Creative battery charging solution

[fraschusa]

With many toys comes the problem to keep the batteries maintained? Looking for some creative ideas on an easy winter set-up to keep 5-6 batteries charged without buying 5-6 chargers....I somehow end up every spring with one or two batteries dead as I forgot to put them on the trickler...

TIA

[Ryno]

Battery Tender has a model that will charge multiple batteries, but it isn't cheap

[scottfromboston]

I've kept bike batteries in parallel (positive to positive, negative to negative) on a single Tender through the winter. I'm no EE, but I figured that:

1. Tenders control based on Voltage, which will distribute evenly throughout all of the batteries when connected in parallel (think fluid pressure)

2. Some Lead/Acid batteries are multi-cell, which mainly behave like multiple batteries connected in series.

3. There's plenty of motorhomes out there with multiple batteries managed by one panel/charger. I think that some boats do this as well, and I know that some off-road guys run secondary batteries to run winches + air compressors.

My garage is still standing, and my bike batteries all live 5+ years, but YMMV.

[drinkingmymilk]

I've kept bike batteries in parallel (positive to positive, negative to negative) on a single Tender through the winter. I'm no EE, but I figured that:

Why does this seem so simple?

Anyone else do this?

I was planning on one of these this year seeing I am storing 3 bikes and this will always give me the option to grow.

http://www.walmart.com/ip/Battery-Te...i_sku=15779494

But I am a cheap bastard soooo I like your way.

[scottfromboston]

Why does this seem so simple?

Anyone else do this?

I was planning on one of these this year seeing I am storing 3 bikes and this will always give me the option to grow.

http://www.walmart.com/ip/Battery-Te...i_sku=15779494

But I am a cheap bastard soooo I like your way.

That system is overkill for simple storage. You're better off buying 2 tender juniors and a single tender plus, which will maintain and also charge in an emergency. Half the price.

There's also cheaper off-brand options for both if that's your speed.

[scottfromboston]

Why does this seem so simple?

Anyone else do this?

I was planning on one of these this year seeing I am storing 3 bikes and this will always give me the option to grow.

http://www.walmart.com/ip/Battery-Te...i_sku=15779494

But I am a cheap bastard soooo I like your way.

But yes, it is that simple. Why? I'm sure a resident ee will be along soon to explain (or out me as an idiot).

[drinkingmymilk]

That system is overkill for simple storage. You're better off buying 2 tender juniors and a single tender plus, which will maintain and also charge in an emergency. Half the price.

There's also cheaper off-brand options for both if that's your speed.

My main reason for going the overkill route is I only have one outlet in the garage. I really don't like the idea of plugging them all into a strip and having a million wires all over the place.

I'm also a buy good once vs. buy cheap twice person so I'd hate to buy the juniors and wish I had spent for the one I really needed down the road.

But yes, it is that simple. Why? I'm sure a resident ee will be along soon to explain (or out me as an idiot).

well let's hope you're right.

[tsorfas]

I've kept bike batteries in parallel (positive to positive, negative to negative) on a single Tender through the winter. I'm no EE, but I figured that:

1. Tenders control based on Voltage, which will distribute evenly throughout all of the batteries when connected in parallel (think fluid pressure)

2. Some Lead/Acid batteries are multi-cell, which mainly behave like multiple batteries connected in series.

3. There's plenty of motorhomes out there with multiple batteries managed by one panel/charger. I think that some boats do this as well, and I know that some off-road guys run secondary batteries to run winches + air compressors.

My garage is still standing, and my bike batteries all live 5+ years, but YMMV.

this is so clever and impressive as simple at the same time..
this is seriously brilliant and it makes perfect sense..
ill try it this year

[scottfromboston]

My main reason for going the overkill route is I only have one outlet in the garage. I really don't like the idea of plugging them all into a strip and having a million wires all over the place.

I'm also a buy good once vs. buy cheap twice person so I'd hate to buy the juniors and wish I had spent for the one I really needed down the road.



well let's hope you're right.

I agree that the extra wiring stinks. Same electrons either way though.

The only added value in the big one is the ability to charge multiple batteries as opposed to maintain (store). I don't see a need for this outside of having multiple total loss machines (like electric golf carts).

[nhbubba]

I have one tender and two batteries: one motorcycle and one lawn tractor. I just rotate the tender between the two every month or so, when I think of it. So far it's worked.

I may try Scott's deal out this season though. Seems like a good one.

[NobodySpecific]

The risk you run with connecting them in parallel is that once the charger turns off, you will have the batteries fighting each other and dragging each other down. Yes, the charger will then kick back in and keep them from dying, but it could be taxing on the batteries to be constantly charging and discharging, even if it isn't killing the battery each time. Not sure if that will affect the life of the battery or not.

[drinkingmymilk]

The risk you run with connecting them in parallel is that once the charger turns off, you will have the batteries fighting each other and dragging each other down. Yes, the charger will then kick back in and keep them from dying, but it could be taxing on the batteries to be constantly charging and discharging, even if it isn't killing the battery each time. Not sure if that will affect the life of the battery or not.

Isn't that what happens every time you press the starter button?

[SRTie4k]

The only thing you want to remember when charging in parallel/series is that each extra battery adds its voltage to the sum. So if you are charging 5 12V batteries, you need a tender that can handle at least 60V.

