Should I replace the battery?

concretebox · Nov 2, 2014

I've got an el'cheepo Walmart Deep Cycle/Marine battery, 101Ah it claims. It's also over a year old and didn't hold a charge until my Dad put it on a smart charger for 18 hours. The smart charger "reconditioned" it and it started holding a charge.

A few weeks ago I installed my 100-watt solar rig and connected the battery. The battery has been charging on solar and the convertor (I've been plugged into my parent's house) for the last few weeks. The VoltMinder says it's 14.5 volts when the sun is shining, and 13.3 after dark. But as soon as I disconnect from shore power and turn on the inverter it starts dropping quickly. After about 10 minutes of running the Xbox and TV (about 79 watts, 1 amp combined), I get the low-voltage warning (12.2 volts) from the VoltMinder.

Based on my power readings seen here, I think I have a "phantom load" of 2.6 watts, 0.03 amps. With nothing other than the TV and XBOX on, shouldn't I get close to 50 hours of use before I get the low voltage (50% discharged battery) warning? The only things taking power other than the phantom load is the propane furnace fan, and propane detector (which are 12-volt native).

Either I'm not understanding battery charging or my cheap battery is kaput (or both). I'm having a hard time finding a good replacement battery. The Trojan 105s that are popular here are 225Ah, so I'd never get them fully charged on my 100w solar. Any suggestions? There is an Interstate Battery in town but I can't find a good candidate battery on their website. There is a BatteriesPlus about an hour away but again, no clear choices. I'm looking for a 100Ah, single 12v or two 6v true deep cycle batteries. I can use a sealed or AGM but I don't need to (the battery is stored in the engine compartment) and I'd rather not pay a premium for a feature I don't need. I could buy another cheap walmart marine battery but I'm worried I'll just have the same problems soon if not immediately.

Optimistic Paranoid · Nov 2, 2014

The 14.5 volts is the output of the solar controller, and the 13.3 volts is the output of the convertor. What voltage do you see on the battery with neither of them on?

If you let the battery sit overnight, not hooked up to anything, what kind of voltage do you see the next morning? Is it the same voltage you had last night? If not, how much did it drop?

Is it a sealed battery? Can you get a specific gravity reading with a battery hydrometer?

Regards
John

user 423 · Nov 2, 2014

It's a flooded battery so start with the basics. Is the electrolyte full? Since it's stored in the engine compartment and has endured a summer, the extra heat might have caused it to go through fluid faster?

Autozone, Oreilly,etc. will load test it for free.

concretebox · Nov 2, 2014

Optimistic Paranoid said:
The 14.5 volts is the output of the solar controller, and the 13.3 volts is the output of the convertor. What voltage do you see on the battery with neither of them on?

If you let the battery sit overnight, not hooked up to anything, what kind of voltage do you see the next morning? Is it the same voltage you had last night? If not, how much did it drop?

Is it a sealed battery? Can you get a specific gravity reading with a battery hydrometer?

Regards
John

Before I installed the battery, after it was "reconditioned" by the smart charger, I got 13.07 volts. After 24hours with no load (it was just sitting on the floor, nothing hooked up), it has 12.99 volts. After 48 hours it was down to 12.95 volts.

This is a non-sealed, lead acid battery. I don't have a hydrometer, but I ordered on today. It should arrive Wednesday.

slow2day said:
It's a flooded battery so start with the basics. Is the electrolyte full? Since it's stored in the engine compartment and has endured a summer, the extra heat might have caused it to go through fluid faster?

Autozone, Oreilly,etc. will load test it for free.

These pictures should help. The level looks good to me. What do you think?

Optimistic Paranoid · Nov 2, 2014

concretebox said:
Before I installed the battery, after it was "reconditioned" by the smart charger, I got 13.07 volts. After 24hours with no load (it was just sitting on the floor, nothing hooked up), it has 12.99 volts. After 48 hours it was down to 12.95 volts.

This is a non-sealed, lead acid battery. I don't have a hydrometer, but I ordered on today. It should arrive Wednesday.

So basically it sounds like it's holding a charge. So far, so good. Be interesting to see what the specific gravity readings are. Get a set when it's fully charged, and get another set when the low voltage alarm goes off.

Got any way to measure the dc amps flowing through the wires to your inverter when you are running your tv and Xbox?

What can you tell us about your solar system? What size wire are you running from the panel to the controller, and what size wire from the controller to the battery? Any idea what voltage the controller is set at, and is it user adjustable in any way?

Regards
John

concretebox · Nov 2, 2014

Got any way to measure the dc amps flowing through the wires to your inverter when you are running your tv and Xbox?

I'm not sure. The inverter displays wattage output and voltage input. I just ran a test with the XBOX and TV both on. The inverter's voltage input was 12.0 and it's wattage output was 100.

