Bow Thruster Battery - stupid question time again !!

[Gypsey_Kings]

Going to be sorting out my VETUS 55 kgf (3KW/4HP), 12 Volt Electric bow thruster out soon... Main problem is the battery has seen better days (Numax 110) - first thing to be replaced.

So the question is does a bowthruster require a car starter type battery or a deep-cycle battery? As far as I can see it is just a bigger version of a starter motor, that normally runs for a little longer. I do not use it all the time just as and when appropriate in small doses...Are your normal 110 Ahr el-cheapo liesure batteries the same as a normal car battery?

I was also thinking of upping the total AHr capacity with a larger or maybe two batts, but the manual says Max limit of 200 AHrs. Why would it have a max limit on AHrs?

(PS: Don't bother with the 'Real boaters do not use bowthrusters'... I live by the 'Real people use progress and technology for comfort and safety'.. )

EDIT - Maybe this should be in 'Boat Building & Maintenance'

Edited October 18, 2013 by Gypsey_Kings

[Hawkmoth]

Just a thought, maybe it's in case the contactor sticks on. That will ensure a short run time before failing.

Bob

[by'eck]

A deep cycle thick plate battery wouldn't provide the current, you need lots of thin plates as in a starter battery, although a multi-purpose so called leisure battery (or two) would be fine.

 

There is no limit to the capacity you can use and many bowthruster do use 2 x 110 Ah batteries although for a 4hp motor one would probably be ok. I imagine the recommendation is for a minimum not maximum capacity.

 

Most thrusters have a thermal cut-out but a suitable fuse will ensure damage is not done otherwise if the prop becomes fouled.

Edited October 18, 2013 by by'eck

[Paul's Nulife4-2]

Hi ya Gypsy Kings

My understanding is that when being used,Bow thrusters need a lot of pwr,quickly,as in starting or cranking batteries should be ok..so battery choice should reflect this,or be prepared to replace them more often.

Are you sure it says max battery 200amp..or is it the max fuse 200amp ?.

 

Ime a double softy ,as I've got a Bow & a Stern thruster. Both are 'Max Power 65kgf units' & I run them both from my Single main boat battery bank of 840ahr.

I've had no problems up to now.(5yrs).

Edited October 18, 2013 by Paul's Nulife4-2

[Robbo]

If you want the best battery for the job then get spiral cell batteries. They can be charged at a good range of voltages so good for been on the end of a long run of cable from the charging device which bow thruster batteries usually are and they can also stand traction battery voltages so can be on the same charger as your house bank. They also kick out the juice and be discharged deeply without great harm. In addition they only lose around 2-3% a month of charge so are good for infrequently used and charged items.

 

I got got mine for around £160 each for 900cca.

Edited October 18, 2013 by Robbo

[Grace and Favour]

If you want the best battery for the job then get spiral cell batteries. They can be charged at a good range of voltages so good for been on the end of a long run of cable from the charging device which bow thruster batteries usually are and they can also stand traction battery voltages so can be on the same charger as your house bank. They also kick out the juice and be discharged deeply without great harm. In addition they only lose around 2-3% a month of charge so are good for infrequently used and charged items.

 

I got got mine for around £160 each for 900cca.

Excellent advice, Robbo

✔

[Robbo]

Excellent advice, Robbo

✔

 

It had to happen one day

 

Here's where I got mine from; http://www.tayna.co.uk/EM1000-Exide-Maxxima-AGM-Battery-MAX900-P7503.html

And here's my main source for why using Spiral Cell for bow thruster is a good idea; Energy Unlimited The Book

[smileypete]

Also consider a decent truck batt, something like a Varta 648, maybe get one for £100ish locally if you shop around.

 

Should have the same footprint and terminals as a leisure batt, just be a couple of inches taller. Smaller lorries often have power hungry tail lifts so should cope fine with a BT.

