Multiple battery charging.

[kingtin]

I normally isolate my dual battery system and charge my batteries separately. As I have two in the whittley and two in the tinny it has become a bit of a ballache constantly swopping the charger, as I only have one. This also means that three of the batteries are not on trickle charge whilst the fourth is charging

It would be ideal if, in my dual battery system, I could simply set the battery switch to both and charge them both together. This would result of course, in the electrics being permanently connected whilst I am charging, something I am loathe to do because of electrolysis. I realise that if I opted to do this anyway, then I would need a charger for each boat. If I don't opt to do this, then I would need 4 chargers for all 4 batteries to be charging (trickled) at once.

Any ideas on this?

The reason that I am becoming paranoid is that last weekend I ran the whittley on battery 1 leaving battery 2 in reserve. I prefer to always have one fully charged battery, hence my reason for not running lights etc on one and running the engine on the other. I ran the boat for 2 hours, with the anchor light on for 12 hrs and the radio on for 4............come morning the engine wouldn't kick over on the one battery. I wouldn't have thought I could draw that much from the previous days use, enough to prevent starting and can only assume that it was because although that battery had been fully charged, it had been without a trickle charge for 2 weeks prior to the trip. Would it drain that much after only standing for 2 weeks?

kev

[Dirtysanchez]

Hello Kev

A mate of mine in the Electronics industry has developed a system that will take a trickle charge from the crank battery & feed at about an amp at a time, the accessory battery

Would this be of interest ? I'll swap ya one for an outing in the whittley !!

Russ

[kingtin]

Hello Kev

A mate of mine in the Electronics industry has developed a system that will take a trickle charge from the crank battery & feed at about an amp at a time, the accessory battery

Would this be of interest ? I'll swap ya one for an outing in the whittley !!

Russ

Russ, I'm not quite sure what you mean by that, but I've just had a thought if anyone can tell me if this will, or won't be detrimental to the batteries or charger.
If I want to leave them isolated which prevents me charging both from one charger, then couldn't I simply run a set of jump leads or similar from one to the other thereby charging both when the charger is attached to one?

Russ, once I get into a routine now the foster kids have gone and I won't be taking anymore, I'll hopefully be doing more fishing so PM me your details. I tend to go on at short notice as the deckie is now also involved in the organ retrieval team and it's anyone's guess when she's likely to be on standby ie, she may be day off but they ask her to be on standby for retrieval. I can only go when I don't have school runs mid week or when she is day off weekend but isn't on standby..complicated ain't it?

kev

[Millby]

Why dont you just plug in a small solar panel when you arent on the water? You could set it up with a standard 12 volt plug wired straight to the battery. Will trickle charge them both if you wire them in parallel.

I wouldn think it to be any different to running your 4wd twin battery system, with the engel in the back keeping the brewskies cold, and starting the motor first pop the next day.

[stark]

Hi Kingtin

Charging two batteries in parallel is not recommended due to an unequal internal resistance, one battery would end up taking more charge than the other. This imbalance would eventually cause some problems.

Series charging is ok, except you then need a 24v charger.

It sounds like a solar trickle charge panel would be of some help.

If your battery is not keep it's charge, this is one indicator that it is past it's prime and may need to be replaced.

Hope the above is of some help. You would be best helped by a marine electrician. He would be in the best position to see your rid and suggest improvements.

Cheers
John

[kingtin]

Why dont you just plug in a small solar panel when you arent on the water?

The boat is in the drive and covered with a big tarp. It gets little light inside and if I leave the charger outside, it'd go walkabout.

kev

[kingtin]

Hi Kingtin

Charging two batteries in parallel is not recommended due to an unequal internal resistance, one battery would end up taking more charge than the other. This imbalance would eventually cause some problems.

<snip>

John

Thanks for your response John. I gather from the above that if I were not to isolate the batteries and leave 'em on dual and then put the charger on one of them, then this is likely to be detrimental?

kev

[stark]

Hi Kev

Many do use this system. Over time it can cause problems. I had three house batteries set up like this once and lost all three at the same time. Best not to parallel charge. Isolation diodes and other balancing systems are available but add considerable cost.

Cheers
John

[kingtin]

Hi Kev

Many do use this system. Over time it can cause problems. I had three house batteries set up like this once and lost all three at the same time. Best not to parallel charge. Isolation diodes and other balancing systems are available but add considerable cost.

Cheers
John

OK John, thanks for that.

kev

[Dirtysanchez]

Kev, I appreciate your offer & will get in touch, I am about to fly to Sydney for biz.

The concept of my mates set up is it sits independantly as an electronically controlled monitor, which will draw current only when it senses inbound current from your charging system, so it won't drain the crank battery and let you down when you least expect it. He specifically designed it for boats and 4wds and is keen to field trial it, that's why I have a few on hand

It will pull the 1amp current under the above conditions, and charge your accessory battery.

I'd trust him, he is a top, fully qualified engineer and specialises in high power stuff, including a recent design for a welding protection unit capable of 1000 amps so he's pretty cluey

Perhaps we could fit one to your tinny first to give it a trial ?

BTW I work in the industry, have done for 18 years, so Electronics is my curio

[Hamish73]

as said before, parallel batteries can cause problems. I had this setup in my patrol (hard wired) , and the aux died sucking all the life out of the main battery. It took quite a few charge/discharge cycles to bring the main battery back to full capacity.
here is an idea for you.
Using a voltage controlled switch , have it set so that when the voltage gets to 14v (ie battery fully charged) it switches a relay which disconnects the first and connects the second battery to the charger.
A headlight relay (30A) with normally open and normally closed contacts would be more than sufficient. Shouldnt cost more than $50 all up

[kingtin]

Kev, I appreciate your offer & will get in touch, I am about to fly to Sydney for biz.

OK John. Have a pleasant trip. We'll catch up when you're back.

kev

[kingtin]

as said before, parallel batteries can cause problems. I had this setup in my patrol (hard wired) , and the aux died sucking all the life out of the main battery. It took quite a few charge/discharge cycles to bring the main battery back to full capacity.
here is an idea for you.
Using a voltage controlled switch , have it set so that when the voltage gets to 14v (ie battery fully charged) it switches a relay which disconnects the first and connects the second battery to the charger.
A headlight relay (30A) with normally open and normally closed contacts would be more than sufficient. Shouldnt cost more than $50 all up

Thanks for that Hamish.

kev

[newchum]

hi kingtin, the dual battery setup should work find for you and unless your boat sits for a month or more your batteries shouldn't need constant top ups with a battery charger. if your batteries are not holding charge i would be looking for leakage and have the battery load tested. also sometimes poor battery connections are the problem not the battery itself. bad connections can give the same symptom as a flat battery. keep in mind batteries sit on the shelf for a long time and still hold enough charge to crank a motor

[Cloud_9]

minakota make duel battery chargers that aredesigned to stay plugged in.
your standard suppercheap battery charger will F#CK your battery in quick time.
the trickle charge is unregulated and can over charge. the mina kota system is designed for winter storage ( usa snow bound winters) they will look after your batteries and can be permanantly mounted in the boat. just run power lead to boat or you can fit those 50 amp quick connect plugs thats what i'm doing for my new boat.
or for on the water chargeing there is a elecronic charge diverter that runns charge to start battery first and then to secondary battery after start one is full.
not hard to fit cost a few hundred bucks,
Cheers Cloud 9