Need help choosing a battery

[Atvguy]

Limit the amps to whatever that battery recommeds.

That's the problem though... I can't limit the amps the alternator will put out. The only way is to turn on the headlights and fan to eat up some of the alternator's capacity.

What are you doing mining?

I started doing this in 2008 digging a pond. Since I finished the pond in 2010 I kept moving dirt for a variety of reasons having to do with trail maintenance, gardening, planting trees, cat litter. I'm basically still a kid in a sandbox with excavator and dump truck lol

At some point during your digging and driving cycle you need to stop everything for a half hour at least let the batteries rest

I usually do. I take a break for ME to rest mostly

You could have a battery with 11 volts start your ATV just fine.

It's between 12 and 12.3 now and it starts with a lot of power. The engine fires instantly. Not sure about 11 volts though. The engine is high compression and I have ovate valve springs which are crazy stiff.

You may need to switch to a true deep cycle battery or at least a deep cycle marine battery either way sounds like you definitely need a bigger battery.

I totally agree with you and wish I could find a true deep cycle marine battery that's small enough to fit. I don't think I can squeeze in anything bigger than U1. But U1 is pretty big for an ATV battery.

 

[oil pan 4]

That's the problem though... I can't limit the amps the alternator will put out. The only way is to turn on the headlights and fan to eat up some of the alternator's capacity.



I started doing this in 2008 digging a pond. Since I finished the pond in 2010 I kept moving dirt for a variety of reasons having to do with trail maintenance, gardening, planting trees, cat litter. I'm basically still a kid in a sandbox with excavator and dump truck lol



I usually do. I take a break for ME to rest mostly



It's between 12 and 12.3 now and it starts with a lot of power. The engine fires instantly. Not sure about 11 volts though. The engine is high compression and I have ovate valve springs which are crazy stiff.



I totally agree with you and wish I could find a true deep cycle marine battery that's small enough to fit. I don't think I can squeeze in anything bigger than U1. But U1 is pretty big for an ATV battery.

How many amps go to the battery while driving around? If you have a magneto that says it will do 25 amps I bet the only time its going to put out anywhere near 25 amps is on really dead batteries.
Say the resting voltage is 12 even, which isn't good, you start it and begin driving, it may only be putting out 10 amps to get it up to float voltage. They're likely not drawing 20 amps unless they're really low.
Also to be considered fully charged the batteries should sit and cook at 14.4v for at least an hour drawing around 2 or 3 amps for 2 AGM U1 batteries.
How hot are they getting?
Are they getting hot from charging or discharging?
I bet when you winch they're not staying charged. Probably need to charge every day after you're done winching.

I don't know of a small deep cycle marine. About the smallest I've seen is group 34 and 78. That's a full size car battery to small truck battery.

 

[Atvguy]

How many amps go to the battery while driving around?

Well, I can say this: I had the battery that I'm running now that was damaged from the other one on the charger and I flipped it to "engine start". That made the ammeter peg to the max above 12 amps (that's as high as the meter goes). That made the voltage go up to 14.4 or so. But the thing is I can do the same thing by simply starting the engine and giving it a wee bit of throttle.

So I'm concluding that a wee bit of throttle can push out more than 12 amps. How much more I don't know. But that's already more than the 10 amps max that's printed on the side of AGM batteries.

Also to be considered fully charged the batteries should sit and cook at 14.4v for at least an hour drawing around 2 or 3 amps for 2 AGM U1 batteries.

I know they say alternators are not battery chargers, but my alternator is 1000x better at charging the batteries than my chargers. Maybe what you said is why.

Are they getting hot from charging or discharging?

They never get hot that I can tell.

I don't know of a small deep cycle marine. About the smallest I've seen is group 34 and 78. That's a full size car battery to small truck battery.

Yeah I know that's my problem. No one wants a small marine battery. It kinda defeats the purpose lol. The ones who do just want a battery for a trolling motor.

 

[oil pan 4]

Sounds like those batteries are hungry.
I run a UT1 AGM battery in my car, it's a U1 with normal battery posts. It's got 45 minutes of RC and I think 20ah at 20hr.
I'm sure they can briefly charge at 20 amps no problem. The Nissan leaf can put out up to 100amps of 12v charging power, for some reason they made the 12v system really overkill in that car.
The fastest I've ever charged an AGM battery was about 1.5c that's one and a half time the AH rate. For example I put 3 20 amp battery chargers on one 40ah optima battery. Didn't seem to hurt it and ran 2 chargers on one battery for 40 amps plenty of times. Charging a 40ah optima battery with 40 amps that's a 1c rate.
So a U1 battery, about 20ah should be able to take 20 amps or 1c until it gets hot. 1.5c will definitely heatup an AGM battery quick if it's deeply discharged.
You got 2 or them so they can easy eat up 40 amps which an ATV won't ever make and should gobble up 20 amps even 25 amps no problem.
I'm assuming your AGM batteries are like my deka AGM battery.

