battery bank to the other end of the boat.

If your a masochist you could have a look at the original project here

http://www.australianfishing.com.au/forum?func=view&catid=5&id=4467

So the idea was to install a pair of 12 volt batteries in series to deliver the required 24 volts, whilst preserving the ability to deliver 12 volts to the back of the boat from the front battery bank, and allow easy charging of the batteries using my original 12 volt smart chargers. (You do not want to know what a 24 volt smart charger is worth!)

Having little experience with 24 volts, apart from a few years around trucks (and in my racing days, its amazing how fast a sad 12 volt bosch starter motor will turn when you feed it 24 volts!) I did a little research and pumped Ray for info. Good news is doubling the voltage basically halves the amp load the wire has to carry.

Basically the 65 pound motor will draw around 40 amps running 24 volts. Previously the 54 pound motor would draw around 45 amps at 12 volts. That means the existing fuses and wiring for the 12 volts setup would be fine. However I was a little worried about all the plugs that would be in the front of the boat to allow all the power moving, battery charging and motor removal. I figured London to a brick that one of the kids or a poor deckie would eventually connect the 12 volt directly to the 24 volt, causing a very interesting disruption to the space time continuum whilst 260 amps of juice across 2 battery banks (due to the in series wiring) basically went in to a dead short underneath the seats.

So I made the decision to run the 24 volt system using the bigger more robust 175amp Anderson plugs. (The 12 volt system using the standard 50 amp plugs). That way the two systems could never be accidentally connected. Then I got to thinking, whats the biggest bow mount they make? You have to allow room for expansion in a boat, so seeing there is a 36 volt, 100 amp bow mount now being made, I thought I may as well future proof the wiring loom, and double the cable in the 24 volt harness to give 120amp capacity!

So the eventual setup is as follows.

2 x 100amp hour deep cycle batteries connected in series using 120amp cable, to give 24 volts at 100 amp hours capacity. This connects in to the motor via a 175amp Anderson plug fitted with 1/0 gauge pins (that's the biggest suckers I could get!).

Each battery also has a 60 amp cable 1m long, connected to a standard 50 amp Anderson Plug. This allows charging of the batteries using a 12 volt charger individually. Either of these leads can be connected to the 60 amp wiring harness that runs to the back of the boat should I need power at the back of the boat, or wish to charge the battery from the back of the boat.

Fixed mount wiring from front to rear of boat.

Also in place is a 20amp harness, also doubled to give 40 amp capacity which powers the fuse block in the front of the boat. This harness is only connected to the port battery.

All the cabling is held neatly in place with vulcanising tape, the batteries are held in place by strips of marine ply stopping them sliding, when the seat goes back over the top, a piece of marine ply will also be added to the front to ensure there is no way the batteries can come out of the boat if it sinks or rolls, making it legal for lake Baroon.

Final wiring harness in place

Some labels to try and explain what is where. (Remembering the 24 volt system all has two cables side by side to double the amps capacity)

Final plugs that will come out from under the seat

Final touch before replacing the seat will be a really good bath in Inox for all the terminals and connectors.

So there you have it, my way of running 24 volts for my bow mount. PS I also discovered that when you are tired near the end of the day, and attempt to cut 60 amp twin core cable which you forgot is still connected to the rear battery bank, without the fuse connected in line (some boof head having previously dropped a 35 kilo battery on the bi metallic fuse, cracking it, requiring it to be replaced) it is possible to weld your good pliers in place !

Other random possibly useful info for the aspiring marine electrician.

For comparison, just to give those who dont have with deep cycle batteries, In this photo are the two 160 amp 6 volt batteries I removed from the front of my boat. They weigh 35 kilos each. The little battery in top right is the 12 volt 42amp deep cycle battery I use for Alex's boat. It weighs 14 kilos. Which is still about double the weight of your standard car battery.

Connecting Batteries in Series

Connecting two batteries in Series will deliver twice the voltage, with the same amps. IE two 12 volt 100amp hour bar batteries connected in series will act as a 24 volt 100amp hour battery.

Connecting Batteries in Parallel

Connecting two batteries in Parallel will deliver twice the amperage, with the same volts. IE two 12 volt 100amp hour batteries connected in parallel will act as a 12 volt 200amp hour battery.

Of course please remember this is just my way of doing it, which is pretty conservative, but suites my needs. There are many different ways of connecting it all up, plugs, wire gauge, fuses, all can differ.

[Tom B]

Some very good information there Andrew,

but one question in regards to charging, im going to need the 24v in series upfront so im looking at a 24v charger (only $480 lol) so if i had two 55lb motors on the back, and ran one battery per motor, when charging would i be able to connect the batteries in series to charge? or will being at different voltage levels affect it?

[Terry H]

Nice Andrew!

I'm sure that boat would fly. Lees tomcat motors under a 70

[Davo_Dinkum]

u could have the switched .2 separate battery's to run 2 motors at 12 then switch them in series to charge.24 volt's then.

prob make a wire rig out of 5 or 6 mm cable to do it . a decent switch or a switch and relay should do it

.as charging would only be a trickle charger ?.

[Feral]

Tom, if the batteries are the same size and age, you should have no problems charging them in series with a 24 volt charger. I've been doing exactly that with my 6 volt batteries, charging them in series with a 12 volt charger. However I keep them in series, if yours have been discharged to different levels it may cause issues, I dont know. You can always give them an initial charge with an elcheapo 12 volt charger the finish them off in series with the good charger. I do that as well, when I have used all the batteries a fair bit, the smart charger goes on one lot, the others get charged with an elcheapo car charger over night, then switched to the smart charger the next day.

Davo, My smart charger is a 20 amp unit, On a deep drain it puts in close to 20 amps for the first couple of hours. Thats not a big charge rate though on 160 amp batteries.

[Davo_Dinkum]

ah k

a bit more than a little 4 amp trickle charger.

[Feral]

Well tried her out toda. Quite impressed. This autopilot I could get used to!

Need to beef up the front deck where the motor is mounted, the torque flexes the deck quite a bit on maximum acceleration!

Ran the boat for 9 hours today for just over 9ks on the water, back battery bank still at 12.4 volts, front bank at 12.35 volts after the trip. Hardly even touched them!

Best bit was a sustained top speed with both motors on of 6.2kph, not bad for a riveted hull 4.9m boat on electrics! (with 2 fat bustards and 120 kilos of batteries on board!) Ran at that speed for the first 2.5k's just to make sure I wasn't going to have any issues with the in line fuses, new cabling, or the motor mounts.

[Davo_Dinkum]

bump

good electric info