Renogy batteries

[Moby Burton]

I guess you get what you pay for. I purchased 3 4D AGM batteries from Renogy. They were about 1/3 the cost of name brand batteries. Plus, I purchased the from Amazon so shipping was free. Picture Amazon delivering 3 - 130 pound batteries to my front door! Anyway there were two downsides to these batteries. First they were one inch wider than standard 4D batteries so I could only fit two of them in my battery box. More importantly, after less than 2 years, I am only getting about 50 AH out of each battery and they are rated at 200 AH each. Has anyone else had experience with Renogy AGM 4D batteries?

[Tin Tin]

Don't they have a 2 year warranty?

[Rockinar]

Good news is lithium is now cheaper than AGM.

[Moby Burton]

I did the math and you're right. I just have to figure out if I need to make any changes to go to lithium. At my age, it's difficult to lift half of a 4D AGM.

[Maine Sail]

Not surprising..This was a brand new Renege AGM. Even brand new it could only deliver any more than 72% of rating...

[pianopraze]

This guy tests batteries pretty well.

Breaks them open and examines them too:

https://www.youtube.com/@WillProwse

Here is an example video

https://www.youtube.com/watch?v=2kooJS3wZaA

[dan104]

Might also look at Clark on Temptress on youtube, he tears down and test batteries. And here is the key he has a system to manage LiPO4 & lead together so you can Easly start using Lithium without risk of blowing alternator or burning up things. I have had his system on my boat for over a year and it works well. I have 400ah of Lithium and 400ah of AGM.

here is the link https://www.youtube.com/@EmilyAndClark

[Moby Burton]

Thanks for the info. I'm not sure why but I'm thinking of keeping the AGM for the starting battery and buying 2 100 AH Lithium batteries for the house bank. Do you see a problem with that concept or should I just go for a 4th lithium battery for a starting battery.

[Pandor]

Originally Posted by Moby Burton

Thanks for the info. I'm not sure why but I'm thinking of keeping the AGM for the starting battery and buying 2 100 AH Lithium batteries for the house bank. Do you see a problem with that concept or should I just go for a 4th lithium battery for a starting battery.

I’m one of those that can’t believe people are still buying lead batteries to replace the house bank give the benefits of LFP and now the cost that seems to beat LA and surely does AGM.

However, lead batteries are great for the starter. There really is no advantage in LFP for starters except some simplicity in charging only one battery type.

[Moby Burton]

Well some of us are set in our ways. However, I am now a LFP convert. Thanks all for your input.

[dan104]

Actually the best layout for moving to lithium is house battery lithium, starter battery lead, maybe even a lead in house also.

The problem is the lithium will take every thing the alternator can throw at it, but then when it says I am full it just shuts off, leaving the alternator with no place to dump the power and it melts the diodes in it and is dead.

So if you still have lead in the system it will start trying to charge,even if full. Thant saves th alternator.

I am using Clark’s. BBM ( battery Bank management) it disconnects the lithium bank when it reaches the correct voltage and avoids what is called the hockey stick problem.

When lithium reaches its correct voltages if the onboard BMS doesn’t stop talking a charge the cells go overloaded quickly and. That’s the end of the battery.

Again, look at the videos on Clark and Emily’s adventures. Clark is a retired electrical engineer who has been dealing with the battery problems for couple years and gives great info. He also sells the bbm.

[lifeofreilly57]

Originally Posted by dan104

Actually the best layout for moving to lithium is house battery lithium, starter battery lead, maybe even a lead in house also.

The problem is the lithium will take every thing the alternator can throw at it, but then when it says I am full it just shuts off, leaving the alternator with no place to dump the power and it melts the diodes in it and is dead.

So if you still have lead in the system it will start trying to charge,even if full. Thant saves th alternator.

I am using Clark’s. BBM ( battery Bank management) it disconnects the lithium bank when it reaches the correct voltage and avoids what is called the hockey stick problem.

When lithium reaches its correct voltages if the onboard BMS doesn’t stop talking a charge the cells go overloaded quickly and. That’s the end of the battery.

Again, look at the videos on Clark and Emily’s adventures. Clark is a retired electrical engineer who has been dealing with the battery problems for couple years and gives great info. He also sells the bbm.

When I switched to lithium I used the alternator controller to change the output curve on my 200 amp alternator, it charges at a lower rate but I haven't had any issue with it. There are several ways to avoid tis issue.

[Moby Burton]

I live in Rochester NY. The boat is stored in an unheated shed with intermittent charging. So I'm thinking of keeping my AGM starting battery and buying 3 100AH LFPs which I assume I will have to remove every fall.
I have a new Xantrex inverter / charger with a lithium setting and a new Balmar MC 618 external voltage regulator on a 120 amp alternator. The alternator feeds the starting battery and the house is charged off that circuit through an isolator relay. Will I need an additional BMS to keep the lithium batteries alive?

[Sailshabby]

Originally Posted by Moby Burton

I live in Rochester NY. The boat is stored in an unheated shed with intermittent charging. So I'm thinking of keeping my AGM starting battery and buying 3 100AH LFPs which I assume I will have to remove every fall.
I have a new Xantrex inverter / charger with a lithium setting and a new Balmar MC 618 external voltage regulator on a 120 amp alternator. The alternator feeds the starting battery and the house is charged off that circuit through an isolator relay. Will I need an additional BMS to keep the lithium batteries alive?

Don’t some LFPs come with heaters built in?