 

[Atvguy]

Sounds like those batteries are hungry.
I run a UT1 AGM battery in my car, it's a U1 with normal battery posts. It's got 45 minutes of RC and I think 20ah at 20hr.
I'm sure they can briefly charge at 20 amps no problem. The Nissan leaf can put out up to 100amps of 12v charging power, for some reason they made the 12v system really overkill in that car.
The fastest I've ever charged an AGM battery was about 1.5c that's one and a half time the AH rate. For example I put 3 20 amp battery chargers on one 40ah optima battery. Didn't seem to hurt it and ran 2 chargers on one battery for 40 amps plenty of times. Charging a 40ah optima battery with 40 amps that's a 1c rate.
So a U1 battery, about 20ah should be able to take 20 amps or 1c until it gets hot. 1.5c will definitely heatup an AGM battery quick if it's deeply discharged.
You got 2 or them so they can easy eat up 40 amps which an ATV won't ever make and should gobble up 20 amps even 25 amps no problem.
I'm assuming your AGM batteries are like my deka AGM battery.

Interesting! One thing I want to point out though is my batteries are flooded. I wasn't sure if I said so before. The only AGM I've ever had was in another quad that left me stranded on top of a mountain. I had to walk 2 hours downhill to get the spare flooded battery off the quad we're talking about on here and then walk 2 hours back up to rescue the other quad. The way that AGM simply died with nothing left in it and no warning kinda scared me from using AGM. Flooded batteries will usually get weak before they die so it's a warning to get back home. Even if they do die there is at least some charge left that might turn a starter real slow.

You're using an Optima battery? Another thing I discovered is the internal resistance changes quite a lot from battery to battery and seems like the bigger the battery the lower the resistance. (Probably some cells are paralleled inside rather than series when they make bigger batteries.)

A small Odyssey has 27 milliohm https://www.odysseybattery.com/products/ods-agm8e-battery-pc310/
A big one has 3.5 milliohm https://www.odysseybattery.com/products/ods-agm70a-battery-pc1700t/

That's over 7x difference! Doesn't that mean the big one would draw 7x more current?

Also if I have 2 in parallel that will drop resistance even more, which brings up the concern if it would hurt my charging system. I suppose it's like a stereo amp that's designed for 4 ohm speakers being hooked to 1 ohm speakers.

Most batteries don't have internal resistance published. Some of Odysseys don't. And I've never seen a flooded battery with a published internal resistance.

There is so much about this I don't know.

 

[oil pan 4]

Interesting! One thing I want to point out though is my batteries are flooded. I wasn't sure if I said so before. The only AGM I've ever had was in another quad that left me stranded on top of a mountain. I had to walk 2 hours downhill to get the spare flooded battery off the quad we're talking about on here and then walk 2 hours back up to rescue the other quad. The way that AGM simply died with nothing left in it and no warning kinda scared me from using AGM. Flooded batteries will usually get weak before they die so it's a warning to get back home. Even if they do die there is at least some charge left that might turn a starter real slow.

You're using an Optima battery? Another thing I discovered is the internal resistance changes quite a lot from battery to battery and seems like the bigger the battery the lower the resistance. (Probably some cells are paralleled inside rather than series when they make bigger batteries.)

A small Odyssey has 27 milliohm https://www.odysseybattery.com/products/ods-agm8e-battery-pc310/
A big one has 3.5 milliohm https://www.odysseybattery.com/products/ods-agm70a-battery-pc1700t/

That's over 7x difference! Doesn't that mean the big one would draw 7x more current?

Also if I have 2 in parallel that will drop resistance even more, which brings up the concern if it would hurt my charging system. I suppose it's like a stereo amp that's designed for 4 ohm speakers being hooked to 1 ohm speakers.

Most batteries don't have internal resistance published. Some of Odysseys don't. And I've never seen a flooded battery with a published internal resistance.

There is so much about this I don't know.

Oh I read something wrong. I thought you had AGM already.
U1 batteries are usually made pretty cheaply, flooded starting batteries are generally real bad about deep cycling. Runing flooded starting batteries down even 10 to 20% is considered deep cycling on them and is very bad for them.
The thing I have always seen fail in a magneto charging system is the voltage regulator. They just burn out.
The magnetoes just seem to fail from age, not even really run hours so much.
But you have that heavy duty voltage regulator right?
It's very unlikely you can hurt a magneto. Ive seen them wired completely wrong, the magneto leads shorted together and it ran fine once the wiring was corrected.

