My house bank is coming up on 5 years and is showing signs of poor performance. I’ve been evaluating LiFP04 batteries and found two issues causing me to hesitate. Hoping someone who has done the conversion can address the following:
I’ve read the charging voltage must be in the range of 14.2-14.6. That’s ok for my Westerbeke alternator and solar charge controller but my original, low tech Professional Mariner AC charger has a finishing voltage of only 13.8V. I take it I must replace it to go to LFP batteries? That would add another $500 to the conversion.
I’ve read the LiFP04 fast charging characteristic can pull too much current from an alternator causing it to overheat and fail. I’d really like to avoid any risk to my 37 year old engine.
To those who have transitioned to LiFP04, did you find these concerns valid? If so, how did you address them?
Thanks,
George Berntsen
Wave Dancer, 30U #283
Black Rock Harbor, CT
Clark has developed a battery management system that will allow hybrid bank with AGM and lithium.
BBMS will allow best charging practices for both technologies and probably make both last longer.
He has bunch of YouTube explaining the system.
I bought two. One for independent 24 v inverter system for dome greenhouse and our newly purchased Nonsuch 30U. I haven’t installed them but I see no reason why it won’t work.
Lots U tube stuff out there some of it very sketchy. If it was me I’d get a externally regulated alternator to stat with. Victron sell the kit to deal with charging different battery chemistry , called a DC to DC charger. No doubt there will be a need to review wire size etc etc…
If you are looking for some very complete boat electrical presentations check this utube channel out.
I have also been researching this and have procured all the parts but have not yet made the conversion - did something similar with a camper a couple of years ago and have been very happy with its performance.
I settled on the following design based on some of the links above:
only use the alternator to directly charge the regular Pb starter battery. When running the engine I want the starter to take precedence and I also concluded that a standard alternator will quickly burnout charging Lithium since they can take such high charging current.
use a DC to DC converter to charge the LiFePO4 house from the Pb starter battery, this limits max current and prevents the starter battery becoming discharged completely. Given point #1 above, when running the engine with a full or almost full starter battery, the DC-DC charger will directly charge the LiFePO4 house, protecting the alternator. In my system this replaces an ACR charge combiner.
the shore power charger I already had supported a LiFePO4 profile so I use that when at the dock to maintain the house batteries.
also have small solar setup that keeps starter battery trickle charged and a manual combine option on the two banks should I require an emergency starter option.
This approach seemed the simplest and the only ‘new’ piece of kit over the old system was the DC-DC charger which replaced the ACR so I don’t feel like this is any more complex than the tried and tested configuration I had before.
See what you think of this diagram. Suggestions/improvements welcome.
I have everything going to the house and the DC/DC charger going back to the starter battery. Most of the components are scalable to larger or smaller depending on your needs.
I think Jim’s approach is very similar to the approach I will be taking to installing lithium. As someone said, a lot of advice on the web. Some years ago I purchased solar panels from Tom Trimmer at Custom Marine Products, he has a very good video on lithium and I found him to be very helpful and knowledgeable. One thing he mentioned is that the AC battery charger, most, can be re-programmed, my xantrex has a custom feature allowing this (even though lithium is not labelled it can be used). Another device that should be considered for safety is the Sterling Alternator protection device and finally replacing the fuses (don’t have the class handy) that are specific to lithium batteries might be a consideration.
Another resource to consider is a website called Lithium Solar, he dissects the batteries to see whether or not the BMS works as claimed, the cells are at the grade specified etc. The choice of which battery can overtake a lot of your personal time, but if you settle on a battery maybe a quick check on this site to see whether he has dissected the battery may help.
