question

Paul T avatar image
Paul T asked

Battery Protect not engaging under load? Causes high voltage condition.

Using the BP-100 as a dual battery isolator between cranking/starting and aux batteries. Identical make/model of batteries used. Isolate 12.0V engage 13.0V. Setting 8A.


Issue as follows;

Using 100-140Amp alternators in Toyota's and VW's we found the following;


- if the vehicle is cranked over under 12.0V when the batteries are isolated and left at idle the BP-100 links them back without issue (as the alternator output current is typically 60 ~ 80Amps).


- if the vehicle is cranked over under 12.0V and immediately taken for a drive which pushes the alternator output to near max power output (80 ~ 140Amp), the BP-100 won’t engage and causes the alternator to output erratic voltages upwards of 14-16V which can trigger the vehicles ECU to go into limp mode.

Can Victron replicate the same issue and potentially a firmware update should solve it as I don’t believe it’s a hardware limitation as the BP-100 can handle a 600Amp peak? The BP-100’s should do it with ease.

Battery Protect
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Paul B avatar image Paul B commented ·

Could you please provide a wiring diagram of how this BP is installed.



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Paul T avatar image Paul T commented ·

does anyone have the email address for Victron tech support? It does seems like these forums are no even looked at by tech support?

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wkirby avatar image wkirby ♦♦ commented ·

I wouldn't be surprised if the battery protect is sensing a false short circuit condition. The first paragraph of the manual highlights how to avoid this.

I'm a bit curious as to why you are using a Battery Protect for the purpose of combining batteries? It is not designed for this purpose. More importantly, the Battery Protect is not designed for reverse currents from charging sources. This condition would occur when cranking, the start battery would be at a lower Voltage than the accessory battery.

There are an assortment of Victron battery combiner products available which are much more suited to your task.

https://www.victronenergy.com/battery-isolators-and-combiners

Ask your dealer why he advised you to use a Battery Protect for your application rather than one of the Combiner products.

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1 Answer
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi Paul,

For combining batteries there are battery combiners and isolators, only the cyrix has a standby current

https://www.victronenergy.com/battery-isolators-and-combiners


For protecting batteries against deep discharge there are the Battery Protect products, these only work one way (protecting against deep discharge)

https://www.victronenergy.com/battery_protect

nowhere in the manuals it says it can be used to combine two batteries.

But it doesnt say it the other way around either: we’ll add this to the manual.

I hope you get it sorted soon. And sorry to hear you ended up using the wrong product.

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