Hey all, diagnosing my TM issue and had a question for the experts. As you may know from other posts, I am back to suspecting the batteries as the issue for the behavior. But I am a little stumped.
The issue I am seeing is that the batteries charge fully (14.5 volts no load, 14.3 under load) and equally. The motor runs fine for about an hour or so, and then suddenly, the motor acts like the batteries are completely dead. I get one bar on the TM battery tester and voltage drops down to something in the 12’s (cant remember). It is impossible to deal with this on the water and see what the voltage is actually doing, but the point is, when it drops, it drops suddenly and completely - and after a very short period of time.
Now I am sitting here testing the batteries in the driveway. They are fully charged and I have them under a load. I get a steady 14.2 volts on each battery (28.5 total voltage) for a solid 20 min or so (have to keep the motor from getting hot). I suspect that if I ran it continuously, the voltage will do what I have seen on the water and drop suddenly down to 12.something volts on each batt (or one if one is bad) or 25something volts overall.
Here is the question - is that typical behavior for a bad battery? Operate normally for awhile but suddenly die? I havent had this happen like this in the past, usually they just stop taking a full charge.
I just had intermittent operation from my starting battery (LA). I replaced with an Interstate Group 34 Dual Purpose AGM. Problem gone. The old West Marine battery was about 2.5 years old. I’m not sure they even sell them anymore so it may have been old stock.
That behavior is common on lead acid battery, looks like connectivity is not an issue, that leaves draw, the lead acid battery is surging to keep up, looses juice amps drop, the cells are trying to keep up. Sounds like you have some bad cells that can’t keep up with the load. Load test the batteries, with a good tester. You are probably looking at new batteries. I would go AGM, better power management and more resistance to the marine environment.
How are you load testing the batteries?
I ask because just turning the motor on isn’t enough load to test them. You need to use a legitimate load tester. If you don’t have one, and don’t want to buy one, take the batteries to any independent shop or any parts store, autozone ect.. and have them properly tested. Literally takes 30 seconds.
Making the switch to lithiums will solve any battery problems (make sure the lithiums have an internal BMS system (battery management system - key safety gear with lithiums - cheap lithiums may not have that BMS…). Additionally, you’ll need a charger specifically meant for lithiums (or able to set up for lithiums (I like and run NOCO Genius chargers…).
Now for that wet cell battery… The most you can expect out of one is three years and if you run one down a time or two - much less than that… Lithiums, by comparison will have a ten year life (and only weigh 25% of what your wet cell does…). More to say about this topic - look up lithium batts on both Micro and this site for lots more into… I buy much less expensive litihium batts on Amazon - disregard the hype from advertised brands…
I wont lie. I am highly reluctant to switch to Lithiums for three basic reasons:
it is greek to me to figure out exactly which ones I need. Amp hours, brand, features. If someone can send me a link to the exact set/single I need to replace my two group 27 24v TM system, I would be greatly in your debt.
2). I will have to replace my charger. In all honesty, my charger is pretty old, maybe original with the boat, but works fine. Not looking forward to re-running wires and installing in the console! Also - dont intend to replace my house battery, so need one that can run both. Any specific model suggestions?
3). I am old, these are new, I am skeptical. I have been waiting to see how long these ACTUALLY last. Ten years sounds great as a marketing tool - anyone had one last 10 years yet?
Well, it’s not that difficult to come up with a Li solution. You can actually drop down to 1 TM battery, and keep your house battery. Just look for 24v 100 amp Lithium battery, that will keep you running for days. One battery, and loose a ■■■■ ton of weight.
No need to use two batteries for TM anymore since a single Li battery can handle the load more than adequately.
Any modern charger you get, make sure it has the ability to charge Li, AGM or Wet cell.
You really don’t need a house battery charger unless you dont use your boat for extended periods, in which case you can externally charge the house battery.
Keep it simple. A quick search with @Zika suggests killer deal right now!
I misread your OP. Thought you were talking starting battery.
For trollers, there’s no question. Lithium is the way to go. I’ve had my LiTime for a year and I’ve only charged it 5-6 times. It weighs 19 pounds (12 volt, 100 AH mini). I bought a Victron charger for it and just charge and remove. It will handle all battery types.
LiTime has sales all the time and the cost is comparable to a AGM now.
Thanks @Loogie for the recommendation - this is actually a lot cheaper than I expected. Unfortunately, due to the impossible-to-access location of my batteries, I do need an onboard charger. I am looking at the LiTime site for a 3 bank charger that would handle AGM/Lead Acid/and Lithium . . but man they don’t make it easy. . .
Looking at a Noco genius - looks like the Gen 5 x3 may be the way to go.
One other question for any of you Lithium guys - anyone operate Lithium in NC/SC or north of here? The temp ratings make me wonder a bit - I do fish cold days!
Hey Mav, I made the switch from AGM to Lithium about a year ago, all I can say is I wish I would have done it earlier. I’m using the LiTime brand mentioned above in a single 12v 100ah setup. No temperature issues for me in Wilmington.
I charge it once I’m home from fishing, and once it’s topped off I disconnect the charger.
My battery is in a very inconvenient location under the front deck, and the NOCO pigtail attachment works like a charm (came with my charger). You attach it to the battery terminals, and it has a 3’ish foot cord that connects to the cord on the charger. So you likely will not need to mount the whole charger in your boat unless you want to. Not sure if you can run multiple pigtails to the charger at once, but hopefully it can be done if you go with two 12v’s rather than one 24v.
Sounds typical of lead acid at the end of its life. Go lithium and don’t look back. My single 12v 100amh lithium shaved 30lbs off the bow of my, extended my day on trolling, and hopefully has a longer life than the 2-3 years only lead acid batteries. I’ve disconnected my lithium from my 1-2-Both switch and now the switch is just on-off to my house/start battery.
To use the pigtail method I mentioned earlier, you just unscrew the eyelets from the alligator clamps and connect the eyelets to the battery. If you end up with a two battery 24v system, just make sure you get a two bank charger with proper amps. For my 12v 100ah battery, I wanted 10 amps, I’m not sure how that may or may not change with multiple batteries as I’ve never had a 24v system- but I’m sure someone will chime in who can steer you the right direction.
I run Li batteries for cranking/graph and TM, never had a weather related issue.
One point, ALL lithium batteries must have a BMS, theres no way around it. Without a BMS the cells will over charge and explode. Now, not all BMS’s are made equal, and not all have BT connectivity. I do NOT recommend Ionic batteries, they have a BT module but their BMS is ■■■■ quality and will allow the cells to randomly drain. My Epoch cranking battery has never had an issue.
you can text me, I’ve looked into Li batteries for years and years now, be they in EV’s or boats. When you’re buying a Li battery you’re pretty much paying for the name and BMS, the cells are most likely all made in the same factory in China. That’s not a bad thing because the Chinese know what they’re doing with battery tech.
