Small Engine Start Battery and 1000w Lofrans winch

xeitosaphil

xeitosaphil

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Further to my post question re New Engine Start Battery.

http://www.ybw.com/forums/showthread.php?408523-Engine-Start-Battery-Size

I am considering a Red Flash 750 sealed Lead Acid Battery

One thing I just thought of is, I have a 1000w Lofrans Kobra windlass which is run off of the engine start battery at present. If I change to the Red Flash 750 will it still run the Lofrans bearing in mind I only ever use it when the engine is running.

This being the case will the alternator be replenishing the power the windlass is taking out, thereby leaving the battery relatively safe from major discharge?

The alternator by the way is a 90A Prestolite.

Thanks - Philip
 
I guess really only actual use will show if the battery is OK for the winch job. The power rating of the winch will be for maximum load and generally much less such that one would expect the alternator be able to keep the battery volts up OK. (given enough engine/ alternator revs) If however you have a problem with lifting the anchor ie heavy load for a long time it might be worth stopping winching for a break, both to let the winch cool down and let the alternator recover some battery power. Obviously a higher battery Amp Hour rating would give more reserve against the winch pulling down the battery even with alternator charging. There might be merit if things are heavy to connect the house battery in parallel to provide more reseve capacity. I suggest you buy the chosen engine start battery and monitor the voltage under a typical anchor lift scenario. This should tell you if you have a problem. More engine revs and paralleled house batty might help. good luck olewill
 
If the windlass was delivering the full 1000 watts, probably very rare, it would be consuming 80 amps. Your big alternator provides more than that, although of course it takes time to replenish current delivered from the battery. It would be my guess that the Red Flash 750 alone would be capable of supplying 80 amps for the usual duration of anchor retrieval but being topped up by the alternator by a similar amount should provide a reliable system.

I reasoned that having my windlass wired to the domestic batteries was a better way to do it. I can live with not having a windlass but would prefer the engine start to be as close to perfect as possible. My 300Ah of domestics will operate the windlass for short periods, e.g. setting and recovering the snubber, without the need to start the engine.
 
The 90A alternator will deliver much less current at tickover revs, so the battery will still be working fairly hard. Like Vyv, I'd consider feeding the windlass from the domestic bank.
 
Thanks for the comments, reassuring to know it could possibly be ok, and is definitely not a no, no.

My anchoring is usually only in approx 6 –10mtrs of water max, so between 25 -48 mtrs of chain set. Retrieval is done in short bursts of the windlass maybe only 10-20 secs, so not continuous and maybe only 3-4mins in total run time.

I have to flake the chain back into the locker by hand otherwise it bunches, due to the depth of the locker. It also means that I’m not winching the boat to the anchor and provides less strain on everything and hopefully a little less voltage draw?

I think I will give it a go with the new battery with the wiring as it is, and see how I get on as William suggests. I can always increase tick over to 1600rpm while using the winch which will give me a possible output of around 40amps with the alternator, but also have the option to parallel the domestics if needed.

If there does appear to be a problem I can always re wire the winch to the Domestics as Vyv suggests without too much hassle. The whole reason behind this added small engine battery is to provide an extra 110Ah to the domestic bank making it 330Ah in total, but using the limited space available to re- site a new physically smaller engine battery.

Cheers Philip
 
Having just replaced a red flash battery on my boat I recommend something a little more sturdy, the red flash batteries are apparently designed more for race cars and they don't like being worked hard for periods longer than engine starting. I replaced it with a spiral wound AGM battery, 1000CCA, much more capacity (yes it's a bit larger physically but still a small battery) and it was cheaper than the horrendously priced RF battery.
 
G12 said:
Having just replaced a red flash battery on my boat I recommend something a little more sturdy, the red flash batteries are apparently designed more for race cars and they don't like being worked hard for periods longer than engine starting. I replaced it with a spiral wound AGM battery, 1000CCA, much more capacity (yes it's a bit larger physically but still a small battery) and it was cheaper than the horrendously priced RF battery.
Click to expand...

My windlass is wired to the engine battery, a bog standard car battery. Presumably, with the smaller capacity of the red flash, if you need to haul for an extended period occasionally, you can switch the domestics in on the battery master switch.
 
It's not so much about the capacity, its that apparently they don't like being worked hard for longer than it'd normally take to start an engine. Depending on the type of domestic battery fitted then attaching a windlass to it could be a bad idea, deep cycle domestic batteries are designed to take smaller current's for longer while a cranking battery will have beefier construction to deal with kicking out lots of amps for a shorter time.
 
If you use a small Ah Red Flash battery then that should only be used for engine starting and the windlass should be fed from the house battery, BUT you should then rewire the alternator to charge the house bank first. A VSR or EchoCharge can then be used to charge the starter battery which hardly needs any charging as only about 1% of its Ah capacity will have been used just starting the engine. So you could start the engine maybe 10 times before the starter battery needs charging.
 
We had a 100 CCA battery for the same winch. It was stowed in the fore cabin to be close to the winch with a thicker charging wire from the battery charger to avoid power drop. Under no circumstances use a house battery, which should be a deep cycle battery, unless you want to destroy it.
 
KellysEye said:
Under no circumstances use a house battery, which should be a deep cycle battery, unless you want to destroy it.
Click to expand...

Depends on what the house battery is and how many there are. My Trojan T125s (of which I have 4) quote a reserve capacity of 132 mins @ 75 amps. They're used in electric cars and forklifts so, although deep cycle, can take quite heavy loads.
 
Having gone to the boat yesterday I re- evaluated the battery situation and come to an instant decision.

The current engine starter battery is already connected to the Windlass so when this battery is added to the Domestic Bank to make 310Ah ( only just noticed engine start battery only 90Ah not 110Ah ) this will automatically make the windlass on the domestic bank anyway, so no problems as suggested previously ( can’t see how I didn’t see this before).

All I have to do then is break into the starting circuit with the new re-sited engine battery.

With the engine starter battery being recharge virtually instantly by the Adverc and alternator, any discharge from the Domestic bank will then be recharged via the VSR / alternator or the Solar panel.


Thanks for all the comments received

Philip
 
By the way, if you are adding a Red Flash AGM to replace a wet (or sealed) starter battery, remember that the Red Flash will need different charging voltages.
 
I am suggesting that the bigger capacity of the house bank may be more appropriate. Sorry if my comment came off as aggressive; it certainly was not the intent.
 
RAI said:
By the way, if you are adding a Red Flash AGM to replace a wet (or sealed) starter battery, remember that the Red Flash will need different charging voltages.
Click to expand...

In what way different, could you please expand on this?
I have used a Red Flash as a starter battery for the last nine years, together with a house bank of ordinary leisure batteries, charged together from the alternator. Have not noticed any problems.
 
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