 

[Chris142]

when you are done for the day put the batteries on a charger overnight.

 

[Atvguy]

Oh I read something wrong. I thought you had AGM already.
U1 batteries are usually made pretty cheaply, flooded starting batteries are generally real bad about deep cycling. Runing flooded starting batteries down even 10 to 20% is considered deep cycling on them and is very bad for them.

Yep I've been using the regular ole flooded U1s, which I think are failing due to shock or vibration rather than cycling. Do you think a better flooded U1 like Interstate SP-40 would be a bit more robust? I might be able to squeeze in a SP-70 since it's only a little bigger.

The thing I have always seen fail in a magneto charging system is the voltage regulator. They just burn out.
The magnetoes just seem to fail from age, not even really run hours so much.
But you have that heavy duty voltage regulator right?
It's very unlikely you can hurt a magneto. Ive seen them wired completely wrong, the magneto leads shorted together and it ran fine once the wiring was corrected.

Yeah I went through 2 regulators then contacted Rick's electronics for a solution. They hooked me up with a regulator from a Triumph streetbike that they said would handle 50 amps. Good to know the magneto shouldn't be a problem. I don't want to have to replace that!

I've been thinking about buying a couple Yuasa batteries just to destroy in a test to finally see which is best. They offer 2 for my quad: one AGM and one conventional. That should be a fair test. I could load 1000lb of mud on the trailer, then run the winch up n down to beat the snot out of the batteries. Then drive around for a couple minutes to charge them back before beating them down again. Then let them sit all night half charged before repeating the beating the next day. Do you think that would be a worthwhile test?

 

[Torrid]

What's the max charging voltage?
How deeply are you discharging them?
Normally I recommend AGM but you might not want AGM in your case.
True deep cycle batteries aren't AGM for a few reasons.
AGM seems to need a bit higher voltage to fully charge.
14.4 is bare minimum for AGM. Even then you probably want to throw a charger on once and a while.
After a winching cycle where the batteries are depleted the batteries probably need to sit at float voltage, 14.4v for at least a couple hours.

This is what I recommend as well. A deep cycle might be the answer.

AGM has it's place, but for those vehicles that can be reprogrammed to recognize that it is using an AGM I recommend changing that setting. AGMs tend to want a bit more voltage thrown at it when charging. I'm not sure AGM is a benefit for this application.

 

[Atvguy]

AGMs tend to want a bit more voltage thrown at it when charging.

So many people saying that is still confusing me because AGMs tend to have far lower internal resistance so if they had more voltage thrown at them the lower resistance would draw too much current and overheat the cells.

Interstate batteries says AGM needs less voltage, not more:

"AGM batteries don’t have nearly as much internal resistance, which is how they absorb 30, 40, even 50 amps at a time instead of a regular battery getting stressed out at more than 10 amps.

This is also why an AGM battery needs special charging.

Regular battery charging can break AGM batteries. Regular batteries need 15-17 volts to get the same amps. However, voltage greater than 15 volts can overheat an AGM and generate enough pressure to pop its safety valve. That one-way valve is supposed to relieve excess pressure from the harmless gases that come when a battery’s charging. Too much voltage becomes too much pressure, and pop. Without an airtight seal, an AGM will dry out in hours." https://www.interstatebatteries.com/blog/how-to-charge-an-agm-battery

AGMs seem somewhat delicate and fragile because of their lower internal resistance and the fiberglass mat being a thermal insulator, the combination of which makes them especially prone to overheating.

AGMs are robust in terms of vibration but not so much in terms of heat.

 

[oil pan 4]

So many people saying that is still confusing me because AGMs tend to have far lower internal resistance so if they had more voltage thrown at them the lower resistance would draw too much current and overheat the cells.

Interstate batteries says AGM needs less voltage, not more:

"AGM batteries don’t have nearly as much internal resistance, which is how they absorb 30, 40, even 50 amps at a time instead of a regular battery getting stressed out at more than 10 amps.

This is also why an AGM battery needs special charging.