What can you tell us about your solar system?

It's this kit. Wires from panel to controller are 12AWG (that's what came with it). Wires from controller to battery are 8AWG (I provided these).

The controller's reported battery parameters are:
Load Disconnect 11.1V
Load Reconnect 12.6V
Boost Voltage 14.4V
Float Voltage 13.6V

I don't see anywhere that says they are user-adjustable.

highdesertranger · Nov 2, 2014

well judging from the date code on your battery you could take it back and get a fresh one pretty cheap. how where you recharging the battery you have before the solar? or has the solar always been on it? highdesertranger

concretebox · Nov 2, 2014

It was charging by the alternator before.

highdesertranger · Nov 2, 2014

yeah kinda sounds like you were not fully recharging it. I would replace it with the same battery since it's cheapest option and see how you do now that you have solar. highdesertranger

akrvbob · Nov 2, 2014

Concretebox wrote:
A few weeks ago I installed my 100-watt solar rig and connected the battery. The battery has been charging on solar and the convertor (I've been plugged into my parent's house) for the last few weeks. The VoltMinder says it's 14.5 volts when the sun is shining, and 13.3 after dark. But as soon as I disconnect from shore power and turn on the inverter it starts dropping quickly. After about 10 minutes of running the Xbox and TV (about 79 watts, 1 amp combined), I get the low-voltage warning (12.2 volts) from the VoltMinder.
= = = = = = = = =

If a full battery drops to 12.2 in 10 minutes it's shot. I gotta be honest with you, you are still in the learning process, so you're probably going to wreck your next battery as well (which is totally normal--I SPEAK FROM EXPERIENCE!) So I suggest you buy the cheapest battery with the best warranty. That's probably a group 29 marine from Walmart but check around.
Bob

VanLifeCrisis · Nov 3, 2014

if under warranty..swap it.

GrayWhale · Nov 3, 2014

DazarGaidin said:
if under warranty..swap it.

Would Walmart give you a brand new battery w/o any charge? Most places will start deducting for how long you've had it if I recall.

Walmart warranties their marine deep cycle batts for a year for a reason, they are no dummies. If taken care of and kept charged, they will last 3 to 5 years.

Costco warranties their Marine batteries for only 1 year also. They know that people will wreck them, in thinking that they're real deep cycle batts, but they're just bigger car batts with more plates and extra connectors. Which makes me think that buying their regular, Automotive battery would be better as they have a much longer warranty (if you're going this cheaper battery route). Am I correct or kinda correct on this?

highdesertranger · Nov 3, 2014

yeah that's why I suggested to take the old one back to wally. he is going to get some credit on it, making it even cheaper. highdesertranger

SternWake · Nov 3, 2014

The battery in question is definitely capacity compromised.

However 100watt load is also significant, and might just be the resting wattage. Playing a game this might double. Check.

Dont freak out about 12.2v when under a 100 watt load. When all loads are removed the voltage will rebound. How much it rebounds and how quickly is indicitave of battery condition.

I think you can get a lot more cycles from it. But a hundred watt load is a llot for a single battery to sustain. Perhaps 4 to 5 hours on a semi healthy 100 amp hour battery.

You neex more battery and more solar for runnjng this load more than a few hours. Or just resign yourself to frequent batterycide

Optimistic Paranoid · Nov 3, 2014

GrayWhale said:
Costco warranties their Marine batteries for only 1 year also. They know that people will wreck them, in thinking that they're real deep cycle batts, but they're just bigger car batts with more plates and extra connectors. Which makes me think that buying their regular, Automotive battery would be better as they have a much longer warranty (if you're going this cheaper battery route). Am I correct or kinda correct on this?

Actually, a starting battery has many thin plates. They are trying to maximize the surface area of the plates in each cell, because that's how you get the high amperage a starter needs.

A true deep cycle has fewer, but much thicker plates, that's what maximizes the number of charge - discharge cycles.

A marine battery has plates that are thicker than a starter battery, but more of them than a true deep cycle. This allows them to start a boat engine, and still be usable to keep the anchor lights burning all night.

If you run a marine battery down to 50% charge and then recharge it, you will get 300 to 400 such cycles out of it. Try that with a starter battery, and you'll be lucky to get 40 or 50 cycles, which means you'll be changing it every month or two.

Regards
John

VanLifeCrisis · Nov 3, 2014

batterycide lol

highdesertranger · Nov 3, 2014

yeah I didn't realize wally only guaranties their marine/deep cycle batteries for a year. everyplace I have dealt with gives you a 2 year warranty. highdesertranger

Seraphim · Nov 3, 2014

concretebox said:
I've got an el'cheepo Walmart Deep Cycle/Marine battery, 101Ah it claims. It's also over a year old and didn't hold a charge until my Dad put it on a smart charger for 18 hours. The smart charger "reconditioned" it and it started holding a charge.

