Which battery charger do I need for my marine battery in trailer?

[xxaarraa]

Hey guys,

My trailer has a decent sized marine battery that powers LED lights and a fan on the inside. I want to pickup a charger that will charge it when shore power is available, and also keep it intelligently topped up when parked on my driveway for weeks at a time. The truck's wiring is currently not configured to charge it while moving (truck may be sold soon, so I don't want to mess with rewiring it).

Here's the battery:



What charger do I need for it? I look on Amazon and there seems to be a wide spectrum of chargers in terms of sophistication and cost - anywhere from $50 to $350.

Here's one that seems reasonable - will this do the job?
Amazon.com: NOCO Genius G3500 6V/12V 3.5A UltraSafe Smart Battery Charger: Automotive

For my intended purpose and battery size, do I want the 3.5 amp ($59), 7.2 amp ($93) or 15 amp ($134) model?

Thanks a lot.

[jasnmar]

Do you know the capacity of the battery (amp hours)?

[Kurlon]

Will you be storing the trailer some place where you can leave it plugged in all the time? If not I'd consider a solar trickle charger to keep it from going flat. I normally opt for the lowest charge rate I can get away with when picking chargers, figure out what your max draw is from your accessories and that'll point you to the min charge rate you'll need overnight to recover.

[xxaarraa]

Do you know the capacity of the battery (amp hours)?

I don't jansmar, I can look next time I'm by the trailer. It's a big honking marine battery though.

Will you be storing the trailer some place where you can leave it plugged in all the time? If not I'd consider a solar trickle charger to keep it from going flat. I normally opt for the lowest charge rate I can get away with when picking chargers, figure out what your max draw is from your accessories and that'll point you to the min charge rate you'll need overnight to recover.

Yes, when trailer is not at the track, it will be on a driveway with access to power 24/7. If track doesn't have shore power, I will always have my Honda generator on hand to charge the battery if its completely depleted and needs a recharge before the night when I'll need the lights and fan. Which leads me to say I want a charger that will charge it quickly? Does higher amp rating on the charger mean quicker charge?

[Kurlon]

So yes, higher amp output == faster charge. This is where knowing the capacity comes in handy, you can oversize your charger if you're not careful which shortens the battery life.

[GearHd6]

I use this to maintain my deep cycle camper batteries in the off season. With a true deep cycle battery you're better off letting it deplete down to about 50% and THEN fully charge it.
Amazon.com: SOLAR PL2320 Pro-Logix 20 Amp Battery Charger: Automotive

[jasnmar]

If I were buying a dedicated charger I'd aim at trying to charge at 10-20% capacity. If I had a 100ah battery I'd target 10-20A charger. That would give you a 5-10 hour charge time.

With a hybrid battery (which I assume yours is hybrid between deep cycle and starting) staying at 20% or less charge rates should be safe. You can get away with higher rates on deep cycle as they have heavier plates than pure starting batteries.

[Garandman]

I use this to maintain my deep cycle camper batteries in the off season. With a true deep cycle battery you're better off letting it deplete down to about 50% and THEN fully charge it.
Amazon.com: SOLAR PL2320 Pro-Logix 20 Amp Battery Charger: Automotive

I like Clore products as well. We have this one.

Amazon.com: CHARGE IT! 4512 12V (12/6/2) Amp Smart Charger: Automotive

We use a Battery Tender + on the tractor, as it is higher output than the Battery Tender Jr. But annoyingly, it does not have the detachable pigtail like the Jr.

The AltE store or West Marine will have solar chargers.

[xxaarraa]

So, an update on this. I picked up the "NOCO genius" 7.2A charger, since it was well reviewed and seemed to be the most portable of the bunch. Plugged it into trailer battery which was completely flat and left out all winter (I know, bad). For several hours, it didn't do anything, and reading the booklet it came with, it was supposedly doing an auto diagnostic / desulphation routine. Then it kicked on, and a day and a half later, it now says battery is fully charged. The lights inside trailer didn't work for some reason and neither did my ceiling fan, so I couldn't verify. I need to troubleshoot that - wonder if I blew a fuse or something?

Overall, I am happy with this unit. Came with a nice quick disconnect pigtail with a weatherproof cover on it. Was $93.



Here's my battery - A quick google search says it's a 75 AH battery, so a 7.2A charger should be right on the money jansmar.

[GearHd6]

So that's a starting battery, not really a deep cycle. Don't expect it to stay charged too long with much draw. My RV came with an 85AH battery and it was horrible. I upgraded to two 230AH 6 volt golf cart batteries.