 

http://www.ebay.co.uk/itm/12V-VARTA-TYPE-648-656-J2-HEAVY-DUTY-COMMERCIAL-BATTERY-/271274876714

 

cheers, Pete.

~smpt~

[Odana]

We are also thinking about reviving the bow thruster - when we bought the boat the batteries had been dead for some time and so we negotiated on the basis that there was no BT as we couldn't see it working. But all seems to be in order and as its there it would be useful every now and again. We've been told it may be worth putting a charger at the front of the boat rather than trying to charge down the full length of a 68' boat. Seems sensible - would this make a difference to the the type/quality of battery it is possible to use? Has the OP or anyone else considered this option?

 

We have a front storage cupboard which extends under front deck to up against the bow thruster compartment so could fit a charging unit in there. Any suggestions on what/how welcome.... And I will pillow the battery discussion closely before we go shopping too....

[Robbo]

We are also thinking about reviving the bow thruster - when we bought the boat the batteries had been dead for some time and so we negotiated on the basis that there was no BT as we couldn't see it working. But all seems to be in order and as its there it would be useful every now and again. We've been told it may be worth putting a charger at the front of the boat rather than trying to charge down the full length of a 68' boat. Seems sensible - would this make a difference to the the type/quality of battery it is possible to use? Has the OP or anyone else considered this option?

 

We have a front storage cupboard which extends under front deck to up against the bow thruster compartment so could fit a charging unit in there. Any suggestions on what/how welcome.... And I will pillow the battery discussion closely before we go shopping too....

 

If you have a inverter on that's on when running the engine so your bow thruster battery gets charged via the bow thruster charger then it's a good idea. I would use multiple starter batteries, the best been the spiral cell kind, but the cost of 1 spiral cell battery could get you a few normal ones so it may be more cost effective to go for normal ones even though they don't like been deep cycled as much as spiral - it's a guess which would be more cost effective as the spiral will last longer, but will it last longer per £!

[smileypete]

Bear in mind the spiral is 50Ah, whereas a truck batt can be 125Ah, so a 100% discharge for a spiral would be a 40% discharge for the latter, probably a bit more in reality.

 

cheers, Pete.

~smpt~

Edited October 20, 2013 by smileypete

[blackrose]

If you want the best battery for the job then get spiral cell batteries. They can be charged at a good range of voltages so good for been on the end of a long run of cable from the charging device which bow thruster batteries usually are...

I don't really understand this. Most types of 12v batteries will accept different charging voltages, Do you mean that spiral batteries can compensate for voltage drop down long cables and still get charged?

 

My BT batteries are only connected by 16mm2 cables over probably 50ft run but they still receive 14.6v. The voltage drop down the cables is compensated for by not over-using the BT so it has plenty of time to charge.

[Robbo]

I don't really understand this. Most types of 12v batteries will accept different charging voltages, Do you mean that spiral batteries can compensate for voltage drop down long cables and still get charged?

 

My BT batteries are only connected by 16mm2 cables over probably 50ft run but they still receive 14.6v. The voltage drop down the cables is compensated for by not over-using the BT so it has plenty of time to charge.

I would have to re read the victory book again to confirm but I read it as so. Also remember that your bow thruster batteries are also on the same bank of your house batteries, the charger will be using these voltages. The main issue is that the bow thruster batteries get undercharged, which may be a plus point for having the bow thrusters on a totally separate bank with its own charger.

[by'eck]

One or two cheap leisure or starter batteries will be fine and significantly cheaper than spiral batteries. Just make sure they have a CCA rating.

 

I'm not sure that the expense of up market batteries are justified for the relatively small use they get with a BT. No one fits similar starter batteries which arguably one is more reliant on.

 

Don't underestimate the current taken down the charge cable from engine alternator or remote charger just after using thruster. I specified 35mm² cable for the 50 foot run which I calculated was the minimum required. The fusebox at engine end to protect cable has already blown a 100 amp fuse so now have a 200 amp one in.

Edited October 22, 2013 by by'eck