Regular battery charging can break AGM batteries. Regular batteries need 15-17 volts to get the same amps. However, voltage greater than 15 volts can overheat an AGM and generate enough pressure to pop its safety valve. That one-way valve is supposed to relieve excess pressure from the harmless gases that come when a battery’s charging. Too much voltage becomes too much pressure, and pop. Without up an airtight seal, an AGM will dry out in hours." https://www.interstatebatteries.com/blog/how-to-charge-an-agm-battery

AGMs seem somewhat delicate and fragile because of their lower internal resistance and the fiberglass mat being a thermal insulator, the combination of which makes them especially prone to overheating.

AGMs are robust in terms of vibration but not so much in terms of heat.

I don't know. I'm changing and charging AGM batteries almost daily and that's just what they do.
They'll bulk charge just fine at 14.4 most of the time but when they get ran down you definitely need more than 14.4 to fully charge them back up. They like to see up to 15v when finish charging when they were previously ran down.
During normal use 14.4v is fine.
Charging depleted AGM batteries is when they over heat. They'll surely over heat if you stick a wrench on the posts and leave it there.
If I put an optima battery on the charger and say it's ran down to 11v and current limit charging to 20 amps, if it's a good battery it won't over heat. It will get full before it can over heat.
17v is fine as long as you hit it with 17v at a fraction of the C rate and when the battery is so dead it doesn't want to take charge. Equalization voltage on a flooded lead acid is 17v, abthe end of the charge cycle. Yeah you don't want to hit an AGM with 17v at the end of it's charge cycle.
I save a lot of batteries by hitting them with up to about 21v when they won't charge.
If the battery is dead and ran down to say 8v but it's still a good battery then it could over heat even limited to 20 amps which is around half the C rate of an optima.

 

[Torrid]

I don't know. I'm changing and charging AGM batteries almost daily and that's just what they do.
They'll bulk charge just fine at 14.4 most of the time but when they get ran down you definitely need more than 14.4 to fully charge them back up. They like to see up to 15v when finish charging when they were previously ran down.
During normal use 14.4v is fine.
Charging depleted AGM batteries is when they over heat. They'll surely over heat if you stick a wrench on the posts and leave it there.
If I put an optima battery on the charger and say it's ran down to 11v and current limit charging to 20 amps, if it's a good battery it won't over heat. It will get full before it can over heat.
17v is fine as long as you hit it with 17v at a fraction of the C rate and when the battery is so dead it doesn't want to take charge. Equalization voltage on a flooded lead acid is 17v, abthe end of the charge cycle. Yeah you don't want to hit an AGM with 17v at the end of it's charge cycle.
I save a lot of batteries by hitting them with up to about 21v when they won't charge.
If the battery is dead and ran down to say 8v but it's still a good battery then it could over heat even limited to 20 amps which is around half the C rate of an optima.

This 100%. The biggest issue is the smart charging systems modern cars do to reduce drag on the drivetrain and save battery life. They'll reduce to 13.8 while charging with lead acid batteries after awhile. AGMs don't live a long life and don't leave much reserve being treated this way.

I do think it's fair to say AGMs are happier in a much narrower range for voltage.

 

[Atvguy]

I don't know. I'm changing and charging AGM batteries almost daily and that's just what they do.
They'll bulk charge just fine at 14.4 most of the time but when they get ran down you definitely need more than 14.4 to fully charge them back up. They like to see up to 15v when finish charging when they were previously ran down.
During normal use 14.4v is fine.
Charging depleted AGM batteries is when they over heat. They'll surely over heat if you stick a wrench on the posts and leave it there.
If I put an optima battery on the charger and say it's ran down to 11v and current limit charging to 20 amps, if it's a good battery it won't over heat. It will get full before it can over heat.
17v is fine as long as you hit it with 17v at a fraction of the C rate and when the battery is so dead it doesn't want to take charge. Equalization voltage on a flooded lead acid is 17v, abthe end of the charge cycle. Yeah you don't want to hit an AGM with 17v at the end of it's charge cycle.
I save a lot of batteries by hitting them with up to about 21v when they won't charge.
If the battery is dead and ran down to say 8v but it's still a good battery then it could over heat even limited to 20 amps which is around half the C rate of an optima.

I have a battery down to 8v I could try rolling out the wheeled charger and seeing if I could shock it back to life.

oil pan, did you see this post? https://bobistheoilguy.com/forums/threads/need-help-choosing-a-battery.387769/page-2#post-7028542

 

[oil pan 4]

This 100%. The biggest issue is the smart charging systems modern cars do to reduce drag on the drivetrain and save battery life. They'll reduce to 13.8 while charging with lead acid batteries after awhile. AGMs don't live a long life and don't leave much reserve being treated this way.

I do think it's fair to say AGMs are happier in a much narrower range for voltage.

