Adding batteries in series

[marlattrr]

I just upgraded from a 12v 55lb thrust Endura Transom Mount to a 70lb 24v MinnKota Powerdrive w/ Ipilot.

I bought a 12v Marine deep cycle Diehard from Autozone last year to run the 55lb 90ah if i remember correctly. Would it be okay to buy the same exact battery and add it in series with the 1yr old battery or should i buy two new batteries?

If so... Should i buy one 24v Lithium battery or 2 12v in series?

Thanks for the advice.

 

[MN Fisher]

If your original battery is only a year old - you should be fine adding another...if it was 2-3 years old, then I'd consider replacing the original...more than 3 years old, definitely replace the original.

Yes, exact same model - don't want to mix batteries when they're connected together either in series or parallel.

If you can afford the lithium - go for it. Remember that lead-acid batteries (Gel-cells and AGMs included) should only be drawn down to 50% to maximize lifespan - lithiums on the other hand have no issues being drawn down to 15%-20%.

So that single lithium will give you more time on the water between charges than the two lead-acids...also you'd need to recharge the lead-acids to max after every trip out...the lithiums are again more forgiving, so if you can get 2-3 trips from a single charge the lithium won't care.

 

[marlattrr]

https://www.amazon.com/DJLBERMPW-Lithium-phosphate-rechargeable-suitable/dp/B09JNTF2NB

Any thoughts on this battery?

 

[MN Fisher]

https://www.amazon.com/DJLBERMPW-Lithium-phosphate-rechargeable-suitable/dp/B09JNTF2NB

Any thoughts on this battery?

It looks about the same as others - most of the 'inexpensive' LiFePo batteries are all made in the same factories in China...they just get different labels slapped on them.

Don't forget a charger rated for 24v Lithium batteries.

 

[Butthead]

My only concern with buying a battery off Amazon is if it sh*ts the bed in two years, are you going to be able to get it replaced?
I feel like most of these generic brands are here and gone quickly. Same businesses, but they just keep changing names to not have to bother with warranty concerns or negative reviews.

 

[marlattrr]

Thats definitely a possibility with chinese amazon junk. I read that the chinese batteries dont have the low temp cutoff for charging below 32F. If you charge below 32F it ruins your battery. It looks like you can discharge down to -20 though

 

[MN Fisher]

Thats definitely a possibility with chinese amazon junk. I read that the chinese batteries dont have the low temp cutoff for charging below 32F. If you charge below 32F it ruins your battery. It looks like you can discharge down to -20 though

Unless you're willing to pay the up-charge for Battle Born or Braille batteries - every other Lithium is made in China.
Of course, those two are basically only assembled in America (Arizona and Florida respectively), but parts are from elsewhere.

Good batteries + good price + been around a while = Mighty Max.

 

[poorthang]

a fire in a boat is always a bad day. you might consider a lifepo battery fire that cant be extinguished and then think where said battery was built........

 

[marlattrr]

I've been looking into these and saw some battery experts on Youtube take them apart and according to them they are surprisingly well made. They do have over temp cut-off built into the internal BMS but do not have under temp charging cut off.

Most people that have issues with them charged them under 32F.

I think I'm going to give it a shot.

 

[CRS]

I just bought a 48 volt from Dakota Lithium, it cost less than 4 12's and less weight.

 

[InSaneFisherMan]

Yes to your first question and maybe to the second.

If you insure your boat, check to see if your insurance will cover it if lithium batteries are installed. The boating industry generally does not consider lithium a drop in replacement for lead acid batteries.

TE-13 is the boating recommendation for lithium and will probably become the requirement.

If considering a lithium battery, you should ask if it meets TE-13.

 

[poorthang]

Yes to your first question and maybe to the second.

If you insure your boat, check to see if your insurance will cover it if lithium batteries are installed. The boating industry generally does not consider lithium a drop in replacement for lead acid batteries.

TE-13 is the boating recommendation for lithium and will probably become the requirement.

If considering a lithium battery, you should ask if it meets TE-13.

great info! never heard about that standard before. thanks for that.

 

[JNG]

a fire in a boat is always a bad day. you might consider a lifepo battery fire that cant be extinguished and then think where said battery was built........

Well said.