A few weeks ago I installed my 100-watt solar rig and connected the battery. The battery has been charging on solar and the convertor (I've been plugged into my parent's house) for the last few weeks. The VoltMinder says it's 14.5 volts when the sun is shining, and 13.3 after dark. But as soon as I disconnect from shore power and turn on the inverter it starts dropping quickly. After about 10 minutes of running the Xbox and TV (about 79 watts, 1 amp combined), I get the low-voltage warning (12.2 volts) from the VoltMinder.

Based on my power readings seen here, I think I have a "phantom load" of 2.6 watts, 0.03 amps. With nothing other than the TV and XBOX on, shouldn't I get close to 50 hours of use before I get the low voltage (50% discharged battery) warning? The only things taking power other than the phantom load is the propane furnace fan, and propane detector (which are 12-volt native).

Either I'm not understanding battery charging or my cheap battery is kaput (or both). I'm having a hard time finding a good replacement battery. The Trojan 105s that are popular here are 225Ah, so I'd never get them fully charged on my 100w solar. Any suggestions? There is an Interstate Battery in town but I can't find a good candidate battery on their website. There is a BatteriesPlus about an hour away but again, no clear choices. I'm looking for a 100Ah, single 12v or two 6v true deep cycle batteries. I can use a sealed or AGM but I don't need to (the battery is stored in the engine compartment) and I'd rather not pay a premium for a feature I don't need. I could buy another cheap walmart marine battery but I'm worried I'll just have the same problems soon if not immediately.

You'll only get about 6 hours before your 100ah battery goes down to 50%, not 50 hours, assuming it's in new condition. 79 watts divided by 12 volts (because your batteries are 12 volt batteries) equals 6 amps used every hour. Since the inverter has a power loss associated with it, you'll be using about 8 amps an hour. Half of 100ah (the battery you're looking for) is 50. 50 amps divided by 8 amps per hour is 6.25 hours of usage. That's a high estimate, especially if you're working with an older battery.

Your solar panel's going to recharge your battery at about 5 amps per hour - that's 10 hours of sunlight to replace what you used in 6 hours. It won't be sufficient. Two panels will charge your battery at about 10 amps per hour - that's 5 hours of sunlight to replace what your Xbox used in six hours. Might work some days, but still not sustainable. Every 100 watt panel you add will increase your charge capability by 5 amps per hour.

Approximately.

And your phantom load is pulling .26 amps an hour, not .03 amps per hour. Your math formula is incorrect. 2.6 watts divided by 12 volts equals .26 amps used per hour.

Actually, I used divided 2.6 watts by 10 ( instead of 12) to correct for the power loss of the inverter. That's why it came up .26 amps.

GrayWhale · Nov 4, 2014

Optimistic Paranoid said:
If you run a marine battery down to 50% charge and then recharge it, you will get 300 to 400 such cycles out of it. Try that with a starter battery, and you'll be lucky to get 40 or 50 cycles, which means you'll be changing it every month or two.

Regards
John

Thanks for the info John. In regard to what you said about running a Marine Batt down to 50% and recharging it up to 300-400 times; have you tried this before with them and got 300-400x? I've been using mostly SLA AGM batteries, but they're much more expensive. If I can do as you said with Marine Batts, I'd rather get them but I recall SternWake advising to not go with Marine Batts due to them being very close to a regular car starting batteries. Not 100% sure what he said exactly, so I'd have to dig up that post again. Costco had Marine Batts for $90 with like 100 AH ratings which sounds really too good to be true since a UB12350 true deep cycle, SLA AGM battery is $70 shipped from Amazon, and they're only 35 AH.

concretebox · Nov 4, 2014

I just replaced the battery with a new one. I bought the same one I bought last time, the one I posted a link to. I installed it, drove home, and put it on the smart charger and let it charge until the charger said "full," about 7 hours.

When I disconnected the charger my VoltMinder said 13.07 volts. After about an hour, with it installed but nothing running it said 12.7 volts. I turned on the inverter and started the TV and Xbox. I got the low voltage warning 12.2 volts in about 10 minutes, same as last time. The only difference is the voltage rebounded quickly this time.

Did I get a defective battery? I thought I was going to get 5 hours (optimistically). Is my inverter garbage? Is it too cold (it's 44 degrees here)?

Should I replace the battery?

Help Support Van Living Forum:

Well-known member

Well-known member

Well-known member

Well-known member

Attachments

Well-known member

Well-known member

R.I.P HDR

Well-known member

R.I.P HDR

Well-known member

Well-known member

Well-known member

R.I.P HDR

Well-known member

Well-known member

Well-known member

R.I.P HDR

Well-known member

Well-known member

Well-known member

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!