Originally Posted by WoobaGooba
The boat is a mid 80's Cal. Original electrical. Dual group 27s with the classic 12B0 sw wired as both a USE and CHARGE (alternator) selector. I want to fuse the batteries, add a proper solar controller, one thing leads to another ... you know this goes.
I have read up on all the good info MaineSail, Stu Jackson, s/v Smitty and several of you all have provided. Find attached a JPG of my plan.
- the existing AWG 2 (to the 12BO sw) seems undersized? Proper size?
- is the ACR wired and fused correctly? Must it be fused on both sides? Can I loose the fuse on the left?
- should the solar panel be fused?
- anything else look out or order?
Thanks a bunch
2Ga is better than 4GA and you should be fine. Your starter will experience more VD than with 1/0 but should do okay just be sure all connections are clean and tight..
As for the ACR simply bump the leads to 2GA and use the main battery fuses. This saves you money over buying two additional fuses and holders. These fuses are to protect the wire NOT the ACR so if you are using the same size wire as the main bank then you can use the same fuse too.
If wiring the ACR with solar I recommend using the SI (start isolation) feature and I don't see that shown...
Depending upon the run your solar wire is likely too small for top perforamnce. 16GA should not be used and 14GA is usually the bare minimum we use but for the panel to the GV I'd shoot for 10GA and controller to bank I'd shoot for 10GA as well.
Your group 27 batteries are not 180Ah. They have a "Reserve Capacity" or RC of 180 minutes at 25A before they are at 10.5V... Reserve capacity and ampere hours are NOT one in the same. There is simply no such thing as a 180Ah group 27 battery. If you did your calcs on 180Ah you will need to re-run them, if you can find out the actual 20 hour Ah capacity..
A general rule, when buying deep cycle batteries, is to NOT buy batteries that do not publish a 20 hour AH capacity.
Your batteries are likely under 100Ah's each, most group 27's are in the 80-100Ah range.. Having tried to get this information out of Interstate in the past has resulted in multiple answers from multiple tech support folks NONE of their answers agreeing with one another. I have had them tell me 125Ah's, 90Ah's and 100Ah's all for the same SRM-27 battery.....