Originally Posted by campr
I've been using my LiYPO4 for a year now, could not be happier. Have a 4s3p setup with 200Ah cells 5.7kWh capacity usable. I have also finally found a solution to charging
from the engine: https://www.victronenergy.com/dc-dc-...verter-25a-50a
It switches on a buck-converter when the engine switches on. It converts the starter battery circuit (and alternator) to a fixed-voltage (programmable) voltage source.
Hoping to install the new device on the boat soon (it's a money
After writing all this I notice that this is a VERY old thread. Still pertinent but the poll
results I am sure not very reliable since the last vote was 2013. I see that SV Third Day voted against Li for the poll but we all know he has missionary zeal in favor of Li today.
Good to hear that you are a happy camper with your LiYPO4 battery to date.
One issue I (and some others) are dealing with now is charging the starter battery, with most seeming to recommend using a dc-dc converter such as an Echo Charger
, Sterling, or Duo Charge, and now the Victron one. It is quite a bit more expensive but also more programmable. It seems to be able to change the dc input undervoltage cutoff point. The brochure implies the undervoltage cutoff is set but the manual shows it as programmable but does not give any info as to specifically how (sensitivity or value ranges acceptable). The manual shows 10v in the sample screen
(updated via computer USB).
The issue of using a dc-to-dc converter is when it is charged by the lithium house bank and not limited by engine ignition on, although that is an option. Most posts seem to just install the converters with auto function or a manual switch. But they also have undervoltage cutoff at 13.0v which is not suitable for direct connection to the lithium batteries as they are always at 13.0+ at normal PSOC so the converters are always on even without a charging source on. (That is the issue as I understand it but I may be missing some nuance or other reason entirely.)
A workaround proposed is a manual cutoff switch. This causes a possibility of human error when the switch is not cutoff when needed and when to turn it on and for how long, etc. If you only turn it on with the engine on and with an engine alternator
on then it would only turn on the converter with a charge source on the lithium bank. That might be a good solution that also means the starter battery would not be charged by solar
or other means even though they are on. Just turning it on with the engine running would be a good solution as that is when you will have used the start battery and taken some capacity away from it.
If the Victron buck boost is programmable to a suitable undervoltage cutoff you could keep it powered by the lithium bank regardless of engine ignition on so long as it could be programmed to a suitable lithium PSOC voltage (i.e. settable and sensitive to at least 100mV or less), e.g. 13.6v or something.
The Victron gear
is not inexpensive though. I just saw a price
of $560US for the 25A version and $700 for the 50A version (discounted US retailer).
Any comments or critiques from the usual suspects?