Post by em on Jun 9, 2023 20:01:32 GMT 12
Where do I start?
Firstly @cantab, I owe you a bottle of whisky (or what over poison you take). Which part of the country are you in? Using the multimeter in parallel to check for mA parasitic loads was exactly what we needed to do.
Today's objective was to go to the boat and confirm there we no electrical issues external to the batteries. And to confirm the current settings of our charge controllers, so as to confirm exactly what we need to do to install new batts and charge them properly.
Well, that went sideways:
60mA parasitic load with the main isolator off. 50mA is the screen for the battery monitor, but without it the battery monitor still blu-tooth's to my phone, so bye-bye screen
0.19A parasitic load with the isolators on, but no items turned on. That is about 5 Amphrs / day, and over 30 days easily enough to completely flatten and shag the house batts. Haven't been able to work out what that is, BUT
The Voltage Sensitive Relay is really fucking things up. There is a little float panel on the start batt. 25W. It appears that this can get the VSR to open (opens at 13.7v, closes at 12.8). When it is open the start battery float panel is charging the house batts (we installed my fathers new AGM's to do all this testing).
But when the sun goes off the panel, the house batts start charging the start batt, like, WTF?!?!
Then, the start batt couldn't start the engine. It was at about 13v, but possibly a surface charge from the solar with 1amp actual charging. Paralleled the house and start and got the engine going. Then the alternator regulator was saying the batt voltage it was monitoring was 11 something volts. Voltage sensing lead is on the house batts (as per instructions, put it on the largest batts, but I don't get why its not on the start batt). House batts were at 12.8 rested, and have been all week. So something is wrong for the regulator to be seeing 11 something.
Decided to bring the start batt home for a proper charge and a once over. Extracted it from where it lives, then accidentally left it on the boat and went home. Fuck it.
At any rate, we will be able to get a resting voltage on it, as we only ever check its voltage when the little float panel has been giving it some ergs.
I think that is all the issues we found, oh, accept the alternator went to 15 something volts for a bit, when it was only supposed to go to 14.8
On the old batts, I found a US based spec sheet. They are US batteries US2200. Some of the charging requirements are different to the NZ based Hella Endurant charging requirements. There is a requirement for the charge current to be max 0.1C, which equates to 23amps. Our alternator can go to 51 amps which is about 0.2C, and I've seen it giving these batts 30 amps ish and when they were at 7v, it was giving them a thick 40 amps. Also the float charge is 13.0, where Hella Endurant said 13.5. This could explain some of the issues on short life with these batts, in addition to the clusterfuck of parasitic loads. The 60mA with the isolators off is the batt monitor, and we only installed that recently (late summer?). But clearly there are major issues when I leave the isolator switch on by accident. We are going to install a relay that will isolate the house batt on low voltage. The new batt monitor can do all of that, it will be like a DIY BMS.
But the good news is, the supplier of the new house batts I like the most have 10% off at the moment. I asked them for a checky discount (about 4%, based on buying 3 batts for the discount price based on buying 5 batts) they came back and said they are running a 10% offer via the motor caravan association, of which my father is a member. SO I can get 300Ahrs of lead carbon batts for $840, 2 yr warranty. They might not be that great compared to top shelf lead carbon or lithium, but they are basically AGM batts, and at that price are the same or cheaper price point that standard AGM's.
Lucky they have 10% off, as I may be needing a new start batt, and possibly a full re-wire...
The Balmar smart regulator and the VSR are maybe 20 years old, so we wont be surprised if some hardware item has shat itself. We are also starting on a full disassemble, clean, check and reassemble of the entire heavy duty electrical side, and a similar process for the distribution wiring. Like I sad, bloody farken boats.
Possibly need block diodes to stop the house batt back-feeding to the start, but we will park that until we've confirm the VSR is working properly and doesn't need replacing with something fancy, like a MOSFET battery isolator, or even a DC-DC charger (which would allow me to chuck on lithiums easy peasey)
So today was productive in terms of determining the extent of the issues, but frustrating that we found so many issues. All whilst thinking we knew what we were doing and thinking we look after our boat well. Fuckit.