[xrocket21]

The only thing you want to remember when charging in parallel/series is that each extra battery adds its voltage to the sum. So if you are charging 5 12V batteries, you need a tender that can handle at least 60V.

2 batteries in parallel double the current, but the voltage stays the same

2 batteries in series double the voltage, but the current remains the same

[xrocket21]

I've kept bike batteries in parallel (positive to positive, negative to negative) on a single Tender through the winter. I'm no EE, but I figured that:

1. Tenders control based on Voltage, which will distribute evenly throughout all of the batteries when connected in parallel (think fluid pressure)

2. Some Lead/Acid batteries are multi-cell, which mainly behave like multiple batteries connected in series.

3. There's plenty of motorhomes out there with multiple batteries managed by one panel/charger. I think that some boats do this as well, and I know that some off-road guys run secondary batteries to run winches + air compressors.

My garage is still standing, and my bike batteries all live 5+ years, but YMMV.

I'm an ee, and we have a lot of toys and ive been considering this myself. I haven't tried it yet, but in theory it should work.

Nobody specific is correct though, the batteries may fight each other which could be an issue.

As i've been thinking about this in my mind for about a month now, I was thinking of putting a diode between each battery to prevent power from flowing back into the next battery. This is probably the safest way to do it. But it's probably fine to do it without. Just keep an eye on the temps of the battery tender and the batteries.

Whether or not I use diodes myself depends on how much motivation I have when this project rolls around.

[NobodySpecific]

Isn't that what happens every time you press the starter button?

Yes, sort of. The problem you have is that with the starter system you have an actual load (a resistive/capacitive load), while the method talked about involves shorting the batteries together. There is no load between the terminals, so current spikes can happen (V=IR, and in this case R is very very small). The batteries will never stay at the same potential, so one will start to drift down. The others will charge it back up, but the amount of current flowing from battery to battery is hard to predict. It's these constant micro-corrections that can lead to increased wear on the battery, as it will be doing this any time that the charger isn't actively working. With your starter, it's a one time deal followed by charging. Doing this for a day wouldn't cause any problems, doing this for 5 months might (not likely, but it's possible).

Now they should be relatively stable, but if a cell in one battery goes bad, you could take the whole fleet of batteries down. The reason being that the cells within the battery are connected in series, that is each cell adds to the voltage of the previous one. That means losing a cell will drop the voltage down significantly. This drop means that you might now have 9V (the bad battery) shorted to 12V (all of the good batteries), with no load in between. This will cause a current spike in the good batteries, potentially frying the charger as well.

Now admittedly the risk is low, you could probably connect these up 100 times and have no problems. But that one time that you have a problem could get expensive.

The only thing you want to remember when charging in parallel/series is that each extra battery adds its voltage to the sum. So if you are charging 5 12V batteries, you need a tender that can handle at least 60V.

He talked about charging in parallel, not series, so your 60V claim is completely wrong. I could see the current capacity of the tender being exceeded, but if you get each battery up to it's maintenance level (put it on the charger until the light turns green) and then connect them in parallel, you shouldn't have any issues in that regard.

[nhbubba]

Also how 'alike' are these batteries. I wonder if connecting different size, different manufacturer batteries from different applications (read: different toys) might not be such a great idea. Real batteries aren't ideal systems. I wonder how much variance there is in internal cell count, etc.

[xrocket21]

Also how 'alike' are these batteries. I wonder if connecting different size, different manufacturer batteries from different applications (read: different toys) might not be such a great idea. Real batteries aren't ideal systems. I wonder how much variance there is in internal cell count, etc.

in a charging situation it might be a problem, but this should really be a trickle/maintinence situation, pretty low current, etc

[scottfromboston]

The risk you run with connecting them in parallel is that once the charger turns off, you will have the batteries fighting each other and dragging each other down. Yes, the charger will then kick back in and keep them from dying, but it could be taxing on the batteries to be constantly charging and discharging, even if it isn't killing the battery each time. Not sure if that will affect the life of the battery or not.

As far as I know a proper maintainer is constantly charging or discharging, through small voltage variations.

[scottfromboston]

I would think that unless one battery is dead,all you'll have is the batteries leveling voltage between themselves. Current capacities shouldn't matter.

12v Lead-acid batteries are 6 2-volt cells in series.

[Awesome]

What Scott said, with charger on low current. EE.

[#1 masshole]

We usually just take them all out of our toys and use a single charger, swapping them off every so often.

[Stoneman]

I'm just some dumb old guy. But I have one charger and I simply alternate that amongst the batteries once a month. I would NEVER leave a charger of ANY type on a battery for more than a coupla days. Yeah, I know Tenders and smart chargers and trickles are SUPPOSED to be safe for that. I don't trust 'em. It fails, your battery either dies all out or gets overcharged and it's no good (ask me how I know)...

The beginning of every month throughout winter I'll charge each of 'em for a night or two. I just lay 'em out on my bench in the garage (all SEVEN of 'em - 4-4 wheelers, TLR, boat, Corvette), do one this night, move the leads over to this one the following night, etc., etc., etc...

[TheIglu]

I've had a Battery Tender boil two batteries in the last two years. Stoneman's advice is good.

[tsorfas]

It fails, your battery either dies all out or gets overcharged and it's no good (ask me how I know)...
.

how do you know?