Yes that's definitely bad for AGM. They pretty much just need to sit at about 14.4v to make sure they're happtand get a full charge.
I need to check and make sure my leaf isn't doing that.

 

[oil pan 4]

I have a battery down to 8v I could try rolling out the wheeled charger and seeing if I could shock it back to life.

oil pan, did you see this post? https://bobistheoilguy.com/forums/threads/need-help-choosing-a-battery.387769/page-2#post-7028542

Yeah blast the 8v battery with one of those big dumb rolling chargers.
Just don't burn it up. I've seen those rolling chargers make up to 22v.
Remove the electrolyte fill caps so you can watch for boil over.

As far as destructive tourcher testing leaving the battery depleted over night you can do it. Whichever battery has the higher reserve capacity will win I think.

How easy is the battery to swap out?
Maybe the solution is to run 2 batteries when winching if swapping batteries isn't a pita.

 

[Atvguy]

How easy is the battery to swap out?
Maybe the solution is to run 2 batteries when winching if swapping batteries isn't a pita.

Real easy! I designed the back battery to unplug. Just unhook the quick release and grab the battery and go to the campsite.

The front battery is buried under the front rack. It's real hard to get to. And I have to take a pic of the wiring so I can put it back right.

Wondering if I should put an expensive Interstate up front and a cheap walmart battery in back. It's always the back battery that goes.

What do you suggest? What would you do?

 

[oil pan 4]

I'm thinking when you run the winch, at some point during your mud running, swap out the rear battery and throw it on a small 5 amp charger. Then put a freshly charged battery on the back.
After a winching session, at the end of the day always charge the batteries on the ATV with an external charger, say a 5 or 10 amp battery, since there's 2 of them.

 

[Cujet]

A friend recently purchased this:

https://www.amazon.com/WEIZE-Starti...e-Trolling/dp/B0CJ36GWXQ?ref_=ast_sto_dp&th=1

 

[Atvguy]

A friend recently purchased this:

https://www.amazon.com/WEIZE-Starti...e-Trolling/dp/B0CJ36GWXQ?ref_=ast_sto_dp&th=1

How does it work? Does he use a winch or draw lots of current?

I was looking at the U1 size of that brand and a lot of reviews said they only lasted a few months. https://www.amazon.com/WEIZE-Temperature-Protection-Rechargeable-Scooters/dp/B0CKXVCPWS

They rated it 5 stars anyway because the manufacturer honored the warranty. I wouldn't consider a battery that I had to send back a 5-star battery.

A guy who works for antigravity batteries said lithium isn't so great for winching because the BMS could shut it down for protection. https://rennlist.com/forums/trucks-...imum-battery-size-for-winch.html#post19372198

That scared me because I can see me having trouble starting the engine and the stupid BMS decides to have PMS and I can't start my engine for who knows how long.

After reading and talking I decided to give lithium a few more years to develop.

Also I noticed at Rick's Electronics they sell lithium regulator and stator kits for bikes and atvs, so I'm assuming a conventional charging system isn't ideal. https://ricksmotorsportelectrics.com/products/Charging-Kits

 

[Cujet]

How does it work? Does he use a winch or draw lots of current?

I was looking at the U1 size of that brand and a lot of reviews said they only lasted a few months. https://www.amazon.com/WEIZE-Temperature-Protection-Rechargeable-Scooters/dp/B0CKXVCPWS

They rated it 5 stars anyway because the manufacturer honored the warranty. I wouldn't consider a battery that I had to send back a 5-star battery.

A guy who works for antigravity batteries said lithium isn't so great for winching because the BMS could shut it down for protection. https://rennlist.com/forums/trucks-...imum-battery-size-for-winch.html#post19372198

That scared me because I can see me having trouble starting the engine and the stupid BMS decides to have PMS and I can't start my engine for who knows how long.

After reading and talking I decided to give lithium a few more years to develop.

Also I noticed at Rick's Electronics they sell lithium regulator and stator kits for bikes and atvs, so I'm assuming a conventional charging system isn't ideal. https://ricksmotorsportelectrics.com/products/Charging-Kits

The LiFePO4 batteries that are configured for starting are epic good. I don't know how it would compare in your situation, he uses it to start a 540 cubic inch Lycoming aircraft engine. It will crank and crank seemingly forever. Those engines when hot can be difficult on the best days. They tend to draw quite a bit more than car engines and are tough on batteries.

The BMS on many of these LiFePO4 batteries are not designed for high amp draw. But on the ones that are, they work exceptionally well. Also, the BMS will reset in a few seconds on some models. Others the BMS 'latches" and it may take a pair of jumper cables to bring it back.