[xxaarraa]

OK I wanted to post up a long term positive review of the "NOCO genius" battery charger. It has now revived two completely dead batteries for me - one AGM trailer battery, and one Shorai lithium battery on the RS250. Paid for itself right there, and also serves as a battery tender for all my Ballistic batteries as well. A great, all in one charger and tender. Best part is that you plug it in, and it goes into auto diagnostic mode based on battery, and does what is needed - deep charge, top up, tender, etc.

[number9]

OK I wanted to post up a long term positive review of the "NOCO genius" battery charger. It has now revived two completely dead batteries for me - one AGM trailer battery, and one Shorai lithium battery on the RS250. Paid for itself right there, and also serves as a battery tender for all my Ballistic batteries as well. A great, all in one charger and tender. Best part is that you plug it in, and it goes into auto diagnostic mode based on battery, and does what is needed - deep charge, top up, tender, etc.

Does the NOCO have a setting for lithium batteries? Lithium batteries do not have sulfuric acid, hence the desulfation mode on some battery chargers can kill them.

[xxaarraa]

Does the NOCO have a setting for lithium batteries? Lithium batteries do not have sulfuric acid, hence the desulfation mode on some battery chargers can kill them.

Yes it does. If you look at the photo of the unit I posted above, it has two settings for lithium batteries. It just brought back a completely flat Shorai of mine back to full health.

[number9]

Yes it does. If you look at the photo of the unit I posted above, it has two settings for lithium batteries. It just brought back a completely flat Shorai of mine back to full health.

Oh nice! I only found this out recently as I had to get a charger for the new lithium battery in the Hyper.

[Kurlon]

Yes it does. If you look at the photo of the unit I posted above, it has two settings for lithium batteries. It just brought back a completely flat Shorai of mine back to full health.

It's not full health, you lost a good chunk of capacity when it got drawn down too far. Just FYI.

[xxaarraa]

It's not full health, you lost a good chunk of capacity when it got drawn down too far. Just FYI.

Interesting. The NOCO unit now reads the shorai as "100%" power. Wonder if that means 100% of whatever capacity is left, or 100% of original capacity?

[Kurlon]

100% of whatever capacity it has now. It's going by voltage. If you look at the voltage vs Ah draw on that batt now vs before you'll find the voltage drops off faster than it used to.

[carsick]

I am 2 for 2 on lithium batteries becoming paperweights after accidentally discharging them. Love the light weight and size, very sad how unforgiving they are.

[number9]

I am 2 for 2 on lithium batteries becoming paperweights after accidentally discharging them. Love the light weight and size, very sad how unforgiving they are.

...which is crazy, given the technology for microprocessor-controlled lithium batteries has existed for years. Laptops are a great example!

[carsick]

Are you suggesting they should be able to disconnect if drained or overcharged? Seems too logical.

[ZX-12R]

Are you suggesting they should be able to disconnect if drained or overcharged? Seems too logical.

Lithium battery protection is a well understood subject matter. You can buy modules to prevent excessive discharging, over charging, and even current limits. You can get them for any size battery from cellphone and smaller up through automotive packs. There are lots of controller and protection ICs available so you can spin your own if an off the shelf solution doesn't fit your exact needs.

[number9]

Lithium battery protection is a well understood subject matter. You can buy modules to prevent excessive discharging, over charging, and even current limits. You can get them for any size battery from cellphone and smaller up through automotive packs. There are lots of controller and protection ICs available so you can spin your own if an off the shelf solution doesn't fit your exact needs.

I would love to hear about what can be done for a motorcycle if you have the time

[Kurlon]

EarthX includes a full BMS in the batt IIRC.

[xxaarraa]

I would love to hear about what can be done for a motorcycle if you have the time

+ 1 including any links to modules we can buy.

[ZX-12R]

I would love to hear about what can be done for a motorcycle if you have the time

From a time and effort standpoint, you are better off buying a battery with protection built in. Obviously there is a premium for going that route.

Ideally the monitoring system will keep track of the individual cells in the battery which is hard to do with an aftermarket solution due to the battery being sealed. In the case of adding a simple low voltage disconnect, there are commercial modules available to do this. Littlefuse makes a compact unit that has enough current handling for a typical motorcycle: http://www.littelfuse.com/~/media/co...-datasheet.pdf . The voltage profile on the fixed model looks like it matches a lead acid battery but the programmable model could be set to match the profile of a LiFePO4 battery. I also don't know the price of this module off hand so it's possible it could bring the total cost to something higher than just buying a battery with built in protection.

For me, I've weighed the pros and cons and have settled on a non-protected LiFePO4 for my KTM which I am diligent about keeping on a tender when I'm not using it for long periods. For my street bikes, I'm still using traditional lead acid AGMs.

If you are willing to experiment and tinker, there are plenty of battery monitoring ICs available to mess around with.